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Shooting with HV20 + 16mm or 35mm anamorphic projector lenses?


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#1 Barry Cohen

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Posted 16 August 2007 - 01:00 AM

Hello,

I'm shooting with an HV20 and I'd like to add an anamorphic projector lens to the front of it to achieve a ridiculously wide aspect ratio. The camera has a single, 1/3" 16:9 CMOS sensor to start with, so adding a 2X anamorphic would potentially give me a ratio of 3.55:1. Sounds good to me.

A Mr. Nathan Snyder has a website ( http://owyheesound.c...anamorphic.html ) with multiple examples of stuff shot through, I believe, a Bausch & Lomb 35mm Cinemascope Attachment I projector lens into a Canon GL2. His stuff looks great.

It surprises me that he was able to focus on objects only a few feet from the B&L Cinemascope Attachment I when, if I am not mistaken, said attachment is intended to focus a projector image onto a screen a minimum of 50 feet away... I'd thought that was the reason shooters intending to shoot through projector lenses opt for 16mm anamorphic projector attachments over 35mm ones--because the 16mm anamorphic projector attachments can focus a projection on screens a mere 6 feet away rather than 17 to 50 feet away as is the case with many 35mm anamorphic projector attachments.

I thought, if, say, an Iscorama 54 can't focus a projected image on a screen less than 6 feet away, then it probably can't focus on an object less than 6 feet away while shooting through it. But Nathan Snyder seems to have been achieving focus on objects about 6 feet away or so shooting through a 7" long, 8 lb. 35mm B&L Cinemascope Projector Attachment I...

If this is possible, why would I want to shoot through 16mm attachments over 35mm ones? Wouldn't barrel distortion, and CA likely be superior in a quality Isco 35mm attachment than in a quality Isco 16mm attachment? I suppose the extra length of most 35mm attachments over 16mm ones could increase the likelihood of vignetting, but certainly the size of the front and rear elements in any given attachment would also affect this, and, generally, 35mm attachments have larger diameter front and rear elements... Finally, because of the demand for quality, large-diameter 16mm anamorphic attachments, they are often sold for much more than quality, large-diameter 35mm anamorphic attachments.

Of primary concern to me in my decision as to whether to shoot through 16mm or 35mm attachments is focal length. I want to be able to shoot with as wide angles as possible. The HV20 has a 10X 6.1mm-61mm zoom yielding a widest focal length of 43.6mm, in 35mm still photography terms. The camera's front filter threads are 43mm, though its front optical element looks to be no more than 25mm or so in diameter... If, with any anamorphic projector attachment, I would be forced to zoom in a whole lot to avoid vignetting, I might reconsider the whole thing...

Where do the "Drive-in" attachments fit in to all of this? The Hilux Val and such. The ones that squeeze a projection vertically rather than expand it horizontally? What about shooting through one of those?

I greatly appreciate any information anyone can provide about any of this.

Thanks a lot,
Barry
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#2 Michael Nash

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Posted 16 August 2007 - 04:03 AM

I have to admit all this projector anamorphic stuff is new to me, but close focus would seem to be a function of the camera's macro focus ability. In zoom lenses at least, macro focus moves a different lens element (usually at the rear) to take over where the front-focusing element reaches its limit. Making minimum focus much closer -- often up to the surface of the front element.
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#3 John Sprung

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Posted 16 August 2007 - 07:42 PM

Close focus is mainly a function of how far you can move the lens from the film plane. That's why there are extension tubes and bellows for macro work. The farther from the film, the closer to the subject. You can get a feel for this by using a simple magnifying glass to make an image of a light bulb on a sheet of paper.

It's true that projection lenses are generally long focal lengths by camera standards. For 35mm, most are in the 2" to 10" range.

As for shooting HD using projection anamorphic adapters, the best thing to do is try several of them, shoot some tests. The projection department at a studio, or a regional engineer who works on theaters, would be likely to have some. If you just want to shoot tests thru them, and not take them away with you, you might be able to find someone who'd let you do that. There are a lot more cameras out there than projectors, so projection glass may be more expensive than you might think.



-- J.S.
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