8mm Forum: Scope lens advice needed ...

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Topic: Scope lens advice needed ...

Mike Peckham
Phenomenal Film Handler

Posts: 1461
From: West Sussex, UK.
Registered: Jun 2003

posted November 10, 2004 02:43 PM

I'm having a bit of difficulty setting up my scope lens in such a way that I don't get vignetting at the corners. I'm starting to wonder whether or not it will be possible with my lens or if I should perhaps be investing in a different make and type [Frown]

.

I'm using the F1:1,1 lens on the GS and have a swing away bracket mounted on the front, in that I have a Sankor 16F Anamorphic lens. I'm wondering in part if the problem is with the distance between the two lenses. When I used to use this set up on the Sankyo 800 with a free standing lens holder I was able to get the base of the Anamorphic to slot right into the projector lens and didn't seem to get a problem with vignetting.

I just don't seem to be able to get a clean edge to the frame and an even light across the image area and into the corners.

Any advice would be gratefully received.

Mike [Smile]

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Auntie Em must have stopped wondering where I am by now...

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Tim Christian
Expert Film Handler

Posts: 219
From: Norfolk, UK
Registered: Jun 2003

posted November 10, 2004 03:24 PM

Vignetting in a scope lens is determined by two main factors: projection lens focal length and projector lens to anamorphic spacing. Even a spacing of 2 mm will cause vignetting in marginal cases. With a Proskar 16B, with focal lengths down to 15 mm, there is no vignetting at spacings of 1-2 mm. On the other hand, the smaller 16C starts to vignette at focal lengths below about 20 mm.

It is just the same with cameras.

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Tim

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Tony Milman
Phenomenal Film Handler

Posts: 1336
From: United Kingdom
Registered: Jun 2003

posted November 10, 2004 04:34 PM

Mike,

I am using a Kowa 16Z (I think!) and unless my eyesight is as bad as I thnk I don't seem to get this- why not bring it along to the next get together of the lightwater 6 (hundred)?

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Tony

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Kevin Faulkner
Film God

Posts: 4071
From: Essex UK
Registered: Jun 2003

posted November 13, 2004 05:47 AM

The Scope lens for super 8 needs to have quite a large rear element. The Kowa 8Z has just this and I think is a rebadged version of the 16D. I suspect the rear element, from your description Mike, is a little on the small side especially as it was designed for 16mm.

I think Mike, that if you were to zoom the image to its smallest size then this uneveness would disapear. If it does then its down to the reason above.

Kev.

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GS1200 Xenon with Elmo 1.0...great combo along with a 16-CL Xenon for that super bright white light.

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John Cook
Expert Film Handler

Posts: 183
From: Papillion, NE
Registered: Apr 2004

posted November 13, 2004 11:01 PM

Kevin,

I've been thinking of acquiring a scope lens, if you could only purchase one lens and had limited funding would the Kowa 8Z be your choice to mate to a GS1200 with a F1.1 lens? If not what would be your lens of choice?

Regards, John

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Come visit The Pit
http://members.cox.net/home-theater

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Kevin Faulkner
Film God

Posts: 4071
From: Essex UK
Registered: Jun 2003

posted November 14, 2004 05:39 AM

Hi John,
Yes the Kowa 8Z is an excellent choice of Scope Lens. I have one which I use on both my GS1200 Xenon and also my Elmo 16CL. It has a large rear element which is what's required for super 8 when projecting at the short distances that most of us do and at the magnification required for super 8.
Be wary of using some of the 16mm scope lenses as the rear element will be a bit too small and you wont be able to get it close enough to your prime lens to stop vignetting.

Kev.

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GS1200 Xenon with Elmo 1.0...great combo along with a 16-CL Xenon for that super bright white light.

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Mike Peckham
Phenomenal Film Handler

Posts: 1461
From: West Sussex, UK.
Registered: Jun 2003

posted November 16, 2004 02:11 PM

Thanks for the advice chaps, I tried holding the lens just in front of the projector lens with as little gap as possible and that seemed to improve things but clearly this is the wrong lens to be using for 8mm. I shall now be on the look out for a Kowa 8Z and a new bracket.

This all started after seeing John Clanceys scope set up in his living room, I had no idea that super 8 could look so good in cinemascope, made me realise that I wasn't getting the full benifit [as it were]. [Wink]

Mike

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Auntie Em must have stopped wondering where I am by now...

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John Clancy
Phenomenal Film Handler

Posts: 1954
From: Cornwall
Registered: Jun 2003

posted November 17, 2004 01:57 AM

I also get pretty good results from the cheapie lens Walton were selling years ago. I think it's an Iscomorphot Iscorama and was designed specifically for Super 8. These can be picked up for as little as £25 whereas the Kowa is generally at least £80.

I use the Iscomorphot for 35mm now. Has a bit of vignetting but it saves having to move the Kowa over to a different machine every time I want to watch a 'Scope film. I'm not saying it's as good as the Kowa but it certainly gives good results and represents good value.

Get one with the original box Mike. You'll love it - a scantilly clad girlie on a beach.

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British Film Collectors Convention home page www.bfcc.biz. The site is for the whole of the film collecting hobby and not just the BFCC.

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Paul Adsett
Film God

Posts: 5003
From: USA
Registered: Jun 2003

posted November 17, 2004 05:41 PM

John , you're forgetting that with Mike, nothing can compete with Rexette the stripper!

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The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
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