Pushing the limits of B&W macrophotography

A forum to ask questions, post setups, and generally discuss anything having to do with photomacrography and photomicroscopy.

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Lou Jost
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Post by Lou Jost »

Yes, that's a good suggestion. I should at least check to make sure they are not fluorescing.

Pau
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Post by Pau »

If your sensor has good sensitivity for violet light and the lens good transmittance (as it seems at least in the second case) and the subject is not highly fluorescent like white paper I think that fluorescence will not be an issue:
Typically fluorescence emission light is much weaker that excitation light, often several orders of magnitude.
Anyway testing with emission filters will be interesting.
Pau

Lou Jost
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Post by Lou Jost »

The appropriate filters are hard to find.....

Pau
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Post by Pau »

Lou Jost wrote:The appropriate filters are hard to find.....
Not so much, you just need an adequate yellow filter, just now at Ebay:

- This one will be excellent for sure, the price is ridiculously low but it is 25mm diam
https://www.ebay.com/itm/Chroma-HHQ460L ... SwTVtZZdiu

- This one likely would also work well:
https://www.ebay.com/itm/Bigblue-Fluore ... SwdGFYuIuO
Pau

Lou Jost
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Post by Lou Jost »

Pau, I need the opposite of the one you indicated; I need to pass deep blue and cut off longer wavelengths. The goal is to eliminate fluorescence.

Pau
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Post by Pau »

The emission filters I linked are to see the fluorescence and so could be useful for you to see and eventually study or image it.

To eliminate it if it is enough intense that could damage your pictures (likely it couldn't) you want just the opposite: an excitation filter but placed between the subject and the sensor. It can be a short pass filter or a pass band filter. Pass band filters are in many cases more expensive and have lower transmission factors.

This pass band one will be fully adequate:
https://www.ebay.com/itm/Chroma-ET402-1 ... SwjUhaR3hM

see the spectrum at:
https://www.chroma.com/products/parts/et402-15x
Pau

Lou Jost
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Post by Lou Jost »

Yes, that would do it for this laser, thanks. Are there larger filters though? This is a big lens....

Pau
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Post by Pau »

25mm is the most standard size for fluorescence microscopy. Bigger will be hard to find and extremely expensive if ordered to have it custom made, Chroma can do it, you could contact them, and maybe they could have someones in stock.

What's the diameter of the rear lens element of your objective? If close to 25mm this will be the adequate position for the filter to get minimum image degradation.

Again, I would take the easier way with an inexpensive emission LP filter to test: if the autofluorescence of your samples is low enough, just don't worry.
Pau

Lou Jost
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Post by Lou Jost »

I will take the latter route. I don't think the things that interest me fluoresce....

kds315*
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Post by kds315* »

Lou Jost wrote:Yes, that would do it for this laser, thanks. Are there larger filters though? This is a big lens....
Asahi Optical filters I use, availabe in 50mm size:
http://asahi-spectra.com/opticalfilters ... ey=ZBPA405
Their high transmission Shortpass filters unfortunately are not ideal:
http://asahi-spectra.com/opticalfilters ... ey=ZHS0425

They do offer custom made filters, bit pricey though, but very good.
Last edited by kds315* on Tue Jan 02, 2018 5:24 pm, edited 2 times in total.
Klaus

http://www.macrolenses.de for macro and special lens info
http://www.pbase.com/kds315/uv_photos for UV Images and lens/filter info
http://photographyoftheinvisibleworld.blogspot.com/ my UV diary

Lou Jost
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Post by Lou Jost »

Thanks for the information. They do look good, but are very expensive and inconveniently square.

I see they have round mercury-line filters here
http://asahi-spectra.com/opticalfilters ... lters.html
but I bet they are even more expensive...

kds315*
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Post by kds315* »

Lou Jost wrote:Thanks for the information. They do look good, but are very expensive and inconveniently square.

I see they have round mercury-line filters here
http://asahi-spectra.com/opticalfilters ... lters.html
but I bet they are even more expensive...
Edmund Optivs also has one in 50mm, looks better, cut off at 410nm:
https://www.edmundoptics.com/optics/opt ... ss-filter/
Transmission is here:
https://www.edmundoptics.com/document/download/359503
Klaus

http://www.macrolenses.de for macro and special lens info
http://www.pbase.com/kds315/uv_photos for UV Images and lens/filter info
http://photographyoftheinvisibleworld.blogspot.com/ my UV diary

Lou Jost
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Post by Lou Jost »

Those are perfect but even more expensive. That's 50% of the cost of the lens. I will search for simpler solutions, since I suspect that my subjects don't even fluoresce.

kds315*
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Post by kds315* »

Lou Jost wrote:Those are perfect but even more expensive. That's 50% of the cost of the lens. I will search for simpler solutions, since I suspect that my subjects don't even fluoresce.
Here from China, they make custom sizes, I'm sure 50mm is doable and won't be that expensive:
https://www.ebay.com/itm/405nm-Narrow-B ... 3369251015

Image
Klaus

http://www.macrolenses.de for macro and special lens info
http://www.pbase.com/kds315/uv_photos for UV Images and lens/filter info
http://photographyoftheinvisibleworld.blogspot.com/ my UV diary

Lou Jost
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Post by Lou Jost »

That seller has more reasonable prices. I will get this one, which is big and round, though it might not be narrow enough. (The one you indicated is not for sale now.)

https://www.ebay.com/itm/QB29-type-Glas ... SwuhFaGj8m

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