Ursa pl mount camers

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Asok Kumar

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Ursa pl mount camers

PostMon Dec 11, 2017 3:45 am

On my ursa 4K pl mount camera ,I can't adapt New canon cn 14.5-60 mm t/2.6 PL mount lens!!! ,if anyone knows more on this,please help me,regards,asok
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Tristan Pemberton

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Re: Ursa pl mount camers

PostMon Dec 11, 2017 10:03 am

What do you mean by "adapt"?
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Asok Kumar

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Re: Ursa pl mount camers

PostMon Dec 11, 2017 12:16 pm

I mean to attach the pl mount lens to Ursa pl mount camera
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robert Hart

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Re: Ursa pl mount camers

PostMon Dec 11, 2017 3:24 pm

Asok.


These is something wrong with the image uploader here. I'm sending it a 85kb file and it tells me it is too large. Please go to this web address for my full reply with an image.

http://www.bmcuser.com/showthread.php?2 ... post244119


1. Is the PL-Mount ring jamming before it can turn around to lock the lens?

2. Is the PL-Mount ring turning all the way and still leaving the lens too loose?

3 If the lens is too loose, is the ring in this position against the stop screw like in this image? If it is, then unscrew that stop screw and take it out. Don't lose it. The ring can then turn furthur and maybe lock the lens tight.

Be careful because the ring may turn too far and uncover the lugs on back of the lens. Then the lens will fall out on the floor and break.
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Asok Kumar

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Re: Ursa pl mount camers

PostTue Dec 12, 2017 6:20 am

Yes sir,the pl mount ring jammed before it can be turned also I can't push the lens in slot even after putting the lens the lens in the slot
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rick.lang

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Re: Ursa pl mount camers

PostWed Dec 13, 2017 12:42 am

Do you have the PL lens correctly aligned with pin on the mount? It can be tricky to get it in the proper place before you rotate the locking ring to close it securely.


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robert Hart

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Re: Ursa pl mount camers

PostWed Dec 13, 2017 5:58 am

Rick Lang and others. Please guide me on this. - In looking at a lens on eBay, it seems that the PL-Mount tail on the lens is made of soft surface polished aluminium. The BM URSA 4K PL-Mount is also surface polished soft aluminium. The machining of the clearance for the lugs and the pin locator slots appears to have been done in one pass at the same depth setting with a rotary table and mill. It is very hard to tell just looking at the image but it seems that the depth of the pin slot and the depth of the lug clearances are identical. This would make the Canon PL lens tail non-compliant with the original ARRI registered design in which the locator pin slots are about another 0.5mm deeper towards the optical centre axis. I have compared the BM4K URSA mount with a P+S Technik IMS system PL-Mount and the pin locations match. So the difference it seems may be with Canon's PL-Mount tail and maybe something that company may need to address if the issue is apparent with other cameras. Without a lens in hand to compare directly I am only guessing.


Asok. Please do not do anything until Rick or others have replied.

It seems the lens is not seating deep enough in the mount.

The tail on one of my PL-Mount adaptors was very tight fit under that little pin. The slot for the pin on the PL-Mount tail was not deep enough. The lens would start to fit in at a slight angle but jam before it would go fully in place.

The slot in the tail was just a hair too shallow. I dressed it with a very small round file slightly deeper towards the optical centreline and it fitted.

To check if this is a problem you could remove the pin and then try the lens in the mount again. If the lens tail fits properly and you can turn the ring to the tight position, the fit of the pin in the pin slot on the lens tail is the problem.

Be careful and hold that lens all the time you are trying this. It may turn in the mount because the pin will not be stopping it. So it may turn with the ring and drop out.

The pin in the Blackmagic URSA PL-Mount is a special screw and it can be taken out. You need a special allen screw tool to fit the hex hole in the screw head. Do not try to use anything else because the hex hole in the screw head will be damaged.

If you use hand tools anywhere near the throat of the URSA inside of the PL-Mount, stuff a clean tissue into the camera throat so nothing can drop out of your fingers and break the blue coloured IR filter glass inside.

If the lens does fit in the mount with the pin removed, please come back to us here so we can work out the best fix. That lens is a very valueable piece of gear and I would not like to tamper with it.

Please make a phone photo of the tail of the lens if you can. You may need to join bmcuser.com to post the picture up. It is very hard to post pictures on this forum.
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rick.lang

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Re: Ursa pl mount camers

PostFri Dec 15, 2017 3:56 am

Robert, apologies I’ve been largely absent from the forum while I have some other activities taking up my time. Things should be settled down by the weekend. “I’ll be back.”


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Asok Kumar

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Re: Ursa pl mount camers

PostThu Jun 21, 2018 2:55 pm

Sir ,now new problem,I can't align my newly brought Carl Zeiss jenna 180 mm f/2.8 pl Mount lens on my ursa 4K pl Mount camera,but paradoxically newly brought helos 44 58 mm f/2 pl Mount is easily aligned and capable of locking the lens,please help,regards dr asok
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Denny Smith

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Re: Ursa pl mount camers

PostThu Jun 21, 2018 5:25 pm

Sounds like it is an issue with the PL mount on the lens. PL mounts are very close tolerance, and the camera mount tightens down with a cam like action. But the pin in the camera mount, must align with the slot in the lens mount. Also, their are some other mounting systems that look like a PL min t, but without the slot, and are not an Arri PL mount specification, and will not work.
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Denny Smith
SHA Productions
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Asok Kumar

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Re: Ursa pl mount camers

PostFri Jun 22, 2018 2:30 am

THANKS,but here there is slot for pin,can I remove pl Mount from the lens and compare with pl Mount of other compatible Helios44 58my t/2 pl Mount lens,and doing slight modifications to get the specification of compatible lens,regards dr asok
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Asok Kumar

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Re: Ursa pl mount camers

PostSat Jun 23, 2018 10:35 am

THANKS denny,but my seller told me that it may be the issue with the locking ring,I have to adjust the locking ring to one or two stops of the Ursa camera!,but how can I adjust the locking ring,regards dr asok
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Denny Smith

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Re: Ursa pl mount camers

PostSat Jun 23, 2018 5:08 pm

The Ursa 4K PL Mount is fixed, not designed to be user removable, that said, if you do go this route, yiu will need a Micro Torque driver and the correct bit. See the instructions for removing the mount on the Ursa Mini 4.6 PL camera. I do not think the locking ring cst is adjustable.

That said, I would get a caliber and measure the thickneyof the lens PL mount ring. Compare this to the Arri standard measurement:
ARRI PL mount. Thickness of flange face to front of lugs clamping face is 2mm. Outer diameter is 69mm. Diameter to bottom of opposing inner cutouts for the lugs is 63mm. Diameter to bottom of locator pin cutouts is 62mm. Lugs are about 23mm broad at the outer diameter. Diameter of each locator pin cutout is 3.2mm. Fillet radius at corners of lug cutouts appears to be 2.75mm. Outer diameter of rear shoulder is 54mm.


If the lens PL mount does not meet these specifications, inform the seller and ask to return the lens, as it does not meet the required specifications

That said, if it does meet these measurements, have a second check on thI had a PL mount kens thst fit on one PL mount correctly, but would not tighten up on another. Turned out, the lens was not seated correctly, make sure you insert the lens centered on the mount and square to the camera, and thst thenlens inserts into the mount all the way, and the flange slot is fully engaged on the pin. I had an issue with a little debris on the camera mount, that kept the lens from seating.
Good luck
Denny Smith
SHA Productions
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Asok Kumar

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Re: Ursa pl mount camers

PostSat Jun 23, 2018 5:45 pm

THANKS,I measured all parameters expect first one(thickness of the flange tface to the front of lug,)which I don't understand and except this everything is correct,please explain this,regards,asok
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Denny Smith

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Re: Ursa pl mount camers

PostSat Jun 23, 2018 10:52 pm

The flange has four lugs (or bits that stick out, which go into the lens mount cam. The leading or inside edge is thinner that the opposite side, so the Mavericks PL mount cam will tighten up on it. Measure both sides, and see if the thickness at the edge is close to the measurement I listed above. If the leading edge (the side of the lug the csmera PL mount ring hits first) is too thick, then the PL ring will not rotate up on it. If the opposite side is too thin, then the Locking ring will not tighten down enough to hold the lens firmly in the mount. This is a very precise tolerance, and the difference in thickness gives a little room for wear on the mount. Hope this helps
Cheers
Denny Smith
SHA Productions
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Asok Kumar

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Re: Ursa pl mount camers

PostSun Jun 24, 2018 3:29 pm

THANKS,Smith,finally I succeeded in locking the lens to an extent as after engagement of lens on Mount,the locking ring only moves slightly say5-7 degree,and all the parameters u mentioned was same in this lens,regards asok

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