John Leathwick
Well-known member
I'm close to finishing a little project that brings me much closer to having a set of more lightweight, high-performing lenses to use with my GFX-100s and Arca-Swiss F-Universalis. I had been using Mamiya RZ lenses, but most of them weigh around 1kg apiece, placing an excessive load both on the camera, and the photographer's back. Encouraged by Rob de Loe's setting up of a Schneider Apo Digitar 35mm L, which he transferred from a Rollei electronic shutter to a manual Copal 0 shutter (described in a post on this site), I recently purchased a Schneider Digitar 47mm in a Schneider Electronic shutter along with a cheap SK Componon-S 135 whose glass was long past its use by date.
The Componon-S 135mm arrived first and once the cells were extracted, the B-0 aperture mechanism proved to be in excellent condition. When the Digitar arrived, its cells easily transferred into the B-0 mount and I proceeded to fire some test images. Initial results were not encouraging, with good central resolution but poor resolution in the outer part of the image circle. I did a quick check to see if the inter-cell distance needed adjustment, winding the front cell out in 1/8th turn steps, but this made matters worse. I then took out the 0.1mm shim that was behind the front cell when in the electronic shutter, and which I had retained in the B-0 mount. This gave a much more satisfactory result. Thanks to Rob's generosity, I had a set of shims in 0.02, 0.05 and 0.1 thicknesses so proceeded to test more thoroughly using these, this eliminating any errors resulting from the front cell sitting loosely in its thread. The 0.02 shim was a clear winner, giving a noticeable improvement over mounting the cell with no shim.
Today I went through to my usual test site - our local port - and put the Digitar through its paces. It's performance is closely similar to the Apo-Digitar 35 L-88 that I have - at F/11 it delivers impressive central sharpness, with slight fall off towards the edge of the image circle, a decline that is easily dealt with by sharpening. The rear cell sits within the Rotafoot of my F-Universalis, so shifts are limited to around 8mm, but that is sufficient to deliver a full height flat-stitched image in the 9x16 format that I generally prefer (below). And when I focused on an object close enough for the rear cell to clear the rotafoot, I was able to shift a full 20mm without significant loss of resolution.
And the crucial question - with its lens board, the re-mounted Digitar 47 weighs just 220 gm, a significant gain over the RZ 50, which with its board weighs in at 1170 gm - a more than 5-fold reduction which makes for a happy old back!
-John
The Componon-S 135mm arrived first and once the cells were extracted, the B-0 aperture mechanism proved to be in excellent condition. When the Digitar arrived, its cells easily transferred into the B-0 mount and I proceeded to fire some test images. Initial results were not encouraging, with good central resolution but poor resolution in the outer part of the image circle. I did a quick check to see if the inter-cell distance needed adjustment, winding the front cell out in 1/8th turn steps, but this made matters worse. I then took out the 0.1mm shim that was behind the front cell when in the electronic shutter, and which I had retained in the B-0 mount. This gave a much more satisfactory result. Thanks to Rob's generosity, I had a set of shims in 0.02, 0.05 and 0.1 thicknesses so proceeded to test more thoroughly using these, this eliminating any errors resulting from the front cell sitting loosely in its thread. The 0.02 shim was a clear winner, giving a noticeable improvement over mounting the cell with no shim.
Today I went through to my usual test site - our local port - and put the Digitar through its paces. It's performance is closely similar to the Apo-Digitar 35 L-88 that I have - at F/11 it delivers impressive central sharpness, with slight fall off towards the edge of the image circle, a decline that is easily dealt with by sharpening. The rear cell sits within the Rotafoot of my F-Universalis, so shifts are limited to around 8mm, but that is sufficient to deliver a full height flat-stitched image in the 9x16 format that I generally prefer (below). And when I focused on an object close enough for the rear cell to clear the rotafoot, I was able to shift a full 20mm without significant loss of resolution.
And the crucial question - with its lens board, the re-mounted Digitar 47 weighs just 220 gm, a significant gain over the RZ 50, which with its board weighs in at 1170 gm - a more than 5-fold reduction which makes for a happy old back!
-John
