The DoMeBo Photography Class - Side Conversations (Non-Students Welcome)

[garygnu]

I’m setting up this thread for random photography Q&A, reviews of cameras, posting of resources, and similar stuff. Questions posted in lesson threads will still be answered. This is mostly for very-off-topic subjects.

This is also a good place for posters not taking the class to ask individual questions.

Since I’m here, I’ll announce that I will be changing the class order. Without renumbering them we’ll go:
Lesson #3. “How Big and How Fast?” - Exposure, aperture and shutter speed
Lesson #4. “Picture Framing” - Composing your photographs
Lesson #2. “A Photographic History” - The history of photography

From the first lesson, it’s clear we should get to #3 and #4 sooner rather than later.

[lobotomyboy63]

As I posted over in other threads, I'd like to know more about composition.

The other things I'd like to know involve the correspondence (and lack thereof) between film (35mm) and digital. For instance:

1) Image size, compression...it would seem like you can make a huge image with low compression ---or--- a small image with high compression and end up with basically the same thing when you make a 4x6 print of it. I gather it's more complicated than that, however. Is it in fact that the sensor is teeny and the camera is extrapolating the information, which introduces error?

2) How does depth of field compare with 35mm? Say you take a photo on 35mm with a 28mm lens, then make the equivalent on a P/S (same aperture, shutter speed, equivalent focal length, ISO). Will the zone of focus be the same?

I'm amazed that my Canon can focus down to 1 cm and the Olympus can focus down to 2 inches, maybe less. There must be inherent strengths and weaknesses to the format and/or medium that I don't understand. It would be interesting to hear what some DSLR users have to say, i.e. in what ways they're like 35mm SLRs and in what ways they're like P/S digitals. Are the sensors the same size, for instance?

[NAF1138]

Posting mostly to subscribe. I am following along with the first lesson, but probably won't be able to post since our regular digital camera seems to be awol, having not been seen since we came home from our last vacation. So now I actually have to buy a new one. (As opposed to just wanting to buy a new one).

I have found a couple of camara's that I want, so it's a matter of making sure that we can afford the purchase. I am thinking of getting a point and shoot superzoom. Sort of splitting the difference between a regular point and shoot and an SLR.

[garygnu]

1) Image size, compression...it would seem like you can make a huge image with low compression ---or--- a small image with high compression and end up with basically the same thing when you make a 4x6 print of it. I gather it's more complicated than that, however. Is it in fact that the sensor is teeny and the camera is extrapolating the information, which introduces error?

1) Compression is how much the file is shrunk using complicated algorithms. JPEG, for instance, can be set to very compressed, making them look horrid, or not very compressed. This is a separate issue from pixel dimensions. Setting a lower-than-maximum pixel dimension in the camera’s menu will reduce the size of the pictures.
However, there’s pixel dimensions and printed dimensions. The relationship between the two is dictated by the resolution, measured in pixels per square inch. The lowest resolution you can print at and still have decent looking image quality is 150p/in. I like to keep it at 300, because that’s a normal printer’s resolution anyway.
A 7 megapixel image I just puled up for comparison (2304x3072) could be over 7x10 inches at 300p/in. or 15x20 inches at 150p/in.

2) How does depth of field compare with 35mm? Say you take a photo on 35mm with a 28mm lens, then make the equivalent on a P/S (same aperture, shutter speed, equivalent focal length, ISO). Will the zone of focus be the same?

Depth of field is generally not as tight. That is, more things will be in focus because the sensor is smaller. If you want more in focus, this is a god thing. You can still get good and tight focus, though, so it’s not such a big deal like digital video.

[Cyberhwk]

Oh GOOD! I was just thinking of making a post but wasn't sure whether to put it in the original thread or the lesson thread.

I'm still looking for a new camera and I think I've narrowed it down (a little bit). Doesn't sound like Canons usually have manual exposure modes unless you want to get into their DSLR lines. Panasonic Lumix seems to have a couple that have these modes.

Panasonic Lumix DMC-FX500

Panasonic Lumix DMC-FX150

Panasonic Lumix DMC-FX580

Fujifilm FinePix F60fd

Nikon Coolpix S710

OK. I believe all of these have both Aperture and Shutter Priority modes on them. I still have a couple of questions for those with DSLRs though...

Do you own both? A PnS and a DSLR? How do you use your PnS as opposed to the SLR?

My main thing, as I mentioned in the previous SDMB thread was that I'm wanting something SMALL to take on vacation. I like photography but I'm not quite to the point I want to dedicate my entire vacation to hauling a DSLR around England waiting for decent photo opportunities to arise. So for my Point-and-Shoot I'm looking for something compact first and foremost. Decent quality pictures and exposure options also.

One of my main sticking points is that I'm wondering if I want to get an entry level DSLR later down the road. And if I do, do I really need the Aperture and Shutter Priority functions on my PnS? Or will getting used to the functions of a DSLR only make those functions that much more necessary on my PnS?

[garygnu]

...
Do you own both? A PnS and a DSLR? How do you use your PnS as opposed to the SLR?

My main thing, as I mentioned in the previous SDMB thread was that I'm wanting something SMALL to take on vacation. I like photography but I'm not quite to the point I want to dedicate my entire vacation to hauling a DSLR around England waiting for decent photo opportunities to arise. So for my Point-and-Shoot I'm looking for something compact first and foremost. Decent quality pictures and exposure options also.

One of my main sticking points is that I'm wondering if I want to get an entry level DSLR later down the road. And if I do, do I really need the Aperture and Shutter Priority functions on my PnS? Or will getting used to the functions of a DSLR only make those functions that much more necessary on my PnS?

Technically I own both a PnS and a DSLR. I haven’t seen my PnS Canon in months, though.
Lugging around a DSLR is a chore, and we decided not to take it on our cruise a few years ago and I didn’t miss it. Having a pocket-sized camera is just plain convenient.
I distinguish them by using my PnS for taking pictures and my DSLR for “photography.”

Having aperture priority is nice. Nicer cameras will have it whether you want it or not, so if you’re looking at a nicer PnS anyway, it’s already there.

[Cyberhwk]

Well so far I've been looking at the nicer PnS specifically BECAUSE of the Aperture priority modes (which I haven't seen a compact Canon that has it yet). If it's not important I'd start looking for a different one (and maybe save some money). I've also considered getting a special function PnS like this one that takes underwater photos. Figure that was it'd always have a use and could do something that a DSLR, should I get one eventually, couldn't, but then I don't know when I'd EVER have the occasional to take underwater photos. So why would I pay for that feature (though I like the idea of everything being internal).

[NAF1138]

Since we are posting links to camera's that we are looking at this Cannon SX10 IS is what I would really like to get if I could afford it right now. I might be able to, but I would need to save up for a little while longer. As it is, the SX110 which is almost as nice might be what I end up with.

[sistercoyote]

By the way, for anyone else that's using flickr, I've started using a DoMeBo tag for any pictures I take "during class," as it were. It might be kind of fun for all of us to use a domebo tag, so we can see everyone's pictures in a group as things go on.

Or maybe it's just me.

[garygnu]

Any Powershot with a model number starting with “SD” or “SX” will have what they call “Camera M” mode, which means manual. I rarely used that mode because I do have a Digital Rebel SLR.
If you’re serious about the DSLR, you may not need it. The different auto shooting modes can give a decent approximation, too, if you know what they mean.

That Lumix looks nice a pretty nice camera. I’d probably consider the Canon D10, too, which is similar. It goes down to 10 meters, which would be nice because I scuba dive. Neither is out yet.

[lobotomyboy63]

@gary:

WRT image size/compression, so what would you counsel for a p/s? I have it set to making 4Mb images and fine compression. I'd like the sharpest pics and I have a 2 Gb card. After making images, I transfer them to computer and delete them from the camera, so space on the camera isn't an issue.

WRT depth of field, so f/8 might confer depth of field more like f/11 or f/16 on an equivalent focal length lens/traditional 35mm SLR?

@Cyberhwk:

WRT manual exposure mode: My Canon A720IS, a P/S, has manual exposure mode. I got it for $200 in Dec 07 but I think it may have been discontinued, probably been upgraded.

WRT cameras: If I had it to do all over again, I'd take a good look at those Panasonics. FWIW you can check cnet.com as one resource for camera reviews. Often they have both the editors' ratings as well as user ratings, and sometimes they have video clips talking about the cameras etc. as well.

@Anybody looking to buy a camera:

http://en.wikipedia.org/wiki/Digital_si ... iderations

Look at the right side, which shows image sensor sizes. Geez, 25 sq mm is the smallest...a 35mm negative is 864 square mm!

1/2.5" is not as good as 1/1.8" in terms of the sensor size. That might be another bit of data to look for as you shop.

Here's a chart I found that includes my Canon:

http://en.wikipedia.org/wiki/Canon_PowerShot_A720_IS

The idea with film was that the bigger the negative, the better the finished product was likely to be. I'll assume that the same is true for digital sensors. I read that they make "medium format" (like for Hasselblad, Mamiya, etc.) that are quite large but the cameras end up costing like $20,000.

[Dragon]

Why is RAW cleaner and sharper and have better colors before any reworking?

Fuiji 6000 fd....
In RAW mode, all else the same...
RAW = 13,366 KB & is 1600 X 1200 Pixels.

Same picture in JPG 6Mfine ...(Highest I can go)
JPG = 02,848 KB & is 2848 X 2136

My monitor is 20" LCD at 1024 X 768....

On this camera I have gone to almost all pictures in RAW... Your opinion on that?

[Cyberhwk]

Any Powershot with a model number starting with “SD” or “SX” will have what they call “Camera M” mode, which means manual. I rarely used that mode because I do have a Digital Rebel SLR.

Actually, I don't think this is the case. This CNET review of the Canon Powershot SD780 specifically states "no manual exposure controls." I've been looking a lot at the Canons since I've noticed most of the reviews said they take great pictures, but it's often very hard to track down whether they have manual controls or not.

Then this says the Canon 880IS DOES have Manual controls. Hmmmmmmmmmm. Wonder if the CNET review is mistaken or if it's just that model. (Says nothing regarding manual controls in the Exposure Control Method in the Canon 890IS).

WRT cameras: If I had it to do all over again, I'd take a good look at those Panasonics. FWIW you can check cnet.com as one resource for camera reviews. Often they have both the editors' ratings as well as user ratings, and sometimes they have video clips talking about the cameras etc. as well.

I DO really like the Panasonics. I thought the Canon SD line was completely without the controls so I guess I gotta go back and look at those now. I want my list to get SMALLER, not bigger! :twisted:

[lobotomyboy63]

Why is RAW cleaner and sharper and have better colors before any reworking?

Fuiji 6000 fd....
In RAW mode, all else the same...
RAW = 13,366 KB & is 1600 X 1200 Pixels.

Same picture in JPG 6Mfine ...(Highest I can go)
JPG = 02,848 KB & is 2848 X 2136

My monitor is 20" LCD at 1024 X 768....

On this camera I have gone to almost all pictures in RAW... Your opinion on that?

It's cramming about 4.5 times the info into 1/3 the space...sounds like a recipe for high quality. I'll be interested to see how others explain it b/c I don't have the RAW image option and this seems to go with my "image size/compression" question.

Do you have to wait a long time between shots, shooting RAW? Does your card fill up fast?

[Dragon]

Yes, long timke to store it but that makes sense because of the KB's.... Several seconds.

I have a 1 GIG card.... Checking.... 73 pictures at RAW and 341 at 6M fine (highest setting).

Also the only camera I have with RAW ability....

[lobotomyboy63]

It sounds like a great camera for certain applications. If you like photographing things that are posed or hold still, the wait time isn't a big deal. OTOH if you wanted to photograph a live sporting event with a lot of action, the wait would be unbearable and cost you some important shots.

The fact that you're able to toggle back and forth between RAW and JPEG is a great thing, though. Say you were taking pictures at a wedding: there would be shots of the flower girl, the ring bearer, the bride coming down the aisle in quick succession...JPEG. Then the formal portraits at the altar after the event...RAW. Then throwing the rice, driving away, the reception, etc.: JPEG.

Always tradeoffs, you know. If you found a camera that shot RAW and the delay was much better, maybe you'd need a second mortgage to afford it. Or maybe it would be so heavy you wouldn't want to carry it. Or maybe you would lose other features that your camera already has.

So enjoy what you have and exploit its strengths. I'm ignorant on this point: would a better card help? Don't some store images faster? Or maybe you already have the best available....

[Dragon]

Uses XD, SD are much faster cards.

No problem with the wait 99% of the time for what I use it for. Was just wondering why it was better quality, lack of going through an antilogarithm change? But if so, why are the JPG's so much larger in Pixel size VS the RAW?

Actually. in tests I did when I first got the little f-10, the pictures at the 3M pix setting were the best detail and clarity when enlarged of all settings available and it was #3 of 7 possible??????? It also worked out to about 1600 x 1200 pixels... ??? Hummmmm Both cameras are Fuji....

[don't call me shirley]

Uses XD, SD are much faster cards.

No problem with the wait 99% of the time for what I use it for. Was just wondering why it was better quality, lack of going through an antilogarithm change? But if so, why are the JPG's so much larger in Pixel size VS the RAW?

Actually. in tests I did when I first got the little f-10, the pictures at the 3M pix setting were the best detail and clarity when enlarged of all settings available and it was #3 of 7 possible??????? It also worked out to about 1600 x 1200 pixels... ??? Hummmmm Both cameras are Fuji....

RAW doesn't compress the image at all. The value for every single pixel is saved. I'm guessing that your camera doesn't allow higher resolution pictures to be saved as RAW because of the enormous amount of memory that would be used.

[don't call me shirley]

Any Powershot with a model number starting with “SD” or “SX” will have what they call “Camera M” mode, which means manual. I rarely used that mode because I do have a Digital Rebel SLR.

Actually, I don't think this is the case. This CNET review of the Canon Powershot SD780 specifically states "no manual exposure controls." I've been looking a lot at the Canons since I've noticed most of the reviews said they take great pictures, but it's often very hard to track down whether they have manual controls or not.

Then this says the Canon 880IS DOES have Manual controls. Hmmmmmmmmmm. Wonder if the CNET review is mistaken or if it's just that model. (Says nothing regarding manual controls in the Exposure Control Method in the Canon 890IS).

WRT cameras: If I had it to do all over again, I'd take a good look at those Panasonics. FWIW you can check cnet.com as one resource for camera reviews. Often they have both the editors' ratings as well as user ratings, and sometimes they have video clips talking about the cameras etc. as well.

I DO really like the Panasonics. I thought the Canon SD line was completely without the controls so I guess I gotta go back and look at those now. I want my list to get SMALLER, not bigger! :twisted:

I have a Canon SX110. I'd be happy to answer any questions you have.

[lobotomyboy63]

RAW doesn't compress the image at all. The value for every single pixel is saved. I'm guessing that your camera doesn't allow higher resolution pictures to be saved as RAW because of the enormous amount of memory that would be used.

So when you make a jpeg, what does it save? What does compression do? I've used zip files, mp3s, and I don't really know what it means in those cases either.

[don't call me shirley]

Oh GOOD! I was just thinking of making a post but wasn't sure whether to put it in the original thread or the lesson thread.

I'm still looking for a new camera and I think I've narrowed it down (a little bit). Doesn't sound like Canons usually have manual exposure modes unless you want to get into their DSLR lines. Panasonic Lumix seems to have a couple that have these modes.

Panasonic Lumix DMC-FX500

Panasonic Lumix DMC-FX150

Panasonic Lumix DMC-FX580

Fujifilm FinePix F60fd

Nikon Coolpix S710

OK. I believe all of these have both Aperture and Shutter Priority modes on them. I still have a couple of questions for those with DSLRs though...

Do you own both? A PnS and a DSLR? How do you use your PnS as opposed to the SLR?

My main thing, as I mentioned in the previous SDMB thread was that I'm wanting something SMALL to take on vacation. I like photography but I'm not quite to the point I want to dedicate my entire vacation to hauling a DSLR around England waiting for decent photo opportunities to arise. So for my Point-and-Shoot I'm looking for something compact first and foremost. Decent quality pictures and exposure options also.

One of my main sticking points is that I'm wondering if I want to get an entry level DSLR later down the road. And if I do, do I really need the Aperture and Shutter Priority functions on my PnS? Or will getting used to the functions of a DSLR only make those functions that much more necessary on my PnS?

Hey cyberhwk-
I've had two different Nikon PnS cameras, and I've hated both of them. They could NOT focus in anything approaching low light. Anytime I was indoors, unless the sun was shining brightly and there were a lot of windows, those things would not focus. Even with a couple of bright lamps on. I can't tell you how many times I had a really cute shot lined up, only to see that goddamn flashing red light which meant it couldn't focus.

I recommend something with an autofocus light.

[don't call me shirley]

RAW doesn't compress the image at all. The value for every single pixel is saved. I'm guessing that your camera doesn't allow higher resolution pictures to be saved as RAW because of the enormous amount of memory that would be used.

So when you make a jpeg, what does it save? What does compression do? I've used zip files, mp3s, and I don't really know what it means in those cases either.

jpeg breaks the image up into little squares. It then analyzes each square to see if the whole thing is uniform. So say you're wearing a solid color shirt. It looks at a square of pixels of your shirt and sees that they're all roughly the same color. So rather than saving each pixel individually, it just saves that all the pixels in that square are the same color. If you're wearing a Hawaiian shirt, it won't be able to do that and it will save in more detail to preserve the image. That's why jpegs of the same resolution can vary so widely in size- it depends on how much detail it needed to save. All RAW images, I believe, will be the same size in kb. If you take a picture of a blank piece of paper, the jpeg file would be tiny, because all it would have to store is the fact that all the pixels are the same. The RAW image, however, would still store every single pixel just like with any other picture.

[lobotomyboy63]

[quote=don't call me shirley]

RAW doesn't compress the image at all. The value for every single pixel is saved. I'm guessing that your camera doesn't allow higher resolution pictures to be saved as RAW because of the enormous amount of memory that would be used.

So when you make a jpeg, what does it save? What does compression do? I've used zip files, mp3s, and I don't really know what it means in those cases either.

jpeg breaks the image up into little squares. It then analyzes each square to see if the whole thing is uniform. So say you're wearing a solid color shirt. It looks at a square of pixels of your shirt and sees that they're all roughly the same color. So rather than saving each pixel individually, it just saves that all the pixels in that square are the same color. If you're wearing a Hawaiian shirt, it won't be able to do that and it will save in more detail to preserve the image. That's why jpegs of the same resolution can vary so widely in size- it depends on how much detail it needed to save. All RAW images, I believe, will be the same size in kb. If you take a picture of a blank piece of paper, the jpeg file would be tiny, because all it would have to store is the fact that all the pixels are the same. The RAW image, however, would still store every single pixel just like with any other picture.[/quote:3i4htvni]

So if I set my compression to "fine" it's doing the same with smaller squares?

Saving bigger image sizes is going to take up more space on the card, right? What's the gain?

[Dragon]

So if I set my compression to "fine" it's doing the same with smaller squares?

Saving bigger image sizes is going to take up more space on the card, right? What's the gain?

Now this is what I want to know also.....

I know which camera settings for each camera I have that I THINK give the best results for what I do but....... I only have trial and error and a lot of time just shooting the same scene over and over and comparing on my monitor...

I don't do prints and very seldom make a wallpaper BMP picture, I mostly post in emails and albums for friends and family to see.... The wife uses a bigger screen resolution than I do so I figure anything that makes her scroll to see it all, then it's too big for normal folks to view... I also am very concerned about dial-up, older relatives so, that is in my mix also.....

What are the general rules of thumb and the trade offs? Or should I just stay with trial & error?

[don't call me shirley]

So if I set my compression to "fine" it's doing the same with smaller squares?

No, it always uses blocks of 8x8 pixels. The difference as you go from lower to higher compression is that variations in color and brightness over small areas are reduced further and further, and in cases of very high compression, eliminated. The eye is more sensitive to variations in color and brightness over large areas than small ones. This is a very broad generalization of what it's doing, the actual algorithms are much more complicated, and I don't understand them well enough to explain them. Wikipedia's article goes into pretty good detail if you're mathematically inclined.

Saving bigger image sizes is going to take up more space on the card, right? What's the gain?

With larger images you can make larger prints, like 8x10 or even higher. Also, I usually crop pictures before I print them- I take lots of pictures of kids in motion, so it's much easier to take the picture at a wider angle and then crop it down later. The larger the image file, the more I can crop out and still have a printable picture. Considering that I just bought an 8 gig SDHC card for under $10, storage space is not really a concern any more.

[don't call me shirley]

So if I set my compression to "fine" it's doing the same with smaller squares?

Saving bigger image sizes is going to take up more space on the card, right? What's the gain?

Now this is what I want to know also.....

I know which camera settings for each camera I have that I THINK give the best results for what I do but....... I only have trial and error and a lot of time just shooting the same scene over and over and comparing on my monitor...

I don't do prints and very seldom make a wallpaper BMP picture, I mostly post in emails and albums for friends and family to see.... The wife uses a bigger screen resolution than I do so I figure anything that makes her scroll to see it all, then it's too big for normal folks to view... I also am very concerned about dial-up, older relatives so, that is in my mix also.....

What are the general rules of thumb and the trade offs? Or should I just stay with trial & error?

My recommendation-
Take pictures at 5 megapixels or so. Get Picasa from Google and load all your pictures into that. Picasa has a pretty good email/web album feature. You just select the pictures you want to send/post, and click "email" or "publish." Picasa will automatically resize those images to pretty small files (it's adjustable, I have mine set to 1024x768, which will be about the same size as most computer monitors or a little smaller) and email or post them automatically. It's incredibly easy, like one click, fill in the email addresses, and hit send. All of the manipulation of the files is done for you. That way, if you do decide you want a print of something, you'll have the larger file that you can make a good print from available, but you won't have to do any work to send a smaller file to friends and family. If a relative really likes one of the pictures and wants a larger file to get a print of, you could then email them the larger file too. Like I said, storage space is really not an issue anymore. A 5 megapixel photo is going to be about 1 megabyte, so you could put 1,000 of those on a 1 gigabyte card, and 1 gigabyte cards are currently a couple dollars in clearance bins, if you can even find one. I just got an 8 gig card for under $10.

[Dragon]

Hummmmmm, Thanks

[lobotomyboy63]

My recommendation-
Take pictures at 5 megapixels or so. Get Picasa from Google and load all your pictures into that. Picasa has a pretty good email/web album feature. You just select the pictures you want to send/post, and click "email" or "publish." Picasa will automatically resize those images to pretty small files (it's adjustable, I have mine set to 1024x768, which will be about the same size as most computer monitors or a little smaller) and email or post them automatically. It's incredibly easy, like one click, fill in the email addresses, and hit send. All of the manipulation of the files is done for you. That way, if you do decide you want a print of something, you'll have the larger file that you can make a good print from available, but you won't have to do any work to send a smaller file to friends and family. If a relative really likes one of the pictures and wants a larger file to get a print of, you could then email them the larger file too. Like I said, storage space is really not an issue anymore. A 5 megapixel photo is going to be about 1 megabyte, so you could put 1,000 of those on a 1 gigabyte card, and 1 gigabyte cards are currently a couple dollars in clearance bins, if you can even find one. I just got an 8 gig card for under $10.

I have Picasa and like it quite a bit except that it doesn't provide a hotlink. I have another thread about that in here and one poster showed me a workaround. But hmm, seems easier to also upload to photobucket. That issue aside, yeah, it keeps your originals and exports them to whatever dimensions you like, which is great.

Like you, I'm not that concerned about file size WRT storage space. I regularly transfer to computer so my 2Gb card is more than adequate. However, as my Canon saves bigger files, the lag between shots can be annoying. Dragon is shooting RAW images that must take forever.

[Cyberhwk]

A quick DSLR question I'm hoping some of the more experienced photographers can answer. Is a reasonably affordable (read: amateur) DSLR capable of taking night time pictures of the sky like this:



Or are we talking a completely different level of equipment and investment to take photographs in that environment?

[lobotomyboy63]

A quick DSLR question I'm hoping some of the more experienced photographers can answer. Is a reasonably affordable (read: amateur) DSLR capable of taking night time pictures of the sky like this:



Or are we talking a completely different level of equipment and investment to take photographs in that environment?

The shot doesn't look that difficult to me...I wonder if it couldn't be done with a decent P/S, a few seconds of exposure (and of course a tripod).

Here's a longer exposure---you can tell by the length of the streaks:



Still, check with an actual owner of a DSLR. I could do it with my reasonably priced Minolta 35mm SLR. Image quality, i.e. how sharp it is and how contrasty, might be another issue for consideration.

[garygnu]

Be aware that star lines like that are tricky, if not impossible, with a digital camera.
With a film camera, you simply leave the shutter open however long you want it. With a digital camera, the image ship will eventually heat up too much and affect the picture. Usually this is a purple haze creeping in from the edges. You have to stitch together multiple short short line shots for anything that looks cool, and stitching is fraught with difficulties.

[lobotomyboy63]

Be aware that star lines like that are tricky, if not impossible, with a digital camera.
With a film camera, you simply leave the shutter open however long you want it. With a digital camera, the image ship will eventually heat up too much and affect the picture. Usually this is a purple haze creeping in from the edges. You have to stitch together multiple short short line shots for anything that looks cool, and stitching is fraught with difficulties.

My frame of reference is 35mm. The light enters the lens, bounces off a 45 degree mirror, up to a pentaprism where it's reoriented. When the photog trips the shutter, the mirror flips up, aperture closes down, shutter opens, [flash fires if set], film is exposed, shutter closes, aperture opens fully, mirror flips down.

I read something that said most DSLRs do something similar. The LCD screen shows what the photog took after the fact, not before, so he's using the optical finder. But what do P/S cameras do? There's an image on the LCD screen beforehand, so I figured the sensor was already working. Or are you saying that when you push the shutter release, the amt of electricity starts heating it up?

My Canon has speeds to 15 seconds. I realize that the streaked image I posted would take a lot longer than that, but I figured that you could shoot movies that last several minutes.
What happens with digital?

[garygnu]

...
I read something that said most DSLRs do something similar. The LCD screen shows what the photog took after the fact, not before, so he's using the optical finder. But what do P/S cameras do? There's an image on the LCD screen beforehand, so I figured the sensor was already working. Or are you saying that when you push the shutter release, the amt of electricity starts heating it up?

My Canon has speeds to 15 seconds. I realize that the streaked image I posted would take a lot longer than that, but I figured that you could shoot movies that last several minutes.
What happens with digital?

First off, for really good star trails we’re talking about exposure times measured in hours, or at least portions thereof, not seconds or minutes.
After a little bit of extra research, there are actually two problems. One is power. A film camera takes next to no power to just leave the shutter open. A digital camera is recording the image the whole time, with both the image chip and the processor chip sucking electricity. Most camera batteries won’t last more than 45 minutes or so without external power.

The purple haze appears to be caused by the image sensor’s light amplification function interpreting the heat caused by the camera functioning as light. This only happens in low-light conditions with long exposure times. Under normal conditions, the heat is negligible compared to the available light.

[lobotomyboy63]

...
I read something that said most DSLRs do something similar. The LCD screen shows what the photog took after the fact, not before, so he's using the optical finder. But what do P/S cameras do? There's an image on the LCD screen beforehand, so I figured the sensor was already working. Or are you saying that when you push the shutter release, the amt of electricity starts heating it up?

My Canon has speeds to 15 seconds. I realize that the streaked image I posted would take a lot longer than that, but I figured that you could shoot movies that last several minutes.
What happens with digital?

First off, for really good star trails we’re talking about exposure times measured in hours, or at least portions thereof, not seconds or minutes.
After a little bit of extra research, there are actually two problems. One is power. A film camera takes next to no power to just leave the shutter open. A digital camera is recording the image the whole time, with both the image chip and the processor chip sucking electricity. Most camera batteries won’t last more than 45 minutes or so without external power.

The purple haze appears to be caused by the image sensor’s light amplification function interpreting the heat caused by the camera functioning as light. This only happens in low-light conditions with long exposure times. Under normal conditions, the heat is negligible compared to the available light.

Right, Cyberhwk was asking about a simpler image, of course. I posted the trails to illustrate that his picture wasn't a super long exposure because the stars still look like points. OTOH that sort of picture might be the limit. Next weekend I'll be out in the country for a bit at night. Maybe I'll set up the tripod and see what I get at 15 seconds.

[Cyberhwk]

OK. So average DSLRs can reasonably do long exposures yet "star trails" are probably a no go with current technology. My plan is that I pay off my car in September. I plan on getting a new compact camera for my trip in July then a DSLR will be my reward for paying off my ride.

[lobotomyboy63]

OK. So average DSLRs can reasonably do long exposures yet "star trails" are probably a no go with current technology. My plan is that I pay off my car in September. I plan on getting a new compact camera for my trip in July then a DSLR will be my reward for paying off my ride.

I was poking around in Cnet and found this:

http://reviews.cnet.com/digital-cameras ... =mncol;lst

It will make exposures up to 8 minutes; most seem to stop at 30 seconds or 1 minute. 8 minutes would fall way short of star trails, but it will make RAW files. Body only, $400.

[McNutty]

Speaking in the context of mid-range lenses for DSLRs: I have heard the sentiment from photo nerds that the quality of the optics in a fixed lens is much better than those in a zoom lens in the same general price band (e.g. don't compare a mid-range fixed lens to a pro zoom). Photo instructors also love to say "the best zoom is your feet." These two things add up to the following advice: don't get a camera kit with a body and a zoom lens; just buy the body and a good quality fixed lens. My question is: how big a difference in quality are we talking about? Is there somewhere I can compare side-by-side images taken through various lenses to see the difference?

I'm considering buying a Canon Rebel soon, and I'm trying to decide whether to get the XSi and a fixed lens, or waiting a couple of months for the considerably-more-expensive T1i (which, among other goodies, has the ability to shoot video, which none of the other rebels do) as a kit and living with the zoom lens. I have a sneaking suspicion that the zoom that it comes with would pass my quality standards and be a little more versatile than a fixed lens to boot, but I'd like to know exactly what (if anything) I'd be sacrificing in quality. I know, the T1i is also 15megapixels, but pixels ain't everything; I'm specifically looking for info on how the lens will affect the images.

(for the curious, this is the lens I'm eyeballing.)

[lobotomyboy63]

I don't have a DSLR, McNutty, but some of my 35mm experience probably applies.

A big gain in using prime (non-zoom) lenses is in the largest aperture they can provide. In the case of the one to which you linked, f/1.4. Most zooms are f/2.8 at best, so you're two f/stops ahead in light gathering ability (i.e. 4x as much light). That can be useful.

Another big gain if you buy aftermarket is price. The Sigma lens doesn't seem all that inexpensive but I haven't compared it to a similar Canon offering. The old tradeoff was that you could save money on non-OEM lenses that often were sharp, contrasty, and so on. However, the OEM lenses were built to take the beating that pros dish out. Yeah, you don't sling it around recklessly but someday if you're out in bitter cold weather and the lubricant in your aftermarket lens isn't up to snuff and it won't focus...?

Used to be the normal lens was a true gift. You'd pick up a 50mm f/1.8 for maybe $80 (it was the most produced, which kept the price down). That gave you some low light capability, and it was the best lens in your bag for sharpness, contrast, minimal distoration, and so on.

I'd also get a 28mm f/2.8...they're not too expensive. And then a 70-210 f/4 zoom, maybe. Of course you'll have to translate those into a different format. What's normal for the Rebel?

Tests?

http://www.photozone.de/Reviews/overview

And here's the Sigma:

http://www.photozone.de/canon-eos/298-s ... rt--review

[lobotomyboy63]

So I went in and poked around, looking at a comparable Canon lens. Dayum, $400 for a normal lens?

All I can figure is that not many people buy them these days, so they don't have the "mass production discount" that zooms seem to have. Pity, really: they're not as hard to make.

IIRC Gary has a Canon DSLR and can probably field a lot of your questions. I wonder if you can use this lens, for instance:

http://www.bhphotovideo.com/c/product/1 ... l#features

It would be like a portrait lens in focal length, only costs $85.

[McNutty]

The problem with that is that the midrange cameras aren't full-frame, so there's a focal length multiplier that effectively makes that an 80mm lens.

[lobotomyboy63]

The problem with that is that the midrange cameras aren't full-frame, so there's a focal length multiplier that effectively makes that an 80mm lens.

Right. I was assuming that although you don't want a zoom, you'd like some quality prime lenses. Maybe you start with the normal, then later on add a wide or tele or macro.

Here's a lens B&H has on backorder...

http://www.bhphotovideo.com/c/product/1 ... _35mm.html

35mm f/2.0 for $240.

But like I said, I don't know how interchangeable the lenses are WRT the tier or camera you're buying within the Canon brand.

[pulykamell]

But like I said, I don't know how interchangeable the lenses are WRT the tier or camera you're buying within the Canon brand.

That lens will work fine on the XSi or the T1i.

In regards to zooms vs primes, I don't think it makes much of a difference when you're starting out. I personally love primes. The first lens I buy for any camera system (I'm weird in that I shoot both Canon & Nikon) is an 85mm lens. (I have the 1.8 for Canon and the 1.4 for Nikon). In general, prime lenses tend to be sharper and have a larger maximum aperture compared to zooms in the same focal range. But, my workhorses are two zooms: a 24-70mm f/2.8 and an 80-200mm f/2.8 lens. So both serve their purpose. For reasons of flexibility, I prefer zooms, but for maximum image quality or really dark situations that require wide apertures, I pull out the primes.

The kit zoom lenses that come with camera systems tend to be not that great but, honestly, for the casual to enthusiastic amateur, I really don't think it will make much of a difference. My personal recommendation would be to start with the 18-55mm kit lens. It's not a great lens, but for $100 it does the job well enough. Otherwise, you can upgrade to the 17-85mm, which is a much better lens with image stabilization, but pricier at around $550.

Now, if you want to get into primes, I would start with the "nifty fifty." You can get a 50mm f/1.4 for around $350 and the 50mm f/1.8 for just under $100. That's a damn great price for a sharp, wide maximum aperture lens. The 50mm on a cropped sensor camera like the XSi is the equivalent of about an 80mm on a full-frame camera. That's a great focal length for portraits, especially of the head-and-shoulder variety. As I alluded to above, I'm a huge fan of the 85mm prime, mostly for portraiture, but I use it on full-frame cameras (I have a 5D and a D3), but it works great as a portrait lens on crop sensors, too.

[McNutty]

I should note that I'm not totally "starting out." It's been years since I did any "photography" as opposed to "snapping pictures", but I have taken a couple of classes and am down with the fundamentals. Back then, I had access to a very limited set of gear, though (either borrowing dad's Canon AE-1 or checking stuff out from the photo class), so I didn't do much side-by-side comparison of how your choice of lens might affect your results (other than, obviously, the focal length). Anyway, I'm not going to fret over it too much because I don't fancy myself such a connoisseur, but if I'm going to drop a few bills, I'd just as soon be informed about just how much "better" the "better" option is. I suspect we're talking about the difference between "fabulous" and "very nearly fabulous" here, especially to my relatively untrained eye, but I'd still like to know.

Reading about the zoom that's paired with the T1i here, it seems very unlikely that I'd be disappointed with it.

Talking to a friend about the fixed vs zoom issue, he pointed out that a fixed lens is "faster" in the sense that it lets in more light, so you can get pictures in slightly lower light conditions without having to resort to the flash. In that review I linked, they mention a few times that the image stabilization built into that lens effectively gives you a "gain" of 3 f-stops (Canon claims 4 but the reviewer says 3 is more like it). Can anyone explain to me how this works? Does that actually mean that when I set my camera to f/4 it's going to perform (exposure-wise) like it was set to f/1.4? What physical phenomenon would allow that?

[chacoguy]

I assume they are referring to hand-held shots; there still has to be light coming through the lens to expose the photo. Having an image stabilized lens allows you to take shots in lower light conditions without your breathing, heartbeat and muscle twitches moving the camera while the shutter is open.

[McNutty]

I assume they are referring to hand-held shots; there still has to be light coming through the lens to expose the photo. Having an image stabilized lens allows you to take shots in lower light conditions without your breathing, heartbeat and muscle twitches moving the camera while the shutter is open.

That doesn't make sense for explaining how it's equivalent to a certain number of f-stops. If that were what they were trying to convey, they'd just say the image stabilization lets you hold the shutter open longer without needing a tripod.

[lobotomyboy63]

I assume they are referring to hand-held shots; there still has to be light coming through the lens to expose the photo. Having an image stabilized lens allows you to take shots in lower light conditions without your breathing, heartbeat and muscle twitches moving the camera while the shutter is open.

That doesn't make sense for explaining how it's equivalent to a certain number of f-stops. If that were what they were trying to convey, they'd just say the image stabilization lets you hold the shutter open longer without needing a tripod.

I agree...at first blush it would seem more accurate to say that the gain is three or four shutter speeeds. But then, slower shutter speeds aren't going to freeze action. One shutter speed = one f/stop = one doubling/halving of ISO in light transmission, so take the benefit where you like, I guess.

[garygnu]

...
IIRC Gary has a Canon DSLR and can probably field a lot of your questions...

I have a Canon Digital Rebel 6.3-megapixel and three lenses:
Quantaray 19-35mm 1:3.5-4.5
Sigma 28-80mm 1:3.5-5.6 Macro
Sigma 100-300mm 1:4.5-6.7

(Hey! There’s my circular polarizer filter. I’ve been looking for that.)
None of my lenses are particularly great, and I hardly use my 100-300mm.

[troubleagain]

I have to apologize for my lack of participation so far. I've found myself incredibly time challenged lately, what with trying to put in a vegetable garden. I will try *very* hard to do my assignment for lesson 3 tonight.

[pulykamell]

I assume they are referring to hand-held shots; there still has to be light coming through the lens to expose the photo. Having an image stabilized lens allows you to take shots in lower light conditions without your breathing, heartbeat and muscle twitches moving the camera while the shutter is open.

That doesn't make sense for explaining how it's equivalent to a certain number of f-stops. If that were what they were trying to convey, they'd just say the image stabilization lets you hold the shutter open longer without needing a tripod.

It's just jargon. Usually, though, the term "stop" is used, not "f-stop," and "stop" can refer to shutter speeds OR aperture. When referring to IS or VR lenses, a "gain of three stops" means you can handhold your camera for eight times longer than usual (2x2x2--each stop being a doubling of shutter speed), without camera shake. The problem, as mentioned above, is IS or VR doesn't really do much to minimize subject movement. So, while 1/15 second may be good to eliminate your shaky hands, it's not going to stop the blur of a person walking across your frame.

[McNutty]

It's just jargon. Usually, though, the term "stop" is used, not "f-stop," and "stop" can refer to shutter speeds OR aperture. When referring to IS or VR lenses, a "gain of three stops" means you can handhold your camera for eight times longer than usual (2x2x2--each stop being a doubling of shutter speed), without camera shake. The problem, as mentioned above, is IS or VR doesn't really do much to minimize subject movement. So, while 1/15 second may be good to eliminate your shaky hands, it's not going to stop the blur of a person walking across your frame.

Yeah, that's not nearly as useful as gaining 3 f-stops (which, admittedly, would be magic as far as I know). I did find another cite on the net that had this same explanation (that "stops" doesn't necessarily mean "f-stops"), but the review did specifically say "during the field tests it gave me a more or less reliable gain of about 3 f-stops," so perhaps they're just being sloppy with their terminology.

BTW, I've nearly completely talked myself out of the T1i. It looks like a great camera, but the "movie mode", which was the main extra goody drawing me to it, doesn't look very useful for taking general home-movie type stuff, and I think I'd rather get an XSi (or maybe even XTi) and a nice lens than blowing all that money on the new hotness. The old hotness is plenty for my needs, I'm sure. Is it reasonable to expect the prices of the older models to have a sizable drop when the T1i is released in a couple of months?