Gundlach Radar Anastigmat 8x10 users

[benrains]

The front and rear lens elements seem to be in proper order. It's not even clear to me how the front would be separated into the separate lenses, and I don't see any sort of tampering with it. What I did find is that the spacer rings into which the front and rear elements are screwed into are of different widths. One of the rings is a 3/4" band, the other is about 9/16". The 9/16" one had been situated between the front element and the shutter and the back one was paired with the 3/4" band. The spacers are interchangeable, so I'm guessing they were swapped at some point. For those of you with good examples of the lens, how are they arranged on yours?

[Steven Tribe]

Mounted in a shutter - that gives even more possibilities for a mix up! Don't assume that the front element IS the front element. Or that the lens was correctly installed in the shutter in the first place. The difference in spacer ring size is enough to cause problems (position of the iris) if these have been swapped.

[Jim Graves]

On mine, the front spacer ring is the narrower of the two. But, when I switch just the rings, it makes little difference ... the focal length stays the same and I don't get vignetting ... so I don't think that's your issue.

The Radar is a modified Tessar with the rear element being a cemented triplet. The rear element should have the flat side toward the iris and the convex side toward the film. The front element set should be convex on the front and concave on the iris side.

[benrains]

On mine, the front spacer ring is the narrower of the two. But, when I switch just the rings, it makes little difference ... the focal length stays the same and I don't get vignetting ... so I don't think that's your issue.

The Radar is a modified Tessar with the rear element being a cemented triplet. The rear element should have the flat side toward the iris and the convex side toward the film. The front element set should be convex on the front and concave on the iris side.

Thanks for taking the time to look at your lens and provide that information.

I wouldn't expect swapping the bands would have any effect on the focal length because the combined distance been the front and rear elements wouldn't change... just the position of the aperture opening along the lens axis. The focal length of mine is on par with the other 12" and ~300mm Tessar lenses I have. They don't vignette when used on the same camera, and I'm not using any sort of lens hood that'd cause it to happen.

Everything about the Radar seems to be in order in the way of the surfaces and their orientation, and honestly, I think it'd be all but physically impossible to re-arrange the individual lenses without machining new barrels. There aren't any signs of tampering, damage... or of any separation in the cemented triplet. The front and rear elements have matching serial numbers on their brasswork.

Thankfully it's not a huge deal, just sort of a curiosity. I've a Wollensak Velostigmat 12"/4.5 that I normally use in my studio camera for that focal length.

[Daniel_Buck]

The Gundlach Radar 12"/f4.5 in Betax is one of my most used lenses on 8x10, I really like what it produces, I shoot it wide open and stopped down. It does get just a little bit darker towards the corners than the center, but I think there's still quite a bit of room for decent movements. Though it looses sharpness in the corners when stopped down.

When I'm shooting long exposures (like the last image I'm posting) the reciprocity seems to make the vignetting more pronounced, but I notice this with just about any lens I use for long exposures.

Here's some wide open shots, it covers 8x10 just fine. If I remember correctly, I think I did stop down to f8 on the shot of the little girl, but the other two I know were wide open.