PDA

View Full Version : G-Claron performance at 1:1

Greg Davis
7-Aug-2012, 15:45
I am looking at getting a G-claron lens specifically for 1:1 reproductions of flat work, so basically what the lenses were designed for. I have never used one before and was reading the spec sheet for it and came across this graph. If I am reading this right, since the angle of view at f/22 is 64 degrees, then I can expect a one stop loss in the corners, correct? I was looking at the 150mm or 210mm FL, so the image circle would not be significantly larger than the 8x10 film. Can anyone tell me if I am reading this graph right, or what I can expect in terms of practical use from these lenses at close range? I know a lot of you use them for infinity focus, but that does not relate to my needs.

78446

Ken Lee
7-Aug-2012, 18:11
If you plan to shoot 8x10, a 150mm lens isn't really the best solution. A 150mm lens will cover 8x10, but you're going out to the extremes of coverage. A longer lens will have a larger image circle, and you'll be using the sweet-spot or center. If you're set on using a G-Claron, the consider a 210/240mm/305mm/355mm length.

Dan Fromm
7-Aug-2012, 18:49
Ken, I'm with you, but note that Schneider claims a 150 will cover 378 mm at f/22 and 1:1. Less at larger apertures, of course.

Greg, the way to beat cos(theta)^4 is to use a longer focal length, greater working distance, and smaller angle.

vinny
7-Aug-2012, 19:13
I use a 305 g claron for close work on 8x10. Very good. I wouldn't go any shorter than that either.

Graham Patterson
7-Aug-2012, 19:44
Unless I am missing something with the chart, the X axis is in half-angle degrees, so 25 degrees is 50% at f9, 70% at f22 assuming something around a 50 degree angle of view. At 1:1 the angle should be smaller and with less fall off.

Now an 8x10 at 150mm from the subject will make lighting and metering something of a challenge, so I'd prefer something a little longer as well.

Dan Fromm
8-Aug-2012, 06:23
Graham, at 1:1, 300 mm (2f) from the subject to the lens' front node, which is more or less at the diaphragm. Small lens, tapered bellows (?), but possibly still a problem.

Greg Davis
8-Aug-2012, 07:11
Truth be told, I am looking at using this as an enlarging lens for 8x10 negatives at 1:1 or 1:1.3. I would like to print some images on 11x14 paper with a 1 inch border, making the short side 9 inches, so only a slight enlargement. This is out of range for my standard Componon-S lenses, which need a 16x20 inch print or larger to perform best.