FIXED: BMCC Speedbooster & Tokina 11-16 Infinity Focus Issue

Wondering if anyone else has had the following issue...

The Tokina 11-16mm II (Nikon mount) on a BMCC Speedbooster either on a BMCC or a BMPCC when wide open at 11mm won't focus to infinity (it's not even close, it focuses to a few feet in front of the lens, nice shallow focus and bokeh though!).

On the BMCC you have to shut the Speedbooster down by around 3 stops to achieve infinity focus at 11mm.

I don't think it can be the lens because on a normal Novoflex adapter there are no infinity focus issues at any focal length or aperture on either camera.

Could this be an issue with this lens and Speedbooster combination? (A design problem?)

It sounds like you are describing this issue:
viewtopic.php?p=34191&sid=ac39d41b25f31cde23e6641ff895c169#p34191

EDIT: Oh, wait: Do Speed Boosters have a back focus adjustment?

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It sounds like you are describing this issue:
viewtopic.php?p=34191&sid=ac39d41b25f31cde23e6641ff895c169#p34191

EDIT: Oh, wait: Do Speed Boosters have a back focus adjustment?

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Not sure.

Same issue being discussed here, apparently some back focusing is possible..

http://www.bmcuser.com/showthread.php?6 ... us-problem

The Speed Booster should be calibrated before it leaves the factory. Brain, the designer of the Speed Booster element, has said on the BMCUser forum that they "using an autocollimator and a master lens with a hard stop at infiinity".

The Tokina is notorious for not achieving infinity focus. I would first test another lens to confirm the back focus issue is with the Speed Booster.

Then contact Metabones who can give you instructions on how to adjust it. It's a pretty simple process. Just need to loosen one screw.

Metabones is closed untill early Feb (Chinese Holidays)

The Speed Booster should be calibrated before it leaves the factory. Brain, the designer of the Speed Booster element, has said on the BMCUser forum that they "using an autocollimator and a master lens with a hard stop at infiinity".

The Tokina is notorious for not achieving infinity focus. I would first test another lens to confirm the back focus issue is with the Speed Booster.

Then contact Metabones who can give you instructions on how to adjust it. It's a pretty simple process. Just need to loosen one screw.

Metabones is closed untill early Feb (Chinese Holidays)

Thanks. I've tested the Sigma 18-35mm and the 8-16mm on the Speedbooster and they're both fine.

Just seems to be the Tokina when wide open and at the wide end (it's sharp when about 3 stops closed or when zoomed in a little). The lens itself is OK when on a standard adapter.

Just seems to be the Tokina when wide open and at the wide end (it's sharp when about 3 stops closed or when zoomed in a little). The lens itself is OK when on a standard adapter.

Then I'd say it's the Tokina that is the issue. It's probably not sharp on the normal adaptor either. The Speed Booster is probably just amplifying the issue that is already there. The Speed Booster will cause an image that is sharp to be a little sharper but it won't make something that out of focus sharp...

I just checked mine and have no such issues. Tokina 11-16mm with the BMPCC specific Speedbooster.

I just checked mine and have no such issues. Tokina 11-16mm with the BMPCC specific Speedbooster.

Thanks. Our is the BMCC Speedbooster but I doubt it would be any different in this regard. Must be the lens, will test it thoroughly with a normal adapter to double check and send it back if it's not focusing properly.

BTW is your Tokina the Mk1 or 2?

I have the Mark 1

I have the Mark 1

Hmm. I need to do some final testing tomorrow but I've checked infinity focus with the lens on a Novoflex adapter and it's fine. Just borrowed a Nikon D40X to test it on and it seems OK, can't properly check infinity focus until daylight tomorrow though. Will be slightly confused if the lens is sharp on everything except the Speedbooster (will be difficult to send it back as faulty too).

How's that 8-16mm work on the Speedbooster? Isn't it way too distorted?

How's that 8-16mm work on the Speedbooster? Isn't it way too distorted?

Not really (matter of taste I suppose).

We got it for architectural/corporate work where we needed very wide shots of buildings and interiors etc.

Used it in quite a few shots in this visitors' guide video...(the other lens used was the 18-35 which was useful in areas of the building with low light levels.)

Also there's a quick test I shot here...



EDIT: The idea behind getting the Tokina is that it's almost as wide but faster and you can put filters on it. Really need it to be able to focus to infinity wide open at 11mm. (Ideal for music festivals etc where you need wide shots of areas at night.)

Good news.

After some advice from Brian C on the BMCUser forum this issue is now fixed.

I tested the Tokina on a standard Speedbooster and found it focused to infinity so decided it must be the adapter (the lens focuses to infinity on everything I've tested it on except my BMCC Speedbooster).

I've adjusted the back focus on the BMCC Speedbooster and it now focuses correctly.

Nice.

Glad it was resolved.

Your video makes me wish my cat had a brother!

I love the 11-16 with speed booster, as I'm partial to wides for run and gun.