HOW TO ADJUST THE BACKFOCUS ?

[Mark Andersen]

My New CF Weapon has serious backfocus issues, I've tested on all the mounts I have, including the new MG PL Mount and results are the same. I can't seem to find info on how to fix this myself, I've found the "back focus adjustment screw" but turning it didn't seem to do anything, it just loosens up. What am I missing?

 

[Matthew J]

My New CF Weapon has serious backfocus issues, I've tested on all the mounts I have, including the new MG PL Mount and results are the same. I can't seem to find info on how to fix this myself, I've found the "back focus adjustment screw" but turning it didn't seem to do anything, it just loosens up. What am I missing?

If it's like the Epic, then there is a top screw that you actually screw out and then the adjustment screw is below it.

 

[Patrick Grossien]

If you need to do it manually without the red focus, you need a lens of which you are sure is working perfectly.
Set a focus chart / Siemens star to 6feet or 2m and measure the distance from the focus plane of the camera. Set the lens to its sharpest aperture and set the focus to the measured distance. Now adjust the screw until the chart appears sharp.

 

[Phil Holland]

If it's like the Epic, then there is a top screw that you actually screw out and then the adjustment screw is below it.

It's right near the medallion on the front of the camera on DSMC2 bodies. Way easier to get at.

 

[Patrick Grossien]

If you just need to know how to use the screw, go to

https://www.red.com/downloads?category=Documents&release=final

And download the manual for the RED focus

Current document page 13 is for weapon http://s3.amazonaws.com/red_3/downloads/manuals/RED_Focus/RED_Focus_Operation_Guide_Rev-D.pdf#page13

 

[Jacek Zakowicz]

I might add that the wider the lens (zooms are the best with the fast aperture and long zoom range combo), the closer you are and the faster the lens will make your adjustments more presise
why?
closer distance- less depth of field
Faster aperture- same less depth of field
wider lens- less depth of focus. both the depth of field and depth of focus are your "enemies" for precise back focus adjustment...
Zooms allow you to set the front focus first on the long end (with the lens focus ring) and when you zoom out the focus goes out so it makes it easier to see...
also with zooms you are not tied to the scale- just make sure the long end and wide end are both sharp when you zoom out...
hope that helps...

 

[David Battistella]

Good thread to read here.

http://www.reduser.net/forum/showthread.php?67871-EPIC-Backfocus-Adjustment-Tutorial

I highly suggest

- you window the sensor and put the camera in 2K mode
- map a key to magnify when setting the back focus
- Get a large monitor if possible
- create a a higher contrast look file can help
- set your monitor sharpness to about 80% in the look menu
The rest of the stuff is obvious
-wide (ish) sense to set the back focus, then check your other lenses.
Use a good chart, etc.

Once you have it set it should be set for all mounts as the various mounts are set for the flange focal distance of those lenses.

David

 

[Mark Andersen]

Thanks very much to all, dummy me didn't know that there was a screw covering the actually back focus screw. BTW I had to do several rotations to get is right, it seemed my back focus was WAY out of whack.

 

[Greg M]

Thanks very much to all, dummy me didn't know that there was a screw covering the actually back focus screw. BTW I had to do several rotations to get is right, it seemed my back focus was WAY out of whack.

Not necessarily, its a very fine adjustment so it will take many turns for a basic adjustment.

 

[Nick Fury]

In addition to the BD screw's easier accessibility, tech has told me that the BF adjustment has a more robust ability to hold its adjustment.

Also, remember that RED does a BF adjustment prior to sending the camera out-either new purchase or service.

Thank you very much

Fury

 

[roryhinds]

Can you adjust the back focus while the camera is powered on and running?

 

[Tommaso Alvisi]

You have to...

 

[Christoffer Glans]

Can you adjust the back focus while the camera is powered on and running?

How else would you know that you hit the mark? :mellow: