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1000nm or deeper infrared filter?


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Hello. I'm looking for infrared filter that passes well about from 900nm and deeper spectrum. I tried using previously 808-1064nm infrared filter which blocks well visible light and transmits well infrared radiation. But problem is that it passes a lot of shorter infrared as well what causes somewhat image blur and for painting documentation such spectrum is unwanted. It is advised to use 1000nm or deeper infrared filters because the longer IR wavelength the better is transmission through various materials including oil paints what in turns helps to see underpaintings and drawings. So filter should pass as better as possible long infrared up to 1200nm.

In same website recommending IR filters for painting documentation was mentioned B+W 093 filter which has 1% transmission at 800nm to 88% at 900nm. But it's expensive and when looking at actual spectrum it doesn't differ much from Ebay few dollar IR filters. X-nite1000 filter is somewhat better since if has gradual transmission increase with deeper infrared.

I also consider buying from Ebay 49mm infrared filter which is claimed to pass 1000nm but for some kind of reason no other information sellers provide, I asked them even to do simple test with LED or fluorescent lamp but they wont. Maybe someone had experience with such filters? Here it is:

 

https://www.ebay.com/itm/Infrared-Infra-red-IR-Filter-1000nm-1000-Pass-X-Ray-46-52-55-58-62-67-72-77-82mm/251328490896?var=550275501340

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Ebay filter sellers are NOT to be trusted unless you know them! If you are doing scientific documentation then you need to be using glass with a known spectrum. Much of the stuff on eBay is of poor quality. Get name-brand glass. Talk to Cadmium, he is the expert on filter glass, and he also sells Schott brand.

 

I asked them even to do simple test with LED or fluorescent lamp but they wont.

Yeah, that is NOT a reputable seller. Avoid! Avoid!

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I have a similar IR filter as that ebay listing. The Chinese filters don't seem to be standard yet, and will have variability. The one I have marked as 1000nm, is really 50% at 950nm. I ran a spectrum of it when I still worked in a lab.

Good quality filters over 1000nm will not be cheap and camera sensitivity really drops off above 1100nm. Unless you buy a SWIR camera.

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The photo shown with the linked Ebay ad is definitely NOT a 1000 nm Infrared photo. There should be no mixed false colour at all with a 1000 nm filter. (Note: the raw version of a 1000 nm photo will have a uniform tint prior to white-click).

 

Also, the cost of US$14 for a 49mm filter is definitely telling us that this is not a filter made from good glass.

 

And you must always know the thickness of any filter you buy. For IR 1000 you probably want to stay between 1-2 mm for thickness. (Under 1000 I usually like a 2mm thickness.)

 

Both MaxMax and Uviroptics/Ebay sell authentic Hoya or Schott glass filters. All IR filters from these two vendors are beautifully made and are sold with a nice filter storage case or box. (I own filters from both vendors.)

 

An authentic Hoya or Schott 52mm IR-1000 can be priced between (US)$50-150 depending on diameter and thickness.

 

[uVP has no monetary affiliation with any vendor.]

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That one is exactly like the ones sold by the two vendors I mentioned. But costs more due to the Heliopan branding!

 

It is possible that some makers add a coating?

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'The Real McSchott', so to speak ("the real thing" or "the genuine article" or "the real McCoy").

Here is a plot of Schott RG1000 in both 2mm and 2.5mm thick versions.

 

post-87-0-81404600-1543447024.jpg

 

post-87-0-61926700-1543447064.jpg

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If the diameter of your front lens is small enough to not vignette with a smaller diameter filter, this might be an alternative:

https://www.ebay.com...=item23a0273eac

The photograph of the filter is not correct, but the company is reputable and OK.

 

You have to mount the filter glass disc in a threaded filter ring yourself and will need suitable step rings to attach the filter to the lens.

Here is some tips for this kind of filter mounting at one of our member's website:

http://savazzi.net/p...ng_filters.html

 

Prepare for longer exposure times as the camera sensor is not very sensitive at these long wavelengths.

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Bill De Jager

You can get an idea of what a 1000nm filter will do in a previous topic: http://www.ultravioletphotography.com/content/index.php/topic/579-patriarch-grove-white-mountains-of-california/page__hl__patriarch__fromsearch__1

 

That one is exactly like the ones sold by the two vendors I mentioned. But costs more due to the Heliopan branding!

 

It is possible that some makers add a coating?

 

Thanks for the heads up. Yes, I generally avoid Heliopan when I can due to their much higher cost.

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Added: I also agree that Ulf's reference to "Omega Bob's" filter site on Ebay is worthy. They don't always have what you need available as a surplus sale, but if you hit their sites on the right day, bargains can be found.

 

I'll repeat: Check whether the filters have coatings or not. Sometimes a large manufacturer like B&W or Heliopan or whatever will offer a coated filter which costs more but coatings lessen the need for periodic oxidation maintenance. So perhaps the extra expense is worth it for some.

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I see that infrared photography is also going to be costly and being on budget restrict choice but for professional use I can give a try to non chinese glass which more detailed spectrum descriptions. I actually was lucky to find local optics and filter manufacturer selling RG1000 filter. Although most similar size is 50,8mm but is way cheaper - 47Eu. Seller can resize it but if price will be high I will have to use step up ring: http://eksmaoptics.c...archparam=rg850

I also saw one Ebay chinese but different kind of long pass infrared filter that has also good spectrum but is too expensive at desired size: https://i.ebayimg.com/images/g/T9IAAOSwF8FcAT0P/s-l1600.jpg

 

Is AR coating practical for infrared spectrum? RG1000 could benefit transmission boost in 1000nm or higher wavelength.

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Here is the B+W filter handbook page 62, which lists the coatings they have available for different filter types.

According to this table, none of their IR filters are coated, and not their 403 UV filter either.

I have spit this page into to photos, top and bottom of page 62. Not sure if this is their most recent filter handbook, just the one that comes up when I Googled it.

https://www.schneide.../bwHandbook.pdf

 

By the way, Omegabob2 doesn't seem to be listing items now:

https://www.ebay.com/usr/omegabob2

 

They are still listing items on their other username, Bjomejag:

https://www.ebay.com/usr/bjomejag

 

B+W Filter Handbook P. 62 top:

post-87-0-44876200-1543622052.jpg

 

B+W Filter Handbook P. 62 bottom:

post-87-0-00284100-1543622136.jpg

 

Below is the wider version showing more filter diameters, etc.:

post-87-0-06972100-1543623431.jpg

 

post-87-0-46556700-1543623452.jpg

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Here are some examples on the B+W site. Select one of the filters, then click on the 'Filter Coating' tab.

https://www.schneide...y.aspx?CID=1183

 

"Uncoated Glass

Uncoated glass is usually found with special effects filters and acrylic filters, where coating is either an impossibility or would work against the effect the filter is trying to attain."

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I guess AR coating is not worth it especially with price increase, filter thickness actually can more difference. I found similar spectrum analog to RG1000. It's HWB930. Anybody can advice of polish quality for filters?
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Chinese man... You get what you pay for.

If you want to save money get a Chinese filter, they rip everything off from everyone. There are no rules or ethics there, it is true slop.

And the graph I pull up is for 6mm thick, looks OK, but 6mm... not realistic, so that graph is worthless, because I'm not going to shooting through a 6mm thick piece of Chinese glass, are you?

http://www.ygofg.com/products/Cut_off/Infrared_glass/37.htm

 

Anyway... Find a graph for whatever glass in a more realistic thickness, 2mm or 2.5mm max.

Because unless you are some laser person, camera filters are usually in the range of 2mm to 2.2mm, or 2.5mm max.

When you start stacking filters, then they get even thinner...

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