Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Canon EOS dSLR

Reply
 
Thread Tools Search this Thread
Old Dec 28, 2006, 11:10 AM   #31
Senior Member
 
Join Date: Dec 2002
Posts: 5,803
Default

D.Ann wrote:
Quote:
and also the 30d has a third option, AI Focus AF which switches back and forth as it detects movement in the subject or lack there of...Donna
D.Ann, it is generally considered around this forum that AI Focus is not very useful. I tried it for a little bit and would agree. What seems to happen is that it doesn't catch on quickly enough when movement starts and therefor that amazing instant when the bird takes off is OOF. What works better, from the wildlife Pros that I've talked to, is binding the * button to lock focus and using AI Servo (or if you know your subject and environment really well, just start in One Shot.)

AI Focus doesn't exist on the Pro models, and I think there is a reason. It is based on the assumption that it can pick when to track focus and when to keep focus locked better than you (the photographer can.) Since I believe that is wrong, I would rather have the ability to lock focus with the * button and stay in AF Servo all the time.

And while I agree with JohnG in the above debate, in the effort of full disclosure I want to add that I do know of a few (not many, but a few) Pro nature photographers that use One Shot for flight photography. And they get results just as good as the many, many that I know who use AI Servo. But they are outnumberd.... 98 to 1. I know of many who switched from One Shot to AI Servo and their shots improved.

And JohnG, the facial expression does matter on a bird shot. There are many more "good" ones than with a person, but it still matters 'cause there are bad ones.

Eric
eric s is offline   Reply With Quote
Old Dec 28, 2006, 11:18 AM   #32
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

JohnG

I do use both - I'm not saying one mode is better than another!

I'm just try to pointing out the difference that in AI-servo you do get cases where none of the AF points has a lock on the subject because the camera is predicting (and there are many post on this subject already), vs single-shot AF where there's is always at least one AF point locked or the camera won't release. The test conditions above prove that

You pick whatever AF mode work best for you and in my case it varies with the subject's size: Big birds in flight which can fill an entire frame has no problem with AI, but on the other hand for small bird moving quickly against a busy background it just works better for me in single-shot AF in this case
NHL is offline   Reply With Quote
Old Dec 28, 2006, 1:02 PM   #33
Senior Member
 
D.Ann's Avatar
 
Join Date: Jun 2006
Posts: 2,932
Default

Well, the sun came out today finally, but the birds were scarce...anyway I tried to put into practice the skills that have been shared herel Gradually I am seeing light (understanding) and now need to practice using the camera.

But,and this should have been obvious to me, but wasn't...I noticed when I am in full manual mode the exposure is indicatedin the viewfinder and I can adjust it by tweaking the shutter speed or aperture wheels. I didn't notice this info in shutter or aperture priority modes. I really like this...it reminds me of my old nikkormat with its meter on the side on the viewfinder, and I could tell when I was on target before I took the picture. On the e-500, this info is not available until after the shot. I think I really like this. Donna
D.Ann is offline   Reply With Quote
Old Dec 28, 2006, 3:58 PM   #34
Senior Member
 
Join Date: Dec 2002
Posts: 5,803
Default

Donna,
First off, go experiment. I keep giving info, because I want to clarify things you've said wrong, and reinforce things that are right (and I just like helping people.) But learning by experience and then clarifying and honing that experience with directed question posted here is the right way to learn.

With that said, I will continue:

In Av or Tv the information about improper exposure isn't there because it doesn't need to be (or it can't be, depending on your view.)

In Av or Tv the camera picks what it thinks it "Right" so there is no need for it to tell you if it's "wrong". (Note: what I said is sorta a lie, see my comments further down.)

In Manual mode, where the camera doesn't pick anything, it needs to tell you when it thinks your are wrong. You are using/viewing this mode exactly correctly... it works just like my old Pentax K1000, which only had manual mode and a single needle to show how far off in exposure you were.

In Av or Tv:
1) The little dial on top controls the "main" setting (in Tv it's shutter speed, in Av it's Aperture)
2) The big dial on the back controls "exposure compensation" - the other setting (in Tv it's aperture, in Av it's shutter speed.)

Nothing tells you (except for when stated in the next paragraph) that the exposure is wrong for the current situation because *the camera thinks it's right*... that is why it picked what it picked.

In theory Av will always generate the "Right" exposure as far as the camera is concerned because you pick the aperture and it can always pick a shutter that will work (except when the shutter speed is impossible - like 1/20,000.) In Tv you can set a shutter speed which would require an impossible aperture to work (like say f2.8 was needed on a lens with a max aperture of f4.) In that case the aperture will blink to tell you it's wrong.

This is where exposure compensation comes in (I've mentioned it in an earlier post.) Do you know what exposure compensation is and how to use it? If you're going to stick with manual exposure, then it doesn't matter. If you want to widen your knowledge, or want to use Av or Tv, then it matters quite a lot for outdoor photography and I'll explain it in another post.

And for what it's worth... if you're good at judging exposure in your head, then there is nothing wrong with using manual exposure. I know some Pros that use it and they produce great work. It can be done... I'm not that good at calculating exposure in my head, so I use Av exclusively (except some occasions when using flash.)

Eric
eric s is offline   Reply With Quote
Old Dec 28, 2006, 6:11 PM   #35
Senior Member
 
D.Ann's Avatar
 
Join Date: Jun 2006
Posts: 2,932
Default

Yes I know in theory what exposure compensation is. For example if you are shooting a snow scene you would need to add brightness because the camera will see all that white and try to darken it...right? I have to remind myself where the control is on the camera...I haven't used it that much. Or it a shot has really bright highlights you might need to compensate by reducing exposure by 1/3 or whatever. Is that right...Donna
D.Ann is offline   Reply With Quote
Old Dec 28, 2006, 8:14 PM   #36
Senior Member
 
Join Date: Dec 2002
Posts: 5,803
Default

Yes, you understand exposure comp correctly.
In manual it doesn't apply. But if you shoot in Av or Tv it does... in fact, I'd say its necessary (I wouldn't buy a camera without it.) You use it to fix the exposure when you know the camera will get it wrong.

Eric
eric s is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 7:44 AM.