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UltravioletPhotography

Filter Transmission Charts #1


Andrea B.

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Thanks, John.

I added the reference to Newport's charts in the preceding post and in the index (first post).

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  • 1 month later...

Schott UG11 = UV+IR, dual bandpass

Hoya U-340 = UV+IR, dual bandpass

 

UG11 (1.0mm)

UG11 (2.0mm)

 

U-340 (1.0mm)

U-340 (2.0mm)

 

ug11_u340.jpg

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  • 10 months later...

Baader U and Invisible Vision 308nm filter comparison

 

I recently got a 308nm band pass filter on loan from Invisible Vision in the UK (http://www.invisible...ts/accessories/). I did a direct comparison of this 308nm filter and the Baader U, using a Perkin Elmer Lambda 650S UV-Vis spectrometer (150mm integrating sphere) to measure transmission between 250nm and 800nm (1s collection time per nm). The graphs are shown below.

post-148-0-14772200-1502961408.jpg

 

Edit: Further work has demonstrated that using the 308nm filter alone results in significant IR contamination in the image, likely due to the much higher IR sensitivity of the sensor when compared to the low sensitivity of the sensor to the UV range which is primarily transmitted by the filter. I will share these results separately. Recommendation based on my results is that further IR filtration would be needed to ensure image could be classified as 'UV' when using a standard SLR sensor, however assessment should be undertaken by anyone to understand how it works for their application.

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Thank you, Jonathan! We appreciate these fiter transmission contributions very much.

 

Question:

  • Does the plotting routine permit any kind of graphing transformation of the region between 650-850 nm? Like, could it be expanded by 2x or 3x to show where the leak is occuring? Schott glass uses a particular logarithmic transformation they call "diabatic" to graph the dual bandbass filters and that expands the IR region in a certain way.

  • Alternately, will the plotting routine produce an optical density chart rather than this transmission chart?

  • Finally, is the gathered data available in chart or vector form so that it could be fed to Andy Perrin's MATLAB program to produce a chart rendering the 650-850 nm region in diabatic form?

 

I know you are very busy right now. There is no hurry on these questions. Just want to record them for future consideration as time permits you.

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Thank you John. Copied as follows.


 

NEEWER BK UV IR CUT

by John Dowdy, Ph.D.

 

I purchased one of these just over a year ago. Mine is labeled "NEEWER BK UV IR CUT" on the case and I cost $17.95 with free shipping. It is not a BG type filter, it is pretty much the real deal. That blue color is a reflection from the dichroic coating, held at a different angle the same surface looks pink. I have to confess I have not used it enough to say if it is any good or not.

 

The transmittance band is slightly blue shifted relative to the Baader UV/IR-Cut on both the short and long side. The Newer has 265nm HBW/383-648nm (probably not suitable for UVIVF) and the Baader 264nm HWB/418-682nm. You can see the waviness imparted by multi layered coatings. We also see a tip up toward the long side due to my neglecting to control internal reflectance from the filter back into the sphere because I like to see what it looks like. Since the throughput of the sphere is ~10% this is on the same scale as uncoated 1st surface reflection. I do not know what the reflectance of an unfiltered sensor would be.

 

neewerchart1.jpg

 

If we look at the spectra on a log transmittance scale we a can see just how deep the blocking really goes. I did not scan them beyond 800nm, that is as far as the double grating OL-756-PMT spectroradiometer will scan. One of these days I will scan them out to ~1100-1200nm with a double grating InGaAs spectroradiometer to see just how well the NIR side is blocking.

 

neewerchart2.jpg

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Optima ZBW1 1mm UV+IR Dual Bandpass with ~1% visible leak in 400-660 nm.

 

Optima ZBW2 2mm UV+IR Dual Bandpass with violet leak and ~1% visible leak in 400-680 nm.

 

Optima ZBW3 2mm UV+IR Dual Bandpass with large 28 to 9% violet leak, 1 to .1 % blue/green leak, yellow/orange suppression, 8-54% red leak 670-700 nm.

 

 

zbw1.jpg

 

zbw2.jpg

 

zbw3.jpg

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ZBW1 2mm

ZBW3 1.5mm

OBG39 2.5mm

 

From Jonathan M. Crowther, Ph.D.

 

I recently bought a few filters from Igoriginals on eBay and wanted to share the transmission data I measured for them. The filters were ZWB1 (2mm), ZWB3 (1.5mm) and BG39 (2.5mm). All in 52mm filter thread and priced at 25USD each. I ran them on a Perkin Elmer Lambda 650S UV-Vis spectrometer (150mm integrating sphere) to measure transmission between 250nm and 800nm (1s collection time per nm). The graphs are shown below.

 

zbw1zbw3objg39.jpg

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Thank you, Jonathan! We appreciate these fiter transmission contributions very much.

 

Question:

  • Does the plotting routine permit any kind of graphing transformation of the region between 650-850 nm? Like, could it be expanded by 2x or 3x to show where the leak is occuring? Schott glass uses a particular logarithmic transformation they call "diabatic" to graph the dual bandbass filters and that expands the IR region in a certain way.

  • Alternately, will the plotting routine produce an optical density chart rather than this transmission chart?

  • Finally, is the gathered data available in chart or vector form so that it could be fed to Andy Perrin's MATLAB program to produce a chart rendering the 650-850 nm region in diabatic form?

I know you are very busy right now. There is no hurry on these questions. Just want to record them for future consideration as time permits you.

Hi Andrea, The software for the UV Vis is relatively basic as it's aimed at an analytical chemistry lab. As such there are no fancy plotting options, just % tranmission. The data is available as simple xy data for Excel though, and that's how I do all my charts (I'm 'a bear of little brain' when it comes to this sort of thing). As mentioned in another post I have concerns over plotting the data logarithmically, as I only trust it to about 0.1% - areas which should be 0% transmission, or effectively 0% are being measured as -0.1%. As such I believe plotting it logarithmically, could introduce artifacts which aren't real.

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Edit: added Baader UV/IR Cut L filter (Item number 2459210A) 25th August 2017

 

Two different B+W 486 UV/IR cut filters, and Baader UV/IR Cut L

I bought a couple of B+W UV/IR filters recently. Both marked up as B+W UV/IR cut F-PRO MRC 486. The 77mm one was in new style packaging, and was new stock. The 58mm one was in older stye packaging and was second hand.

 

Also bought a Baader UV/IR cut L (Item number 2459210A) second hand from a well known online auction site. I did run this both ways round in case the coatings on each side were different but the spectra were the same, so I only plotted one here.

 

I ran them on a Perkin Elmer Lambda 650S UV-Vis spectrometer (150mm integrating sphere) to measure transmission between 250nm and 800nm (1s collection time per nm). The graphs are shown below.

post-148-0-96998700-1503683850.jpg

 

Similar overall behaviour for the 2 B+W filters, but with some subtle differences in the fine structure - I'm guessing due to changes in coating technique/batch. 50% max occurs at 683nm and 391nm +/-1nm for both filters. The B+W's had measurable transmission into the IR and UV. The Baader UV/IR cut L was significantly different to the B+W ones. 50% max now 678nm and 419nm with a much cleaner cutoff at both ends.

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As Visible bandpass filters, these 486s certainly do provide a lot of UV and IR !!!!!
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I only trust it to about 0.1% - areas which should be 0% transmission, or effectively 0% are being measured as -0.1%. As such I believe plotting it logarithmically, could introduce artifacts which aren't real.

 

...literally not real (numbers)!

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  • 1 year later...

In a recent thread there has been discussion about the "Nikon FF Filter";

 

http://www.ultravioletphotography.com/content/index.php/topic/2950-like-meyer-trioplan-but-so-much-cooler/

 

I recently got one of these filters, and here is a measured spectra (run on my Ocean Optics spectrometer).

 

post-148-0-05345500-1535721687.jpg

 

It matches very well with the spectra provided in the UV Nikkor 105mm manual;

 

http://www.company7.com/library/nikon/UV-Nikkor_manual_39pg.108.p.pdf

 

There is definitely quite a lot of visible light coming through as I can see through it quite easily.

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This is a new filter to me. Do you have a link for it? What is its purpose? Thanks!!!
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This is a new filter to me. Do you have a link for it? What is its purpose? Thanks!!!

It was the one that originally came with the UV Nikkor, Andrea.

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Yep, the square glass filter seen here, part of the original UV-Nikkor kit.

I could not find any photos of the filter box showing a part name/#, so I don't know what it is technically called. And I don't know if that is what Bjorn meant by "FF filter".

UVNikkor4.jpg

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Thanks Jonathan. :-)

I am betting that the original square filter that came with the UV-Nikkor is in actuality Hoya U-325c, Which is very similar to U-330, which is the Hoya equivalent to Schott UG5.

I am pretty sure the square filter is made of Hoya U-325c filter glass.

So that means that it has a fairly strong visual transmission, not quite as strong as U-330/UG5, but close, having some blue and even green depending on thickness.

What is the thickness of your square?

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Thanks Jonathan. :-)

Here is a fairly rough and not exactly exact overlay of these three filters, so it looks like I was slightly off on my guess, but still.

Keeping in mind then that the Hoya graphs/data is for 2.5mm thick, and the Nikon filter graph/data is for 3.5mm thick, as Jonathan has noted above.

My overlay may be a little off here and there, but close, best I could do.

 

post-87-0-40667100-1535818697.jpg

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  • 1 year later...
Andy Perrin
What does it look like to you when you look through it with your eyes? You would see blue and red from the spectrum, but I'm having some trouble imagining how things would appear. Trees would be black obviously and the sky would be blue...
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Looking through my ZWB2 filter I see a violet sky and bright red trees. The sky is out of focus because we are short-sighted in blue light and below. Some objects (like an incandescent lightbulb) appear with a red filament surrounded by a violet blob.

 

Of course this filter is more "leaky" than a ZWB2 (even if there are a lot of different ZWB2s, depending on the manufacturer), but I would expect to see the same thing.

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Andy Perrin
Yeah, I should have expected the red trees since I know they reflect near IR well in addition to green and you an see them even by eye through an R72 in sunshine.
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