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Back focus issues with my Tokina 11-16

M

Mike Quill

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Sometimes when I go to use my Tokina 11-16 EF mount on my Scarlet I'm unable to focus to infinity (both in manual and auto focus). The issue seems to come and go, though, because sometimes I can get infinity focus. I'm wondering if this is a back focus or electronic issue? I use both PL and Canon mount glass, so is it possible that the back focus got screwed up after switching mounts? In general, when would you consider checking the back focus on RED?

Thanks,
Mike
 
So what is the root of the issue? Is it something wrong with the lens? Or could a firmware upgrade fix this issue?

Thanks,
Mike
 
I think it's the lens, some copies are bad and some are good, because there are infinity focus issues on other cameras too.
 
For my particular copy of this lens I had to tweak the back focus to grab infinity at 11mm.
 
Maybe the cine versions of the lens will be a bit better. Just hope they offer a pl mount. I guess buying one from duclos will ensure quality but I still think the price is a bit steep given the lens prce. Dont mean to undermine work done during rehousing but I think that its reality. Even Tokina wll offer the cine vrsion around 2k.
 
Tokina issue

Tokina issue

I have seen this problem with the standard version of this lens myself some times tweaking the back focus helps. How ever I have not seen this problem in the duclose version.
 
Kirk.Attard said:
Even Tokina wll offer the cine vrsion around 2k.
Click to expand...

And Tokina will still only offer it with a plastic housing and brass EF or F mount.
A billet aluminum, anodized housing with a stainless steel mount manufactured in the US is usually going to be more expensive than a lens made of plastic and brass made in Japan.
 
I have a bit of experience with the Tokina 11-16mm....
The back focus is usually out of spec from the manufacturer. It can be adjusted to an extent but there isn't any simple shim to add or remove like a cinema lens. Adjusting the back focus on the Tokina 11-16mm can also effect front focus and flatness of field which also need to be tuned to correct for any adjustments made in back focus. I think a lot of people were seeing this issue with the Blackmagic cam at first, possibly because the spec was a tad bit farther out on their Canon EF mount. Which brings the next potential error. If the flange depth on your Canon EF mount Red camera is slightly off, your lens will have issues obtaining infinity focus. Most people don't see any issues because they would be using a Canon L-series or other EF mount lens which is designed to travel well through infinity to allow for error in manufacturing. Great for auto-focus photography... Not great for cinema.
 
Hi Matt. I know you put great care in your work and use the best materials for your lenses. In fact I pointed him to you because I'm sure you hand pick the lens before you rehouse it. I'd much prefer an anodized housing of course. Would be much more comfortable handing out a duclos 11-16 to a dp than the one I saw at NAB. But in this day and age prices are what they are. Competition is everywhere for good and bad. everyone to his budget and preference. But please in no way I meant to disrespect your work or somehow implied that its not priced fairly.
 
This issue goes further than RED cameras.
its been an issue with BMCC as well.
Anyone want to buy a used Tokina 11-16mm :)
 
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