Backfocus Fix with 1080 output

[cinemano]

Hello, I take it should be easier to do a back focus calibration now we get a higher res output onto a plasma :) Is there any tutorial for doing it risk free?
Im afraid of making it worst.. I sense the nikon mount needs a little adjustment, seems not entirely sharp..

[William Wedig]

I think 1080 is only a playback function, which would make it possible to shoot and then playback to check it but I would think for back focus you would want it live to make adjustments quickly and easily.

Good idea though. What was your thinking on the method to do that?

[Jorge Díaz-Amador]

In my opinion, the only really accurate way to set back focus is to use a sensitive autocollimator and a dedicated test lens (sharp, fast and wide).

Through my collimator I can see a bounce off the pixel grid clearly. Each pixel is only 5.4 µm wide (0.0054 mm). The only way to see that resolution on a monitor would be a 1:1 pixel ratio 4k monitor, and that's not possible at the moment. And I'm talking 4k without debayer.

The type of target and the quality of the test lens greatly influence the accuracy of the result as well. The test lens has to be very accurately calibrated.

While I recognize that RED has revolutionized the industry in a lot of ways, I think that there is a tendency to assume that all procedures that used to be standards in the past can be thrown out too, without considering them on their own merits.

There has never been a film camera where the user expected to be able to change the lens mount himself. The ARRI 35-3 had interchangeable lens mounts (ARRI Bayonet, PL, BNCR, Nikon and PV-35)*, but they were meant to be changed and calibrated by an experienced technician.

I know I'm speaking heresy here (and I will be putting my asbestos undies on in a moment), but I urge the RED users to consider taking advantage of the services of an experienced technician if you desire a truly accurate back focus calibration.

Here are some photos of a RED ONE being tested on my Möeller-Wedel autocollimator.

http://www.cinematechnic.com/images/digital_cinema/RED_One_on_Collimator.jpg

http://www.cinematechnic.com/images/digital_cinema/RED_LCD_Collimator.jpg

*Panavision PV-35 mounts for the 35-3 were made by Panavision. Nikon mount for 35-3 was made by PED Denz. The other mounts were available from ARRI. I've got a 35-3 for sale with all the mounts except PV-35 if anyone's interested.

[Uli Plank]

IMHO, you don't need asbestos undies, Jorge!
We have to respect the Red One for being a delicate optical instrument. Why should anything regarding optics change with it, when it has been true for all other 35mm cameras? You are just spreading wisdom when making this very clear.

[Gary Ploj]

In my opinion, I urge the RED users to consider taking advantage of the services of an experienced technician if you desire a truly accurate back focus calibration.




Curious, how much would a back focus calibration cost? Say on Nikon lenses or Zeiss stadard lenses? As you can tell, I never did this before...so I'm curious...

Thanks.