Coverage of 180/315mm convertible symmar

[Enrico Faini]

I am planning to move into large format, and as my first lens I was considering the purchase of a Schneider Symmar 180mm convertible which I will use on a 5x7 camera.
Schneider's website states that the 180mm Symmar has an image circle of 255mm, which I believe shoud be enough for 5x7 with a bit of movements.
But does anybody know what the image circle will be when the front element is removed to convert the lens to a 315mm f/12? Will the lens still have sufficent coverage for 5x7?

[Emmanuel BIGLER]

Hi

The information you are looking for is available in the Schneider archive made of scans of old brochures

http://www.schneiderkreuznach.com/archiv/archiv.htm

The document describing the Symmars are
symmar_1964.pdf and sr_5.6_a.pdf

In this last document you have all the data about wat happens when the rear unit of a symmar is used.
The listed angle of coverage is 40°.
So the expected image circle for 40°, for the rear unit, 315mm focal length of the 180 symmar is about 230 mm. So it covers 13x18cm - 5x7" but barely ; the diagonal of 5x7" is about 210 mm. And do not expect with the "convertible" lens of course an image quality on par with a "true" 300mm lens.

[Jerry Flynn]

An additional consideration: I used one of these for years and it gave me very good service. I did not use the 315mm length, though, because it required more extension than my camera could provide. While you migh think that it would need a bit more than 12 inches, it turns out to require quite a bit more. When converted, the optical center of the lens shifts rearward. (Plus, the whole lens is mounted behind the lensboard when converted.)

[Enrico Faini]

Thankyou all.
Although it does cover 5x7, it looks like I would not be able to use the 315mm focal lenght with the camera I was planning to buy (a 5x7 nagaoka) due to the excessively long bellows extension it requires. So since I would no longer have the advantage of having two focal lenghts I think that I might as well get something more modern and multicoated.

[Kevin Crisp]

Enrico: This was my main lens for 5X7 for several years. The room for movements as a 180mm lens was more than recommended, I certainly used it with more than 1 1/2" of rise on several occasions and the prints in 16X20 are very sharp. You can use the front lens alone and get a longer lens, it doesn't exactly match focal length with using the rear alone, and the green (longer) aperture scale is close to accurate and this way you need much less bellow draw. I would still be using this lens had I not found an exceptional price on a multi-coated "S" version. Good luck with it whatever you do.