What am I doing wrong?? (DOF question)

[Madison]

I have been travelling up to the Museum Of Natural History for two days now because I got obsessed with this incredibly weird Baboon. His mounth is terrifying, his eyes look so sad (this is a dead animal on display in one of the staircases, not really a main attraction).





Here's the problem. Yesterday I went and took a shot. The mouth was in focus, the rest was not (picture is here: http://community.the-digital-picture...x?PageIndex=26 halfway on the page).


I went back today, to re-do it nd make sure everything was okay. I decided to shoot at F8, which should be more than enough, right? Wrong. Now, the eyes are in focus and the mouth is not. Is it because I am too close to the monkey? That's it, isn't it? I need some tips because no matter what I do, I cannot get the entire monkey in focus. And I can get as close or as far away as I want. I can lick it if I have to.





Tips?


This is the picture from today: (Oh the monkey is up against a white wall with glass next to it and loads of daylight so it's a horror to shoot it anyway because of the enormous contrast and the reflectve surface behind it that I want to keep out of the picture).





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[Sean Setters]

A few questions:


What camera/lens are you using?


What's the EXIF info? (shutter speed, ISO, focal length)


Just how close were you to the subject?


What focus point were you using and where was it on the animal?

[Fred Doane]

Madison,





All you need is this...


DOF Calculator


DOF has to do with a lot of things. Distance to the subject, focal length,apperature, and even if your using a FF or crop sensor. The calculator will help u with deciding what you'll be able to get in focus. Don't forget after a certain point defraction will be a concern if you use too high of a f-stop. Usually it's said you want the eyes in focus but if the teeth are your main subject you may have to live with the eyes being a little out of focus if you can't use a smaller apperature. I believe all Canon cameras have a DOF preview button next to where the lens is mounted that if you press down the image will get darker inyour viewfinder but it will allow you to see what will be in and out of focus. You might choose to focus on a point between the teeth and eyes since when the lens is stopped down there will be a point in front and behind your focus point that is still in focus (see "in front of subject" & "behind subject" in the online DOF Calculator) Hope this was somewhat helpful.





Fred~

[Madison]

A few questions: What camera/lens are you using?, What's the EXIF info? (shutter speed, ISO, focal length), Just how close were you to the subject?, What focus point were you using and where was it on the animal?

Hi Sean!


I am using the 5D MkII with the 24-105. EXIF for this particular shot is: 1/13 at F8. ISO400. 58mm. I need to be closer to the subject that I would like (not close enough for me to lose my minimum focus distance though) to avoid problems. (There are white walls everywhere, there is a giant glass wall directly behint the baboon that I am trying to hide in the shot, there is MASSIVE back-light as well and high contrast so I overexposed to get the proper exposure for the baboon itself).


I tried focusing with a focus point on the teeth (sharp teeth, unsharp eyes (while the distance between them is minimal) at F8. And I tried using a focus point for the yes resulting in sharp eyes and not so sharp teeth.





Now tell me. With an object like this, it shouldnt be difficult at all to get it all in focus, right? Or am I saying/doing something incredibly stupid? It wouldn't be the frst time.

[Chuck Lee]

I'm going to guess 5DMII with 24-105 f4L.


Based on the info below I'm also going to guess that you were 3ft-5ft away and shooting at 70mm - 105mm to get this close up head shot.


Min focus distance is aprox 18". I'm thinking that if your in a hall you can get a little further away. Say 4-6 ft.


@ 50mm- DOF @f8 from 4ft= 11" 6ft = 25.5"


@ 70mm - DOF @f8 from 4ft= 5.4" 6ft = 12.5"


@ 105mm- DOF @f8 from 4ft = 2.25" 6ft = 5.4"


Like Sean said: What were the settings?


The catch 22: The further back you get the more DOF you will have. The more you zoom in the less DOF you have.


Try shooting at a wider angle and cropping or shoot at a higher aperture. If you can stand another stop go to f16 same composure/crop.


Sorry for stating the obvious.


I'm still struggling with FF and this very same thing.


Oh and...........Don't lick the monkey! It'll leave a bad taste in your mouth I'm sure.


Chuck

[Daniel Browning]

Now, the eyes are in focus and the mouth is not. Is it because I am too
close to the monkey? That's it, isn't it? I need some tips because no
matter what I do, I cannot get the entire monkey in focus.

Once you've decided on a composition, there is no way to get deeper depth of field except by using a narrower iris diameter (i.e., stopping down). [There are some hard ways, such as using a tilt-shift lens or focus stacking.]

And I can
get as close or as far away as I want. I can lick it if I have to.

If you move forward and zoom out (to get the same framing), the DOF will remain the same.


If you move backward and zoom in (to get the same framing), the DOF will remain the same.


So moving doesn't really affect the DOF. However, it does affect the perspective and background blur. Further away + longer focal length = flatter perspective and more background blur.

Tips?

If you want the eyes *and* teeth in focus, then you should focus in between them: not on one or the other. With liveview this is straightforward:

1. Compose your shot
2. Start liveview
3. Zoom in to focus on the closest feature (front teeth)
4. Hold down the DOF preview button (or use a liveview mode that does it for you).
   
5. See how far you can move the focus point back before the teeth go out of focus.
6. Zoom in on the furthest feature (back eye) to see if it is in focus.
   
7. If not, stop down further and go back to step 6.

If you're only using the image on the web (i.e. very low resolution), then you don't need to use the full 10X zoom (that would more accurately depict the DOF of a large print or heavy crop.)

I am using the 5D MkII with the 24-105. EXIF for this particular shot is: 1/13 at F8. ISO400. 58mm.

For most people, 1/13 would not be near enough to prevent camera shake, even with image stabilization. That may be what caused the blur in your image. I would suggest a monopod if you're not using one already. (Of course a tripod is better, but not always an option.) If you only plan to use the image on the web (low resolution), you could use a higher ISO and faster shutter speed.

With an object like this, it shouldnt be difficult at all to get it all in focus, right?

It's not the object, per se, that makes DOF difficult: it's the composition and light. It's possible to get deeper DOF if you change your composition, e.g. doing a full body portrait instead of headshot, but that doesn't help you if you've already got the composition you want. More light it would be easier as well, since then you could use a narrower iris diameter (i.e. stop down).


By the way, the reason I'm using the term "iris diameter" instead of f-number is because it works for all sensor sizes. Some people think that small sensors (e.g. digicams) have a DOF "advantage" over large sensors (e.g. 5D2). But that's not true: once you stop down the 5D2 to the same iris diameter (focal length divided by f-number, e.g. f/45 on 5D2 vs f/2.8 on the digicam): the DOF, noise, and diffraction are all the same as the digicam.

[Madison]

Chuck: EXF data is in my earlier post.


Daniel: Monopods or tripods are not allowed inside the museum. Changing the composition is not an option. First of all there is no body attached to the head, and any other angle than this one will create a huge reflection of the rest of the room because the head hangs next to a giant glass wall (that I am trying to hide from the shot).

I will need to up the ISO and make sure I get the DOF right, I figured at F8 (which I thought should cover it), it would not be a problem but I guess I was wrong.

[Sean Setters]

I think Daniel hit the nail on the head with most of his points. Also, I certainly agree taking a look at the DOF calculator. I've used it several times to get an idea of what my settings ought to be. My first instinct was to suggest a monopod, but I figured they wouldn't be allowed in the museum (as well as flash, probably).


You might want to spend about 5 minutes researching the absolute best way to handhold a camera. I know that seems silly, but I read Joe McNally's Hot Shoe Diaries a while back and he devoted a few pages to the different techniques he uses to steady the camera (while sometimes holding a flash) when he doesn't have access to a tripod/monopod. One thing in particular is that he locks the elbow holding the lens to his body, stands straight up, with his chest weight distributed above his center of gravity. Holding the camera for maximum steadiness probably buys you an extra stop of exposure.

[Chuck Lee]

Madison,


Is there another time of day that would cut down on the glaring light?


Do you have an assistant that could hold up a gobo or two? Experiment with some subtractive lighting.


Daniels suggestion to focus between the eyes and mouth was spot on.


58mm would put you out around 2.5 ft depending on the size of the head? Try ISO800, f11 to ISO1600, f16. Take bursts of 3 and keep the sharpest.Sean's Joe McNally suggestion is good too. The steadier the better.


Would the addition of flash help? Try on camera and off. In fact, you could kill a lot of that back light by introducing key light into that scene. Keep your aperture down around f11 and play your ISO up and down along with shutter speed. Aperture sets the power of the flash on the subject, shutter speed controls the ambient power.


What do you think Sean? Would flash help him in this situation? I think it would.


Unless the museum doesn't allow it. That'd be wack. But it is a stairwell.


Just think'n out loud,


Chuck

[Daniel Browning]

Good post Chuck Lee, just one minor correction:

Try shooting at a wider angle and cropping...

Cropping in post ("digital zoom") will make the DOF just as thin as if you had zoomed optically. The only time a wider angle has more DOF is if you don't compensate for the change in framing (composition). When you compensate for it by moving closer or cropping, it makes the DOF thinner again.