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Crazy idea of the week.


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#1 Paul Bruening

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Posted 17 January 2008 - 09:00 AM

A recent thread asking about reflex conversion got me thinking. Since old Mitchells have the rack-over viewer built into the door, why not put it to use getting rid of that clumsy rack-over system.

First, get rid of the L-Plate. Next, put a plate on the front of the head for the lens mount that also extends over the front of the viewer. Put an exact match of the gate's lens mount. Given the affordability of old Baltars, you could run two matched lenses that were gear-locked together on the focus rings through an intermediate gear... even the focus drive gear. There would be only a negligible parallax offset. You'd be looking through a matched lens as what the camera is seeing. The viewing lens could run wide open while the gate lens could be properly stopped and even over filtered.

That might be a precise and cheap solution as long as you weren't using the most expensive lenses. It could get pricey putting super speeds (doubled each size) on this thing. Then again, if they're just rentals, how bad could it be?
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#2 Jess Haas

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Posted 17 January 2008 - 01:57 PM

If you want to really get critical you would want a parallax offset (angles the viewfinder) geared to that focus as well.

The closest I have seen is on the Bell & Howell Filmo 16mm cameras. Instead of using two of the taking lens it has little interchangeable viewfinder lenses. You can't see focus or depth of field but you do get a very bright image. It has a parallax offset adjustment that you set to the distance of your subject. I have found this system to be very accurate and really great for shooting in low light since you can actually see through the viewfinder.

I actually sometimes miss my non reflex viewfinder when using modern movie cameras, especially in low light. For some reason a bright clear image is more useful for framing than a really dark flickery one. Of course you can't tell if focus is on the mark so you have to trust your AC.

~Jess
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#3 John Sprung

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Posted 17 January 2008 - 03:13 PM

That's pretty much what Mitchell did -- They had a very nice parallax finder. The long forgotten advantage of parallax is that you can sit back and look at the finder with both eyes, you don't have to keep your eye pressed against it. That makes a difference at the end of a 19 hour day.





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#4 Leo Anthony Vale

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Posted 17 January 2008 - 03:43 PM

First, get rid of the L-Plate. Next, put a plate on the front of the head for the lens mount that also extends over the front of the viewer. Put an exact match of the gate's lens mount. Given the affordability of old Baltars, you could run two matched lenses that were gear-locked together on the focus rings through an intermediate gear... even the focus drive gear. There would be only a negligible parallax offset. You'd be looking through a matched lens as what the camera is seeing. The viewing lens could run wide open while the gate lens could be properly stopped and even over filtered.


The Wall Movitone Newsreel single system cameras did that. But they still had rackover for setting up shots and focusing.

wall_camera.jpg

& a Mitchell side finder could also be used.

The Akeley pancake camera was more of a true twin lens reflex. The taking and finder lenses were on a single plate, they could so they could be focused simultaneously. This camera was designed by Carl Akeley the father of modern taxidermy and museum diorama displays. It was designed for photograghing animals in the wild. The footage would be reference material for designing the poses and dioramas.

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