8mm Forum: Sankor Anamorphic lens

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Posted by Winbert Hutahaean (Member # 58) on July 27, 2006, 03:39 AM:

My friend here offered me an Anamorphic lens, Sankor, which I believe not for 8mm. This is due to the diameter which was 6 inch (15cm) for the front lens and 3 inch (8 cm) for the rear one.

1. Can we still use this to our 8mm projector (I saw one picture a GS1200 with that big lens, but I don't have GS only ST1200).

2. Will it work properly compared to a dedicated 8mm anamorphic lens

3. What do you figure the value of this lens (this Sankor is chrome finished body) which does not have any fungus with it.

thanks,

Posted by Jan Bister (Member # 332) on July 27, 2006, 09:41 AM:

Sounds like it's a 35mm lens (I mean, made for 35mm projectors). But to answer your questions:

1. Yes. (You'll just have to make your own bracket for the lens.)

2. Absolutely!

3. Hard to say... in good condition maybe $75 to $100. I know I wouldn't pay much more than that...

Posted by Steve Klare (Member # 12) on July 27, 2006, 11:20 AM:

Other than being big and heavy it would probably be a great lens to use for anamorphic filmmaking. The classic problem when doing this (...once you've worked out the mounting) is vignetting caused by the lens diameter being too small.

With this big diameter anamorphic I don't think that will happen. It would basically be usable with any camera at any focal length.

Up for an adventure, Winbert?

Posted by Joerg Polzfusz (Member # 602) on July 27, 2006, 11:53 AM:

Hi,

don't forget to check whether such a big lens can be attached to your projector without any problems due to its size/bulkiness. E.g. using a large "Rectimascope"-anamorphot on my Bauer T610 nearly makes the anamorphot collide with a knob that can be used to advance single frames and that rotates while projecting.

Jörg

Posted by Jan Bister (Member # 332) on July 27, 2006, 02:04 PM:

Ah, but the nice thing about scope lenses - particularly such large ones - is that they don't have to be all that close to the prime lens. So, Joerg, I bet you could easily place your scope lens further away from the T610, possibly far enough to still allow you easy access to the frame advance knob if need be.

I've never seen anyone use a 35mm scope lens with a super-8 camera... that must look absolutely wild. Of course, weight alone would make it impossible to screw it right into the camera lens so something would have to be devised much like a "macro bar" (which extends forward from underneath the camera and allows one to mount slides or keyhole cutouts in front of the lens for macro filming, etc.)

Posted by Knut Nordahl (Member # 518) on July 28, 2006, 03:25 AM:

quote:
I've never seen anyone use a 35mm scope lens with a super-8 camera... that must look absolutely wild. Of course, weight alone would make it impossible to screw it right into the camera lens so something would have to be devised much like a "macro bar" (which extends forward from underneath the camera and allows one to mount slides or keyhole cutouts in front of the lens for macro filming, etc.)

You can not screw the anamorph right onto a super8 camera for the reason you mention, but also nearly all super8 cameras have a focus ring, and attaching the anamorphic to the focus ring would mean that as you focus you turn the anamorpic element as well and you would change the squeezing of the image.

Posted by Joerg Polzfusz (Member # 602) on July 28, 2006, 03:36 AM:

quote:
So, Joerg, I bet you could easily place your scope lens further away from the T610, possibly far enough to still allow you easy access to the frame advance knob if need be.

Yes, it works. But it's a very close thing - if I move the scope lens a single millimeter close to the projector, it'll touch that knob. If I move it more than 5mm further away, I can't focus anymore and get vignetting.

quote:
I've never seen anyone use a 35mm scope lens with a super-8 camera...

I've spoken to some other amateur filmmakers. They agree that the rectimascope gives a very sharp projected image. But according to them using it for filming is a waste of filmstock since the image will allways be out of focus. And due to its lengths, you'll run into the same vignetting problems as when using smaler anamorphot. (Not to mention that e.g. a Kowa wheights much, much less!)
I don't know if this applies to other 35mm-projection-anamorphots from Schneider/Isco/Möller/... though.

Jörg

Posted by John Whittle (Member # 22) on July 28, 2006, 05:12 PM:

Be very careful about focusing disctances when using lenses made for theatres. They often don't focus closer than 50 or 100 feet which means any shorter throw will not be sharp. Technically you can't say out of focus since a scope lens only works in one direct and the focusing scale is really an astigmatism correction.

Lenses designed for 8mm/16mm focus much closer, usually from six feet (two meters) to infinity.

There are some converted Sankor design lenses that were modified for telecine use and these focus at about three feet. If you find a "short length" Sankor 16C/F, DO Industires or Eiki lens on Ebay, it is likely one of these modified by LAird to the the US Navy telecines they made.

John

Posted by Jan Bister (Member # 332) on July 28, 2006, 05:34 PM:

What is an 'astigmatism'? (Sounds like some sort of illness to me, actually) [Eek!]

Posted by Winbert Hutahaean (Member # 58) on July 31, 2006, 07:20 AM:

I finally decided to take the lense, no matter it will work or not to my projector.

The reason was becausemy friend asked a price that I could not resist.He asked for Rp 100,000 which if I converted it to US$ it equals to US$ 11.

Yes...that is true....

Posted by John Whittle (Member # 22) on July 31, 2006, 10:42 AM:

quote:
What is an 'astigmatism'? (Sounds like some sort of illness to me, actually)

It is an eye condition as well (I know, I have it and have it corrected in my glasses).

What it means is the scope lens only converges in the horizontal. To properly focus a scope lens you would would an SMPTE target with the scope lens off and get good overall focus of the chart. Then you put the scope lens in place and you'll notice as you "focus" that the vertical lines will be the ones that become wider or narrow (as it gets "in to focus").

If the front and back elements are not perfectly aligned, then it can never get into razor sharp focus and the first thing you notice is a drop in contast, then an overall softness to the image.

With the proper tools, you can align the lens. But I think those days, those technicians and those tools are long gone for the small lenses. In any event it would cost five to ten times what a used lens sells for to fix one.

The short take, that's why I always recommend you try a lens in your screening room before committing to purchase--I've had my share of soft lenses and have actually corrected a couple.

For the record, the further apart the front and back scope elements are, the more distant the focus. The closer together the shorter the focus distance. This will vary with lens formula somewhat but it's one of the reasons that theatre scope lenses won't focus at a twenty foot throw.

John

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