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UltravioletPhotography

A few ultraviolet people. Portraits


ins13

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I don't exactly agree with the colors in the link in post #23. Too much red, for one thing, leads me to believe there may be something out of band in the mix.

http://www.ultraviol...asonic-lumix-g3

 

Regardless, I don't have the Sigma 30mm, but I can show examples of the typical colors in the UV-A range via a few other lenses below.

My Sparticle doesn't have a 370BP filter installed, so I can't show anything definitive for that exact nm center.

 

I don't trust gratings as much as bandpass filters, because bandpass filters are not based on color, they are based on a narrow band.

Gratings are based on colors, colors which all run together in one continuous shift, and for those who argue about the colors produced by bandpass filters, I wonder why they don't argue the same about grating colors,

because the grating method has no delineation without color, and those colors would need to be correct, and people would need to agree on some base reference for those colors,

if the colors or white balance are not correct, then reading it is thrown off. Gratings can become more complex to define.

Bandpass filters can be desaturated to monochrome and you still know at least what range is transmitted, which is the whole point, not the colors.

 

post-87-0-05062900-1553923429.jpg

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I don't exactly agree with the colors in the link in post #23. Too much red

 

Yes. It is an interpretation of the program of processing of the picture

Other program give such picture. the colors are the same

post-237-0-02720600-1553924637.jpg

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That looks nice, and I agree with those colors, but what does it tell us, unless we first agree on what each color means, what range each color represents, and some will not agree on that.

That is why I trust bandpass filters more, because they have more defined ranges that are a bit hard to argue, they are predefined, in color or monochrome.

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My photo processing is probably happens quite wrong / I often forget about "correctness" and go after " beautiful"...

 

gratings and bandpass filters - I guess I am a little out of touch. I will try to explore and understand the differences

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My photo processing is probably happens quite wrong / I often forget about "correctness" and go after " beautiful"...

 

gratings and bandpass filters - I guess I am a little out of touch. I will try to explore and understand the differences

 

For your type of photography going after " beautiful" there are no wrong!

Your resulting images talks for themself and are quite nice and refreshing!!

 

It is only when doing scientific experiments when you need all facts absolutely correct then you need a specific well controlled processing.

On this forum there are many scientists and the discussions can give the impression that it always is true.

 

For artistic work it is not!

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Thank you! You're right. I look at a strictly scientific approach to UV photography and therefore such thoughts.

My purpose is artistic photo. Although science I, too, love))

Well, then I'll just continue to do what I like :) but if any questions will been raised concerning how it happened, I'll just tell how I did it ..

And maybe in the end I'll make friends with science

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I am often asked how I manage to get a certain photo and although the gear-centred technical details are easily answerable, the process of making the capture into the final outcome is hidden even for me. It just happens and I never bother about that aspect. Even though I perhaps should, being a scientist with a degree myself.

 

Just go on like you already do. That way the photography keeps its admirable freshness.

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That looks nice, and I agree with those colors, but what does it tell us, unless we first agree on what each color means, what range each color represents, and some will not agree on that. That is why I trust bandpass filters more, because they have more defined ranges that are a bit hard to argue, they are predefined, in color or monochrome.

 

False colours from a grating is not a reliable way of identifying wavelengths.

Analysing an image from a grating and getting a correct identification of the darker banding is even better than bandpass filters.

The wavelength of the bands are rather well defined:

https://en.wikipedia.org/wiki/Fraunhofer_lines

I think that method was used with Dimitry's method.

 

A bandpass filter can have a different transmission peak and width than the nominal values.

The width number for the filter is also just where it has lost transmission by 50%.

Also the actual center wavelength of the bandpass filter when combined with another filter with a slope in its range will shift in a similar way as when creating your filter stacks.

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Dmitry was using a jewlers prism, and the Fraunhofer lines for identification. Prisms are nonlinear, so you have to be careful where you think you are. But the Fraunhofer lines help with that.

See here for better placement of his colors:

http://www.ultravioletphotography.com/content/index.php/topic/2810-program-to-label-dmitrys-solar-lens-tests/

 

The end of the white balance yellow is most likely 359 and not 350nm as positioned in the linear plot.

 

Eka, there may be too many scientists here. I do admire your creativity and I like to throw things out to bring that back. Many scientists get stuck in dogma and what they think physics is.

Please have fun and don't worry too much before your shots. Collect them, so we have them, and then we can figure out what happened. But do try to keep notes, that is the critical part. The camera will not record the odd filter combinations and way we stack them, and that can matter.

 

I think what I am trying to say, is that you should use science to get a certain look or effect. But don't get too caught up in the details. I think I would want my daughter to have a PTFE dress after seeing your images :P

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