Newbie DOF question.

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David

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Dave
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Hi,

I've been pondering again.

Lets say that I was shooting a subject that is about the size of a PC motherboard (bit bigger than an a4 sheet of paper) at this kind of angle. (thats not my pic by the way).

With the gear I have, I'm struggling to get all of the item in focus. I have gone down a few stops, all the way to 11 and that has definitely improved things, but the front corner and back corners are out of focus.

I'm using a 40d, an EF-S 60mm and a 17-55mm f/2.8 IS to do the shots, but I was wondering if using a bigger lens from further away (say an extra 5 feet or so) and then zoomed in would correct the DOF?

Or am I going about this all wrong :bonk:

Any help would be greatly received :)

thanks

David.
 
DoF is a function of magnification and aperture so using a different lens won't change the result if the shot is framed the same. You could stop down to f/22 to increase the DoF but it still might not be enough. Another option would be to try focus stacking (google it).
 
Thanks pxl8,

What would be the drawbacks of using f22, are there any if I'm using a tripod and the subject isn't moving?

Just reading about focus stacking - I was thinking a similar thing by taking a shot with the focus point being the top and one in the middle and blend in photoshop. I was hoping I was doing it wrong at the camera end :)
 
F/22 could introduce softening due to diffraction effects.
 
Ok thanks :)

I'm just checking out that Helicon focus, but I can't see any mention of it accepting 40D RAW files.
 
have a look here, you will see how far back from the subject you need to be to get the desired DOF.
 
How big does the final image need to be?

In some cases when there's room to crop the easiest solution is to move the camera back a tad, with the lens you're using and then crop the section that you want to use.
 
Dogfish_magnet said:
have a look here, you will see how far back from the subject you need to be to get the desired DOF.
Click to expand...

Thanks, it would appear that with a 60mm lens at 5ft with f/11, I would get around 0.88ft, which is about right for what I'm seeing.

I think things are finally starting to fall into place. So further back = slightly better DoF and also higher stop number = better DoF.

Anything else, from a photography point of view (as opposed to a post processing one) = better DoF?

Bulletraptor said:
All this reminds me how little i know lol
Click to expand...

Join the club mate :bonk:

dazzajl said:
How big does the final image need to be?

In some cases when there's room to crop the easiest solution is to move the camera back a tad, with the lens you're using and then crop the section that you want to use.
Click to expand...

Final image size will be around 1500px wide maximum.

The problem I'm having is that when I move backwards, I'm seeing noise in my pics and they look much softer - I've even borrowed a second off camera flash from my mate and everything is well lit (look it to me).

I'm sure this is all the nuts and bolts of photography and I'm trying to absorb as much as possible, so please forgive my silly questions :)
 
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