Stefano Posted June 4, 2021 Share Posted June 4, 2021 I am searching a lot on eBay these days hoping to find interesting stuff. I found these UV laser scan lenses, I don't know if they are any good for UV photography. Quite expensive for me. Here's two:https://www.ebay.fr/itm/254985169572https://www.ebay.com/itm/124635178395 Link to comment
Andrea B. Posted June 4, 2021 Share Posted June 4, 2021 I tried to google for use of f-theta lenses for photography but found nothing - so far. One thing I have observed is that the working distances (for scanning) are quite large and some must be added to that to obtain the flange focal distance. Looking at JenOptik's 355 nm f-theta lenses, I saw that the minimum working distance is 60 mm. Other example working distances are 135 mm, 182mm and larger.So you would have to put quite a long extension on the lens to adapt it to a Sony, Nikon Z or m4/3 FFD. Nikon, Pentax, Canon DSLRs already have at least 40+ mm in their FFD, so such a lens might be more adaptable to a DSLR than to a mirrorless. Link to comment
nfoto Posted June 4, 2021 Share Posted June 4, 2021 These lenses are likely designed for a very narrow passband. I have a Rodenstock f-theta lens somewhere that delived "rain-bow" coloured images all over due to the manner in which it did (or rather, did not) handle chromaticity. Link to comment
Stefano Posted June 4, 2021 Author Share Posted June 4, 2021 What I wonder is if they have a good image quality and if their reach goes deep. But a lens optimized for 355 nm probably doesn't reach UVB. Edit: I posted this before reading Birna's post. Link to comment
Andy Perrin Posted June 4, 2021 Share Posted June 4, 2021 When you need to have antireflection coating for only a single wavelength, you can use a 1/4 wavelength single layer coating. It will cancel the reflection at just that single wavelength. However, that implies that for any incoming light at half the design wavelength, it becomes a perfect mirror... (And this, of course, is what leads to the idea of multilayer coatings.) Link to comment
Andrea B. Posted June 4, 2021 Share Posted June 4, 2021 So forget about f-theta lenses for general reflected UV photography ! Link to comment
Andy Perrin Posted June 4, 2021 Share Posted June 4, 2021 So forget about f-theta lenses for general reflected UV photography !Emphatically so. It might be okay if you paired it with a very narrow bandpass filter at the exact wavelength of interest. Not sure why you'd want a lens/filter combo that only works at a single wavelength, but perhaps someone around here might dream up a future use for such a thing. Link to comment
Stefano Posted June 4, 2021 Author Share Posted June 4, 2021 I didn't find such lenses made for wavelengths below 355 nm. Having one optimized for a UVB band in the low 300s and a narrow bandpass filter may be useful to some. But that would be limited to that specific wavelength. Link to comment
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