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Iscorama 36 questions

greg weisert

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hey guys,

i own a pre-36 iscorama and have some questions. first off, i have a tokina +0.5 diopter. just to understand, how much does this diopter make the iscorama focus closer? normal it is 2 meters and with the diopter is it one meter or how do i calculate that?

i'm looking for another diopter to focus even closer. can u recommend one? how about the +1 from slr magic, does it work fine with the isco?

i find it somehow hard to judge focus with the isco. when i look at the peaking on my gh4 it shows up on elements even though they are nearer or more further away than the distance shown on the scalings of the isco. and sometimes things seem to be in focus but peaking doesnt really show up..maybe u have some advices for me?




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To calculate you take the max and minimum distance and do 1/distance. So if your lens goes from infinity to 2 meters you do these calculations.

1/infinity = 0

1/2 meters = 0.5

So the isco has a 0 to 0.5 focus strength. Next you add the power of the diopter(+0.5) to these numbers, so it now goes from 0.5 to 1.0. Last you divide 1 by the new focus strength.


A +0.5 diopter would be.

1/ 0.5  = 2 meters maximum focus

1/1 = 1 meter minumum focus distance.


If you had a +1 diopter it would be

1/1 = 1 meter maximum focus

1/1.5 = 0.67 meters minimum focus.


And so on...

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  • 3 months later...

Hi Gregory...

How close do you want to get? I'm using an Iscorama pre-36 for macro anamorphic still photography, using objectives from old telephoto lenses reverse mounted on the Isco compression module, used with a variety of prime lenses. I have no trouble shooting down to a working distance of around an inch, with a field width of about .5 inch. I'm not sure whether this would have any value in video production, though. As an example, the front cell (objective) from an old Soligor 450mm telephoto lens (cheap price generally, gives a field width of 5 inches at a working distance of 12 inches when reverse mounted on the Isco, used with my Nikkor-H 85mm.

Art V.

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