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EPIC - Backfocus Adjustment Tutorial

J

Jeremy 0sbern

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Hey,

I just wanted to create a thread that made it easy for people to find how to adjust the back focus on their Epics. When our camera came in, the back focus was slightly off. I generally knew how to adjust it, but after doing several searches on Reduser, the most of what I found was "It's easy" or "There's a screw".

It is easy, and there is a screw... but wanted to make it a little more clear for people. The information is not in the EPIC manual. It is, however, in the manual for the RED Focus:

http://red.cachefly.net/REDFocus_draft.pdf

Starting on Page 13, it gives a nice description of how to adjust the backfocus for the EPIC, where the easy-to-adjust screw can be found (on top, next to the row of 1/4" - 20 holes) and the proper screwdriver to use (T-10 Torx).

What it does not say anywhere is that the actual screw to turn is protected by another screw on top of it. Remove the protective screw, and you can see within a small recessed hole the actual screw to turn to adjust your back focus. This protective screw is also removed by a T-10 Torx Screwdriver.

Set mine first off, and it's crystal clear. Hope this helps somebody!

Best,
Jeremy
 
Heh, when I first tried adjusting it I thought my Epic was faulty since turning the screw didn't change anything! Of course I was turning the cover plug, not the back focus adjustment! D'oh!
 
Presume this will apply to Scarlet too. Thank you for posting this!

Stu Aull
Alaska
 
I did the same thing!, the ET top plate still on I slipped the torx in and turned till it stopped and looked at the red focus and said"that doesn't look any different" well the plug had hit the top mount....doooh!!
 
Thanks for the tip. You'd think it would be mentioned somewhere about there being a protective top screw. It would freak me out to remove a screw only to find out there wasn't a protective top screw, then what happens? I'm sure there are stops, i.e. a maximum number of turns before no more adjustment is possible, but how many?
 
Do you HAVE to use the Red Focus to adjust back focus? Can I use a DSC Labs chart to do it too? I think mine is out, but I'm not sure if I MUST purchase the Red Focus to adjust the back focus.
 
On page 13, in that RED Manual, it doesn't say anything about removing a protective screw? I've got a Canon mount pretty much permanently mounted to my EPIC and the whole concept of back-focus scares the be-Jesus out of me. Hopefully, down under, they'll make LEMAC a service centre and solve all the cross-planet problems. That said; that screw on my 'M' isn't removable.
 
Jeremy 0sbern said:
What it does not say anywhere is that the actual screw to turn is protected by another screw on top of it. Remove the protective screw, and you can see within a small recessed hole the actual screw to turn to adjust your back focus. This protective screw is also removed by a T-10 Torx Screwdriver.
Click to expand...

It might be worth noting that this appears to be a difference between the EPIC-X and the current configuration of EPIC-M brains. Our EPIC-X is exactly as you describe, but our EPIC-M has no protective screw. Perhaps this will be adjusted when EPIC-M's are recalled for top mount modifications.
 
Thank you Jeremy for your threat. Some time small things make your life difficult and they are just in front of you.
 
Curt Pair said:
Do you HAVE to use the Red Focus to adjust back focus? Can I use a DSC Labs chart to do it too? I think mine is out, but I'm not sure if I MUST purchase the Red Focus to adjust the back focus.
Click to expand...
Does any one know how to do it in a field.
I'm in the middle of no where with 2 dragons, Cooke s4 set and Optimo 12x1. My B cam back focus is not right. I need to fix it ASAP. What can I do just only using this lenses. Please some one help
 
Karim Belkasemi said:
Does any one know how to do it in a field.
I'm in the middle of no where with 2 dragons, Cooke s4 set and Optimo 12x1. My B cam back focus is not right. I need to fix it ASAP. What can I do just only using this lenses. Please some one help
Click to expand...

Use the widest lens set to infinity, should get you close assuming the lenses ate property collumated.
 
Curt Pair said:
Do you HAVE to use the Red Focus to adjust back focus? Can I use a DSC Labs chart to do it too? I think mine is out, but I'm not sure if I MUST purchase the Red Focus to adjust the back focus.
Click to expand...

Hey curt,

before I had a REDFocus I just used a focus chart on wide lens at about 6 feet or two 2 meters measured from the focus plane to the chart. One thing you could use is a large monitor and get the camera in magnify 1:1 mode in order to see the adjustments you are making. The focus assist tool is handy as well, as that will zero down (show you how close to the center) to the center of the chart as much as your lens resolves.

Cheers,

battistella
 
I'd've thought 8/5.6 might be better as it's the sharpest center on most lenses. With the redfocus this point becomes mute as it projects the chart onto the sensor at a fixed distance and luminance.

Battistella
 
Be careful putting that protective screw back in. I got mine out fine with the top plate on, but I had to remove the top plate to get the screw back in straight. It was cross threading like crazy.
 
Curt Pair said:
Do you HAVE to use the Red Focus to adjust back focus? Can I use a DSC Labs chart to do it too? I think mine is out, but I'm not sure if I MUST purchase the Red Focus to adjust the back focus.
Click to expand...

You do not need the Red Focus, and you may even achieve better results without it. You can simply use a chart, tape measure, and a lens with wide focal length. Obviously you need to use a lens which you know is properly collimated. Also, wait for the camera to reach operating temp before changing the flange.
 
Jamison Stark said:
It might be worth noting that this appears to be a difference between the EPIC-X and the current configuration of EPIC-M brains. Our EPIC-X is exactly as you describe, but our EPIC-M has no protective screw. Perhaps this will be adjusted when EPIC-M's are recalled for top mount modifications.
Click to expand...

Yes.
 
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