More diatoms

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Radazz
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More diatoms

#1 Post by Radazz » Sat Aug 04, 2018 12:42 am

Polarizer and analyzer removed really brightens up the phase contrast.
Green Interference filter on field lens improves contrast and color.
Saturation and contrast enhanced in photoshop elements
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Brighter image. (Wow!)
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Radazz
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GaryB
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Re: More diatoms

#2 Post by GaryB » Sat Aug 04, 2018 8:33 pm

Those colors are gorgeous, well done!

What type of green interference filter are you using? I'm not very familiar with other than standard filters and I've never used an interference type.

Hobbyst46
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Re: More diatoms

#3 Post by Hobbyst46 » Sat Aug 04, 2018 9:31 pm

GaryB wrote:Those colors are gorgeous, well done!

What type of green interference filter are you using? I'm not very familiar with other than standard filters and I've never used an interference type.
In agreement with both compliment and first question of GaryB, may I elaborate on the question.

For convenience, I will call 546nm "green", although it might be slightly different figure.
An ideal bandpass "green" interference filter can only transmit green, say wavelength of 545-546nm, and block all other wavelengths.
A non ideal interference filter will transmit a broader portion, say only those within 540-550nm, and cutoff all the rest.
That is a distinct advantage of interference filters over the cheaper absorption filters, those transmit a much broader portion of the spectrum, say within 500-600nm, and cutoff all the rest - below and above. Peak transmittance will be at 546nm, but significant transmittance will cover from 500 to 600nm (all numbers are suggested, according to my experience).
Your photo displays a very wide spectrum. Red and blue can be there only if they were included in the filtered light that hit the specimen.
Was it not a bandpass filter?
Or, were the colors added in software?
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

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Radazz
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Re: More diatoms

#4 Post by Radazz » Sun Aug 05, 2018 2:30 am

I’m guessing it’s a GIF at all. Looking at it obliquely, it looks a bit like the coating on a dvd, while looking through into the light is a sort of milky green. I got it on the field lens of one of the Nikon labophot2 scopes I got from the medical school. Fit the Olympus perfectly, so I appropriated it.
As you see, it really enhances Phase contrast.
As I say, I’m guessing :oops:
Radazz
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GaryB
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Re: More diatoms

#5 Post by GaryB » Sun Aug 05, 2018 10:25 am

Wow, I just did a search on ebay and what you describe appears to be a GIF 550nm phase contrast. They seem to cost around $90 or so.
Olympus 45mm 550nm green phase contrast interference filter, Part # 43IF550W45

I'll need to see if there is a generic version for less.

https://m.ebay.com/itm/Olympus-45mm-Gre ... %7Ciid%3A1

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Radazz
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Re: More diatoms

#6 Post by Radazz » Sun Aug 05, 2018 12:51 pm

That looks like the one. Mine is not in a frame, and looks like two pieces of glass with the coating between them.
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Radazz
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Re: More diatoms

#7 Post by Radazz » Sun Aug 05, 2018 4:01 pm

Arnold, Missouri
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Hobbyst46
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Re: More diatoms

#8 Post by Hobbyst46 » Sun Aug 05, 2018 4:23 pm

I searched the web to find the transmission spectrum of the Olympus 43IF550-W45 filter but could not find it.
However, Olympus brochures specify it as a filter to produce monochromatic light, of wavelength 550nm, which is exactly the way to improve contrast in phase contrast microscopy. It almost certainly transmits narrow band, say 550+/- 10nm, that is, green light, without blue or red.
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vasselle
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Re: More diatoms

#9 Post by vasselle » Sun Aug 05, 2018 8:10 pm

Bonjour
Très belles images
Cordialement seb
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