Flange distance issue

Lenses have marks
3 meters wouldn´t be 3 meters anymore, infinity not infinity
That´s why red cameras have a backfocus adjustment which is user controllable. But you can´t expect this form a 2200 € camera.

This FIX also breaks some lenses because it means those that have accurate witness mark, and hard stops at infinity will no longer be accurate once the BMCC is "fixed". A lot of lenses that haven't worked ALSO have versions that do...

jb

In what way would shortening the flange distance affect these accurate lenses? Wouldn't it just make them go past infinity?

Christian, did you miss your morning coffee? John just told you how accurate lenses witness marks would no longer be accurate. They will focus but not at the same distance settings as the lens markings would indicate.

Rick Lang
Sent from my iPad using Tapatalk HD

This FIX also breaks some lenses because it means those that have accurate witness mark, and hard stops at infinity will no longer be accurate once the BMCC is "fixed". A lot of lenses that haven't worked ALSO have versions that do...

In what way would shortening the flange distance affect these accurate lenses? Wouldn't it just make them go past infinity?

Christian, did you miss your morning coffee? John just told you how accurate lenses witness marks would no longer be accurate. They will focus but not at the same distance settings as the lens markings would indicate

I didn't get how this can be the case with still lenses though, if Canon themselves seem to shorten the flange distance a little (see below)? So if I understood correctly, after the adjustment/fix the distance markings won't be accurate on the BMCC, but they aren't on the 5D, 7D, and C300 either anyway?

When I tried the same collimated lens on some 5Ds, 7Ds and even a C300, the witness marks fall short of the expected distance which indicates to me that there's some fair amount of tolerances built into the Canon cameras to cater for still lenses where the tolerances are not as critical as cine lenses.

Witness marks being off or not accurate are not going to be a problem for most DP's as they pull their own focus and use a monitor or evf to get accurate focus, a 1st Assistant /Focus Puller on the other hand may rely on the marks to judge focus and depth of field.
I doubt many of us including me will ever need to worry about the lens markings being accurate.

http://www.theblackandblue.com/2011/04/ ... surements/

I didn't get how this can be the case with still lenses though, if Canon themselves seem to shorten the flange distance a little (see below)? So if I understood correctly, after the adjustment/fix the distance markings won't be accurate on the BMCC, but they aren't on the 5D, 7D, and C300 either anyway?

Correct.

SOME lenses are, but because they are STILLS lenses designed to be autofocused quickly that have NOW started to be used for VIDEO, they tend to have a WIDER tolerance range.

In stills, no one ever ever cares if the witness marks lined up. A lot of cheaper and even medium range Canon lenses don't even HAVE witness marks.

Most 5D shooters get Follow FOcus gears, but again, because a lot of the AF rings on these lenses are continuous, it's never mattered that they don't line up. Its not that they SHORTENED it. it's that the lenses have a wide tolerance in manufacturing from lens to lens.

The FFD is the most crucial in WIDE lenses and at LOWER apertures. So the Tokina is very critical, and it seems Tokina have even LESSOR tolerances. There are many stories with this lens not hitting infinity on other cameras before the BMCC floating around.

Deliberately shortening the FFD on the body of a camera that doesn't have a user adjustable FFD is a way to allow these lenses to work.

I'm pretty sure people would yell louder if they didn't do this *fix*.

jb

I wonder, out loud, how well CPs would line up witness wise on these fixed BMCCs.

I wonder, out loud, how well CPs would line up witness wise on these fixed BMCCs.

I'd love to answer.

My BMCC's are all *hand calibrated* not at the factory so my experience doesn't tell much here.

At least with CP's if you really wanted to, you could SHIM the lenses to the FIXED mount and have them accurate then.

jb

[CaptainHook]

My BMCC's are all *hand calibrated* not at the factory so my experience doesn't tell much here.

Are they calibrated to the new 'fixed' point, the original position, or something else?

I'm leaving mine 'as is' as it works with most of what I've tried so far.
My Tokina is a pain, but I just stop down and its fine - and that makes sense if I need to focus to infinity.

My BMCC's are all *hand calibrated* not at the factory so my experience doesn't tell much here.

Are they calibrated to the new 'fixed' point, the original position, or something else?

Guestimation standard.

JB

[CaptainHook]

Guestimation standard.

I forgot you use to do lens tech work.

Guestimation standard.

I forgot you use to do lens tech work.

Not really. But i did my time in a gear rental company and worked closely with lens techs and saw enough lens problems to last me a lifetime.

JB.

I'm leaving mine 'as is' as it works with most of what I've tried so far.
My Tokina is a pain, but I just stop down and its fine - and that makes sense if I need to focus to infinity.

Not sure why you would risk "leaving yours as is" What lenses are you using, and what Future lenses do you intend to use?

Canon L series
• 14/2.8L MK2
• 24/1.4 MK2

Canon EF-S
• EF-S 17-55/2.8

Canon Non L
• 50/1.4

Non-Canon
• Tonkina 11-16 DX 2.8

Future lens? Man, its going to depend on the gig.

Future lens? Man, its going to depend on the gig.

That's kind of my point, If the gig requires another lens, and lets say you can rent it locally?
or you decide to go ahead and buy it thinking you will make money enough to pay for it from the gig plus some, And lets say you try and use it and it won't focus at infinity? or worse, Now what?

Better get it fixed before a paying gig if it needs it, before you realize you need it fixed during a paying gig.

FYI, I'm only questioning you because you said "it works with most of what I've tried so far".

If you feel comfortable with your findings then ignore my Curiosity.

Point taken.
But I think I'll wait to hear your, and others, experience with their 'fixed' camera first.

Point taken.
But I think I'll wait to hear your, and others, experience with their 'fixed' camera first.

That's cool and a decision I would probably have made if 2 of my lenses didn't have issues.
I updated my post above.

Totally agree with your thinking had I been in your shoes.
But I'm unsure if my BMCC needs fixing yet and it may not need it.
I just need time to try other lens that are listed here that have cause repeatable problems.
So far the only lens I have had my hands on that's caused infinity focus issues is a lens I own.
Just my luck!

So far the only lens I have had my hands on that's caused infinity focus issues is a lens I own.
Just my luck!

Well that's the point of Getting it fixed!

I'm confused, but you should consider finding a way to test Rent/Barrow/Steal lenses you think you may purchase in the future.

Forget what "John Brawley" is saying here with his "hand calibrated lenses" since his lenses are not your lenses, get your camera fixed!

Sorry John but I think your posts are confusing people, and the fact is you received the BMCC many, many, months before Manufacturing was an issue.

I hope there is no need for a "MASS RECALL" and or something worse.
And I understand tolerances and the fact Tokina may have a QC problem.

yea well, I have decent gig for a wine client in a couple of weeks shooting the grape harvest down here in NZ. So plan to beg, borrow, steal some lens for further testing before then. Will post the results here.
Your camera must be due back any day? Keep us posted.

yea well, I have decent gig for a wine client in a couple of weeks shooting the grape harvest down here in NZ. So plan to beg, borrow, steal some lens for further testing before then. Will post the results here.
Your camera must be due back any day? Keep us posted.

Yeah I'm sorry Cam, I didn't mean to put you on the hot seat.

have fun on your shoot, and drink "little" sips of wine, or you may find your focus way off

My camera may as well be in the twilight zone, They have it, I don't, But hey 10 days has come and gone, lets see how many days it takes, I'll post the time it takes, and the results,
In the words of "Cajun Chef Justin Wilson" "I Guarantee!" >>

!

This is Kinda like how many licks it takes to get to the center of a tootsie pop! nobody knows!

another parody version

hey, no sweat. What's the bet your camera arrives tomorrow. Think positive.

This cajun chef is laugh!

Ha! Nice.

Ha! Nice.

Yeah!

[CaptainHook]

yea well, I have decent gig for a wine client in a couple of weeks shooting the grape harvest down here in NZ. So plan to beg, borrow, steal some lens for further testing before then.

Let me know if you're up in Auckland sometime, we can go dual BMCC shooting.. haha.

yea well, I have decent gig for a wine client in a couple of weeks shooting the grape harvest down here in NZ. So plan to beg, borrow, steal some lens for further testing before then.

Let me know if you're up in Auckland sometime, we can go dual BMCC shooting.. haha.

Definitely will Capt.Hook. And what the heck are you doing up at 4.50am in the morning? Even my kids don't wake me that early. Gotta job on?

Thanks for posting all your test footage and the shots of your shoulder rig. How do you find the balance?

[CaptainHook]

Maybe you don't have your forum settings set for NZ time? That was posted at 8am.

Balance is pretty good so far, want to get the cam slightly back more and figure out faster switching for going to sticks/jib/steadicam etc. Looking at maybe using those low profile manfrotto plates for a cheap option.

//Way off topic here sorry..

Yea, sorry, will re-post in the gear thread.

I'm definitely interested in the fix but don't want to "break" other lenses. Like other users, I'm going to wait to see what happens when these "fixed" cameras start to return from BMD. I don't own the Tokina 11-16 yet but was planning to purchase one along with either the Canon 17-55 or the Sigma 17-50. I'd hate to have one of these other lenses not work as well because I wanted the Tokina to focus correctly.

I wil be holding off on any lens purchases or returning my camera until there is more conclusive data about this fix and how it effects other lenses. Thanks for your input

I'm definitely interested in the fix but don't want to "break" other lenses. Like other users, I'm going to wait to see what happens when these "fixed" cameras start to return from BMD. I don't own the Tokina 11-16 yet but was planning to purchase one along with either the Canon 17-55 or the Sigma 17-50. I'd hate to have one of these other lenses not work as well because I wanted the Tokina to focus correctly.

I wil be holding off on any lens purchases or returning my camera until there is more conclusive data about this fix and how it effects other lenses. Thanks for your input

Returning the camera if you are not using it is Highly suggested by...Well Me!

Mine was sent in to deal with the back focus issue a full month ago and I still didn't get it back!!!!

BM in Fremont, CA rec'ed ours on 3/6 and we received it back yesterday on 3/27.

So it was roughly 16 biz days. I was updated several times by BMCC customer service as well as rec'ed FedX tracking info.

BM took care of freight costs both ways.

I mounted the Tokina 11-16mm and set the lens at 11mm/2.8f - have not had a chance yet to offload and closely inspect the infinity focus on a large monitor yet, but from the BMCC LCD panel it appears to infinity focus.

All in all I am quite happy with BM handling and response to this issue and continue to hold the high opinion of this company and this camera system.

Got my shipping info today!
waiting on the camera to arrive tomorrow.

Please let us know what lenses this fixed and those it "broke", if any. Thanks

I will test the following:
Sigma 10-20mm 3.5
Tokina 11-16mm 2.8
Sigma 17-50mm 2.8
canon 20mm 1.8
Rokinon 24mm 1.4
Canon 28mm 2
Canon 50mm 1.4
Canon 85mm 1.I forgot
Canon 100macro 2.8
Canon L 80-200mm 2.8

I will test the following:
Sigma 10-20mm 3.5
Tokina 11-16mm 2.8
Sigma 17-50mm 2.8
canon 20mm 1.8
Rokinon 24mm 1.4
Canon 28mm 2
Canon 50mm 1.4
Canon 85mm 1.I forgot
Canon 100macro 2.8
Canon L 80-200mm 2.8

Looking forward to the results, I sent my cam back two days ago.

Please let us know what lenses this fixed and those it "broke", if any. Thanks

The lenses won't "break". It's just that witness marks will be potentially less accurate. They will all hit infiinty though. Most of the lenses listed here don't have accurate witness marks anyway.

JB.

The lenses won't "break". It's just that witness marks will be potentially less accurate. They will all hit infiinty though. Most of the lenses listed here don't have accurate witness marks anyway

Cool, this is good news. So some lenses will not focus without the fix but once the flange fix has been applied to the camera there aren't any lenses that won't focus? I hope that's what I'm reading here. Thanks, John!

I sent my camera on Friday, March 16th. Back today. That's only 7 working days. Thanks BMD!

The lenses won't "break". It's just that witness marks will be potentially less accurate. They will all hit infiinty though. Most of the lenses listed here don't have accurate witness marks anyway

Cool, this is good news. So some lenses will not focus without the fix but once the flange fix has been applied to the camera there aren't any lenses that won't focus? I hope that's what I'm reading here. Thanks, John!

Yes.

With a deliberately shortened FFD, all lenses should focus and hit infinity.

Most witness marks won't be accurate ( but most EF lenses aren't accurate in the first place)

Lenses with a hard stop at infinity ( cine lenses ) will hit infinity before the hard stop.

JB.

Thanks for clarifying, John. I'm not worried about the marks, I just want the lenses to pull the image into focus. Cheers

The lenses won't "break". It's just that witness marks will be potentially less accurate. They will all hit infiinty though. Most of the lenses listed here don't have accurate witness marks anyway

Cool, this is good news. So some lenses will not focus without the fix but once the flange fix has been applied to the camera there aren't any lenses that won't focus? I hope that's what I'm reading here. Thanks, John!

Yes.

With a deliberately shortened FFD, all lenses should focus and hit infinity.

Most witness marks won't be accurate ( but most EF lenses aren't accurate in the first place)

Lenses with a hard stop at infinity ( cine lenses ) will hit infinity before the hard stop.

JB.

That was the missing info I needed. The Tokina 11-16 also has the hard stop at infinity and I kept having the unpleasant feeling I needed to go past the hard stop to focus correctly. Even if it was o so little. I too sent it back.

thnx JB.

Any news about Cameras with the flange adjusted?

How are your lenses performing now?

yes, was wondering that too.
Darryl a.k.a: pain in the neck, did you get your camera back man?
Fixed? or still with problems on various lens?

I've picked up a new BMC this week and sadly the flange distance is not set right and the battery is going down from 100% to 0% under half an hour. Luckily I can change the shims in my CP.2's mount so there is just the battery problem left

yes, was wondering that too.
Darryl a.k.a: pain in the neck, did you get your camera back man?
Fixed? or still with problems on various lens?

Hi Cam,
I had it on Craigslist before It was even returned, and sold it literally the day I got it back for $3650.00
Not sure if the flange repair was worth the 4 1/2 to 5 weeks wait since I never tested it with my lenses, the guy who bought it knew I had just got it back from the repair since I kept the return box unopened and showed him the online delivery time & Date, and he had a Canon 24-70mm that seemed to work fine @infinity when he tested the camera, so he was satisfied. Wish I could be more help, but now I'm going to buy the Production & Pocket Cameras, I hope I made the right decision since I never did get a chance to even shoot anything with the cinema camera after All I went through..Uhgggg

On the upside I did make a profit for all the hassle.

Oh Darryl! Mate! Holy Frigging Guacamole.
That's a lot of grief for little satisfaction.
Here's hoping you actually get to shoot something with 4K and Pocket versions!
Thanks for letting us know though

:o Oh Darryl! Mate! Holy Frigging Guacamole.
That's a lot of grief for little satisfaction.
Here's hoping you actually get to shoot something with 4K and Pocket versions!
Thanks for letting us know though

Not really that much grief,
I have some third eye intuition about NAB every year (lets not turn that into a quote ) I knew that BMD Had another Camera ready, Not sure how... but I knew, So I sold both of the BMD Cinema Cameras on that intuition and made a decent profit, No big deal, A gamble really.

Nice hearing from you again Cam, I'm here if you need anything.

Cheers

Well, that makes you smarter than me. I really didn't expect either.
Least you made a profit and can put it towards the new cameras.
Will stay in touch.