Iron Glass MKII Soviet Image Circles & Sensor Coverage
Image circles of the Iron Glass MKII Soviet lenses and coverage of ARRI LF open gate, 4.3K LF 16:9, 3.8K LF 16:9, S35 open gate and Alexa Mini 3.2K formats.
Ben Bateman
Updated 29 Sep 2025
·
2 min read
The Iron Glass MKII Soviets are vintage lenses with designs going back to the 1950s. Our seven lens set consists of a 20mm T3.6 Mir-20M, 28mm T3.6 Mir-10A, 37mm T2.9 Mir-1V, 50mm T2.1 Helios-77M-4, 58mm T2.1 Helios 44-2, 85mm T2.1 Jupiter-9 and 135mm T2.9 Tair-11A.
All lenses in the set fully cover the 44.71mm diameter ARRI LF Open Gate format, except the 20mm - which has some slight portholing in the corners. The 28mm has some slight vignetting.
See below for coverage details of each lens.
20mm T3.6 Mir-20M
The 20mm is the only lens in the set that shows portholing in the corners of the frame on LF open gate (rather than just lower illumination, or vignetting). It very nearly covers open gate, but the image circle at about 43mm is just shy of the 44.71mm needed for LF open gate.
The 20mm almost covers LF open gate but there is obvious portholing in the corners of the frame.
28mm T3.6 Mir-10A
The 28mm does show some vignetting in the corners of LF Open Gate format but, unlike the 20mm, it does not porthole.
The 28mm has some slight vignetting of LF Open Gate, but coverage is good overall.
37mm T2.9 Mir-1V
The 37mm lens fully covers LF Open Gate without any obvious vignetting.
The 37mm fully covers LF Open Gate.
50mm T2.1 Helios-77M-4
The 50mm also fully covers LF Open Gate without issue.
The 50mm fully covers LF Open Gate.
58mm T2.1 Helios 44-2
The 58mm fully covers the LF Open Gate format.
The 58mm fully covers LF Open Gate.
85mm T2.1 Jupiter-9
The 85mm lens also fully covers LF Open Gate with ease.
The 85mm fully covers LF Open Gate.
135mm T2.9 Tair-11A
Finally, the 135mm also fully covers LF Open Gate format with no trouble.
The 135mm fully covers LF Open Gate.
