8mm Forum: anamorphotic lens question

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Posted by Joerg Polzfusz (Member # 602) on June 28, 2006, 07:01 AM:

Hi,

yesterday I was trying whether my Iscomorphot 8/1.5x can be used for projecting (in combination with my Bauer T610) or not... It was working, but with the anamorphot the picture is only half as bright as without. I think this is very strange since when putting the Isco in front of a camera, the picture is nearly as bright as before. (The Isco is so small that it only fits my Fujica P2 which hasn't got TTL-exposure, but other Iscos do have a lightloss of 1/3 f-stop.)
Why is this?
Some guesses:
1) When using the Isco in front of a camera the eye somehow gets tricked - the lightloss is always the same.
2) When using the Isco in front of a camera the light of 1.5 frames gets bundled onto a single frame. Hence the lightloss is less than compared to projecting (since then the projector's light for a single frame has to enlight 1.5 frames).
3) Same as 2, but with an additional factor: the distance between projector's lens and Isco is too large (can't get below 2cm, while it's only 3-4mm on my Fujica P2), hence there's some additional lightloss due to reflectations, ... .

Does any of the above makes sense? Or is there another cause?

Jörg

Posted by Kevin Faulkner (Member # 6) on June 28, 2006, 06:47 PM:

I think your answer in (2) is probably spot on. Also lens coatings and the direction the light is travelling along with the lens elements physical sizes will all be factors where light loss is concerned.

Kev.

Posted by David Kilderry (Member # 549) on June 28, 2006, 09:19 PM:

Whenever you make a projected image larger, the light will fall off. This applies if you use your zoom, move the projector back from the screen or add an anamorphic.

In Super 8 and 16mm when you add an anamorphic for projection the light will decrease because of this. In 35mm, the opposite occurs! Normal 1.85:1 widescreen 35mm projection uses a very small frame to achieve its width. In 35mm scope the full height frame is used and even though the screen size is increased, the frame size increases by a greater percentage thus allowing more light through the aperture.

Next time you go to the cinema take note when the format changes and see the light improve when it changes to scope. This will be even more dramatic if the theatre uses the dreaded top masking only to alter the aspect ratio. The correct adjustment is always with side masking only for scope ratio. These days around 75% of features are released in scope (2.39:1).

David

Posted by Joerg Polzfusz (Member # 602) on June 29, 2006, 08:10 AM:

Hi,

thanks alot for your answers.

Jörg

Posted by Steven Sigel (Member # 21) on June 29, 2006, 09:05 AM:

If your lens is a 1.5x, it's not going to work for normal scope features. Scope on 16mm and super 8 is printed with a 2X squeeze, so you need a 2X lens to show it in proper ratio.

There are a few 16mm prints (Warnerscope and some airline stuff) that was printed at a 1.5X squeeze, but they're very rare.. Not sure if there's any super 8 printed that way...

Posted by Dimitrios Kremalis (Member # 272) on June 29, 2006, 09:57 AM:

Steven,
I understand that a 1.5x lens can't work with scope films. But couldn't a 1.5x lens be used to project flat features in widescreen? Would the squeeze negatively affect the picture?

Posted by Steven Sigel (Member # 21) on June 29, 2006, 10:08 AM:

Hi Dimitrios --

Not really -- you would get a wider picture, but since the film wasn't squeezed, you'd just be stretching out the picture so that people would look squashed (fat and short) etc... Not very pleasing effect

Posted by Joerg Polzfusz (Member # 602) on June 29, 2006, 11:31 AM:

Thanks, I know that I'll be "incompatible". But my P2 with the Isco wheights much less than the smalest 2x anamorphot I own (a Kowa 16D).
I'm working on getting any of my 2x-anamorphots to work with any of my "serious" Super8/Single8-cameras, but -when travelling- wheight and bulkiness will be an issue. So using my cheap P2 (10EUR at eBay incl. shipping) with that cheap Isco (15EUR at eBay incl. shipping) as a 18:9 (or 2:1)-camera seems to be the perfect choice [Smile]

Jörg

Posted by Jan Bister (Member # 332) on June 29, 2006, 10:07 PM:

OK, I have an anamorphic-lens question of my own. [Cool]

What 2x scope lenses are out there that have a 52mm rear barrel? Which ones are generally recommended and which ones should I stay away from (regardless of rear barrel diameter)?
As for the 52mm deal, it would be neat to have one like that because my free-standing scope bracket has a 52mm mounting ring, and it would allow me to shoot movies with my super-8 camera in scope format without running smack into vignetting (at least with larger focal lenghts).

Posted by John Whittle (Member # 22) on June 29, 2006, 11:07 PM:

The two most common are the Sankor 16D and the Kowa 16H (which is the same as the 8Z). These optics appear with many different engravings on them (Elmo, Eiki, Victor, Singer, etc).

The problem is you really need to test the lens since any slight misalignment of the front and back optics kills contrast of the image (you'll notice when you focus a scope lens, the elements don't turn).

To use a lens for photography, remember that you'll have to focus both the prime (back lens) AND the scope lens. Professional lenses (i. e. Panavision & Arriflex et al) have a single focusing ring that does both sets of elements at once.

You can get acceptable results, but restrain youself from zooming during a shot since you might notice some lens imperfections in the shot.

There are also some German lense with a 52mm barrel, but they're fewer and generally sell for more money. But in any case test the lens before you buy (or get a money back guarantee) since the lenses can go out of alignment over time with rough handling.

John

Posted by Joerg Polzfusz (Member # 602) on June 30, 2006, 05:06 AM:

Some specifications of 2x anamorphots with a 52mm rear (collected by Martin W. Baumgarten):

1. KOWA 16-H (or 8-Z) lens
* Magnification (horizontal).....2x
* Distance Scale.................5ft to Infinity
* Rear Barrel Diameter...........52mm
* Length.........................84mm
* Net Weight.....................530 grams
* Filter thread..................none (must use add on Centafit {72mm} or similar)
* Rear Barrel Threading..........50mm
* Light-loss Absorbtion..........1/3 F-Stop or less
2. ISCO CENTAVISION (sold by Widescreen Centre in England and Scoptimax in Germany)
* Magnification (horizontal).....2x
* Distance Scale.................5ft to infinity
* Rear Barrel Diameter...........52mm
* Length.........................87mm (at infinity setting, 81mm at 5ft setting)
* Net Weight.....................520 grams
* Filter Thread..................72mm
* Rear Barrel Threading..........49mm
* Light-loss Absorbtion..........1/3 Stop or less
3. SANKOR 16D (aka JAN 16-D)
* Magnification (horizontal).....2x
* Distance Scale.................5ft to infinity
* Front outside diameter.........74mm
* Rear Barrel Diameter...........52mm
* Length.........................129mm (at Infinity setting)
* Net Weight.....................700 grams
* Filter Thread..................none
* Rear Barrel Threading..........52mm(?)
* Light-loss Absorbtion..........1/3 Stop or less

There's also a "Kowa 16-F" that's similar to the "Kowa 16-H", but longer at infinity (hence vignetting will be worse than onthe 16-H). (Using the "Kowa 16-H", you won't be able to use the zoom-range below 15mm or 20mm, depending on the camera.)
There's also a "Bell & Howell" anamorphot made by Kowa with a rear-barrel with a 54mm-filter-thread (There are cheap 52mm-to-54mm-step-up-rings!). It's a slightly modified version of either "Kowa 16-F" or "Kowa 16-H".

BTW: FFR-Film is selling a "CS Adapterring" to mount a Kowa 16-H/8-Z to any lens with a M52, M55 or M58-filter-thread for 45EUR:
http://www.ffr-film.de/Katalog/Seiten/Anamorphotenhalter.htm
Of course this will only be of help when your super8-camera's filter thread doesn't rotate while zooming/focusing.

Jörg

Posted by Jan Bister (Member # 332) on June 30, 2006, 07:04 PM:

Terrific! I'm once again amazed at the wealth of info that some of you carry around with you. Thanks guys [Smile]

Posted by Kevin Faulkner (Member # 6) on July 01, 2006, 05:20 AM:

I was also reliably informed recently that the Widescreen Centre in London can still produce custom made adaptors to special order.

Kev.

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