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Investigating IR-Leak from the Baader U-Filter


kogakunippon

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kogakunippon

I just made a small test to check how big ist he IR-Leak from the Baader U-Filter.

 

 

 

http://gallery.photo.net/photo/18263663-lg.jpg

 

 

I used my modified Nikon D7100 (fused Silica 2000) plus the EL-Nikkor 105mm

 

 

http://gallery.photo.net/photo/18263669-md.jpg

 

 

 

The Filters

 

 

http://gallery.photo.net/photo/18263668-md.jpg

 

 

My Lamps....

 

 

http://gallery.photo.net/photo/18263667-md.jpg

 

The 375nm torch that creates this wonderful dark violet colour in my Japan nightshots before.

 

http://gallery.photo.net/photo/18263666-md.jpg

 

 

My small LED Panel

 

 

http://gallery.photo.net/photo/18263665-md.jpg

 

 

And most important, my Phillips Infrared 150W lamp

 

 

http://gallery.photo.net/photo/18263664-md.jpg

 

 

 

 

 

without a filter

WB on the gray card in the photo

 

http://gallery.photo.net/photo/18263662-lg.jpg

 

 

this time with the Schott S-8612 Filter

WB on grey Card again

 

http://gallery.photo.net/photo/18263661-lg.jpg

 

 

 

Now we finally come to the important Part from my Show.

 

Baader U-Filter only

No WB made yet

 

30 sec

F5.6

ISO 100

 

http://gallery.photo.net/photo/18263660-lg.jpg

 

 

same photo but WB on PTFE Board

 

http://gallery.photo.net/photo/18263659-lg.jpg

 

 

plus the Schott S-8612 it looks like this:

 

http://gallery.photo.net/photo/18263658-lg.jpg

 

 

after prodessing the correct WB on PTFE

 

http://gallery.photo.net/photo/18263657-lg.jpg

 

 

I would say 30 sec is anything but a long or extreme Exposure time when we talk about UV-Photos.

 

 

 

Kind Regards

Wolfgang

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Nice test, Wolfgang.

This shows me that your IR lamp is very strong, and has no UV, and is blocked quite well by your S8612 filter.

Notice how the IR lamp is white light, yet black when blocked by the S8612. This points out how the Baader U does have some minor leak in the 800-1000nm range, which when given an extreme IR lamp will be quite apparent.

The rest of your lights show expected results.

Keep in mind your 'black light' probably has a slightly lower UV peak (365nm?) but it also has a wider UV bandwidth, both of which would translate into a more yellow color when white balanced against the 375nm torch.

This is not really any issue here, just pointing it out as to the color difference.

 

So the only test of IR leak here is the IR lamp, which would make sense with such a strong IR source.

I think if you tried that with more normal lighting you might not see such strong results.

30 seconds is not really the issue here, it is the IR bulb being used.

Once again I strongly suggest that yellow light is not from visual or IR range light, when using a Baader U yellow comes from UV range.

 

PS: This may seem trivial, yet Schott does not use a "-" in their filter numbers. Hoya uses a "-" in their filter numbers. So S8612 not S-8612, and U-340 not U340 (for example).

 

Also, of those two UV light sources, the black light has the wider UV band width, so I think I would white balance from from that light rather than the narrow band of the torch.

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As I stated earlier, the only manner in which I can provoke an IR leak from my Baader U is by firing a very strong studio flash straight into the lens.

 

Apparently you have duplicated that setup by different means.

 

Instead, I suggest you turn your IR lamp and let it shine on something behind it, then repeat your test shot.

 

All of the above of course assume you have the latest generation of the Baader U filter. The very first version did leak IR and hence was replaced by the maker short time thereafter.

 

By the way, the thread title is misleading. There is no "massive IR-leak" from this filter.

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kogakunippon
PS: This may seem trivial, yet Schott does not use a "-" in their filter numbers. Hoya uses a "-" in their filter numbers. So S8612 not S-8612, and U-340 not U340 (for example).

 

Thanks for your information Steve.

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kogakunippon
By the way, the thread title is misleading. There is no "massive IR-leak" from this filter.

 

I think it depends on what kind of picture you are making Bjørn. If you are only into flowers, or daytime UV-photos illuminated by the Sun, this might not be an issue for you, as long as your exposure times are below 5 sec.

 

But as handheld UV-photos require already 1/4 sec at f/5.6 and ISO 6400 on a sunny day, we are not far from the 30 sec when using a tripod and ISO 100. And because 30 sec are not a long exposure time, my test is applicable to all kind of UV-photography. I would rethink if I could be right or not.

 

But if you want to take pictures at night with different torches, my Thread Title was absolute correct, because there is a massive IR-Leak when you need exposure times from 150 sec upwards. The question is just if the S8612 Filter is enough to block the whole IR transmission, or if the KG3 is also necessary? I will test this later....

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kogakunippon

And if someone think the 30 sec exposure time was unfair in my small test.

 

What about the same sujet with just 2 sec and ISO 800?

 

Artist: Wolfgang Steiner;

Exposure Date: 2016:07:22 17:36:03;

Copyright: Wolfgang Steiner;

Make: NIKON CORPORATION;

Model: NIKON D7100;

ExposureTime: 2/1 s;

FNumber: f/3;

ISOSpeedRatings: 800;

ExposureProgram: Manual;

ExposureBiasValue: 0/6;

MeteringMode: Pattern;

Flash: Flash did not fire, compulsory flash mode;

FocalLength: 35 mm;

FocalLengthIn35mmFilm: 52 mm;

Software: Adobe Photoshop CS6 (Windows);

 

http://gallery.photo.net/photo/18263695-lg.jpg

 

The result is pretty much the same.

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Indeed, there is no 'massive IR leak' with a Baader U.

Keep in mind that every filter can be forced to leak.

First of all, the IR bulb is not a good test, but it is not about exposure time, in a real situation it is about the mix of UV% and IR%.

Let's go back to the situation of your 'extreme' night time UV shooting for example for the moment, if you shoot with a UV only filter, you will get UV, even if the filter has some minor IR leak it will not show up in your photos, because with your Baader you have overpowering UV compared to any minor IR. The IR would only show up as with an extreme IR bulb pointed at the camera lens.

So unless you block out the UV transmission of the filter, IR is not going to be something you see in your night shots.

I think a better test would be to use a real night time shot, set it up however you like, but don't use that IR heat lamp, just do it like you were doing it on your trip,

you could even do a test comparing a normal UV night shot and the same shot stacked with a red filter (590nm for example, or even higher, 720nm, etc.).

You have already shown the Baader + S8612 'normal' night shot, which shows me that there was no difference in color, just some minor of exposure potential due to semi-truncated UV transmission due to 2mm of S8612.

At this point, the test to show your self is stack the Baader with a longpass/IR filter, and do one of your normal long exposure UV night shots.

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By the way, you can perform the same trick with an IR remote (as seen in these shots below).

You may want to compare the Baader U with your absorptive stack. When pushed you will get IR with either, but the Baader U will have a monochrome 800-1000nm leak,

and the absorptive stack will have a red/brown 700nm leak.

It would be interesting to see the difference with one of your cool night shots. Also test the difference with each using the stacked longpass test.

UG11 2.5mm + S8612 2mm? That is a pretty dense stack, so you will need more exposure time with that than the Baader U, but if you make it leak, the leak will be more red/brown as below,

and it will not show a higher nm IR remote LED light.

 

post-87-0-81395900-1469212859.jpg

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Cadmium has quite made the point that overwhelming IR pointed directly at the lens will be recorded under the BaaderU if the exposure is long enough. That does not necessarily prove that the BaaderU is violating the terms of its stated transmission chart in the IR region where it is said to suppress IR transmission on the order of OD4? OD5? (I don't recall at the moment.)

 

As a cautionary note, we see that the conditions of Wolfgang's night shots involved large amounts of UV illumination and (0 - N%) of ambient IR under the BaaderU using long exposures. (We have no way to know how much if any ambient IR was available in the scenes.) And we see that the ambient IR would have been reflected IR instead of an IR illumination source aimed directly at the lens.

 

And don't forget that under most broadband UV-pass filters, some small amounts of visible light on the violet end can also be transmitted. And many UV-LEDs emit violet light. We can see it with our eyes. How does this violet light affect the scene if the exposure is 3 - 5 minutes long? (I don't know.)

 

So, to prove anything meaningful in an experiment, that kind of shooting condition should be recreated.

Lots of UV-LED as illumination, reflected off of subject.

Tiny to small amounts of IR, reflected off of a subject.

Long exposure of 3-4 minutes under the BaaderU.

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Wolfgang,

 

There is nothing inherently unfair about your test. You have utilized the sources and methods you have at your disposal which all that anyone can do. Your results have given you insight into the performance of your gear which I count as a successful experiment.

 

My critique is similar to others, you have a large effect of proportionality with the sources. The small T5 blacklight is at best ~4W, the 375nm LED is likely <1W, but your IR lamp is 150W. The different exposure geometry with the arrangement of the sources also additionally favors the IR element in the scene. Much like your night, or dusk, scenes and Cadmium's Baader U + RG610 example above this experimental setup is disproportionately IR rich, greatly emphasizing of the very much weaker, high OD secondary band.

 

By shooting through the Baader U with scant ambient UV you enabled UV light painting on top of the IR secondary band in a way not possible in daylight. I rather thought you had composed your night shots that way intentionally.

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The fundamental misunderstanding is believing exposure time has a bearing on the leakage. It has not, at least not the way is claimed. . The problem is the ratio UV to IR and the response of the lens + camera. If UV is extremely low, which is has to be with no sun light and only relatively weak LED lights as the UV source, you in fact use the sideband of the filter to make the exposure. UV plays only a secondary role.

 

I can shoot hand-held UV at f/4 and 1/15 sec at ISO 200. This with my CO 60/4 lens and daylight. For tripod work, I routinely do 30 sec. or longer as I often use f/16 and ISO 100. Never had any issue with IR (using the Baader U)..

 

Added: went outside and did a 120 sec. exposure with my Baader U filter. No IR leakage. As expected. Except for the exposure time, the false colours and tonality were rather like as in broad daylight. At my latitude this time of the year it doesn't get any darker unfortunately.

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Andy Perrin
Andrea, see my example in the original thread for how much IR is available at night. It is a substantial amount. I have no way of determining the ratio of IR to UV directly, however.
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Yes, exactly, "ratio" ("it is not about exposure time, in a real situation it is about the mix of UV% and IR%").

The original question was 'where are those colors coming from, UV, Visual, or where?'

Using a Baader U, color is not coming from visual or IR ranges. That filter is wide open to UV-only, and only transmits slight amounts of monochrome IR when there is not UV present to overpower IR.

It is not about exposure time.

So, where is the color coming from?

Wolfgang's original night shot brought up this question in my mind with the yellow street lamp, which I believe is from UV.

Andy's shot of the red wind power light may be coming from something other than UV.

 

Update:

Oops! Sorry Andy:

http://www.ultravioletphotography.com/content/index.php/topic/1878-ultraviolet-photography-at-night/page__view__findpost__p__13345

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OK, here is an attempt to better understand what is going on.

 

(1) First, I made an IR foto of part of the outside deck at the shore cottage where we are staying in Maine to illustrate the ambient IR light emanating from the house. Inside the house there is an incandescent lamp next to the windows (on the right). The scene includes some IR-reflecting shrubbery, a wood-slat fence and the wooden side of an outdoor box for fireplace wood. I used the B+W 092 IR-Pass filter because it also passes a tiny bit of high red - which can also be a contaminant under some (not all) UV-pass filters.

 

Infrared [D600-broadband + UV-Nikkor 105/4.5 + B+W 092 IR-Pass Filter + Ambient IR Light from Incandescent Lamp]

f/8 for 1/2.5" @ ISO-3200. Slight underexposure. Should have gone to 1/1.6" perhaps.

Resize, no edits.

600_4110.jpg

 

 

(2) Second, I put the BaaderU onto the lens and made a 3 minute exposure of the same scene to determine whether I could record any of the ambient IR light through the BaaderU filter. The answer is NO. There was a bump in the blue part of the histogram which might have meant that a bit of visible violet light was passed. But not enough to show up in the foto.

 

Ultraviolet [D600-broadband + UV-Nikkor 105/4.5 + BaaderU UV-Pass Filter + Ambient IR Light from Incandescent Lamp]

f/8 for 180" @ ISO-3200.

Resize, no edits.

600_4111.jpg

 

 

(3) Finally I took my two UV-LED torches and painted the area with UV light during another 3 minute exposure. One torch is a 385nm Nichia. The other torch is a 365nm Nichia. The expected UV foto was recorded. It was overexposed by about a stop.

 

Ultraviolet [D600-broadband + UV-Nikkor 105/4.5 + BaaderU UV-Pass Filter + Ambient IR Light from Incandescent Lamp + Large Amounts of UV-LED Illumination]

f/8 for 180" @ ISO-3200.

Exposure slider dialed back by -1. Resize, no other edits. Shown in raw colours.

Note that the leaves are UV-dark, as expected. The wood is UV-bright, as expected.

There is no doubt that a UV scene has been recorded.

600_4112pn.jpg

 

 

Conclusion: There was a large amount of ambient IR light available in this night scene making the IR exposure a very short 1/2.5". The corresponding non-UV-illuminated BaaderU exposure was 450 times as long and picked up no IR. This indicates IR contamination under the BaaderU is not a factor in a 3-minute night exposure illuminated with UV-LED torches.

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As expected. The Baader U has no "massive" IR leak.

 

Do note that the subject you "painted" with the UV torches was pretty close. Try the same when a whole building is in the scene and the relationship UV to IR becomes different. Then UV becomes very weak as a tiny UV-LED torch is no substitute for daylight. Any residual IR then can be "forced" through the filter's sideband if the total exposure is long enough. However, this is no indication of a filter flaw, merely showing the relative lack of UV.

 

At this time of the year, I have only some semi-darkness between 0200 and 0230 so have to stay up for a while to make my own experiments with long exposures and the Baader U.

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Cadmium has quite made the point that overwhelming IR pointed directly at the lens will be recorded under the BaaderU if the exposure is long enough. That does not necessarily prove that the BaaderU is violating the terms of its stated transmission chart in the IR region where it is said to suppress IR transmission on the order of OD4? OD5? (I don't recall at the moment.)

 

As a cautionary note, we see that the conditions of Wolfgang's night shots involved large amounts of UV illumination and (0 - N%) of ambient IR under the BaaderU using long exposures. (We have no way to know how much if any ambient IR was available in the scenes.) And we see that the ambient IR would have been reflected IR instead of an IR illumination source aimed directly at the lens.

 

And don't forget that under most broadband UV-pass filters, some small amounts of visible light on the violet end can also be transmitted. And many UV-LEDs emit violet light. We can see it with our eyes. How does this violet light affect the scene if the exposure is 3 - 5 minutes long? (I don't know.)

 

So, to prove anything meaningful in an experiment, that kind of shooting condition should be recreated.

Lots of UV-LED as illumination, reflected off of subject.

Tiny to small amounts of IR, reflected off of a subject.

Long exposure of 3-4 minutes under the BaaderU.

 

Just for the record, in case I have been misinterpreted, I was in no way trying to prove that the Baader U has a massive leak, in fact, just the opposite.

The only side note I was addressing, which is the question all this hoopla came out of originally, was the color of any possible potential out of band transmission from a Baader U.

That is what my old test is intended to illustrated, and is also quite similar to the lens facing IR lamp that Wolfgang shows.

My posts here in this topic have been intended to refute the topic title implication.

So please don't intemperate my IR remote examples to mean anything other than 1) extreme IR lights can show up through a Baader U, however this is something you alomost have to force to happen, and 2) mostly that any IR seen transmitted through a Baader U will be monochromatic, white, without color.

That has always been by main point, that the wavelength of Wolfgang's Baader U night shot colors are not not derived from out of band wavelengths.

Also to calm Wolfgang, and let him know that his results are not tainted with Visual or IR, especially when it comes to yellow and red.

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kogakunippon

I have to tell you a short story , so you can understand why I 'm so confused . In 2006, I was already pretty busy with the UV photography. At that time I bought a lot of my filters from Schneider Kreuznach . Unfortunately it turned out to intense tests that the filters were not working in the way they should. Non of them, and I got plenty of their filters.

 

After my tests I confronted Schneider Kreuznach directly with the results from my test, and after worthless days of disussing the topic via Mail I sended all my filters to them. Then I had to wait some weeks till they told me their own results about my filters. Mr. Kappler from Schneider Kreuznach told me in his E-Mail, that they are sorry, but it seems that the charge from my filters was mislabeled.

 

That means for example the B+W 403 Filter wasn’t even a Schott Filter Glass and all the test I made can’t be correct because oft he mislabeling from Schneider Kreuznach. This wasn’t easy, and after this long hard fight with this Company I got my money back, but had lost my pleasure about taking UV-pictures.

 

Now, after some you guys starting telling me about the IR Leak I had a very similar feeling like in 2006 and thats why I was a bit confused after making this small IR test with my Baader U-Filter.

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To add to your story: the first version of the Baader U apparently did a very good job keeping IR in check. However, at that time, I (and probably a lot of others) used this filter with unmodified cameras like a D1, D40, or D70. These had of course the stock internal filter still intact and that filter by itself cut IR quite aggressively. However, once "broad spectrum"/"full spectrum" modifications arrived, the positive experiences turned into disaster, because the added IR protection by the internal filter no longer existed and the mediocre IR reduction of this Gen.1 filter overwhelmed the outcome. The next Gen.2 of the Baader U put the matter straight again. Now, I can work without any fear of IR leakage in my studio with several studio flash devices (uncoated Xenon tube for maximum UV output) and rely on the Baader to make my captures true UV. In fact, when I test the identical subject in daylight using the Baader U, only the shorter exposure time and a slightly sharper rendition of details indicate a UV flash has been active. Otherwise natural light vs studio flash frames are identical. Just repeated this test today with a Ligularia coming into bloom and confirmed this behaviour is, as expected, still present with my current UV gear.
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Cadmium, your writing is always clear. I don't think you need worry about that! Thank you for your support in investigating the BaaderU IR supression.

 

*********************

 

Bjørn: Do note that the subject you "painted" with the UV torches was pretty close. Try the same when a whole building is in the scene and the relationship UV to IR becomes different. Then UV becomes very weak as a tiny UV-LED torch is no substitute for daylight. Any residual IR then can be "forced" through the filter's sideband if the total exposure is long enough. However, this is no indication of a filter flaw, merely showing the relative lack of UV.

 

Thank you for the good suggestion. I will continue with the experiment at a further distance from the Shore Cottage. I am very interested in this experiment. I have to be "fair" to my UV-LEDs and not get too far from the subject which is to be light-painted in order to re-create the conditions as best I can from Wolfgang's photos. But, in addition, I will try to find the point where the ambient IR from the incandescent light inside the house "wipes out" the UV.

 

I don't have a way while here at Shore Cottage to investigate any potential violet/blue leakage.

 

*********************

 

Wolfgang, thank you for telling us about your bad experience with the Schneider Kreuznach filters. It is a rather shocking story to hear that SK mislabeled some filters.

 

If you read about the UV-pass filters and UV-pass glass in our Filter Sticky, you will find that varying amounts of IR transmission, or "leakage" as we call it, is not unusual in the finished filter. We typically like to see the IR leakage supressed to an approximate optical density of OD4 or greater. However a UV-pass filter with IR supression in the region between OD3 - OD4 is still useable. While I cannot find a direct statement about the optical density of the BaaderU in the Baader website, I think I recall that it is stronger than OD4. (If anyone can point me to a link about that, I would be very grateful.)

 

It is next important to note - as Bjørn has so often pointed out - that one can force any wavelength through any filter (or lens) if the exposure is long enough and if the intensity of the light, reflected or otherwise, is strong enough. You have certainly reminded us all of that with your 150W IR lamp!

 

The supportive experiments performed by Cadmium and myself are intended to show you that your series of night photographs made in Japan with the BaaderU represent overwhelming reflected UV-LED light and have no bad effects from any ambient IR light. I will continue my own experiments along those lines iin my current summer situation by photographing the Shore Cottage at night with some ambient IR and my UV-LED torches.

 

It would be good for you to also continue to investigate by making more night shots with your UV-LED torches under different conditions of ambient IR.

  • First, photograph the scene using an IR-pass filter (from around 700nm or so).
  • Second, photograph the scene using the BaaderU while UV light painting with the UV-LED torches as you normally would when making this kind of photograph.
  • Third, photograph the scene using the Baader U but without using the UV-LED torches. Set the same exposure length as used for the 2nd photograph.

The title of this topic should be "Forcing IR through the BaaderU" because the BaaderU is considered - across the world - as having excellent IR supression. The BaaderU has no "massive IR-leak". Bjørn and I will take into consideration changing the topic title. Should you wish to go ahead with that, it would be helpful.

 

I will say again that I think your Japanese night UV photographs are valid. If there was any IR leakage at the very long exposures, it could only have been minimal. You should be happy with these photographs and enjoy them. :D

 

****************

 

Now, I think this topic has gone on long enough. If Wolfgang wants to add another comment, that's OK. But the rest of should probably let the topic rest now.

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  • 3 months later...

Today i was testing an UVC lamp with my Baader U-Filter.....

 

 

http://gallery.photo.net/photo/18311956-lg.jpg

 

LG

Wolfgang

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