Flange distance issue

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Uli Plank

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Re: Flange distance issue

PostFri Feb 08, 2013 9:37 am

It's not simply about "wiggle room". I have used quite a few professional cine lenses and heaps of good stills lenses. They all focus a tad beyond infinity!

It's needed, there are not only inevitable production tolerances, even under tightest QC, but temperature changes as well. Plus, electronic lenses carry looser tolerances than manual ones, that's inevitable not to stress the tiny motors in them. We are talking fractions of a millimeter here, and even the combination of materials used for the lens mount and the ones carrying the sensor matters when heat or cold strikes. The RED One suffered from that, but at least you could adjust it yourself. They cured it in the Epic/Scarlet with a better choice of materials, which are compensating each others temperature effects, but they still have an (even better) mechanism for adjusting flange distance.

The BMCC has no such provision, but it needs even higher precision, since we need shorter focal lengths for the smaller sensor. Flange distance is more critical the wider the lens is, that's why we see it in the Tokina at 11 but not at 16mm.

I have compared the same lenses on an Epic which was carefully adjusted for flange distance by a professional service and the BMCC, using adapted Zeiss Contax primes and the Tokina. All lenses focus a tad beyond infinity on the Epic, but the witness marks are dead on. The same Contax lenses focus just to infinity on the BMCC at room temperature, and they are not as wide (obviously) as the Tokina.

Sorry, BM, but we have a problem here. There are not many choices to replace the Tokina, which is very good for it's price on RED and very attractive if one chooses the EF version of the BMCC. I hope the MFT version will do better, I'm looking forward to use the beautiful lenses from Cosina/Voigtländer.
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Felix Steinhardt

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Re: Flange distance issue

PostFri Feb 08, 2013 1:18 pm

Oops, that doesn´t sound good at all!

I have just bought the Nikon 10-24mm and if it turns out it doesn´t work, I´ll sell the camera right away.

What are the wide angle options anyway?
The Sigma 8-16 seems to work but is totally slow and Sigma...
Tokina 11-16 -> No luck, even some Nikon version don´t work, so it´s not worth a try.
Nikon 10-24 -> We´ll find out when I get mine, but since I´m European that will be Xmas 2013.
Canon 10-22 -> No luck, no iris control and no tests if it reaches infinity.
Tamron 10-24 -> Received the worst reviews by customers because it´s so soft.
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Uli Plank

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Re: Flange distance issue

PostFri Feb 08, 2013 2:24 pm

I had the chance to test another Tokina 11-16 sample.

Turns out that the issue must be on both sides: this one is even worse on the BMCC, but barely touches infinity @ 11mm even on the RED Epic, while ours is safely getting there. Sample variation seems to be massive with these Tokinas, I can understand why professionals swear on getting them re-housed to PL by Duclos. The glass is great, but mechanical precision seems to be a game of luck. If we only could adjust flange distance by ourselves…
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Kholi Hicks

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Re: Flange distance issue

PostFri Feb 08, 2013 3:40 pm

If you google around you'll find that the 11-16 has issues in general, always has.

Another user reported that his Canon 28/2.8 couldn't infinity, but my 28/1.8 USM does. Slightly beyond, in fact.

I don't think it rests only on the camera.
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danap

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Re: Flange distance issue

PostFri Feb 08, 2013 3:47 pm

unlikely? ...MURPHY'S LAW....
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Marshall Harrington

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Re: Flange distance issue

PostMon Feb 11, 2013 4:34 pm

Kristian Lam wrote:
MarshallHarrington wrote:
Kristian Lam wrote:Also if the problem is with the lens, is it possible for Blackmagic to be in contact with Tokina's engineers to find a transparent solution to the problem that all of us can rally to. No one is in a better position than you.


Yup, I'll see what I can do.


Kristian . . . just wondering if you are having any luck with contacting Tokina?

I've been wondering if Matthew Duclos is following this post? I'm planning on sending him a Tokina for a Cinemod and knowing that they have a somewhat rebuilt Tokina of this model he might be an authoritative voice to weigh in on.

Thanks again for your getting into all this.
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Abobakr M. Alshiblie

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Re: Flange distance issue

PostMon Feb 11, 2013 7:11 pm

MarshallHarrington wrote:
Kristian . . . just wondering if you are having any luck with contacting Tokina?

I've been wondering if Matthew Duclos is following this post? I'm planning on sending him a Tokina for a Cinemod and knowing that they have a somewhat rebuilt Tokina of this model he might be an authoritative voice to weigh in on.

Thanks again for your getting into all this.


I emailed the Tokina guys through a message regarding my lens flange distance issue with the Blackmagic and I even directed them a link to the thread in the bmcuser forum, about a week ago but they didn't reply
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Kristian Lam

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Re: Flange distance issue

PostMon Feb 11, 2013 10:46 pm

MarshallHarrington wrote:Kristian . . . just wondering if you are having any luck with contacting Tokina?


I'm still working on it.
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Marshall Harrington

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Re: Flange distance issue

PostMon Feb 11, 2013 11:16 pm

Kristian Lam wrote:
MarshallHarrington wrote:Kristian . . . just wondering if you are having any luck with contacting Tokina?


I'm still working on it.

Thanks Kristian . . . sent an email to Matthew Duclos. Hoping he checks in. He really knows this lens and I'm sure the folks at Tokina as well. That might help.
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Phillip Mortimer

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Re: Flange distance issue

PostMon Feb 11, 2013 11:24 pm

--- Update 5 March 2013 ---

My camera has been adjusted by Blackmagic and I can now achieve infinity focus with all my lenses, including the Tokina 11-16, Voigtlander 40mm and Zeiss 85mm.

--- Original post ---

I have tried a number of lenses from Zeiss, Voigtlander, Nikon, Tokina and Canon on two separate BMCCs. My manual focus EF mount lenses from Zeiss and Voigtlander with a hard infinity stop cannot focus to infinity on either BMCC. My Nikon mount manual focus lenses cannot focus to infinity on the BMCC when used with a high quality Rayqual adapter, but do focus to infinity when used with a cheap eBay adapter. My Canon autofocus lenses all focus past infinity by design, and can all achieve infinity focus on the BMCC. All these lenses can focus to infinity on both my Canon 5D mark III and 500D.

Results from 1st BMCC received early January. I tested the infinity focus on the camera and put some files here: http://www.phillipmortimer.com/BMCC/. Follow the link and right click to download them if you are interested. The tall building in the background is the Tokyo Metropolitan Government building which is approximately 5km from my apartment and is my infinity reference.
    01 Nikon 28mm f2.8 Ai-S with high quality Rayqual Nikon to EOS adaptor. Furthest focus ~10m.
    02 Nikon 28mm f2.8 Ai-S with cheap eBay adaptor which is too thin. Can achieve infinity focus. Indeed you can focus past infinity with this adaptor on both the BMCC and my Canon cameras.
    03 Voigtlander 58mm f1.4 Nikon F mount. Rayqual adaptor. Furthest focus ~40m.
    04 Voigtlander 58mm f1.4. eBay adaptor. Can achieve infinity focus.
    05 Voigtlander 40mm f2. EOS mount version. Furthest focus ~20m.
    06 Zeiss 85mm f1.4. EOS mount version. Furthest focus ~70m.
    07 Tokina 11-16mm f2.8 at 11mm. EOS mount version. Furthest focus ~2-3m.
      As a control, same lenses on other cameras:
    08 Tokina 11-16mm f2.8 at 11mm on Canon 5D mark III. Can achieve infinity focus.
    09 Voigtlander 40mm f2 on Canon 5D mark III. Can achieve infinity focus.
    10 Zeiss 85mm f1.4 on 5D mark III. Can achieve infinity focus.
    11 Tokina 11-16mm on 500D. Can achieve infinity focus.
I contacted Blackmagic support in Japan who were fantastic and arranged for the camera to be replaced. I received the replacement camera last week. It has the same problem.

Here are the files for the second camera. http://www.phillipmortimer.com/BMCC2/
    01 Zeiss 85mm f1.4 EOS mount version. Furthest focus again about 70m.
    02 Voigtlander 40mm f2 EOS mount version. Furthest focus again about 20m.
    03 Tokina 11-16mm f2.8 EOS at 11mm EOS mount version. Furthest focus ~1m.
      Again, as a control, on my 5D mark III:
    04 Zeiss 85mm f1.4 on 5D mark III. Can achieve infinity focus.
    05 Voigtlander 40mm f2 on 5D mark III. Can achieve infinity focus.
Last edited by Phillip Mortimer on Tue Mar 05, 2013 11:51 am, edited 1 time in total.
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Cam Macduff

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Re: Flange distance issue

PostTue Feb 12, 2013 9:25 am

Wow, awesome work Phillip, thanks!
Think we're seeing a pattern here possibly when you consider all the other people here with similar results.
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Felix Steinhardt

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Re: Flange distance issue

PostTue Feb 12, 2013 12:58 pm

Your Nikon AI-S lenses have hard stops at infinity, too?
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John Bauer

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Re: Flange distance issue

PostTue Feb 12, 2013 6:40 pm

this is very worrying indeed
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Kristian Lam

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Re: Flange distance issue

PostWed Feb 13, 2013 8:09 am

Hey guys

Just to let you know Phillip has also sent us some data and we are looking into this issue.

Thanks
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Cam Macduff

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Re: Flange distance issue

PostWed Feb 13, 2013 9:10 am

Yah!! Thank-you!
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danap

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Re: Flange distance issue

PostWed Feb 13, 2013 2:51 pm

BMCC owner here. I have a kind of premonition that BlackMagic Design will issue a general recall on all camera models and reinstall a THINNER Canon EF mount ring; or -alternatively ask owners to do it themselves. Your opinion?
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John Richard

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Re: Flange distance issue

PostWed Feb 13, 2013 3:03 pm

I sincerely hope that a resolution such as this is forthcoming.

The one thing that worries me though is that the early beta testers with the original sensor/glass cover did not experience infinity focus issues. Think these cinematographers were straight up and did not see this. Then after the sensor glass issues, this infinity focus issue on many lenses cropped up.

Maybe a new replacement flange would fix this too?

Just adjusted my Tokina 11-16mm/2.8 per the Christian 3-screw method move to the left (Canon) and it did improve somewhat but still not usable at 11mm on our BMCC. But when I remounted on the Canon 7D it works fine at 11mm down to 2.8 iris. Sure seems like a BMCC flange issue.
Last edited by John Richard on Wed Feb 13, 2013 4:35 pm, edited 1 time in total.
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Abobakr M. Alshiblie

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Re: Flange distance issue

PostWed Feb 13, 2013 3:28 pm

John Richard wrote:I sincerely hope that a resolution such as this is forthcoming.

The one thing that worries me though is that the early beta testers with the original sensor/glass cover did not experience infinity focus issues. Think these cinematographers were straight up and did not see this. Then after the sensor glass issues, this infinity focus issue on many lenses cropped up.


I don't think it has anything to do with the glass. Frank Glencairn, one of the early people to recieve his camera is experiencing the same issue with his Tokina 11-16mm
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Felix Steinhardt

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Re: Flange distance issue

PostWed Feb 13, 2013 3:35 pm

danap wrote:BMCC owner here. I have a kind of premonition that BlackMagic Design will issue a general recall on all camera models and reinstall a THINNER Canon EF mount ring; or -alternatively ask owners to do it themselves. Your opinion?


Second option is perfect. Please no general recall that interferes with production.
But they should stop building cameras now (!) and continue with a thinner mount.
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Jules Bushell

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Re: Flange distance issue

PostWed Feb 13, 2013 7:19 pm

I assume this issue won't occur on the MFT BMCC or with an EF adaptor on it?

Jules
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Darryl Gregory

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Re: Flange distance issue

PostThu Feb 14, 2013 3:12 am

Jules Bushell wrote:I assume this issue won't occur on the MFT BMCC or with an EF adaptor on it?

Jules


And I assume this issue should not occur at all with the EF BMCC, I had plans to buy the MFT but after this fiasco I have my doubts, and Just to clarify with Phillips findings the Zeiss 85mm f1.4. EOS mount version. Furthest focus ~70m, I may be getting 73m-75m but need more testing.
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Christian Schmeer

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Re: Flange distance issue

PostThu Feb 14, 2013 3:49 am

Most of my lenses, also the ones that achieve infinity focus or go past it, do not hold focus after zooming on the BMCC (e.g. Canon 24-105mm F/4.0 IS L), whereas they do on my 5D Mark III. Why is that? This was also mentioned by someone else in another thread.
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Scott Pultz

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Re: Flange distance issue

PostThu Feb 14, 2013 4:11 am

Christian Schmeer wrote:Most of my lenses, also the ones that achieve infinity focus or go past it, do not hold focus after zooming on the BMCC (e.g. Canon 24-105mm F/4.0 IS L), whereas they do on my 5D Mark III. Why is that? This was also mentioned by someone else in another thread.


That lens is probably not parfocal (holds focus as it zoom)

http://www.lensrentals.com/blog/2011/02 ... or-video/4
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Alexandre Hotton

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Re: Flange distance issue

PostThu Feb 14, 2013 8:57 am

Christian Schmeer wrote:Most of my lenses, also the ones that achieve infinity focus or go past it, do not hold focus after zooming on the BMCC (e.g. Canon 24-105mm F/4.0 IS L), whereas they do on my 5D Mark III. Why is that? This was also mentioned by someone else in another thread.

I have the same problem with the Canon 16-35 . + flange issue
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Darryl Gregory

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Re: Flange distance issue

PostThu Feb 14, 2013 9:26 am

I hate to get upset and complain but I have no choice this is ridiculous,
$3000 later and half my lenses can not focus @ infinity,
I can not imagine BM would release a camera without thoroughly testing
the flange distance on various lenses, it's like boring a cylinder for a new piston
and not using a micrometer.

It's just not done that way, you must use a micrometer before you bore a cylinder period!

Sadly I think I need to return my BMCC, I'll wait and see what comes in V2.
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Nilscrompton

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Re: Flange distance issue

PostThu Feb 14, 2013 9:45 am

In my case I'm prepared to navigate these 'hiccups', the benefits of this camera vastly outweigh them. I used to shoot on Canon DSLRs and I dont miss the workarounds I had to use with them. There isn't really another option for independent shooters looking for post options. For shoot to finish workflows a C100 might be smoother sailing, but it is still double the price... So the only option is back to the 5D... no thanks.
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Darryl Gregory

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Re: Flange distance issue

PostThu Feb 14, 2013 9:54 am

nilsonium wrote:In my case I'm prepared to navigate these 'hiccups', the benefits of this camera vastly outweigh them. I used to shoot on Canon DSLRs and I dont miss the workarounds I had to use with them. There isn't really another option for independent shooters looking for post options. For shoot to finish workflows a C100 might be smoother sailing, but it is still double the price... So the only option is back to the 5D... no thanks.


I understand how your feel nilsonium,
but I have shot with plenty of cameras, I get hired as a DP, not by what cameras I own,
The fact I own several cameras some on par with.. or below the BMCC, and one that far surpasses it at 6+ times the price is not an excuse for me to keep the BMCC, Simple fact is this camera is still a BETA camera, should have never made it to market till 2014-2015.

Signs of this are obvious!
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Nilscrompton

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Re: Flange distance issue

PostThu Feb 14, 2013 11:41 am

Ah I see. Yes, if you're a working DP I can see that 'hiccups' are the last thing you want, especially if you have an existing set of lenses you're expecting it to work with. I can see your point about it being 'BETA'.

As an aspiring DP, I suppose my market is micro budget music clips, where not having to hire a camera means I get to pocket the hire fee 8-) , and as an actual editor/compositor, I was always going to be fan of the RAW options... perhaps it really is a camera by post people for post people...

Do you have any suggestions for Tokina 11-16mm replacements that aren't going to short focus? I'm sussing out the Rokinon 14mm, but I'm perplexed how to get ND to work with it without a matte box... and the Sigmas seem a bit slow...
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Darryl Gregory

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Re: Flange distance issue

PostThu Feb 14, 2013 11:50 am

I tested my friends Sigma 17-50mm and it is awesome on the BMCC
IS/OS works, The BMCC auto Focus button worked, it is sharp, color is nice, it just worked great all around.
It's Just not very fast--> f/2.8 or wide enough :|
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Bill Rich

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Re: Flange distance issue

PostThu Feb 14, 2013 2:05 pm

I am very happy with the IQ of the BMCC.. but the fact that half my EF lenses don't communicate with the camera.. Now the infinity focus issue has me concerned as well.. I have the 14mm Rokinon cine lens but it's much softer than my Sigma or Canon Lenses so I'm less likely to use it in favor of something else.. ..

I'm waiting for BMD to come up with solutions for these recent issues before I talk about returning my BMCC.. I just can't wait too long before it's too late to return it. I was so excited when I got the camera.. but then discovered that Resolve doesn't work on my computer.. now this.. I need to make up my mind soon.. Please let us know what's going on Blackmagic! I want this camera to work! but I can't spend $3K on a camera that I'm not 100% confident in..

Edit.. I just put in a request to return the camera.. what a freaking shame.. I've waited so long for it!
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cengizözgök

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Re: Flange distance issue

PostThu Feb 14, 2013 4:26 pm

B.T,W
Zeiss 25mm 2.0 works perfect with focus infinity
You can put this lens on the list
Also tried the old version metal canon 50mm 1.8 OK !
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greg fiske

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Re: Flange distance issue

PostThu Feb 14, 2013 7:11 pm

I actu­al­ly have a nag­ging feel­ing the mount of the Black­mag­ic Cin­e­ma Cam­era flex­es with heavy lens­es so if you have infin­i­ty focus issues (like with the Tok­i­na 11-16mm) it might be worth check­ing for this and using rails to sup­port the larg­er lens­es when­ev­er pos­si­ble.
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John Richard

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Re: Flange distance issue

PostThu Feb 14, 2013 8:27 pm

Don't think the weight of the lens is the issue. I and others are using a Canon 70-200mm (a.k.a. "The Magic Drain Pipe") on the BMCC with no barrel support and it infinity focuses fine. This lens is much heavier than the Tokina 11-16mm.

Wished you were right as that would be an easy fix.
Last edited by John Richard on Fri Feb 15, 2013 5:11 pm, edited 1 time in total.
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Scott Pultz

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Re: Flange distance issue

PostThu Feb 14, 2013 8:40 pm

Say it is the flange distance, which sounds like it probably is. Is the front metal piece removable so that it could be replaced? Are the electric contacts spring loaded such that moving the camera closer or further away would still allow contact? I'm assuming that if the distance needs to be change, the actual amount will be very small.
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Nilscrompton

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Re: Flange distance issue

PostThu Feb 14, 2013 9:09 pm

Scott Pultz wrote:Is the front metal piece removable so that it could be replaced?


Yep it's removable via a few screws. I've taken it off and from the look of it there would be at least 1mm that could be made up by replacing this part. I think someone suggested this in another post. So if it isn't possible to simply have the sensor distance adjusted by BM then this would be another simple and fairly low cost avenue. Perhaps even a third party could develop a solution?

In the meantime, I'm looking for a Tokina 11-16 replacement that will focus and accept filters. Anyone with experience with the Canon 10-22mmm or the Sigma 10-20mm?
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Kristian Lam

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Re: Flange distance issue

PostThu Feb 14, 2013 9:11 pm

Hi,

If the focal flange distance is off, we can also adjust it under warranty.

Hang in there while we get to the bottom of this.
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Kristian Lam

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Re: Flange distance issue

PostThu Feb 14, 2013 9:12 pm

John Richard wrote:Don't think the weight of the lens is the issue. I and others are using a Canon 7-200mm (a.k.a. "The Magic Drain Pipe") on the BMCC with no barrel support and it infinity focuses fine. This lens is much heavier than the Tokina 11-16mm.

Wished you were right as that would be an easy fix.


The lens mount of the camera is very solid and flex is not an issue.
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Nilscrompton

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Re: Flange distance issue

PostThu Feb 14, 2013 9:17 pm

Kristian Lam wrote:Hi,

If the focal flange distance is off, we can also adjust it under warranty.

Hang in there while we get to the bottom of this.


Thanks for posting this Kristian, this actually makes me feel a lot better! :)
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John Richard

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Re: Flange distance issue

PostFri Feb 15, 2013 3:02 pm

I also thank Kristian Lam for weighing in. Surely helps to know that BM folks are on it.
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Bill Rich

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Re: Flange distance issue

PostFri Feb 15, 2013 7:16 pm

well damn.. this camera's just too good to return.. I'm keeping it.. I hope BMD is hard at work on EF lens compatibility (I sure would love my 17-40 to be controlled) and the infinity focus thing.. audio quirks.. it's just too good of a camera to let this little things drag it down!
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Malcolm Purnell

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Re: Flange distance issue

PostSat Feb 16, 2013 5:20 am

Greetings,
I wanted to take a moment to comment on this flange issue with some members. I'm probably one of the older members so please forgive me in advance of stating some of the obvious. Still lenses that we buy and mix and match are nowhere near the same quality as a true cinema lens you get from a rental house. I'm a fully professional cameraman I'm the union over 15 years and sadly have checked out lenses and found them to be off from Panavison ,CSC , and Clairmont. It is more common than we realize. As you handle the lenses put them in different temps it does force wear and tear on the mounts. The se holds true for our lens mounts. I check all of that carefully during a checkout. Now that your buying and commuting to the camera you will probably have to shim your lenses specifically to the BMCC for now. For my part I ordered a MTF version because the higher end mounts are adjustable to account for this potential problem. Take your camera to a rental house with a lens collimating and really check it out on the bench to be sure. The tech might have some great short term answers.
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Nilscrompton

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Re: Flange distance issue

PostSat Feb 16, 2013 5:49 am

Thanks for posting Malc84cine, great to have your input.

Could you elaborate on shimming lenses. How exactly do you do this? And, can this be done with consumer lenses like the Tokina 11-16mm?
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Larry Sellers

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Re: Flange distance issue

PostSat Feb 16, 2013 5:49 am

Malc84cine wrote:Greetings,
I wanted to take a moment to comment on this flange issue with some members. I'm probably one of the older members so please forgive me in advance of stating some of the obvious. Still lenses that we buy and mix and match are nowhere near the same quality as a true cinema lens you get from a rental house. I'm a fully professional cameraman I'm the union over 15 years and sadly have checked out lenses and found them to be off from Panavison ,CSC , and Clairmont. It is more common than we realize. As you handle the lenses put them in different temps it does force wear and tear on the mounts. The se holds true for our lens mounts. I check all of that carefully during a checkout. Now that your buying and commuting to the camera you will probably have to shim your lenses specifically to the BMCC for now. For my part I ordered a MTF version because the higher end mounts are adjustable to account for this potential problem. Take your camera to a rental house with a lens collimating and really check it out on the bench to be sure. The tech might have some great short term answers.


All valid info, but not applicable here. In this case, it appears that the mount is too far away from the sensor. Shimming would only make it worse. If the flange distance is in fact too long, then the only thing that would help is to install a shorter mount, or somehow move the sensor forward.
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Christian Schmeer

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Re: Flange distance issue

PostSat Feb 16, 2013 5:51 am

To be honest, if cinema lenses are better quality than lenses made for still photography is irrelevant. The still lenses focus perfectly fine on Canon cameras, so they should work on the BMCC with Canon mount, too. I'm curious to see what BMD will offer to rectify this, especially if every camera produced so far has the issue...
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Malcolm Purnell

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Re: Flange distance issue

PostSat Feb 16, 2013 6:04 am

nilsonium wrote:Thanks for posting Malc84cine, great to have your input.

Could you elaborate on shimming lenses. How exactly do you do this? And, can this be done with consumer lenses like the Tokina 11-16mm?

- to answer the question for both directions before we throw the baby out with the bath water. Take your camera and lenses to a camera shop with some reputable experience and have them look at the situation as I mentioned in my earlier post. The lenses are adjustable in small increments t both directions. If the camera is really offyou can see what BMCC's warranty and offices suggest first. I'm not implying voiding the warranty or sticking with a truly bad factory spec. Camera but after that having a good lens tech. Setting some of your lenses just for the BMCC'S could be a real viable option. In the early days of video everyone in the field pretty much set their own back focus on their lenses and that was that. When HD cam into vogue back focus became a much more serious concern in the video world than ever before. So all of the technology and manufacturing standards are still catching up to the standard of cinema lenses. So if you use consumer products they are going to have a looser tolerance than a pro standard.
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Malcolm Purnell

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Re: Flange distance issue

PostSat Feb 16, 2013 6:16 am

Christian Schmeer wrote:To be honest, if cinema lenses are better quality than lenses made for still photography is irrelevant. The still lenses focus perfectly fine on Canon cameras, so they should work on the BMCC with Canon mount, too. I'm curious to see what BMD will offer to rectify this, especially if every camera produced so far has the issue...

All that you said is totally true but should work and it working 100% of the time is not my experience. I've used lenses that have come direct from the rental house just serviced sworn up and down were perfect yet was off. It happens sadly even at the highest levels of production but my whole point is every camera and lens I've ever used has a little work done on it to keep it up to that high standard.
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Nilscrompton

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Re: Flange distance issue

PostSat Feb 16, 2013 6:56 am

Just de-shimmed my Tokina. Have infinity focus now. Will post info in Tokina focus thread: viewtopic.php?f=2&t=3807&p=32130#p32130
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Nilscrompton

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Re: Flange distance issue

PostSat Feb 16, 2013 8:39 am

Thanks heaps Malc84cine, your suggestions have been super helpful!
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Uli Plank

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Re: Flange distance issue

PostSat Feb 16, 2013 12:30 pm

I did another test with a Scarlet carefully calibrated to known good lenses (Zeiss) on an EF Titanium mount and moved them to the BMCC. They are spot on!

If BM has taken temperature extension into account (by pairing the right metals, e.g.), it should be fine. But I think the theory about Canon deliberately leaving leeway on their own cameras for "not so tight" tolerances on lenses should hold water then. You could always shim, but who wants to file their mount down?
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Malcolm Purnell

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Re: Flange distance issue

PostSat Feb 16, 2013 5:13 pm

One other thing before we get too upset I wanna add is, go to a rental house on an off day have them pull out an angienuex 10-1 look at their chart at various distances then look out a window and eye focus the lens what you find is your farthest distance by eye won't hit the infinity mark. Try it with a Panavision 24-250mm the same thing will happen. The reason is in the end infinity is theoretical. It's darn close but I've personally never hit it. This is where the depth of field charts become important because when you play with hyper focal you use that to truly hold infinity to like 50' in focus. What you really want to do is check your lenses ant various distances to see if your lenses are really off. Again before we start posting BMCC cheaping out we need to bench test the camera take it through some real paces with good tech's. personally I always bounce the lens back off infinity when ever I throw focus deep. I worry more when my focus marks don't line up at all meaning 10' is at 9'9 the still lenses have a lot of space like 10-20' that stuff really frustrates the guy that has to pull focus. Hope this adds. If your still not sure refer to Doug Hart's "Camera Assistant" manual he goes very deep on these issues.
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