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UltravioletPhotography

Mystery IR filter - transmission spectra and images


JMC

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Yes, there is also the hoyafilterusa site, like you link to there. Yet another site.

That is why I went to Hoya.com first, then paged my way to their filters. Thinking it would give me the "real deal", but who is to say if that info is outdated compared to what they are manufacturing now?

Regardless, Jonathan has something that matches the graph on the site he posted, and that site seems to be a Kenko site, given the Kenko info on the info page for that site.

However, I suppose we don't even know for sure that side is really Hoya or Kenko? But that might be a stretch. But...these days? I tell ya, what can you believe these days? You can believe a spectrometer.

I don't know... the mystery plot thickens.

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Now, you want to get even MORE confused? I know you do. :-)

OK, so go to the site Jonathan posted first:

https://hoyafilter.com/product/r72_infrared/

 

Then go to the "support/distributors" link on the above site top menu:

https://hoyafilter.com/support/distributors/

 

Then scroll down to the North America/U.S.A section, and go the site for that:

https://www.kenkotokinausa.com/

 

OK, now click on the top menu there, "brands/Hoya Filters", and that takes you to hoyafiltersua:

https://www.kenkotokinausa.com/

 

Then select "shop/specialized", then scroll down and choose R72, and you are at the same page showing the longpass graph.

https://hoyafilterusa.com/product/hoya-r72-infrared/

(I think that is the same link that David posted above)

 

See what I am saying, these are all connected, yet one shows a bandpass and most show a longpass, and I am wondering... have they changed something, perhaps?

That is what I think, Hoya has some new glass they are starting to use for the R72.

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So... I wrote them, not holding my breath, but want to know what they say.

---

I need to know which is accurate, has Hoya changed the type of glass they are using. Why are these two graphs different? Which graph is correct for the R72 you are selling?

 

Hoya R72 showing a bandpass type transmission graph plot:

https://hoyafilter.com/product/r72_infrared/

 

Hoya R72 showing a longpass type transmission graph plot:

https://hoyafilterusa.com/product/hoya-r72-infrared/

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Furthermore... sorry, but just looked through that entire catalog, and the only bandpass type IR range filter they show is the RT830 (like I mentioned on the previous page), similar but not the same as Jonathan's scan or the graph shown on the page like he posted. So I don't know what is going on.
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Here is something interesting that I was reading on Jonathan's Hoya link from above: https://hoyafilter.c...t/r72_infrared/ [The R72] can be paired with colored black and white contrast filters such as the R25 (red), K2 (yellow), O (orange) or other color filters to change the color rendition or contrast effects. But how could stacking the R72 with, say, a K2 make any change in color/contrast? The filter with the fartherest-out cut-in, the R72, would be the filter controlling the transmission, right? What am I missing here?

You are only missing that the maketing departments don't need technical understanding of their products.

The statement might generate some extra sales.

 

Your analysis is otherwise perfect. The fartherest-out cut-in, is controlling the transmission.

The pairing statement above is true for some other filters, like the two green filters on their program.

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Cadmium,

Whats truely funny is the only site, the one Jonathan linked to) with the only bandpass filter spectrum is also the only site that says to watch out for counterfeit products.

 

Lets see what they tell you. If Kenko now controls Hoya, I would say its gone to Chinese glass. This maybe why Zwb glass got better?

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Blimey this has moved on since I left it last night. Mine was bought from ebay from a private seller, who had it and a U-360 from when he worked in forensics. I doubt it's counterfeit, but it could well be quite old.

 

My guess, is that they have changed materials at some point.

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This is quite perplexing. Especially given Jonathan's scan.

Hoya is a very excellent filter company, and is it not good to have variation in their products.

Disconcerting to anyone using their glass for filters. We want to know what we are buying. We want consistency.

These are the kinds of things that military specifications are based on.

 

In my opinion, it appears that this filter that Jonathan has and the graph that is shown on that link he posted are not actual Hoya glass.

I don't think Kenko owns Hoya, if anything it is the other way around, more likely Kenko is licensed to make/sell Hoya camera filters.

Hoya sells glass sheets, I don't know if they make camera filters themselves these days or not.

It seems strange that anyone making filters under license from Hoya would then use some other brand of glass and sell it as being Hoya,

and it seems strange that they would show a graph revealing such a discrepancy.

Jonathan has discovered something that I doubt anyone else has.

I can't find any actual Hoya glass that has that transmission curve.

Very weird.

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OK, this just back from Hoya, basically:

They don't make camera filters, "call Kenko Japan".

So you see, Hoya makes glass, Kenko uses the glass to make filters with Hoya on the ring... That part is actually good, I like knowing what exact glass is in the ring, and having a real graph to go with that.

I like that part, I mean if the graph and glass were what was on the ring...

However, I don't like what is going on here, Kenko making the Hoya R72 out of some other brand and even type of glass...

This is unreal, how is this any different than someone on eBay making a filter out of some Chinese ZWB glass and labeling it Schott,

and this is Kenko doing it?! And seemingly, Hoya doesn't sound like they care...?

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This is getting silly now.

 

I ran my Heliopan 715 filter, expecting it to be a simple long pass filter. But, I get the same thing - it's not a pure long pass filter, and transmission drops towards 880nm. Thinking I am going mad, I get out my B+W091 red filter, and run that. No drop at the high end. I also ran no filter, light on (+ve control) and no filter, light off (-ve control), just to make sure the device was behaving as it should.

 

post-148-0-70047100-1568382578.jpg

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However, I don't like what is going on here, Kenko making the Hoya R72 out of some other brand and even type of glass...

 

I don't think we can make that assumption just yet!

 

First of all, Hoya would never permit their glass to be misrepresented by a major company like Kenko.

 

Secondly, it is becoming apparent that the IR bandpass glass cutting in just before 700 nm and hitting its height at about 715-720 nm is of two forms: one is longpass and one is bandpass. Both types of glass could fairly be labeled and sold and sold as IR-pass filters under names such as Heliopan 715 or Hoya R72 (or some other similar designation). I would only worry if bandpass glass is mis-labeled longpass.

 

The question which immediately occurs to me here is this: How is that right shoulder created for the 720/IR-bandpass type of glass? Is there some kind of natural glass formula being used? Or is the drop-off created by some kind of coating or layering?

 

The formulas for the glass being poured seem to be quite standard across the various glass manufacturers. You see in the product brochures or online pages that all they all offer the same stuff (mostly). The IR-bandpass filters I have from MaxMax are quite obviously coated (dichroic, shiny side). But my Hoya R72 does not have that shiny side. It's coated with something, I assume, because I've never had to clean it for oxidation. But I don't think I can see whether it is layered or stacked unless I try to take it out of the filter ring.

 

Thanks for the measurements, Jonathan. I'm sure we will figure this out.

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Addendum

 

provenance: place or source of origin.

 

Counterfeits are everywhere but especially found on Ebay or Amazon.

Compare your filters to the authentic product photos in online pages or brochures.

The labeling should be identical. The ring material should be the same.

 

If the price is too good to be true, then..........

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Yes, is too early to start screaming FAKE just yet.

 

The Heliopan 715 and B+W 091 filters I have tested today were dealer bought and new.

 

The appearance of the Hoya R72, did not give me any reason to doubt its authenticity. Even the info online about the R72 transmission doesn't seem 100% consistent. However the reason for that is not clear yet, at least not to me.

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Kenko Global https://kenkoglobal.com/

 

It is as I suspected. Some 72s are bandpass, some are longpass.

Scratch that. As I continued looking, I came to a different conclusion.

See next post.

 

Under their own label Kenko sells 3 IR-pass filters having a "72" designation.

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Hoya makes 21 sharpcut longpass filter glasses amongst which is W-R715.

http://www.hoyaoptic...m/color/02.html

 

Hoya also makes 7 IR filter glass types amongst which is the IR-bandpass RT830

which is almost like the Schott RG9 IR-bandpass.

(I couldn't tell you why the W-R715 IR longpass is not in the following

IR filter glass section. Only Hoya knows.)

http://www.hoyaoptic...m/color/03.html

 

Now to me it would be odd if that IR longpass W-R715 would be labeled as R72.

So I am thinking now that all R72 filters are IR-bandpass??

 

And I think there are some idiots in marketing who don't know a longpass from a bandpass.

The same guys who mentioned stacking the IR filter with a visible yellow or red filter.

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Argh. All I want to know is what the spectrum of the filter I own is. It makes a difference to me, especially with the TriWave since it records well past the bandpass for those R72s that seem to be bandpass.
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Andy,

Well you may need to get some cheap 1000 line/mm film and check it using a hallogen bulb. If it cuts off compated to a known Lp filter. Then you will know.

 

Or buy a spectrometer.

 

I may need to test my IR filters.

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There are two possibilities:

1) Kenko is not making Hoya R72 filters out of Hoya R72 glass, and apparently neither is Heliopan.

2) Hoya is making some new bandpass type IR filter glass that they have yet to announce or show on any graphs, that they are replacing R72 with.

And if #2 is the case, then that would be rather problematic to be selling two types of glass under the same glass name. I don't think Hoya would do that,

that could cause big problems with customers.

 

It isn't a shiny side or coated or layered, it is just a different kind of glass, similar in idea to Schott RG9, which is a bandpass not just a longpass.

Hoya R72 is a longpass, practically identical to RG715, 5nm difference at 50%. Those are equivalent. RG9 is 720nm at 50%, but is bandpass.

Andrea, you have both RG9 and RG715, and R72 (assuming your R72 is the expected longpass type).

Frankly, I can't see any difference in photos between RG715 and RG9 (longpass vs bandpass), so the same is probably true between real longpass Hoya R72 and this non-Hoya bandpass R72.

Hoya doesn't make R72 bandpass, only longpass, and Hoya doesn't make camera filters, Hoya only makes filter glass.

Kenko has not replied to my inquiry. Hoya has, basically they said Hoya doesn't make camera filters, and suggested I ask Kenko, which I already had.

B+W makes their longpass filter out of Schott glass.

 

I think David said he thought Kenko owns Hoya, but no. I also read someone say that on DP review, but Hoya is not owned by Kenko. Kenko doesn't appear to be owned by anyone either.

Hoya doesn't make camera filters, just like Schott doesn't make camera filters. Hoya and Kenko are separate companies. Kenko buys filter glass from Hoya.

 

It is quite possible that Kenko is buying a lower cost IR filter glass which performs essentially and almost exactly the same in usual IR photographs (like I said), and using it to make the Hoya R72 filters, simply to save money.

It may even be a mutually agreed upon scenario.

 

You tell me if you can see any difference between RG715 and RG9 ? Maybe, but I would guess not.

 

These bandpass scans are not Hoya R72 filter glass, and not even Hoya glass, none that anyone knows about or that has been published.

Even two Kenko R72 pages have disagreeing graphs, one has the expected Hoya R72 graph, the other has the graph that Jonathan scanned.

 

Kenko page showing expected Hoya R72 graph (click on "specifications"):

https://hoyafilterus...a-r72-infrared/

 

Kenko page showing same as Jonathan's scan:

https://hoyafilter.c...t/r72_infrared/

 

I thought Heliopan 715 was made of Schott RG715 glass, but it could possibly be made from Hoya W-R715, but it is longpass, not bandpass.

Hoya W-R715 graph:

http://www.hoyacandeo.co.jp/english/products/eo/color/02/images/img_graph_2.png

 

Hoya R72 graph:

http://www.hoyacandeo.co.jp/english/products/eo/color/01/images/img_graph_1_201712.png

 

More HOYA IR filter glass :

http://www.hoyacandeo.co.jp/english/products/eo/color/03/images/img_graph_3_201712.png

 

Schott longpass and longpass/bandpass (as the Schott catalog refers to RG9):

post-87-0-58016200-1568433893.jpg

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