#10

My copy still opens up right were I left off.

#1

It is even easier to remove any glare from photos that are printed on textured papers if you also place polarizers over the lights. The filters over the lights must be oriented in the same direction and the one on the camera at 90 degrees to that. Any kind of light source will work. When I did this frequently I used sealed photo floods, similar to the floodlights with built-in reflectors to light you yard.

#2

#4

That was fun, thanks.

(Download)

What evidence do you have of that? I taught high school for 33 years and what you are saying is entirely the opposite of my impression.

That is my next project. I saw how to calculate it in a book by Enrico Savazzi, "Digital Photography for Science." The results from his formula are very different from the Photopills calculator. Looks like I am going to make a few prints. Thanks for you data as well. Which camera are you using it with, sensor dimensions and resolution as a role to play as well.

Thank-you. I surprised how close the two lenses are. I tried averaging your values with mine and when I graphed it the best fit line was a near perfect line. Thank-you for helping me to verify my results.

I wish I were there right now.

(Download)

That calculator is not for macro work. The link that is:

https://www.photopills.com/calculators/dof-macro

asks for the pupil magnification.

Yes, but they require the user to input the pupil magnification ratio, that is what I am trying to find.

I would like to be able to calculate the depth of field with my Canon 100/2.8L macro lens. The formulas are very sensitive to the ration of the exit pupil diameter to the entrance pupil diameter. Has anyone else tried to measure these? The values change with magnification starting near 1 at infinity and going down to 0.41 at 1:1. I placed the lens on a light table and set the focus at the marked magnifications on the lens barrel and measured both the exit and entrance pupil. The values I got were:

Pin Pout M P
∞ 25 25 0 1
1:5 28 24 0.2 0.857142857
1:3 26 22 0.33 0.846153846
1:2 26 18 0.5 0.692307692
1:1.5 27 15 0.67 0.555555556
1:1 32 13 1 0.40625

Where the first column contains the markings on the lens, Pin is the diameter of the entrance pupil, Pout is the diameter of the exit pupil, M is the magnification, and P is the ratio Pout/Pin.

The formula I found for depth of field is: D = 2*CoC*N*(M/P+1)/M^2

Where D is the depth of field, CoC is the diameter of the circle of confusion, N is the nominal aperture, M is magnification, and P is the pupil ratio defined above.

Has anyone else measured the exit and entrance pupils, it was not very easy to do so I am not to sure of the values I got.

Thanks.

Thankyou for all your wonderful comments.