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K-100 shutter angle and Angenieux lens light loss


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#1 kaif

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Posted 19 January 2006 - 09:40 AM

Hi,

I'm trying to find out what the shutter angle on the Kodak K-100 is, and how much light the viewfinder on the attached Angenieux F17-68 1:2.2 lens is likely to "eat" (One of thoes "dog leg" lenses with viewfinder attached to it).
I take it the stop scale on the lens won't take that loss into account?

I also seem to remember reading that you could get the K-100 to hand crank (early movie style), I guess by attaching a crank into the motor shaft socket. Has anyone got any experience with that?

Any help much appreciated!

Kai
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#2 Ian Marks

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Posted 19 January 2006 - 12:32 PM

Aren't K100's great? Small form factor, an optical viewfinder that you can actually use, and a very long running time when compared to the Bolex. Plus, as you know, you can slap a reflex finder-equipped Angenieux or Pan Cinor and it becomes a reflex camera about the same size as a large Super-8.

Many, if not most, zooms are marked in "T" stops as well as "F" stops, and these should take into account the light lost inside the zoom. Your particular lens is a very old design and might not have the "T" stops indicated. If you're shooting negative film, you could probably open up a half stop or two thirds of a stop and be okay.

There is a coin slotted cover on the right side of the camera which gives access to the motor/crank drive. I have never seen the actual hand crank or electric motor, but I have one of the couplings rattling around somewhere. I thought one day it would be a fun project to use the coupling to try to adapt a crystal motor - Possibly a Tobin - to the camera, which would make it an especially compact sync camera. As I recall the shaft was 2:1, producing 24 frames for every twelve rotations of the shaft.
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#3 Will Montgomery

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Posted 19 January 2006 - 07:23 PM

Aren't K100's great? Small form factor, an optical viewfinder that you can actually use, and a very long running time when compared to the Bolex. Plus, as you know, you can slap a reflex finder-equipped Angenieux or Pan Cinor and it becomes a reflex camera about the same size as a large Super-8.

Where can I find a reflex finder? I've seen a few of these on K-100's and I would love to have one for mine. Its a great camera, I'm just not that great at focusing based on distance.
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#4 Ian Marks

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Posted 19 January 2006 - 08:37 PM

Maybe I should have been clearer. The camera isn't a reflex model, but by mounting a lens that has its own reflex finder (these were made by Pan-Cinor and Angenieux), you gain the advantage of reflex viewing (but obviously only with that particular lens). The lenses with built-in finders are all pretty old now, but they sure improve a cheap 16mm non-reflex camera. They show up on Ebay regularly. Kaif, the original poster on this thread, refers to a "dog leg" because on some of the lenses the finder resembles a dog's leg in the way it comes off the barrel - maybe hard to picture in your mind, but immediately understandable when you see one of these lenses.
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#5 kaif

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Posted 19 January 2006 - 09:16 PM

Thanks everyone for the replies! Yes, the lens only has the F-scale. Ian, I found the connection for the motor / crank, thanks for that. Will give the 2/3 correction a shot, and maybe start hunting for that hand crank adaptor...

Will I just assume a 180 degree shutter angle or thereabouts for the K-100?

One more question regarding the lenses for these: I understand C-mount lenses aren't always interchangable between different camera makes (even apart from the obvious Bolex Reflex / non-reflex camera issue.) Different manufacturers apparently assumed a slightly different distance from the C-mount fitting to the film gate? So should lenses for a non-reflex Bolex camera work fine on this camera? Does anyone have experience or had problems with that on the K-100?

Thanks again,

Kai
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#6 Robert Hughes

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Posted 20 January 2006 - 11:40 AM

In theory, all C mount lenses have a common focus point. But after however many decades of use, each lens drifts. If you need bang-on focus with a lens for your camera, present both to your local camera shop for collimation.

K100 is a fine camera, it was the consumer equivalent of the Cine Kodak without the removable magazines and other bells & whistles. I used one that would film 45 seconds on a wind at 24fps; that easily beats a Filmo or Bolex. I prefer the Filmo 70-DR myself, I think it's more comfortable handheld, but it's a matter of taste.
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#7 John Pytlak RIP

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Posted 20 January 2006 - 12:05 PM

You might be able to estimate the shutter opening by shooting a test of moving objects and evaluating motion blur.

For example, photograph a rotating disk on a motor running at 1440 rpm, so you know the disk rotates one revolution for each 1/24 second frame.

Or just observe the opening and closing of the shutter through the lens relative to the pulldown cycle, as you slowly advance the camera drive.
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#8 Ian Marks

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Posted 20 January 2006 - 12:54 PM

I think that other than the Bolex RX/non-RX issue, you can use just about any C-mount lenses intended for cine use on the K100 - the Ektars, non-RX Switars, Angenieux, etc. Just watch out for TV "surveillance" lenses, especially ultra wides, with a rear element that protrudes too far into the camera. Even many of these will probably be okay (though not necessarily sharp enough for film work) as the K100 has no mirror or prism. I have a Tamron 6mm that fits okay. I'm sorry that I don't know the shutter speed for the K100 - I had an owner's manual but when I sold my turret K100, that went along with it. It may be somewhere on the net.
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#9 kaif

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Posted 20 January 2006 - 04:38 PM

Thanks everyone for your replies, that's pretty much answered all my questions, so it's been a great help,
much appreciated!

Kai
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#10 Clive Tobin

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Posted 20 January 2006 - 06:18 PM

I'm trying to find out what the shutter angle on the Kodak K-100 is, ...


I used to have a couple and I don't have the instruction manual any more, but it is close to 170 degrees or 1/50 at 24 FPS.

The older style reflex zoom lenses used to be marked in an early equivalent of T stops although they were marked in F stops. That is, the marked f/2.2 was really T/2.8 but the marked f/2.8 was T/2.8. So your exposure would come out right using a light meter, allowing for the extra elements and the light diversion to the finder.
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