DZOFILM Pictor Zooms on the Gemini EF mount

[Acen Razvi]

Hey,

After waiting a long time for these affordable cine zooms to arrive I finally picked up a pair of Pictor Zooms for the Gemini.

They vignette "slightly" not as bad as the Sigma 18-35 but it's there...

I just really like the image these lenses produce - not overly sharp or clinical and has some character along with really interesting, pleasing flares - that was probably the main thing that sold me as I am a sucker for flares, especially on the 50-125.

My question here is - how many of you Gemini folk have also picked these up? and and what are your thoughts on getting perfect 100% par-focal with the EF mount ?

I haven't had a chance to adjust yet - Im not much of lens tech, i haven't really had to test back focus with charts etc much before as mostly rented etc.

The lenses came with a bunch of shims but i just thought'd I throw this thread out there and see if anyone has any notes on ideal number of shims to add for 100% par focal and any other notes you want to share.

Thanks!

 

[James Sielaff]

I'd love to get them. Seems like a great way to turn the Gemini into a solution for fast paced and two camera shoots, while still producing beautiful images.

Have you edited your resolution list in camera to include the 4.5K HD. option? I wonder if that would solve the vignette while maximizing the resolution?

 

[Nick Gardner]

Shims aren't changing the parfocalness of the lens, just adjusting back focus. One would hope they come correctly calibrated from the factory. Make sure your camera has it's FFD set correctly or you will be chasing your tail.

Nick

 

[James Sielaff]

Nick is correct.


In an ideal world, you'll want to make sure your RED DSMC2 has the sensor flange depth adjusted to be accurate first. Then set the back focus of the lens with shims.

DZO manual is on their website, and they give a good formula for making educated guesses as to whether you should add or subtract shims:
http://en.dzofilm.com/upload/202007/29/202007291009472869.pdf

In a not ideal world, just put the lens on and adjust the shims till it stays in focus no matter where you zoom, through trial and error... if it works, it works.

Hope that helps.

 

[Alex Lubensky]

Nick is correct.


In an ideal world, you'll want to make sure your RED DSMC2 has the sensor flange depth adjusted to be accurate first. Then set the back focus of the lens with shims.

DZO manual is on their website, and they give a good formula for making educated guesses as to whether you should add or subtract shims:
http://en.dzofilm.com/upload/202007/29/202007291009472869.pdf

In a not ideal world, just put the lens on and adjust the shims till it stays in focus no matter where you zoom, through trial and error... if it works, it works.

Hope that helps.

Also, it's important to mention - sensor flange adjustment is RELATIVE to the mount you use. No mount is perfect, and you can't adjust the flange to fit all mounts (I have 3 - PL, EF, Nikon F). For example - I've set my flange on sensor in combination with PL mount. EF is not as crucial, unless you are going to use EF cinema lenses. AF photographic lenses usually go past infinity, so longer or shorter flange on my PL mount could easily accomodate also a EF option with photo lenses. I can't use EF cine lenses without readjustment of the flange.

 

[Alex Lubensky]

Also, if you're planning to use motors to rotate focus and zoom, EF mount might be not the best choise. You'll def. want to add a fixed support on the end of the lens.