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Rectimascop 48 2x focusing problems / adjusting?


varjohukka
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Hi,

I recently got a Rectimascop 48 2x and I'm having problems getting sharp images with my GH4. As a taking lens I tried a Nikkor 50mm 1.8, Nikkor 50mm 1.2, Nikkor 85mm 1.8 and a Helios 44 58mm 2.0. I saw several videos on youtube/vimeo using the GH4 with the Helios 58mm and the Rectimascop 48 and they seemed to be pretty sharp (sharper than my tries at least).

The Rectimascop is attached to the taking lens as close as possible by a filterclamp and I make sure it is rotated such that the image doesn't skew.

I can't seem to get a sharp image if I don't stop down to f8 or further on my taking lens. Trying to focus on a target wide open and stop down later, like some guides suggest, is impossible. Even at 2.8 I only manage to either get my focus plane slighty unsharp with round bokeh or only the horizontal or vertical plane sharp with a weird pointy 45° bokeh. (Focus distances I tried ranged from 10m to infinity)

I focus by focusing the taking lens first, trying to dial in the distance to the target. Then I adjust the anamorphot until I get a fairly round bokeh at the distance I want to focus. Now I carefully adjust the taking lens and the Rectimascop and vice versa until I can't get any sharper. It is only at f8 and smaller that I get a resonably sharp picture.

Now my question is: Am I expecting too much? Can I only use the Rectimascop stopped down to f8 and smaller if I want sharp pictures? Or maybe there is a problem with the anamorphot? (I thought that maybe the front and back lens are not 100% alligned, is that possible?) User error?

I would be glad for some help/advice. I'm fairly experienced with cameras and filming but an absolute newbie with anamorphotic lenses.

Thank you,

varjohukka

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Thank you, that sounds promising. Is that something you can try and do yourself? I assume you have to unscrew the back lens, rotate it and maybe even adjust its distance? And you probably need a grid or something to aim the lens at...with my luck, I knock it even more out of allignment... :)

 

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Here's some tips for u, maybe it will be helpfull: take some long focal lens and set it in focus (as much as possible in current condition) with rectimascope, u can use page with small font text as a focus target, loose the screws on a back lens of rectimascop, put rubberglove and place two fingers on opposite sides of a glass so there is space in between so u can see a result of your rotations in liveview (of course set it to max zoom). When u get a best sharpness press a glass tightly so it cant rotate anymore, put rectimascope vertically and tighten it. Then check sharpness again using liveview. Thats how i set sharpness with my d.o.industries 16f, things were easier for me because i rotate front glass, but i hope that scheme will work for u to)

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1 hour ago, varjohukka said:

Thank you, guys! That totally did the trick. Now it's sharp even with the 50mm @ f1.2  (well as sharp as it gets at this aperture). I'm excited :)

Enjoy it) And now its time to find out that u need a positive diopters to focus closer than 4-5 meters. So give u another tip how to place it on rectima: unscrew front outer metal ring and u can use that thread - its standard diameter, dont know exactly number but i have 82mm lens hood that perfectly fits on that thread with front. And then u can easily screw 82mm diopters on a back of placed lens hood or use step-down (actually step-up ) rings to use any diameters u like

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Yeah I got it with a filter adapter clamp and a +4 diopter filter which enables me to focus pretty close but I think I'll need another less strong diopter to cover the range between 3m-5m. I have yet to measure exactly which range it covers though.

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