arri
21-Jun-2023, 15:10
I just finished my new lens. I used two single meniscus lenses:
Ø 160mm F=500mm fused silica glass
Ø 120mm F= 1200mm, CaFl glass
Makes a lens 350mm f/2.8
The aperture is only nominal, maybe usable but not tested. For my sample shot I used f/22
After setting the sharpness I have to reduse the focus point minus 7mm to compensate the chemical focus shift.
Both kinds of glass having a very high UV transmission, down to 190nm. This makes it perfect for wetplate or dryplates with non sensitive coatings.
I find it very interesting to see that the closer objects are sharper than the ones at infinty, a result of the not corrected spherical distortion, I guess.
I used the orthochromatic X-Ray film from Fuji, UM-MA in 18x24cm size. Wehner Developer
https://live.staticflickr.com/65535/52989974323_b3957b4e93_k.jpg
Ø 160mm F=500mm fused silica glass
Ø 120mm F= 1200mm, CaFl glass
Makes a lens 350mm f/2.8
The aperture is only nominal, maybe usable but not tested. For my sample shot I used f/22
After setting the sharpness I have to reduse the focus point minus 7mm to compensate the chemical focus shift.
Both kinds of glass having a very high UV transmission, down to 190nm. This makes it perfect for wetplate or dryplates with non sensitive coatings.
I find it very interesting to see that the closer objects are sharper than the ones at infinty, a result of the not corrected spherical distortion, I guess.
I used the orthochromatic X-Ray film from Fuji, UM-MA in 18x24cm size. Wehner Developer
https://live.staticflickr.com/65535/52989974323_b3957b4e93_k.jpg