proxar lens help

[andrea gazzoni]

Hello, I've recently acquired a 2x Proxar for my Super Ikonta 531/2.
I've searched here and on google but there seem to be little to none information on how to use these lenses.
The Super Ikonta manual includes this table

So I've set the lens focus to 6', put my subject 3 feet (91cm) away from the lens and shot at any f between 4 and 11.
I've shot two rolls, nothing's in focus.. I mean THIS out of focus:

Where am I doing wrong?

thank you for any help
Andrea

 

[KoNickon]

I believe you need to measure the actual distance to the subject, and using the table, determine what focus setting on the camera is needed. So you do need to adjust the focusing distance rather than leaving it alone. I think it's advisable to use a smaller aperture (like f8 or smaller) to cover depth of field.

 

[02Pilot]

If the chart proves inaccurate even with careful measuring, you may have to create your own. It shouldn't be too hard - just set up a ground glass on the film plane and a few objects at known distances, check focus with a loupe, and note the settings.

 

[andrea gazzoni]

in fact the distance lens to subject was determined by a tape measure in each of the 16 shots

 

[VictorM.]

You say you used a 2x proxar. Is that the same as the "F=2 m" Proxar? Or is it one of the other two? It looks as if it might be the "F=.05 m" Proxar.

 

[KoNickon]

If it's the same table I am looking at, and the Proxar is in fact the 2m Proxar as VictorM speculates, then if the subject is roughly 3 feet away, then according to the table you should have set the lens at somewhere between infinity and 48 feet (or the metric equivalent), not 6 feet.

 

[andrea gazzoni]

You say you used a 2x proxar. Is that the same as the "F=2 m" Proxar? Or is it one of the other two? It looks as if it might be the "F=.05 m" Proxar.

how do I know? mine is marked "2x37" on the front rim.
wait... now I see that the tiny reference table inside the Proxar's case mentions a Tessar 13,5cm, while my Super Ikonta has a 10,5cm lens.
Where these Proxars specific to any focal lenght? 😕

Will do the check with the groundglass soon

 

[KoNickon]

Yes, very specific to focal length. That might explain the problem -- not sure which lens or camera yours fits, however.

 

[mburns]

2x is definitely not 2 meters. You need to use the table on the right in your illustration. Use infinity on the main lens and the focal length of the camera will not matter.

 

[andrea gazzoni]

2x is definitely not 2 meters. You need to use the table on the right in your illustration. Use infinity on the main lens and the focal length of the camera will not matter.

I understand I should buy a "F=2m" marked lens instead of a "2X".
Before I trash this lens, I am curious about where do the focus would fall now if I use it and, as you suggest, set the focus to infinity? 1' 7 ¾" ?

 

[mburns]

Yes, the focus is 1'73/4".

 

[Denverdad]

I am not familiar with Zeiss designations, but assuming the 2 in the inscription is the strength of the closeup lens, it must refer either to the focal length (i.e., f= 2m) or else diopters. If the latter, it would imply a focal length of 0.5m, since diopters and focal length are simply reciprocals of each other. Hence, the last column will be accurate at least at infinity focus, as mrburns indicated.

If there is any doubt about the focal length, it is easy enough to measure. Just hold the lens up to and focus the image of a distant light source onto a target (a wall, piece of paper, etc.), and then the focal length can be seen as the distance between the lens and target. You don't have to be especially accurate in doing this either if your goal is just to distinguish between 2m and 0.5m - that difference will be readily apparent! Good luck!

Jeff

 

[andrea gazzoni]

Ok, thank you all for the great help, after putting a groundglass on the camera and checking it with a loupe everything was clear. Sometimes shooting large format really helps, being lucky means to find a spare 6x4,5cm Bronica groundglass that fits the Super Ikonta reducing mask for the same format 🙂

My Proxar "2X" is for a 135mm lens, the rendition I've measured is in fact similar to the "F=0,5m" on a 105mm like VictorM was suggesting but not equal. Here is a table with my findings for the 2X on a 105mm lens, plus some conversion to centimeters for the "right" Proxars for the Super Ikonta. It takes in account a couple millimeters for the positioning of the groundglass, not perfectly flush with the film plane. I hope it can be of some help to anyone using Proxars.
I also started some tests about DOF on the 2X Proxar and found it goes from approximately +-1cm wide open (3.5) to about +-4cm at f16. Talking about shallow DOF 😉
As for the bw sample in the starting post, I was off by about half a meter...
Again thank you
Andrea

 

[Guest]

I have my later Fathers Super Ikonta, same model as yours. I also have a Proxar, the kit has two glass parts, one for the lens and another that goes in front of the rangefinder, it clips over it. they then work in combination together. So are you sure you are not missing the rangefinder glass part.