enlarging depth of field

[Gary Holliday]

Is there a way to calculate in mm or inches how the f stops on enlarging lenses affect depth of field?

So if you were using triple weight paper or your enlarger alignment was slightly out, you could set the minimum aperture to give you edge to edge sharpness.

 

[RobC]

if you think about it, your enlarger is a camera. You are taking a photograph of your negative from very close up indeed. Your enlarger is therefore a macro camera for close ups of negatives. And in macro photography you should be aware that depth of field is very very very narrow. And also you should be aware that depth of filed is on the negative and not the paper since its the negative which is the subject and not the paper. And depth of focus on macro photography is less of an issue but still needs to be correct.

In short, your enlarger alignment of negative stage and lens is far more critical than the depth of focus on paper.

 

[Pinholemaster]

Re-align the enlarger.

 

[cowanw]

If you tilt your paper, for example to correct architectural perspective, depth of focus is important. Although I don't know of any formulae to calculate it. You can tilt paper and negative to to select a plane of focus just as with large format cameras.
Regards
Bill

 

[matti]

I suppose the formula is here. But do you really want to calculate this? I find my grain focuser really useful to look for any misalignment. If I stop down more than two stops with any of my enlarging lenses the grain gets blurred, so stopping down isn't really the solution. But do I really trust my only grain focuser? That is another issue...
/matti

 

[RobC]

well here's the deal on depth of field. But somehow I think your're gonna find aligning your enalrger correctly much simpler.

http://www.largeformatphotography.info/articles/DoFinDepth.pdf

 

[Gary Holliday]

Some light physics reading Rob!

My alignment is fine Pineholemaster, but I've been using maximum aperture for some printing and was nervous about choice of aperture if the focusing were to slip whilst changing filters...hoping that a certain aperture would cover any problems.

 

[RobC]

Some light physics reading Rob!

My alignment is fine Pineholemaster, but I've been using maximum aperture for some printing and was nervous about choice of aperture if the focusing were to slip whilst changing filters...hoping that a certain aperture would cover any problems.

If your focus slips the depth of field on the negative will be completely off and depth of focus on the paper will not cover that in any way. Focus on the negative is critical for sharp images.