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Beaulieu Super 8 camera internal gelatin filters


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#1 Joel Pierre

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Posted 13 June 2011 - 06:09 AM

I have read on a french forum (Google Translation) that if the internal gelatin filters are removed of the cameras, it is necessary to re-calibrate the internal optics (especially for very short focal lengths).

But it seems that cameras with interchangeable lenses like Beaulieu (2008-4008) and Leicina Special have no internal lens that could be re-calibrated.

Can we remove the internal filters of Beaulieu (2008-4008) without focus problem (with no other changes)?
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#2 Will Montgomery

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Posted 13 June 2011 - 09:02 AM

I believe there is a small calibration issue when removing the filter as Björn Andersson made those adjustments on my 4008s. Not sure if it is internal only or if the lens needs adjustment as well.

However, I'd shoot some tests and check yourself as the adjustment may not be absolutely critical.
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#3 Glenn Brady

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Posted 14 June 2011 - 08:52 AM

There aren't any "internal optics" in the path from the lens to the film in the Beaulieu 4008 series cameras except for the gelatin filters. Their removal affects the back focus of the lens, although this is only an issue when the lens is used at or near full aperture and at or near its shortest focal length. Björn Andersson will recollimate the lens when the gelatin filters are removed.
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#4 Marc Marti

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Posted 14 June 2011 - 10:49 AM

I'm planning to remove the internal filters from the Zeiss Moviflex GS8.
Do I need to recollimate the lens too?
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#5 Glenn Brady

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Posted 14 June 2011 - 12:50 PM

I'm planning to remove the internal filters from the Zeiss Moviflex GS8.
Do I need to recollimate the lens too?


Strictly speaking, yes. The laws of optics don't change with a different brand or model camera. Having said that, it might be preferable to replace the filters rather than remove them. The lens of this camera is fixed in place, isn't it? If that's the case, recollimation might not be possible.
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#6 Martin Baumgarten

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Posted 15 June 2011 - 04:11 PM

The ZEISS MoviFlex uses the traditional Super 8 camera lens design, where the Daylight Color Conversion Filter moves into position between the Zoom lens module and the 15mm fixed internal prime lens. This design is used on virtually all fixed zoom and non-zoom Super 8mm cameras, and they do not use a clear UV filter as is common on the BEAULIEU 2008S and up interchangeable models (only) to maintain focus collimation to the film plane. So, yes, you can remove the filter in your Zeiss without any serious effect at all.

As for the BEAULIEU lens interchangeable cameras....they are very usable as they are with the filters removed. Since collimation and shipping costs will be significant to the repair station, I recommend doing a focus test at various focal lengths with the lens fully open, then at F/2.8, and then at F/4. Examine the tests and see where the focus is off the most....make notes of those settings....then conduct another test at those settings, but with the focus changed slightly to just before and just after the correct focus point. Slate your shots so you can tell what you're doing....just make a sheet of paper for example....F/4 at minus focus or plus focus; whatever helps you out. Adjusting the lens for correct focus at the film plane also affects the image seen on the ground glass, so that has to be reset as well sometimes.
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#7 Glenn Brady

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Posted 16 June 2011 - 08:32 AM

There's an informative parallel thread elsewhere that includes contributions by Jean-Louis Séguin, a camera technician in Montréal (In-Camera Filters). As is the case here, opinion varies about the effect of the removal of built-in filters.

Edited by Glenn Brady, 16 June 2011 - 08:36 AM.

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#8 Mark Dunn

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Posted 16 June 2011 - 11:06 AM

Just about every Super-8 camera ever made has the built-in 85 filter which is removed as appropriate, so the effect can't be to serious.
Since the pressure plate is plastic and built into the cartridge anyway, it's debatable that the position of the film plane is sufficiently precisely defined for it to make any difference.
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#9 Andries Molenaar

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Posted 16 June 2011 - 03:12 PM

...sometimes.



That is a serious and systematic way to determine one's camera's focal properties.

But considering the properties of the cartridge and other materials it is a bit a waste of time. Also most Super-8 filmers shoot from hand and not from tripod so most have plenty other worries/opties to improve image quality. Rather then spending $200-300 on removal and adjustments or spending hours and $100-s on testing their equipment.

So if nothing is wrong with your filters leave them in. And if you take them out (yourself) just shoot some film and see how focus is. LIkely you couldn't tell the difference :)
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#10 Marc Marti

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Posted 16 June 2011 - 05:54 PM

Thanks for the responses!

The fact is that I had a Nizo 4080 with the filter blocked in and I removed it. The results after the operation were great!
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