How do you determine the DoF?

[scraggles]

When I'm at home, it's simple, just plug in the numbers to an online calculator, and its done... but when I'm out of the house, I get crappy shot after crappy shot because I'm a moron. How can I find the depth of field so I don't ruin so many good shots?

[SuzyView]

What are you taking pictures of? The 17-40 should have no trouble with DoF. Do you want everything in focus or do you want only the subject?

SuzyView

[scraggles]

Well, I guess my question is, what is this lens best for? I have used it for taking pictures of my girlfriend jumping her horses and rarely do many of them turn out perfectly focused. I've tried using a tripod and still I have clarity problems.

[PhotosGuy]

What mode are you shooting in? M?

[scraggles]

AV usually.

[SuzyView]

Borrow an 85 1.8 from a store and try that. Put it on the sports mode and try it.

SuzyView

[Crypto]

What do you have the AF point set at? I'm by no means an expert (so this may be really bad advice), but I seem to have better luck with things like this when I set my AF point in the center position. I will run into problems if i miss the subject, but I take a lot of shots and I usually end up with a couple great shots that are nice an sharp with a shallow DOF, provided ofcourse the shutter speed is right. Just a thought

[Curtis N]

In the field, some people carry DOF charts for various lenses & focal lengths.
Some of the online DOF calculators let you make printable charts.
Try this one (http://boonecounty.info/photocalc.htm)if you have Microsoft Excel.

[Crypto]

In the field, some people carry DOF charts for various lenses & focal lengths.
Some of the online DOF calculators let you make printable charts.
Try this one (http://boonecounty.info/photocalc.htm)if you have Microsoft Excel.

that's a great resource. Thanks

[scraggles]

I have the AF mode set usually to the middle when I'm taking shots of her jumping.

[snibbetsj]

I printed up the charts from:

http://www.dofmaster.com/custom.html

and keep them in my bag. After a while you kinda remember the DOF and don't really have to refer to them much.

Sometimes when I shoot Av mode (very rarely), I get caught up in going to a small aperature for large DOF, this, of course, lowers the shutter speed. I find, if I'm not careful, the SS will be to slow and I get blur from camera shake.
Don't let it happen to you :D

[scraggles]

I might just be a lost cause for photography. :-(

[SuzyView]

Don't understand the chart, right?

SuzyView

[grego]

You have center point focus. That's good. AI servo is important.

17-40 is a good lens, but for sports/action, its not the easiest to use. You'd be well off with a telephoto type lens. 85 1.8 is a pretty good deal or 200 2.8L.

[snibbetsj]

I might just be a lost cause for photography. :-(

Nah, It sounds like you need get a good book to read up about this stuff. I believe a highly recommended one is called "Understanding Exposure". If you search the forum, someone has posted a link to the author/amazon page. This should help immensely.

[Curtis N]

I might just be a lost cause for photography.I doubt it. The breakthrough comes when you learn how to look at an image and figure out what went wrong.

Post a few of your "problem" shots (be sure to include all the pertinent info like shutter speed, aperture, focal length, etc.), and there are many people here who can help you figure out if it's motion blur, improper focus, DOF or whatever.

You'll soon learn to do such diagnosis yourself, and then the learning is easier.

[scraggles]

Well, I've got to install photoshop so I can edit my .CR2 files. But, I can see that a lot of the problem is that the 17-40 flat out sucks indoors at night. I know I can use the flash, but the onboard flash ruins photos so much. Is there a good alternative to using the flash?

[scraggles]

What uses would you recommend that the 17-40 is good for? I"m still not good at determining which lenses are good for certain applications. Any way to tell other than bothering the forum every time I want a new lens?

[snibbetsj]

Without using the flash, the 17-40 f4 is really not made for indoor low-light work unless you want to photo a still life using a tripod (long shutter speed). You need adequate light for this lens, it's a great outdoor/landscape lens and very good indoors when there's adequate lighting.

For low-light photos at a handholdable shutter speed, you're going to need a large aperature, a lens such as the 50mm f1.4 or the 35 mm f1.4 or even the 85 f1.2. It sounds like you want to shoot in nightclubs (or similar venues), these lens will allow you to do so. They're not cheap though.

If you get yourself a good flash diffuser and flash, with practice, your flash shots won't suck.:)

[Curtis N]

Is there a good alternative to using the flash?Crank up the ISO enough to get a usable shutter speed.

[scraggles]

Crank up the ISO enough to get a usable shutter speed.

Ahhh, yes... but noise is worse than camera shake to me. I'm only using an XT, so the higher ISO's are a bit noisy.

[scraggles]

Without using the flash, the 17-40 f4 is really not made for indoor low-light work unless you want to photo a still life using a tripod (long shutter speed). You need adequate light for this lens, it's a great outdoor/landscape lens and very good indoors when there's adequate lighting.

For low-light photos at a handholdable shutter speed, you're going to need a large aperature, a lens such as the 50mm f1.4 or the 35 mm f1.4 or even the 85 f1.2. It sounds like you want to shoot in nightclubs (or similar venues), these lens will allow you to do so. They're not cheap though.

If you get yourself a good flash diffuser and flash, with practice, your flash shots won't suck.:)

I do have the nifty fifty. I'm thinking of upgrading to the 50mm f1.4.

[snibbetsj]

I do have the nifty fifty. I'm thinking of upgrading to the 50mm f1.4.

The nifty fifty's a fine lens, I have one myself. It's just a little slow to focus, especially in low-light. Use it, crank the ISO to 1600 or even 3200, get a free copy of the community version of noiseware at:

http://www.imagenomic.com/

and try it out.

[Curtis N]

but noise is worse than camera shake to me.I have to disagree. Noise can be dealt with via various software programs, but a blurry picture will always be a blurry picture.

I have processed over a thousand theatre shots in the past year, shot with a 300D at ISO 1600. Noise Ninja did its job.

In terms of noise reduction software, there are free options, too.

[dandan]

a depth of field preview button?

[SkipD]

a depth of field preview button?You took the words right out of my mouth.....

In 40 years I have never needed a DOF calculator. I merely check the effect by stopping the lens down to the set value with the preview button. I've done this on my Nikon F's and do it with my 20D.

[kenyc]

Well, I've got to install photoshop so I can edit my .CR2 files. But, I can see that a lot of the problem is that the 17-40 flat out sucks indoors at night. I know I can use the flash, but the onboard flash ruins photos so much. Is there a good alternative to using the flash?

You seem to be jumping all over the board here. First you are talking about DOF with outdoors horse jumping and then complaining about indoor shots and flash. You say maybe you're a lost cause, but you only are if you think so. :)

Slow down, learn one thing at a time. Don't worry about perfection, worry about the next shot.

First DOF, don't worry about the details of setting the exact right shutter speed and aperature. The main thing to keep in mind with the outdoor horse pics (which are no different than shooting other sports) is that the trade-off is between freezing the motion and capturing the focus/DOF. With DOF just remember that the smaller the aperature (higher F numbers) the greater the DOF. The larger the aperature, the smaller the DOF. Experiment with this and play around, examine the pictures and the exif data til you get a feel for the results at various aperatures.

Learn to see what the camera sees, that the most important thing you can do.

Now the trade-offs! Ofter the perfect DOF will result in a shutter speed so slow the motion will be blurred so you have to decide which is more important, the correct DOF/Focus or freezing the motion etc. This is really again just experimentation and determining what works for you.

You have to take a lot of pictures and examine them with a critical eye.

Indoors is a whole different question. A 5.6 lens will certainly work indoors with a flash or good lighting (but the white balance has to be adjusted to match the lighting). If you are going to be doing "serious" indoor photography you're going to need an external flash unit or studio lights. Again it will be a learning experience which involves experimenting and taking many pictures and examining them carefully and is completely different than outdoor shots.

The best thing you can do is what you are already doing, post your questions here and read, read, read, and study other images and how they were achieved, if you see something you particularly like, ask how they did it?

Even more importantly post some of your "trouble" shots for others to analyze and help you with.

KAC

[kenyc]

You took the words right out of my mouth.....

In 40 years I have never needed a DOF calculator. I merely check the effect by stopping the lens down to the set value with the preview button. I've done this on my Nikon F's and do it with my 20D.

Yep, and I don't even use that much, except in a difficult lighting or composing situation.

KAC

[scraggles]

a depth of field preview button?
I don't understand how to use it. I push the button and all it does is make the entire viewfinder dark. What good is that?

[kenyc]

I don't understand how to use it. I push the button and all it does is make the entire viewfinder dark. What good is that?

Well yes, admittedly it can be difficult to see (that's why I don't use it much), but if you look carefully you'll see the DOF and focus change (you have to ignore the change in brightness :) ).

KAC

[SkipD]

I don't understand how to use it. I push the button and all it does is make the entire viewfinder dark. What good is that?To really see the effect demonstrated, set your camera to M mode and dial in f/16 for the exposure (shutter speed makes no difference for this demonstration). Get fairly close (a couple of feet or so) to a subject outdoors with bright sunlight illuminating everything. Observe stuff in the distant background in the viewfinder - it will be badly out of focus. Now press the DOF Preview button. While holding the button, the background will come much closer to being in focus.

Yes, the viewfinder will darken when you press the button. When you press the DOF Preview button, the iris in the lens closes to the f-stop that is dialed in (or controlled by the camera). That cuts down the amount of light that comes through the lens which is why the viewfinder darkens. However, the scene in the viewfinder now has the same depth of field as the image will. You just can't see it as well as on an enlargement.

One cool way to use the DOF Preview button is to figure out how much brighter a fast lens could make your viewfinder. Let's say your lens has a max aperture of f/4. Set the aperture (in M mode) to f/8 and press the DOF Preview button while looking at the scene. The difference in brightness between the two settings (with and without the button pressed) is the difference see if you changed to a lens with a max aperture of f/2.0 (you'd see an image that much brighter, that is).