Nikon F Mount for URSA Mini Pro

I uploaded a super quick clip of the view on the screen when I wiggle the lens. The camera is not moving at all. Granted it's an 85mm lens, but still. How does that compare to yours?

That appears similar to what I'm seeing with the 70-200 on there... yours may be a bit worse. I had never tried this particular lens with the MB speedbooster when I had my BMCC... so, unfortunately, I have no basis for comparison there.
---
c

Just tried a few more lenses... including my Nikkor 70-200/2.8. This lens, being rather long and heavy, shows quite a bit more play than the smaller lenses. I'm not too surprised, given the size/weight and I'd probably use a lens support anyway. However, this same lens on my Nikon 7200 has virtually no play at all.
---
c

I've emailed BM support, they are looking into it. I've got some pretty heavy lenses, but they are way more stable on my Metabones and BMMCC than the Ursa. Mine's looser than an unbraced cheap Fotodiox adapter. Not what I'd expect from an official BM mount. Or, at least not what I'd want to expect, but issues seem to keep popping up. I uploaded a super quick clip of the view on the screen when I wiggle the lens. The camera is not moving at all. Granted it's an 85mm lens, but still. How does that compare to yours?

https://vimeo.com/239688783/c5b7eb8ee0

Thank you for the info Dave. Let us know what you hear back from support and whether they are able to fix it. The amount of motion you're getting in the mount is shocking to see.

That is more than some slight rotational play. This much movement makes the new mount worthless for any video work! This looks like the same issue BM had with the MFT mount on the first Pocket cameras, only worse.
Cheers

I've emailed BM support, they are looking into it. I've got some pretty heavy lenses, but they are way more stable on my Metabones and BMMCC than the Ursa. Mine's looser than an unbraced cheap Fotodiox adapter. Not what I'd expect from an official BM mount. Or, at least not what I'd want to expect, but issues seem to keep popping up. I uploaded a super quick clip of the view on the screen when I wiggle the lens. The camera is not moving at all. Granted it's an 85mm lens, but still. How does that compare to yours?

https://vimeo.com/239688783/c5b7eb8ee0

Hey Drew,

Just wondering if you've had any more conversation with BMD on this issue?
---
Chris

Hey Drew,

Just wondering if you've had any more conversation with BMD on this issue?
---
Chris

Hey, yeah, I've just sent the mount to BM for them to take a look. Should get to them on Monday. Supposedly their Australian headquarters is working on aquiring a Milvus lens to test as well, though it's been weeks and there's been no indication that that's happened. Have you contacted them at all about yours?

Hey Drew,

Just wondering if you've had any more conversation with BMD on this issue?
---
Chris

Hey, yeah, I've just sent the mount to BM for them to take a look. Should get to them on Monday. Supposedly their Australian headquarters is working on aquiring a Milvus lens to test as well, though it's been weeks and there's been no indication that that's happened. Have you contacted them at all about yours?

I have not, yet. Curious to see what the response is to yours.
---
c

Update for anyone following:

Received my RMA'ed F mount back from BM today. Apparently there was a "clear abnormality" with my specific F mount. The new one is much better. I'm not convinced it's as solid as my Metabones, but it's pretty close, and definitely acceptable for a Nikon mount and the large lenses. Did some footage testing with it, and things are looking much better, infinity focus is better, and the overall picture quality has improved over our crappy third party F mount adapter (no way the lens distance to the censor was accurate or consistent).

Unfortunately we had hoped (unlikely, I know) that it might fix the magenta corner issue as well. It did not...So there's still that to contend with.

Hmmm... thanks for the update, Drew. Seems I should probably look into this further.
---
Chris

Good to know is was a one off build error. You can get th BM shim kit and reset the Nikon mount to correct FFD if needed.
Cheers

[Tim Schumann]

You get a shim kit with each mount.

Just finished testing with my Nikon F -mount for UMP.

There is a lot of play with my unit. Small twist of the lens (pulling focus) effects the aperture so exposure changes. It feels like the best result comes with G-type Nikkors that have the O-ring installed. This in comparison to older AI-s or third party lenses makes a small difference but there's still considerable play. Worst play comes with Tokina 11-20mm, 85/1.4 AI-s, 135/2 AI-s and the least play with 50/1.8G (smallest and lightest too).

So maybe the designers took for granted that most users have G-type Nikkors?

Focus distances seem to be fine, so I guess the shims have been inserted correctly.

I tried to find any video review of the nikon mount, there is none. I wonder if the mount is really that bad as many in this thread have expirienced. Or is anybody happy with it? thanks for sharing the expirience.

I have the wiggly mount issue and it does affect the aperture for me on every lens I want to use with the thing. After sending it in to Blackmagic they sent it back with a note that seemed to say "looks good to us, here you go."

The design is, in my experience, flawed and I would strongly recommend against buying it. I'm stuck with a useless mount since the time it took to get, discover the issue, and do an RMA exceeded my return window. For reference, these are the lenses I've tried with it that show the issue:

Nikon 17-35mm f2.8
Nikon 70-200 f4
Zeiss 21mm f2.8 Milvus
Ziess 25mm f2 Zf.2 Classic
Zeiss 35mm f2 Milvus
Zeiss 50mm f2 Milvus
Zeiss 100mm f2 Zf.2

What a waste of money.

Hi Jon

Sorry to hear that. the opinions on the adapter go from useless to nearly useless, so nothing else left than stick with the ef mount and use adapters and hope someday theyll bring a lockable nikon-mount with lens-metadata support.

After sending it in to Blackmagic they sent it back with a note that seemed to say "looks good to us, here you go."

Hmmm... I was thinking of sending mine back to see what they'd say, but I'm guessing it would be the same response. I actually put the EF back on after only using the nikon briefly twice. I was thinking of putting it back on for a shoot early next week so I could use some of my better nikon lenses... guess I'll have to run some tests first.
---
c

So I got an email back that they did actually switch the mount, which wasn't clear from the return sheet. But after messing around with it a bit I think the issue is still there, though maybe a little less bad? Still enough of a problem with my lenses that I'll be taking the mount off. I think maybe with lightly damped lenses it would be OK.

Here's a video fo the issue. Obviously I'm racking focus quite fast so you can really see it. With my Nikon I can only get the effect to happen if I grab the whole lens barrel rather than the focus ring and really crank on it.

https://vimeo.com/254712872/89b22252ac

I'd say it's roughly on par with my Fotodiox F mount to E mount adapters with the aperture ring.

If anyone is in Perth Western Australia, has one of these, is having a problem and does not live too far from me, I could have a look at it. I am not about to go buy one to find out for myself as I already have made my own mount.

If the BM Nikon F-Mount is constructed in a similar arrangement to the genuine Nikon F-Mount, whilst the issue cannot be eliminated entirely, even for the genuine Nikon F-Mount, it can be minimised.

The only full solution is the positive locking arrangement like the PL-Mount which uses a threaded design versus spring pressure to secure the flange face tight. This was offered by P+S Technik with their IMS Professional Nikon F-Mount which uses a threaded front clamp ring and I think Jacek at Optitek also offered a clamp-ring style mount.

It is rather a pity that BM did not follow that design principle but then again, there may have been some registered design/patent issues plus added cost.

All still camera mounts have lens movement, that is why big Cinema cameras use PL or other Locking mounts. The EF is worse, then MFT and Nikon always seemed a little tighter, than the rest, but they All move when using normally dampened manual focus. The only real solution is to lock the lens to rails, via a Matte Boc or lens support, to keep the lens from shifting in its mount.
Cheers

But why is Red solving the problem with a locking mechanism for the EF-mount then?
Couldn't this be done with the Nikon mount too? Or did they get that method patented?

But why is Red solving the problem with a locking mechanism for the EF-mount then?
Couldn't this be done with the Nikon mount too? Or did they get that method patented?

metabones have adapters with locking-mechanism:
http://www.metabones.com/products/detai ... EF-m43-BT5

maybe a third party like wooden-camera could do mount with locking for the ursa mini, they did a pl mount for the panasonic eva1.

bm probably didnt do it because of cost, but i would pay double for a locking-mount, would love to see this.

Red's Nikon mount is also locking but it does cost twice as much (powers IS and gets lens data though).

After messing around and talking to support a bit more here's what I think:

The tech who looked at my mount did adjust or replace something and said that if it was any tighter it would be outside Nikon's mechanical spec.

Despite this, I can say that none of my lenses move as much in the mount on my D850 and I don't see the rotational issue with aperture. After testing my G type Nikon lenses on the repaired mount I think they'd generally be OK with the BM mount as it is now (they were not good before the repair.) My Zeiss classic lenses have enough damping that it seems to still be an issue. They're equally tight in the mount but the AF lenses have almost no resistance on the focus rings.

I'd say if you mainly have very lightly dampened lenses you'll probably be OK, though you may have to send it in if it's loose. If you have stiffer lenses like my Zeiss stuff (which I have to say I don't think is THAT stiff), you may be better off with F-EF adapters on the regular mount.

For me I'd hoped to make my life easier switching between my DSLR and the UMP, but I think I'll just go back to using the EF adapters.

Thank you very much for the info Jon. Really useful!

I had the same rotational issue with my Zeiss ZF lenses on a Metabones Speed Booster/MFT Mount, rotational play is MFT was worse than the Nikon. Metsbones straight MFT/Nik Mount is fisrlyntight too, the still some play with the Zeiss lenses. The MFT and Nikon Mount are designed for still camera, and new Nikon G, auto focus lenses, which are manual by wire, no damping. Add a damped lens like the Zeiss ZF lenses, and you need to clamp the lens down.

Yes, BM could have make a locking mount, but it might not be completely compatible with some Nikon lenses, so they went with the Nikon specification, which has some play in it. Manufacturing tollerences on still camera mounts vsries some also. The only real solution to this is the PL mount which is a cam locking system that adjusts for wear.
Cheers

It is a mechanical mount.

Works with AF-D and AF-S G series lenses but it does not have electronic pins so won't work with AF-S E series lenses.

If there is enough demand for electronic control we could look at doing a version with the electronic pins but as Nikon do not publish or share their protocol information it would take a long time for us to implement in camera. If you would be keen on this then please speak to Nikon about it and request that they provide us with this information to support these in our cameras.

I use a Viltrox F-MFT adaptor on P4K and it has electronic pins with F mount lenses which works!

How did they pull it off? Can you do the same?


Sent from my iPhone using Tapatalk

In the normal Nikon F-Mount, there is a spring arrangement which pulls the lens to flange contact but this can be defeated by the hanging weight of a heavy lens.

There is another rough and ready solution for an alternative design Nikon F-Mount. The original Letus35 groundglass adaptor for 1/3" videocameras had a mount machined from aluminium. The lugs inside were slightly tapered to provide a wedging action as the lens was rotated in the mount to pull it firmly to flange contact.

It works well with no rocking and the mount itself will pull from the Delrin housing before letting the lens droop. There is no pin latch mechanism which is where the unwanted rotational movement comes from when focusing. Various third-party lenses have their own flavours of locating hole for the pin to engage in. Some are quite loose.

A lens in the wedge-styled early Letus F-Mount would unwind out of the mount if the focus helicoid on the Nikon lens was stiff. I added a small setscrew on radial axis to bear against the inner diameter rim of the bayonet of the lens tail to bind it from winding loose in the mount.

It is crude and if too much Tarzan force instead of common sense is applied to the screw, crush deformation of the lens tail and chipping the rear element might occur. The screwhead is also a fiddly sod to get at with fingers and the screw being long, risks being bent or damaging the mount. But it works.

The camlike inner bayonet surfaces of the soft aluminium Letus mount soon wore and the lens would turn furthur in the mount before wedging tight to flange. A stainless steel mount would solve this issue.

Like the PL-Mount style of locking mount, two distinct two-handed operations are required versus the single-handed offer and twist task of fixing a Nikon or Canon lens to a camera. Offer and hold the lens to the mount and twist to security, then secure the locking screw with the other hand.

In my example, the small screw position was about fourty-five degrees higher around the mount on left side of the camera. If a really draggy lens focus did twist the lens tail under the screw-end, a bayonet barb would already almost be engaged against the side of the screw-end before the lens could fall out of the mount.

I guess I should have registered the design but I was never much of a patent troll and the original was Quyen Le's design slightly modified.

LETUS F-MOUNT MOD..jpg (277.67 KiB) Viewed 4707 times

If anyone is curious about the offset holes for rails, this was a means of securing this early generation Letus35 adaptor securely to the the camera via the camera's own base without overstressing the relay lens-to-camera fitment.

This image illustrates an original short screw. A much longer screw with a tube shoulder ended up being re-used on another project.