Depth of Field question

[joe_bailey2]

Please forgive my newbie question. I recently upgraded from a Canon

G5 to a 5D with a 24-70 2.8L lens and a 550EX flash. Most of my

pictures have been of my 5 month old daughter and are taken indoors

with low light. These are typically taken at a distance of 5-7

feet. I am ending up with a very narrow DOF even when I use the

manual settings and bump the apperture up to 11. There aren't any

focal distance markings like what I used to rely on with my old.

film SLR. Is there some easy way of calculating/estimating my focal

distance without having to plug in numbers to an online DOF

calculator? The low light makes it difficult to use the DOF preview

button. Maybe I just need increase the distance between me and my

subject.

[digitmstr]

The 24-70L will behave the same on the 5D as it does on a 35mm film SRL.

 

Shooting a 5 mos old baby from 5-7 feet at f/11 should give you plenty of DOF by normal standards. I don't know what exactly you want to achieve and without a sample it's too much of a guesswork.

 

I mean, do you want everything to be in focus? What focal length are you using the most? If you are comparing the 5D to the G5 then, yes...those P&S with their small sensor have a relatively huge DOF, which is why their lenses only stops down to f/8.

 

If you want more DOF than a regular lens can offer the only other solution would be a T/S lens.

[joe_bailey2]

Thanks for the response, Giampi. I was using focal lengths of 50 and 70mm. After reviewing the charts, I only had a few inches of depth to work with at that distance. My daughter was in focus, but the family member behind her started to get fuzzy. I guess I am still used to the greater DOF with my P&S camera. I'll keep working at it.

[neild]

The larger the sensor, the shallower the DOF. If you prefer all of your photos to show almost infinite DOF then the P&S is a good tool to achieve this - perhaps the 5D will not be what you want after all (think carefully, as you may be able to get a decent price on it if you sell it in new condition, which usually means selling sooner rather than later).

 

If you have to have a dSLR, consider the 20D - it will always have more DOF at a given f-stop and field of view than will the 5D.

[mark_man]

The optimal DOF for candids or portraits in general is a matter of personal taste. Having said that, most photographers would agree that the setup you have is an ideal one for this purpose. The relatively narrow DOF allows you to isolate the subject, making her stand out from an otherwise distracting background.

[joe_bailey2]

Maybe I wasn't very clear with my question. I love my 5D and can't wait to get outdoors with better lighting to start shooting. I just wish there was an easier way to figure out what my DOF is. Even my old Pentax zoom lens had markings on the lens to show what would be in focus at any giver aperture. I mean, how does one know that when focusing on a subject at 7 feet, 50mm focal length, f11, that they will have a DOF of 5.5 - 9.6'. Does this just come with experience?

[joe_bailey2]

Here is an example of what I am referring to. This was my very first shot with this camera. This was taken with a FL of 70mm @ f4. The front of her face is in focus but it goes out of focus quickly. I realize my error now.<div></div>

[michael_matsil]

Joe.....

With due respect to Neil D, it's not the sensor size that gives those little cameras super

human depth of field, it's the fact that those tiny sensors require super wide lenses (like

10 or 12mm!) just to give "normal" coverage. So let's be clear, it's the focal length that's

responsible for that. At a given subject to lens distance, a 10mm lens will always have the

same DOF charactersistics regardless of what format it's attached to.

 

Since you haven't provided a sample of your low light, f11, 5-7 ft., indoor flash pictures,

it's hard to say what the effect you are calling shallow DOF really is. I agree with Giampi

that with that lens, at that distance at f11 your DOF should not be shallow at all. If you are

shooting at f11 with flash in low light and your camera is set to let the shutter go long,

what you may be seeing in your images is 'flash blur.' The effect of the 'smearing' of the

ambient light after the flash has already popped. It creates a blurry effect on the areas of

the image that are not effectively covered by the flash (the areas further from the flash.)

Post an image and we'll know.

[michael_matsil]

OK....you're at the long end of the lens and you're at f4. What you're showing and telling

us seems perfectly predictable. So, I'm not sure what the problem is anymore. It's not

flash blur effect as I proposed in the above post.

[jennifer valencia]

hi Joe,

your first picture looked great! What a cute baby. :) f/4 is pretty wide, actually, and your picture shows the appropriate depth of field that I'd expect. Always be sure to focus on the eyes -- like you did -- in order to make sure they are sharp.

 

You asked if experience is needed to "know" how DOF will look, and I think the answer is yes. The more you shoot, the more you'll become aware of how various f stops will affect your DOF.

 

Does your camera have a DOF preview button? If so, you can press that button and see what your picture will look like. Most cameras let you see your scene through the viewfinder at the widest aperture, and only stop down when they take the picture. To get a glimpse of how it will look, you can press the DOF preview button to stop down the aperture. It gets darker, usually, because as the aperture narrow it lets in less light. BUt if you let your eyes acclimate for a few seconds, you can often get a rough idea of whether your DOF is "right."

 

If you want a baby's face AND people right behind him/her to be in sharp focus, I'd recommend using an f stop or f/11 or greater. With group portraits especially, you need to be careful or someone's face will be fuzzy with a wide f stop.

 

Again though, with more practice this will all become very natural to you. Good luck and keep shooting that beautiful baby!

 

Jennifer

[desmond_kidman]

As was said earlier, this is the depth of field to be expected at that distance with that lens and aperture combo. Maybe a little higher camera position and focusing on the close eye would have pleased you more.

 

When wishing for greater depth of field, also ask yourself how much more distracting the details of the bouncer seat and plastic box in the background would be with greater dof. Limited dof can be a great tool unless you just do not like that look.

 

As far as getting group shots with folks behind other folks in focus, you can use any combination of the following: try to position people so that the depth is minimized, use a smaller aperture while dialing up ISO if necessary, live with distracting backgrounds, give up on many candids with folks at widely varying distances in the same shot, use a camera with a smaller sensor, use a shorter lens thereby not filling the frame and crop later (this simulates a smaller sensor camera without stepping down in camera).

[neild]

Michael, of course you are correct... but in the real world, what I said was not wrong: as you shrink your sensor size, you are going to pick whatever lens gives the FOV that you want. This means that <i>in a practical sense</i> a smaller sensor will give you larger DOF because naturally you'd be using a lens of smaller focal length on it. I know you were stating the technically correct reasoning, but as shrinking the sensor size naturally leads to the photographer shrinking the focal length used, I think that our explanations are 100% equivalent. Your average photographer is concerned with the FOV of a lens, not its focal length. We are only in the habit (a bad habit I think) of thinking of lenses in terms of their focal lengths because we've been using only one sensor size for many years (for those who used 35mm film).

[michael_matsil]

Neil....I understand what you are saying. But think about this: you made a declaritive

statement to a newbie: "The larger the sensor, the shallower the DOF." Then you suggest

that he not only choose his camera but his format, by what FOV and DOF he desires. Does

anybody out there really choose to NOT buy a camera in the medium or large format

because of diminishing DOF? You get the format you want or need and work within it's

limitations; in the case of 35mm format...not much limitation at all. The man said he's

gone from a G5 to a 5D....period. Sounds like he's got everything he needs to shoot

whatever DOF or FOV he wants. He just needs to learn how. Why send him on a goose

chase for different cameras and formats? Tail wagging the dog, here.

 

Joe...stick with your 5D, I hear it's a great camera. You'll get the DOF thing down in no

time.

 

Neil: good healthy debate here. No offense. Thanks.

[joe_bailey2]

Thanks for all the responses. I do love the greater DOF control with my new DSLR. I also understand many of the technical aspects of what you are saying. Photography was my hobby then I was in my teens. I guess the main problem for me is that on newer lenses, they do not put DOF chart markings on the lenses. Maybe I'll just print out some charts at different focal lenghts and use these as a cheat sheet until I get more accustomed to my camera. What is a predictable result for many of you was a bit of a surprise for me. I didn't know that from a distance of 4 feet with a wide open aperture and 70mm FL, my DOF was so shallow. I'm looking forward to getting this control to work in my favor. Thanks again...

[neild]

Michael, no offense taken! :-)

 

Perhaps I was wrong to advise Joe to sell the camera, but my initial post was based 90% on his apparent dissatisfaction with the DOF, which was apparently too shallow for him. Anyway, I bow out of this now. The 5D is an excellent camera (I have one) and one of the reasons I was holding out for a FF camera was the slight decrease in DOF I would be getting... which was worth it (the other reason was ultra-wides and fisheyes). The Mp count wasn't something I based my decision on, but now I realise it's advantages too (and disadvantages in terms of storage, but what can you do?).

 

Joe, the 5D is a very classy camera - I love mine to bits! But DOF will be much less on the 5D than on the G5. Good luck with however you solve your problem! Another thing: the DOF scales on the old lenses should be able to be applied to the new lenses too. Do you still have your old lenses? If so, you could put some tape on the new lens and make some markings - DOF depends upon focal length, f-stop, and distance focused only. Just an idea for a rough guide, and you can verify how accurate it is quite easily, being digital and all. If you don't have the old lenses anymore, I'm sure someone would tell you where the markings appear on thieir lenses, or use the charts as you've said.