The NPR viewfinder thread

[Duncan Brown]

I recently picked up the other, less common, kind of NPR viewfinder so I figure it's time for a thread for all things NPR viewfinder.  I'll talk about them, then add all kinds of pictures.

First up, the ubiquitous Kinoptik orientable viewfinder.  This seems to be on the vast majority of NPRs I see on ebay and elsewhere.  I think there's actually a less useful fixed version of the VF but I've never seen one.  And of course, since the specs for the mount are identical to the Cinema Products CP-16, and mount made for that would fit too, though the ergonomics might leave something to be desired.

The Kinoptic mount can only screw onto the camera one way.  There's a little lock lever next to the mount that, when loosened, allows the whole viewfinder to rotate toward the front or back of the camera, a full 360 degrees.  There are detents at the most useful positions (every 90 degrees).  When the VF is pointed straight back, the image is upright.  As you rotate the finder forward, the image starts to spin clockwise, ending up spun 90 degrees for every 90 degrees you rotate the finder.  So if you point it straight up, then stand to the VF side of the camera and look down, the image appears upright to you but it's twisted vs reality.  If you were to stay behind the camera and look into it, it's on its side.  Useful in a pinch with some getting used to it, but mostly you're going to want to keep it pointing straight back (and lock the little lever).

With it locked from rotating and pointing straight back, you can spin the more rearward section of the finder to any angle (no detents), also a full 360 degrees.  In this case, however, the image orientation does not change - if it's pointing straight back and you rotate it for comfort vs which eye you sue, for instance, the image stays upright.

There's a tiny knob near the eyepiece that, when loosened, allows you to make diopter adjustments to match you vision, by spinning the eyepiece.  Then you lock it in place again with the little knob.

There's a shutter built into the eyepiece.  If it's loose, the idea is that it springs into the closed position all on its own, though at this point every one I've seen takes a little help sometimes.  Then if you push the eyecup in (with your eye, or with your hands), the shutter springs open and (if all goes well) clicks into the open position and stays there while you film.

All in all a respectable little finder, with the caveat that spinning it around in the fore/aft direction makes the image orientation wonky.

Some pictures:

 

Edited November 8, 2023 by Duncan Brown

[Duncan Brown]

Some more Kinoptic VF pictures:

 

 

[Duncan Brown]

Now for the much less often seen Angenieux  fully orientable always-upright-image viewfinder.  The basic functionality is the same as the Kinoptik, but without the goofy image spinning.  In this case rotating it fore and aft does NOT spin the image in the VF - it's always upright!  Also, no detents.  And there's a lock ring instead of a little lever - turn it towards the S to lock it; the other way to allow it to rotate.  I thought it was weird that there are two slots in the mount, so it can be put on the camera one of two ways but if you think about it, it makes sense.  The standard way to mount it is with the red dot upward.  Then the image is always upright.  But if you were to spin it 180 degrees, then stand in front of the camera and look into it the image would be upside down!  (Well, strictly speaking, you are looking into it upside down compared to where it started.)  So if you absolutely have to operate the camera in that position, you could mount it with the red dot down, and be all set.

Just like the Kinoptik, the rear part can spin around 360 degrees for matching up with where you want to put your eye, and doing so does not change the orientation of the image through the finder.

It has the same little lock knob and diopter adjustment as the Kinoptik.  But the eyepiece shutter is opened and closed with a big skinny ring right behind the eyecup, and is not done automatically for you as you press your eye to it.

Some pictures:

.

[Duncan Brown]

Some more pictures:

 

[Kamran Pakseresht]

That angeniux is beautiful, I’d really love to find one. Thanks for this post, was unaware there were options. I remember getting my NPR out of storage some time back and thinking it had been damaged because I could not get the lens to properly focus. Turned out it was just the viewfinder needing an adjustment, was a huge relief!

[Duncan Brown]

The standard Angenieux VF on the ACL spins the image as you rotate it, but then there's another ring you can turn to put it back where it needs to be again.  That's perfectly fine, as you don't generally rotate your viewfinder mid-shot or anything.   But this one that does it automatically is like magic!  I can't even wrap my head around how it works.  Very happy to have found a loose one.

Duncan

 

[David Sekanina]

https://www.linkedin.com/feed/update/urn:li:activity:7124126878960922626/

[Gregg MacPherson]

4 hours ago, David Sekanina said:

https://www.linkedin.com/feed/update/urn:li:activity:7124126878960922626/

Thank you David. Searching Schmidt–Pechan prism on google is a fine start point to understanding how the Kinoptik and Ang VFs on the ACL work. I wish you had pointed to that sooner. Hope your S16 camera devpt is gong well.

Gregg.

[Gregg MacPherson]

Nice as it is to have self leveling viewfinders, I remember coping quite well without one. Most of the time with an ACL on sticks I was leaning over it, the VF rotated 45 to 90deg and my head  the same, to level the image. The young, unspoilt directors also seemed fine with it...

[Duncan Brown]

8 hours ago, David Sekanina said:

https://www.linkedin.com/feed/update/urn:li:activity:7124126878960922626/

<mind blown>

Duncan

Edited November 8, 2023 by Duncan Brown

[Duncan Brown]

3 hours ago, Gregg MacPherson said:

Nice as it is to have self leveling viewfinders, I remember coping quite well without one. Most of the time with an ACL on sticks I was leaning over it, the VF rotated 45 to 90deg and my head  the same, to level the image. The young, unspoilt directors also seemed fine with it...

OK old man, and you probably walked to the set and back, uphill both ways, barefoot in the snow, too!  (I kid, since I think I'm actually older than you are...)

Duncan

[Boris Belay]

Cinema Products used the same VF mount on their reflex models, so the CP viewfinders are compatible with NPRs as far as I know (no first--hand experience).

ACL VFs are not compatible (wrong optical distance to the Ground Glass), although Eclair USA sold the Kinoptik NPR VF for the ACL with an adapater ring (it's an option mentioned in one of their Price List from the mid 70's).  Which means the distance is longer on the ACL, so conversely there is no way to adapt an ACL VF to a NPR.

[Duncan Brown]

If someone wants to sell me cheaply one of those legendary CP-16R fully self-orienting viewfinders, I'd be happy to try it on my NPR ?    In general, it looks to me like the CP-16R finders put the eyepiece a little too far forward to be comfortable when operating an NPR, but that's just a guess.

By the same token, I think adapting an NPR VF to an ACL would put the eyepiece farther back then the standard VFs... but that could possibly be a good thing in some cases?  I guess someone needs to come up with a 3D-printed design for that mythical adapter!

Duncan

Edited November 9, 2023 by Duncan Brown

[Gregg MacPherson]

6 hours ago, Boris Belay said:

.....Eclair USA sold the Kinoptik NPR VF for the ACL with an adapater ring (it's an option mentioned in one of their Price List from the mid 70's).  Which means the distance is longer on the ACL, so conversely there is no way to adapt an ACL VF to a NPR.

Did the adapter ring have any optical elements? If not then a simple spacer shifting the VF mount away from the camera body would work..?

[Duncan Brown]

1 hour ago, Gregg MacPherson said:

Did the adapter ring have any optical elements? If not then a simple spacer shifting the VF mount away from the camera body would work..?

That's my interpretation of what he's saying.  Of course it also has to adapt the different mounts, but that should be...straightforward?  They're the same idea, but different sizes, and I think different orientations of the nub.

Duncan

[Boris Belay]

On 11/9/2023 at 8:21 PM, Gregg MacPherson said:

Did the adapter ring have any optical elements? If not then a simple spacer shifting the VF mount away from the camera body would work..?

No optical elements, just a screw mount and attaching base.

[Duncan Brown]

On 11/9/2023 at 7:08 AM, Boris Belay said:

Cinema Products used the same VF mount on their reflex models, so the CP viewfinders are compatible with NPRs as far as I know (no first--hand experience).

I meant to post here when I discovered a few months ago: you can attach a CP-16 VF to an NPR just fine.  The CP VF has two slots in it so you can mount it in two orientations on the NPR with its one tab.  BUT the other way around doesn't work!  The Kinoptik VF, with only one slot, will not mount on a CP camera, which has two tabs.

Duncan

[Duncan Brown]

Let's discuss this amazing Angenieux VF on the NPR.  Everyone knows that's the one you really want.  And let's discuss the S16-converted NPR.  Everyone knows that's the one you really want.  But wait - when you get everything you want all at once, you can't see the whole S16 frame in the Angie VF.  It's zoomed in too much.  Or am I doing something wrong?  Anyone else with both of those things seeing this?

Duncan

[Aapo Lettinen]

On 11/9/2023 at 9:21 PM, Gregg MacPherson said:

Did the adapter ring have any optical elements? If not then a simple spacer shifting the VF mount away from the camera body would work..?

I have two Kinoptic finders for NPR and they will NOT work on the ACL without very extensive modifications and simple mechanical adaptor does not work.

the main issue is that the NPR seems to have shorter viewfinder distance and it cannot be focused to the ACL ground glass at all. one needs to take the whole silver-coloured assembly out of the finder which has the mounting threaded ring, slot system etc. , completely out and either heavily modifying it in lathe to allow the optics module inside to be moved and the slotted mounting part being shorter at the same time to make it focus close enough with correct magnification, OR take the silver part completely off and making new part out of scratch which mounts to the ACL's different mounting flange and has adjustable inside cavity for the optics module and allows the viewfinder fastened on top of it.

So basically making the whole silver-coloured cylindrical part out of scratch just to be able to mount it.

I am intending on doing the latter (making a completely new replacement for the silver cylindrical part with completely new mounting system etc. because I am pretty desperate getting a working viewfinder for my ACL, there is no original finders available or they are very expensive and I happen to have leftover NPR finder which is just collecting dust and would work fine if just can be mounted to the camera some way.

[Aapo Lettinen]

10 hours ago, Aapo Lettinen said:

I have two Kinoptic finders for NPR and they will NOT work on the ACL without very extensive modifications and simple mechanical adaptor does not work.

the main issue is that the NPR seems to have shorter viewfinder distance and it cannot be focused to the ACL ground glass at all. one needs to take the whole silver-coloured assembly out of the finder which has the mounting threaded ring, slot system etc. , completely out and either heavily modifying it in lathe to allow the optics module inside to be moved and the slotted mounting part being shorter at the same time to make it focus close enough with correct magnification, OR take the silver part completely off and making new part out of scratch which mounts to the ACL's different mounting flange and has adjustable inside cavity for the optics module and allows the viewfinder fastened on top of it.

So basically making the whole silver-coloured cylindrical part out of scratch just to be able to mount it.

I am intending on doing the latter (making a completely new replacement for the silver cylindrical part with completely new mounting system etc. because I am pretty desperate getting a working viewfinder for my ACL, there is no original finders available or they are very expensive and I happen to have leftover NPR finder which is just collecting dust and would work fine if just can be mounted to the camera some way.

I already designed it and test printed it and it works nicely, focuses correctly to the groundglass after some adjusting and even the alignment notches for the viewfinder positions work 😄  will get this machined out of metal next but even the 3d printed one can maybe used for some basic testing if being very careful to not knock it off 😄 

 

[Duncan Brown]

I'm confused.  You've taken the screw collar off of the Kinoptic finder?  How does it secure on to this adapter?

Duncan

[Aapo Lettinen]

5 minutes ago, Duncan Brown said:

I'm confused.  You've taken the screw collar off of the Kinoptic finder?  How does it secure on to this adapter?

Duncan

I will make a new thinner split ring which holds the finder on the adapter.

because the optics block had to be moved WAY forward (not millimeters, multiple centimeters compared to the original NPR arrangement) it was not possible to use the original split ring as it has smaller inner diameter than the optic block outer diameter has.

the downside is that it is time consuming to remove the finder from the camera body and thus it is a bit more work to transport the camera as special care and padding for the viewfinder is needed. Normally I like to remove the finder on eclairs for transport so that they are lower profile and can protect the finder, but in this case the finder needs to stay on the camera body most of the time.

the new position for the optics block is very close to the mounting flange of the adapter, so it is almost hitting the camera body. It is not possible to modify the screw collar type design this way and one would likely need additional (expensive and difficult to arrange) optical elements if not being able to move the whole block this way.

my way is much quicker and cheaper as well, took couple of hours to measure and design. will need to figure out a good way to make new split ring for it but I could technically manage half of the time with non-secured finder so can design the split ring system later

[Duncan Brown]

Oh, OK cool.  I didn't realize you needed to move it that far!  So if anyone ever needs to mount a (nearly nonexistent) spare ACL finder on an NPR, it sounds like a big spacer design will do the trick 🙂

Duncan

[Aapo Lettinen]

The final adapter for installing NPR finder on ACL camera. the optic block is removed from the original tube part and installed inside this one. CNC machined stainless steel :)

[Duncan Brown]

Very impressive!

Duncan