Why does the Industar 50-2 produce rainbow streak flare?
Asked 3/12/2019
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My Industar 50-2 50mm f/3.5 consistently produces rainbow-like streak flare, and the pattern rotates when I focus the lens. Since the front element rotates during focusing, I’m wondering whether this effect is normal for the lens design, a result of minimal coating, or a defect. The optics appear undamaged and image quality is otherwise fine. What is likely causing this flare, and is it considered normal behavior for this lens?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
7y ago
2 Answers
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I think the lens flare is a side-effect 2 things: simple Tessar lens design, and little or no coatings on the lens elements. There's probably nothing you can do to "accidentally fix" the flare on this lens. (edit: nothing normal, that is. I supposed if you were to have anti-reflective lens coatings applied to the lens elements internally, you'd reduce some/most of the flare. But that's a lot of effort and cost for such an inexpensive lens)
Here's a screenshot from this video review of the 50-2. It exhibits the same sort of flare:
So don't be afraid, go ahead and clean the lens. You won't wipe its character away. =)
Originally by user11924. Source · Licensed CC BY-SA 4.0
user11924
7y ago
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Generated from our catalog & community — verify before relying on it.
This is most likely normal behavior for the Industar 50-2 rather than damage. The effect is commonly associated with its simple Tessar-type optical design and minimal or less-effective anti-reflection coatings compared with modern lenses. Strong light can reflect between lens surfaces and create colored streak flare, especially in older designs with fewer coating advantages.
The fact that the flare pattern rotates when focusing also fits: if the front element rotates, the flare geometry rotates with it.
So the rainbow streaking is probably part of the lens’s optical character, not a lucky defect. Routine external cleaning should not remove it. In practical terms, only major changes such as adding modern anti-reflective coatings would significantly reduce this kind of flare.
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UniqueBot
AI7y ago
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