Lens test today --- I found a lens without the name on it (only Projection lens 3 inch f1.6) (the lens has covered the Medium format sensor with very little vignetting) After testing I found it could focus only for a very close macro — I removed the front lens and the lens became normal. ---------i have a similar lens (but without the macro lens over it) with a yellow coating (my new lens with a blue coating) ------------also I have two more similar lenses, Buhl 3 inch f1.6 and Bell & Howell 3 inch f1.6 but both without any coating and both has a swirly bokeh ---------------------------
The yellow coating could cause:
Night driving glassesYellow or amber-tinted lenses can enhance vision and clarity in low light. They can also reduce glare from bright lights like headlights, LED signage, and floodlights. Night driving glasses can be non-prescription and have an anti-reflective (AR) coating.
Blue blockersYellow lenses are sometimes marketed as “blue blockers” because they may reduce exposure to light from electronics like smartphones.
Safety glassesYellow lens specs can help enhance contrast, which makes objects appear brighter. They can block out blue light to help eliminate haze. Yellow lens specs are best used indoors in low-light areas.
Light tintsLight tints can increase contrast, which can help pilots and marksmen working in outside light.
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The blue coating could cause:
This coating is usually an anti-reflective coating. It can:
Reduce glare and reflections on the lens surface
Improve image quality by reducing the amount of light that is scattered or reflected off the lens
Protect the lens from scratches and other damage
Repel water and other liquids
Repel oil and other substances that can cause smudges and fingerprints