Getting Tokina 11-6mm F2.8 to work on BMCC EF

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alanfocus

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Getting Tokina 11-6mm F2.8 to work on BMCC EF

PostWed Jan 22, 2014 9:16 am

As many of you have discovered the Tokina 11-16mm (which is a fantastic lens for the BMCC) does not usually focus to infinity. I recently purchased this lens and had to wait a week for it to arrive. While waiting the shop lent me their demo model. On checking it out I found it was not even close to reaching infinity (at 11mm infinity was focusing at less than 3 feet and 16mm at about 6 feet), the lens was unusable. I tested it on 3 BMCCs and 4 Canons all failed to get to infinity even at F5.6. As it was not my lens there was nothing I could do with it.
When my lens arrived i checked it out to find it was just a little short of infinity, 11mm would make it with a stop of F11. It was good on my 5Dmk. 2. Not good enough for the BMCC, but the images in focus looked really good so I decided to solve the problem rather than return it.

Here was my solution.

Firstly, I should point out that I do have professional experience. I am not a lens technician but am a 1st. AC with 36 years experience and over 120 movies and major TV series behind me so I do understand the issues.

Looking at the camera I could see adjusting the flange depth myself was not an option (I was impressed with the sturdy build of the mount though) so that left adjusting the lens for the BMCC. I was OK with this as I didn't mind the lens focusing through infinity on my Canons as the autofocus worked on phase detection.

For those brave enough the following is on your own head. I decided to remove a couple of shims (there were about 8 of various thickness behind the mount).

It is not difficult to do but do it carefully.

Firstly remove the 3 screws holding the mount to the lens. Next the 3 black screws holding the black baffle inside the mount. lastly with great care remove the 2 screws holding the electronic connections in place.
The mount can now be removed but note the red dot alignment to the red notch on the outside of the lens.
The shims are now visible.
How much to remove? This is were my years of experience came in. I knew it wasn't too far off so I just took out the first 2 very thin shims and put the lens back together and tested it.

I got lucky, it was bang on. Even the distance scales were almost perfect but I was prepared to readjust if necessary. As I expected autofocus infinity on my 5D is now at about 7 feet but thats OK.

To sum up, this is a great lens for the BMCC and worth the effort.

P.S. Iknow the lens is not full frame for the 5D but is still somewhat usable on it for stills.

Good Luck
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Tom

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Re: Getting Tokina 11-6mm F2.8 to work on BMCC EF

PostWed Jan 22, 2014 9:23 am

Sounds like their demo model was from before the infinity focus problem had been fixed on the cameras. My BMCC arrived in March 2013 and the tokina focuses to infinity just fine.

The best and safest thing to do is to post the camera back to Blackmagic and they will adjust it.

Also, thank you for posting the helpful guide, but it has been posted before with photos.
Tom Majerski
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alanfocus

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Re: Getting Tokina 11-6mm F2.8 to work on BMCC EF

PostWed Jan 22, 2014 10:04 am

I accepted when buying the BMCC that there would be tolerance issues and fine adjustments would be difficult if not impossible.
Sending back the camera would mean paying shipping from Ireland, this is a lot cheaper and it works.
Also I am convinced agter checking a few Tokinas that there are variations there too.
For me it was easier to just sort it myself. No downsides.
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adamroberts

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Re: Getting Tokina 11-6mm F2.8 to work on BMCC EF

PostWed Jan 22, 2014 10:18 am

Tom wrote:Sounds like their demo model was from before the infinity focus problem had been fixed on the cameras. My BMCC arrived in March 2013 and the tokina focuses to infinity just fine.


Tom he had a demo lens not a demo BMCC.

The Tokina is notorious for having infinity focus issues. It's not unique to the BMCC. It has issues on RED, Canon, etc. Some are spot on, others way off.

Last year Christian Schmeer and I tested 2 Tokina 11-16mm lenses on 2 different BMCCs. His lens was way off. At first we thought it might be the adaptor.
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alanfocus

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Re: Getting Tokina 11-6mm F2.8 to work on BMCC EF

PostWed Jan 22, 2014 2:29 pm

Sorry, should have made clear it was the lens that was a demo.
Also I have 3 BMCCs so it would have meant returning all.
All my other lenses work great on the cameras as is, so happy days!
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Dustin Svehlak

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Re: Getting Tokina 11-6mm F2.8 to work on BMCC EF

PostWed Jan 22, 2014 3:00 pm

Just to reiterate, the Tokina 11-16mm has a wide variance in the manufacturing process that can lead to infinity focus issues. I personally have the DX II lens and have no issues, but there is nothing consistent about the quality for this lens.
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Tom

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Re: Getting Tokina 11-6mm F2.8 to work on BMCC EF

PostWed Jan 22, 2014 3:45 pm

adamroberts wrote:Tom he had a demo lens not a demo BMCC.



ah silly me, apologies I should not skim read.


Bring on the Samyang 10mm 2.8! My tokina is soft even at near focus.
Tom Majerski
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adamroberts

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Re: Getting Tokina 11-6mm F2.8 to work on BMCC EF

PostWed Jan 22, 2014 7:01 pm

Tom wrote:
adamroberts wrote:Bring on the Samyang 10mm 2.8!


It does look like a good option for the BMCC. Pity the lens hood is fixed...
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Tom

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Re: Getting Tokina 11-6mm F2.8 to work on BMCC EF

PostWed Jan 22, 2014 9:14 pm

adamroberts wrote:
Tom wrote:
adamroberts wrote:Bring on the Samyang 10mm 2.8!


It does look like a good option for the BMCC. Pity the lens hood is fixed...



Perhaps they will release a Cine version with removable hood.....a guy can dream.
Tom Majerski
http://tetragrade.com/
http://www.imdb.com/name/nm5157752/
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joechiazza

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Re: Getting Tokina 11-6mm F2.8 to work on BMCC EF

PostWed Jan 22, 2014 9:47 pm

I didn't love the 11-16. Sold it. Waiting for the 10mm rokinon.


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