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UltravioletPhotography

Lee 729 IR - West Green House garden


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We are only using KG3 to reduce the higher IR, without removing the lower range IR that 729 transmits.

And I use the Hoya 80C for the same reason. No idea about transmission, but I know that the results are better with it than without it. I will do an experiment with Hoya 80C and IR960 filter to see how much it reduces. But with the Hoya I am not getting red tinting on concrete. KG3 is just way out of my budget.

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Wow only 2 hours wait. Thats fast! Thank you Ulf, I am on a roll firstguessed Bassa filters to the thickness and now the IR profile of the Scuba. Should bought a lottery ticket before all the luck wore off. But I am pretty sure too late for that. I just have to be care not too get hit with lightning in the same spot twice.

 

I will look forward to seeing your Tiffen 2A haze scan. I just got a 52mm one from KEH as part of the labour day clearance. Also got a rare canon sync cord A and 2 199A flashes. Sadly one 1 of the 2 fully works. The other lights up, just no humm and the flash will not fire.

Most likely the capacitor needs to be refreshed, as it looks to have never been used. As in never, the end contacts were clean and not scrapped as it seems to have never been placed on top of a camera.

 

 

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Here comes the result from the measurement of my Tiffen Haze 2A filter.

 

The general passband transmission above 400nm:

post-150-0-21844100-1567520731.png

The blue graph is the result averaged from 1000 spectra á 32ms, measured using full bandwidth of the light source.

No boxcar averaging as the data is above the noise floor.

The toe to the left of 400nm is as usual crosstalk from the passed strong light at longer wavelengths.

 

Measurement with improved crosstalk, valid around the transition area at 400nm - 425nm:

post-150-0-34606100-1567520754.png

Averaged from 5000 spectra á 37ms.

No boxcar averaging as the data is above the noise floor.

 

With light only from the deuterium lamp and more averaging I can decrease the crosstalk a bit.

The red graph show that the filter has almost OD 3 at 400nm.

It is likely that the decay continues a bit further at shorter wavelengths.

The orange graph, related to the red graph, is the dark noise at current configuration, almost one magnitude lower.


Maybe we should start a series of more formal individual topics with more detailed analysis of different filters.

Is that a good idea?

To make it easier to find the information they might be placed in a separate subsection of the forum.

I could suggest a tentative template for that kind of topic.

The naming of the topics maybe also should be in a suitable format.

If this post was such a topic I would have named it [Filter transmission, Tiffen Haze 2A].

I would like a more complete format of such a topic than this one above, but it could possibly be something to build on.

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Thank you Ulf.

Yes your filter scans should probably be completely different posts.

The 2A looks great. A good filter for UVIVF. I was using a kodak 2A wratten 2 gel, most likely polyester. But I scratched the surface. So have been using a 2E gel. I am glad I got the Tiffen looks like maybe the best to just snag 400nm.

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No I have none of the Hoya 80 A-, B- or C-filters.

I have all six Hoya 81- and 82-filters.

I also have a Nikon B12, that might be using some blue Hoya filter glass type.

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Jonathan, was your test made using the 729 sample I sent you? Or maybe from the swatch book I sent?

If so, the surface quality of the material seems a bit poor to me,

dents, and such, what do you think of the surface, optically?

I have purchased the 729 from two separate sources, one seemed only slightly better, not much. The samples in the swatch book seems the best.

Just wondered if you have had any thoughts on all that?

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Jonathan, was your test made using the 729 sample I sent you? Or maybe from the swatch book I sent?

If so, the surface quality of the material seems a bit poor to me,

dents, and such, what do you think of the surface, optically?

I have purchased the 729 from two separate sources, one seemed only slightly better, not much. The samples in the swatch book seems the best.

Just wondered if you have had any thoughts on all that?

 

I used the piece you sent me Steve, not the swatch book. And yes, the quality wasn't great, with plenty of dings and dents. I presume because it's mainly used as a lighting gel, the quality control isn't as high.

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Thanks Jonathan. :-)

 

Ulf, thanks! Indeed, those don't suppress IR any more above 750nm than they do at 750nm, even less. So those don't taper the IR down, and they don't create a 780nm peak like the KG3 does,

however they do act as a kind of neutral density filter for the IR, attenuating it to a lower level across the entire range. This has the same % of lower IR to higher IR however.

http://www.hoyaoptics.com/color/06/images/img_graph_6-2.png

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  • 3 months later...

Pardon my ignorance but when I combine the KG3 graph and the 729 graph Ulf posted above, there's not much IR being transmitted with this stack.

729 blocks up to 750 and KG3 only transmits 30% at that wavelength, going down to 0 at little over 900. If the purpose is to only block higher wavelengths, wouldn't a short pass 850 or 900 be better in this case?

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Nisei, Interesting question. A shortpass filter like that would be dichroic, and I don't have such filter to test. The closest filter I have to that would be the Baader UV/IR-Cut, and that it cuts at 700nm.

Here is the composite graph of 729 + KG3 2mm (up to 800nm).

 

post-87-0-12484100-1578369019.jpg

 

KG3 2mm is handy for attenuating the IR content of other longpass and dualband IR filters also.

I have tried using 1mm, and other KG#'s also, but KG3 2mm seems to work best to my preference with the filters I have tried pairing it with.

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Pardon my ignorance but when I combine the KG3 graph and the 729 graph Ulf posted above, there's not much IR being transmitted with this stack.

729 blocks up to 750 and KG3 only transmits 30% at that wavelength, going down to 0 at little over 900. If the purpose is to only block higher wavelengths, wouldn't a short pass 850 or 900 be better in this case? (Sorry, could only find a pic for an 800nm)

 

Yes a shortpass filter should work. The Original David Twede article, he mentioned using an inefficient hot-mirror glass, called the Permacolor #8000 that should also work.

https://next-eyes.blogspot.com/2018/11/my-history-re-inventing-digital-ir.html?m=1

 

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Hmmm, I think I finally get what this is about now.

I thought the idea was to block higher wavelength IR but that's not the case. It's about bringing down IR to around the same transmittance value as blue so IR doesn't get overexposed (or blue getting underexposed).

The Lee 729 + KG3 stack is not very efficient. 729 only transmits around 40% peak for blue and we therefore have to use KG3 to lower the IR curve to match it to the low blue transmittance value.

Is that the idea?

 

When looking for filter graphs I came across Kopp 5031

The curve looks close to Lee 729 but with a much higher transmittance value for blue so blue and IR are well balanced here.

No idea about price but I'd love to see the results of this sooc.

Perhaps stacked with a 450 long pass filter?

Or, if it's indeed your goal to block higher wavelength IR, stacked with short pass 800 or 850.

post-244-0-15883200-1578396942.gif

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It may just give an orange image which seems to be easy. What I have found to be most tricky is actually the White balance setting. Using a lee 729 with kg3 to lock in a wb preset, I can then use the lee 183 filter to get similar look, but 1 to 2 stops more light.

 

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Nisei, Kopp 5030 might be a better choice, it is closer to 729 and cuts off the orange/red like 729 does.

I am not sure if cutting off the UV is important.

 

http://www.grayglass...s.cfm/conid/141

 

Just noticed that those Kopp graphs are for pretty thick glass, so it is hard to say what part of the visual range is actually blocked by those filters at any 'normal thickness'.

The graph you posted says it is for 3.50mm thick, the graph I posted says it is for 5.10mm thick.

I have no direct experience with Kopp filter glass myself, but I have been told it isn't good quality glass, which might mean a lot of things.

Regardless of that rumor, I would be hesitant to use those two Kopp glass types thinner than what they show, otherwise you will get a red visual leak, which is partly the problem what happens with B-410.

The 5030 looked pretty interesting until I saw the 5.10mm thickness... of course you can have them make it whatever thickness you want, but then you get some visible 600nm range light also.

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  • 3 weeks later...

Looks like some BG type filter for the substrate, like BG38, or BG40, or BG39 types, probably Chinese or Hoya equivalents, the Schott glass types would be more expensive.

UV/IR-Cut filters are designed to cut off IR at about 700nm (target transmission would be the 400nm to 700nm visual range),

which removes the 'NNIR' (near near IR) that you want to preserve from the 729 filter.

I don't see any graph for it.

 

Do you have 729? Costs about $7 for a big sheet.

729 will work alone, adding KG will clean it up, makes whites whiter, grays grayer, and overall cleaning and more differentiated and contrasted.

 

Once again I refer to David Twede's page about 729.

https://next-eyes.bl...tal-ir.html?m=1

 

Schott BG glass types @2mm thick, and Schott KG glass types @2mm thick.

post-87-0-16653500-1579828698.jpg

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Would this dirt cheap dichroic hot mirror leak enough IR to be useful combined with Lee 729?

https://a.aliexpress.com/_UK25e

 

Actually based in the angle and comments it looks to be a copy of the BW 486 dichroic filter. Might be similar to a SVBONY uv/IR cut filter which are very cheap. They cut off hard around 400nm and 700nm, but leak into both. Expect down to 380nm leakage and 750nm with some small IR bumps.

Not useful at all for IRchrome. But if it does leak enough into the IR, it could work. Will depend on how bad/good for you that coating leak is.

post-188-0-54742200-1579841771.jpg

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B+W 486 is clear, has no blue/green color, no BG substrate, only dichroic, only interference type.

(by the way, B+W 489 is KG3, but I no longer see that listed in their newer catalog, but if you can find it, that is what it is, KG3, probably 2mm or there abouts)

The filter in the link you show looks like it has a BG type substrate, with an added dichroic coating (possible, but could just be AR). I don't think the blue green color is not from the coating alone.

So I would not say it is a copy of B+W 486.

I am not even sure that filter is for sure dichroic, or what the coating is, does it say anything about that in the ad (maybe I missed it)?

Also the title of the filter is kind of confusing, why does it say "Infrared Pass" in the title?

Assume nothing about that filter unless you somehow test it.

 

post-87-0-80505700-1579849730.jpg

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I am not even sure that filter is for sure dichroic, or what the coating is, does it say anything about that in the ad (maybe I missed it)?

That's why user reviews on AliExpress can sometimes give more information than the product description from the sellers (who often don't even know what they're selling).

Scroll down a bit and click on Customer Reviews. Multiple pictures there.

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Cadmium,

If I photograph my recent bw 486 filter at an angle like that, about 30 degrees, it looks the same bluish.

I have 486 in 58mm, 72mm, 46mm and 37mm.

I will see if I can take a photo to show that they do look like that. They are dichroic filters.

 

I just recently purchased 4 Svbony filters. When they arrive, I can take a photo to compare.

 

Actual spectrum of my 72mm 486 filter, I took when still in a lab:

post-188-0-95473400-1579872038.jpg

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