How to photograph a ring all in focus?

Just shot these two. Both are shot at 50 mm f/2, first one from about 50 cm away, second one from about 100 cm. Second one cropped in Lr.

I'd say the focal plane on the second is larger than the first one.

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toxic wrote in post #10115252
DoF, by definition, is related to enlargement. When you crop, you have to enlarge the image more to arrive at the same final viewing size. This reduces the circle of confusion and makes the DoF smaller.

Cropping an image taken with a 50mm lens to the same FoV as a 100mm lens yields the exact same DoF for the same framing. This is proved in the perspective tutorial at the top of this forum.

You said that stepping back and cropping in doesn't increase depth of field. That's wrong. You're getting confused with the cropping part.

If you photograph something that has whatever depth of field in it you care to imagine, you can crop that photograph down to any size you like, but it will still retain the depth of field that was there at the point of capture.

Depth of field is related to focal length, aperture and subject distance. Regarding the original poster's question, if he moves further from his subject, keeping the same settings, his depth of field will increase. He was looking for a way to achieve a greater depth of field.

The fact that it is possible to then change his set-up to re-create the problem by achieving the same depth of field that was causing him the problem in the first place is not much help, is it?

The question regarded how to achieve a greater depth of field to solve a problem, not how to re-create the same problem using alternative set-ups.

Mike

That....that....so...m​akes...no...sense...ah​hhh.
That's like saying that you have a picture hanging on the wall with an entire person's face in focus. Now step up close to it and only the tip of their nose is in focus. How does where you're standing/how close you look at a picture make ANY difference!?

Beat you to it once again

FatCat0 wrote in post #10115369
That....that....so...m​akes...no...sense...ah​hhh.
That's like saying that you have a picture hanging on the wall with an entire person's face in focus. Now step up close to it and only the tip of their nose is in focus. How does where you're standing/how close you look at a picture make ANY difference!?

http://www.dofmaster.c​om/dofjs.html <- Enjoy

anj273 wrote in post #10115373
Beat you to it once again

Yes, I know, BOOYAH!

FatCat0 wrote in post #10115369
That....that....so...m​akes...no...sense...ah​hhh.
That's like saying that you have a picture hanging on the wall with an entire person's face in focus. Now step up close to it and only the tip of their nose is in focus. How does where you're standing/how close you look at a picture make ANY difference!?

Viewing distance changes the size of the out-of-focus disks which are discernable by the human eye, within its 0.5 second of arc limitation of acuity.

Look at this DOF calculator, and it includes viewing distance and the human visual acuity as two factors.

http://www.cambridgein​colour.com/tutorials/D​OF-calculator.htm

My comment was to toxic, not you guys =P

FatCat0 wrote in post #10115404
My comment was to toxic, not you guys =P

Wilt and I are talking about the same thing. DoF is more than just FL, f-stop, and subject distance. CoC is a critical part of any DoF calculation, and CoC is determined by enlargement factor, visual acuity, viewing size, and viewing distance.

Wilt wrote in post #10115389
Viewing distance changes the size of the out-of-focus disks which are discernable by the human eye, within its 0.5 second of arc limitation of acuity.

Look at this DOF calculator, and it includes viewing distance and the human visual acuity as two factors.

http://www.cambridgein​colour.com/tutorials/D​OF-calculator.htm

The theory makes sense. But if you take a look at the pictures posted above, the theory seems to lose some credibility...

I know, I know - It's all just physics, and we can't really argue about it. But the second one of my pictures still appears to have a larger DOF.

anj273 wrote in post #10115061
That's just plain wrong. How in the world would cropping a shot ever change the DOF? Get your facts straight mate

Sorry, but he is correct! Read some texts on DOF and what factors all enter into the DOF perception. It is ALL related to the absolute size of the CofC blurry disks at the viewing distance, and the limitation of human visual acuity. Cropping and then enlarging by a larger amount does indeed magnify the CofC blurry disks so they can be better perceived by the human eye.

In truth, alteration of FL and distance has greater affect on DOF when the distances are close, then when the distances are quite long...it is a CURVE, not a straight line relationship. So changes from 2' to 20' (with proportionaly FL change) are much more of a change than the almost-nothing change from 200' to 400' subject distance

Wilt - Look up

Perhaps reading a text book written by professors at the Rochest Institute of Technology would convince those who doubt the truth!

It does appear here that people are arguing that to move back from your subject, i.e. increase the distance to the subject, whilst keeping the same aperture and focal length (and same camera body) doesn't increase the depth of field.

That's nonsense!

Mike