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UltravioletPhotography

Accidental IR-filter, a bit like Aerochrome?


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This spring I was mainly collecting filter for IR-photography. (This was before I leaped over to the UV-side)

After reading about filter problems for simulation of Aerochrome, I became interested in comparing a cheap Orange filter against my B+W Yellow-Orange 040 (orange) and ordered one.

 

When the package arrived it also contained a second green filter in a slightly worn outer box.

I assumed it was a reject item that they sent as bonus.

This is the green filter I got:

http://www.ebay.com/...m-/121537504290

 

I never got around testing either filter and assumed that I never would have any use for the green one, until last week.

Then a friend helped me doing transmission measurements on most of my filters and the green filter gave this response:

post-150-0-91871000-1501700367.jpg

The transmission graph with the big IR-leakage sparked my interest and motivated me to take some test images with the green Pixonyx filter.

 

This is the result:

 

post-150-0-07843200-1501700709.jpg

 

post-150-0-53655800-1501700779.jpg

 

I have not processed the images very much. Appart from a white balance against the clouds, I have adjusted the saturation and slightly tweaked the hue of foliage and sky.

Directly after white balance the foliage got a very saturated bright magenta tone and the sky has a pale slightly blue-green tone.

 

Could this filter be useful for simulating a Kodak IR-film?

 

Used camera and lenses:

Canon EOS 60D, full spectrum modified by replacing the sensor filter and dust shaker window with a sensor window from Astronomik.de

Canon 24-105mm/4.0L, Canon EF-S 10-22/3.5-4.5

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Aerochrome produces an IRG-->RGB cross-sampled image. One property of such an image is vegetation that appears reddish, because vegetation is a good reflector of infrared light and infrared light is mapped to red in an IRG image. There are other kinds of image which can also produce red vegetation, for reasons similar (but not identical) to those circumstances which produce it in an Aerochrome image. Such images do not reliably reproduce the other properties of an IRG image---so do we call them similar? The ultimate answer depends on how much one cares about these differences. It is possible to produce real IRG images with digital gear, if that is what is desired, but the process is more complex than simply slapping a filter over the lens.
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JMC -

The UK is not on the exclusion list and they state that they ship worldwide.

UK is not in the list of selectable destinations, but they might still accept an order if you ask them.

If the answer is no, I might help you as I think I'll buy a second filter from them soon.

The shipping cost of an additional filter is only 0.3€.

 

However we do not know if the filter material always is of the same type for such a cheap filter. This is a risk.

 

 

OIDoinyo -

I do not think that it is possible to do any simulation prefect, only more or less accurate.

A map always differ a bit from the real world.

 

The results with this filter might still be interesting as it rejects blue and red mainly transmit IR and green from the source before it has contaminated the image data in the infrared-dominated areas.

 

I agree that it is a quick and dirty way to just slap a filter over the lens.

The result from the filter is absolutely not as from a real Aerochrome, but might still be useful for artistic pictures.

That is why the title was "a bit like Aerochrome".

 

Do the quest to simulate the Aerochrome with digital technology have a real scientific reason?

How close is good enough to be acceptable as a good simulation of the film?

 

Is grain, similar to the film needed?

Is a film-like intensity response needed or is a gamma response enough?

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Thanks UlfW I'll keep that in mind - I assumed it was not an option to buy from them direct as UK wasn't on the list for shipping. I also have a few old filters up in the loft, and I think it'll be worth me running them through the UV Vis spectrometer at work to see what they look like before going ahead and ordering more. While my spectrometer only goes up to 800nm it'll be interesting to see what they look like in the IR.
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enricosavazzi

Good find, I ordered this and a few others. At this price, we cannot go wrong.

 

eBay did accept shipment to Sweden, but gave me no shipment discount for an order of 5 filters (it just added up the individual shipment costs five times, about the same total shipment cost as the total items' price). I sent the seller an email via eBay about this.

 

Edit - The seller refunded 24.80 € excess shipment charges.

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Do the quest to simulate the Aerochrome with digital technology have a real scientific reason?

How close is good enough to be acceptable as a good simulation of the film?

Is grain, similar to the film needed?

Is a film-like intensity response needed or is a gamma response enough?

 

Today, the primary technical applications for IRG imaging are for vegetation health monitoring and archaeological prospecting. Much of this work is done from satellites, many of which are capable of other kinds of multispectral imaging as well. The images these satellite cameras produce are not simulations; though they may not look exactly the way a film image would have, they encode the same kinds of information (and in fact, they do look somewhat similar.)

 

There are historical preservationists who try to reproduce the exact characteristics of a particular film emulsion by digital means. I have never attempted to do this, myself--it is very difficult to do convincingly and I would rather just try to make images that are pleasing.

 

It may amuse you to read this forum:

 

https://www.flickr.c...57601045395608/

 

Among the things described is a method to get reddish foliage by reprocessing an ordinary color image--no infrared needed at all!

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Thank you for the link. The first look there was amusing.

 

I also would prefer to make images pleasing.

I hope I can do that with the filter I found, with some practice.

 

Of the IR-type images I have found so far, my two absolute favourites are

 

a image by Bjørn of a field with a narrow road in the middle. This, I think, is a real AIR.

And a second one of a spruce? in fog. Possible a digital dual exposure composition.

 

I think I have seen both on this forum, but cannot find them just now. Help please?

 

Both are very nice in their composition.

They also have a very controlled well balanced color scale without the typical highly saturated color often seen in bad AIR-simulations.

 

These images are for me some kind of reference images.

If I could come close to those qualities with my pictures I would be happy.

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Interesting filter.

Typically, with EIR/Aerochrome, things that are red in visual look yellow. So test that out, see if red things end up being yellow.

For example, a good test is a non illuminated red plastic tail light of a car, those should look yellow. If they stay red in the photo, then...

Often red clothing, will be yellow... look for that.

 

See the yellow tail lights below?

post-87-0-71016800-1501823202.jpg

 

Yellow cars and sign in this pano were visually red.

post-87-0-25679000-1501823286.jpg

 

Promaster P01 and Petri P01 are green filters, they both work the same, they may not be the same filter glass as the Pixonyx Green filter, but seem to have some similarity with how they function on a full spectrum camera.

This is a Promaster P01 shot, white balanced only. Note that with the P01 filter the red barn stays red, sorry, no yellow barn.

post-87-0-03621400-1501824274.jpg

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Noted.

OK, I see the yellow lights.

 

Pixonyx green do not make visually red objects yellow directly.

The image is just white balansed.

post-150-0-56934600-1501827113.jpg

 

Are those pictures real AIR or simulated?

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That is the tree I was referring to. A very nice image!

 

My botanical knowledge isn't big enough to tell the difference from that picture.

It looks like a christmas tree without ornaments.

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My first two were processed, simulated from Wratten/Tiffen Yellow #12 (minus blue) filters.

Kodak EIR/Aerochrome film will also render yellow from visual red as do the simulations.

If you do a two shot composite (visual + IR) you will also get yellow from red.

Basic transposition from IRG-->RGB (as OlDoinyo mentioned). IR > Red, Red > Green, Green > Blue.

Yellow being part of green.

Many of the more 'normal' green filters (other than the P01 which is slightly non normal) will look like this below 060 green filter, I have tried them all except the one you are testing.

P01 is a little different than most Green filters, but here is an example of a more common green filter:

 

B+W 060 green (purple/pink foliage and green skies...and also no yellow tail lights of the horses):

post-87-0-99418500-1501835916.jpg

 

Various green filters

post-87-0-64199000-1501835931.jpg

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Here is the graph of Schott VG green filters, the only one I have is the VG9, and it only starts to show some red (but not much) at 1mm thickness.

post-87-0-19028500-1501879178.jpg

 

post-87-0-55360000-1501879232.jpg

 

 

Here is a comparison of VG9 with P01.

post-87-0-98554700-1501879283.jpg

 

Visual (Schott BG38).

post-87-0-71471400-1501879298.jpg

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Some of the images with green skies and purplish foliage remind me not so much of IRG as they do of RBG (the Lomochrome look.)
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VG9 1mm is about the same as VG6 2mm. So VG4, VG5, and VG10 might show a lot more red foliage than the VG9 1mm, however, the 'on request' makes those hard to acquire.

Comparing Pixonyx.Green with P01 will be interesting.

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Here is Pixonyx Green, direct form Germany. This looks similar to your lavender foliage example in post #11. Tail light is red, not yellow.

I have not processed this at all other than white balance with CNX2 on gray. Whole frame Marquess was about that same.

No mater how I white balanced it, i could not get red foliage like is shown in post #1.

The main difference I note with this green filter is that it has blue skies instead of green skies.

post-87-0-78789400-1502493258.jpg

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In post #1 I have shifted the hue and decreased the saturation to get a more AIR-like look.

 

The Pixonyx filter is not useful for simulating an AIR style, but might be useful anyhow as it give a G-IR image with a very dominant IR signature directly out of the camera after white balance.

It cancels most blue and red parts of the image quite well.

The CA was as expected terrible in IR with my normal Canon EOS lenses.

 

Recently I think I have successfully gotten a good AIR-simulation with my B+W orange filter (040), with all red objects turning yellow.

The B+W 040 is close to the O-56 mentioned by Bjørn at Digital EIR Experiment . The B+W 040 is based on the Schott OG550 glass.

 

The image is just a a quick snapshot out from my balcony of the first red objects I could find. No taillights in sight.

 

I used the PS-action Tiffen12 after white-balancing in PhotoNinja at a neutral area

After the PS-action I have just slightly tuned the hue a little bit towards red and decreased the saturation slightly, to get closer to the tone in the nice image by Bjørn at Digital EIR Experiment

post-150-0-97390700-1502559625.jpg

 

I also tried the B+W filters 022 and 090 (GG495 and OG590) on the same scene, but the results from the action wasn't useful the same way as images taken with the 040-filter.

 

The glass types used for the B+W filters can be found in https://www.schneide.../BWHandbook.pdf

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This thread may be straying a bit from its original topic, but since others are posting Tiffen 12 shots, here are a couple of my recent ones. The Sony A900 was used with the Steinheil Cassar-S and the aforementioned filter. Workup was via the Pixelbender macro pursuant to J.W. Wong's mathematical work.

 

"Cascade Mountain and Provo Canyon:"

post-66-0-24627000-1502677623.jpg

 

"Timpanogos from Round Valley:"

post-66-0-51283600-1502677652.jpg

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I ordered a second Pixonyx green to use the glass rear-mounted on my fisheye lens.

 

The new one is not at all as dense and dark green as the first one. It transmits a lot of red.

When stacking with a OG590 I see almost as much red as without the new Pixonyx green.

The result from the same test with the old dark green filter is almost black.

 

I asked Pixonyx if they still had the original dark green type. The answer was "Sorry, not available anymore".

 

It would be interesting to know if any of the members that bought the Pixonyx green got the dark green type.

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One can sometimes figure out a filter type by looking at the raw composite of a photo before white balance is applied. Many of the filters we use have characteristic raw signatures.
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