therealblowers
Potts 11 raw
Zeiss Ikonta 521
Zeiss-Opton Tessar 75mm f/3.5 (Issues)
Yellow filter
Ilford Delta 400
Caffenol CHrs modified - 45g/L Sodium Carb. 10g/L Iodised salt
12'30" 20C
f/8 1/100 handheld inf. focus
I took a chance on this quite-clean-looking Zeiss folder with an Opton Tessar objective. Prior to this I'd read about the Opton branch of Zeiss electing to use pitch in some of their lenses, rather than mechanical fasteners, to secure the lens elements in place - and the shortcomings of this approach when it came to long-term reliability of the lens' optical alignment. I'd also read that Zeiss-Opton produced excellent optics which at some point were enlisted to address QC issues coming from Zeiss Jena. So, a mixed bag of opinion.
Unfortunately, it seems this copy has lived up its reputation for misalignment - the mess of yellow adhesive around the perimeter of the middle group element would suggest this is the culprit - I presume it has been subject to some less-favourable conditions which have caused the adhesive to creep over time.
I haven't investigated the lens fully yet (particularly: whether the elements rest against a hard stop, making their position easy to locate) but I'm hoping I might be able to clean & re-cement the element in place at some point.
The few images taken at f/22 have been acceptable. I like the contrast and some of the detail here at f/8 too, considering the obvious problem.., so I'm remaining positive that the Opton Tessar should make a good lens were it properly aligned.
Potts 11 raw
Zeiss Ikonta 521
Zeiss-Opton Tessar 75mm f/3.5 (Issues)
Yellow filter
Ilford Delta 400
Caffenol CHrs modified - 45g/L Sodium Carb. 10g/L Iodised salt
12'30" 20C
f/8 1/100 handheld inf. focus
I took a chance on this quite-clean-looking Zeiss folder with an Opton Tessar objective. Prior to this I'd read about the Opton branch of Zeiss electing to use pitch in some of their lenses, rather than mechanical fasteners, to secure the lens elements in place - and the shortcomings of this approach when it came to long-term reliability of the lens' optical alignment. I'd also read that Zeiss-Opton produced excellent optics which at some point were enlisted to address QC issues coming from Zeiss Jena. So, a mixed bag of opinion.
Unfortunately, it seems this copy has lived up its reputation for misalignment - the mess of yellow adhesive around the perimeter of the middle group element would suggest this is the culprit - I presume it has been subject to some less-favourable conditions which have caused the adhesive to creep over time.
I haven't investigated the lens fully yet (particularly: whether the elements rest against a hard stop, making their position easy to locate) but I'm hoping I might be able to clean & re-cement the element in place at some point.
The few images taken at f/22 have been acceptable. I like the contrast and some of the detail here at f/8 too, considering the obvious problem.., so I'm remaining positive that the Opton Tessar should make a good lens were it properly aligned.