Jump to content
UltravioletPhotography

N00b Incoming!


Recommended Posts

digitalhecht

Well, sort of. I have been dabbling in IR photography for over 10 years now. And the truth is, whether going for standard (720nm), Super Color (590nm), deep b&w (830+nm), or Kodak Aerochrome (Kolari's latest offering), I have rarely been happy with my results. I currently use a Sony A7RII converted to full spectrum. I was just wondering if there exists anywhere in here a stickie for recommended best practices? TIA.

Ed

Link to comment
Andy Perrin
Hi! We have endless discussions about this. Many people have many practices and different people like different things. Personally I’m not a fan of the original film Aerochrome colors to the extent of wanting to precisely imitate them. But loads of people feel differently.
Link to comment

Most likely what one person likes an other won't. So best to find what you like.

I like the golden look and go with a wratten #47 or #38 and white balance in camera to get a look.

I also like the results with a Zwb3 filter only. Skies are blue and trees are slightly yellow.

An other fun filter is a plastic FLD filter that came with a lens purchase.

 

There is a lot to test in IR and software will let you seap or push the colors around. But I like getting it straight out of camera.

Link to comment

I can quell my interest for emulating the garish "Aerochrome" colours of the Kodak Ektachrome Infrared (EIR) which used E-6 processing. However, I initiated my excursions into the world of false-colour infrared with the Ektachrome IE 2443 fim in the late '60s and early '70s. This film needed the E4 process and had a far superior and more subtle color gradation compared to the later EIR (E-6) version. Thus this is my yardstick for false-colour infrared.

 

I find that I can emulate my favourite IE with digital techniques. Some cameras have sensor qualities which make them especially advantageous for IE emulations, for example, the Fuji S3/S5 models. The Z5 does well too. All of these cameras are of course full spectrum and used with the appropriate filters (deep orange functions best in my opinion).

Link to comment
digitalhecht

I can quell my interest for emulating the garish "Aerochrome" colours of the Kodak Ektachrome Infrared (EIR) which used E-6 processing. However, I initiated my excursions into the world of false-colour infrared with the Ektachrome IE 2443 fim in the late '60s and early '70s. This film needed the E4 process and had a far superior and more subtle color gradation compared to the later EIR (E-6) version. Thus this is my yardstick for false-colour infrared.

 

I find that I can emulate my favourite IE with digital techniques. Some cameras have sensor qualities which make them especially advantageous for IE emulations, for example, the Fuji S3/S5 models. The Z5 does well too. All of these cameras are of course full spectrum and used with the appropriate filters (deep orange functions best in my opinion).

Hmm. Thanks, nfoto. Can you recommend a specific deep orange?

Link to comment

The Nikon O-56 kind is the one I use these days. In the days of IE, Wratten 12 did the trick, but this class of yellow filters leads to colour balancing troubles later so not recommended for digital. Any filter cutting just below 600 nm should be fine, however.

 

Do note that, depending on your actual system, you can get excess IR registered into all channels not just red. This needs to be taken care of in the psot processing stages.

Link to comment
digitalhecht

The Nikon O-56 kind is the one I use these days. In the days of IE, Wratten 12 did the trick, but this class of yellow filters leads to colour balancing troubles later so not recommended for digital. Any filter cutting just below 600 nm should be fine, however.

 

Do note that, depending on your actual system, you can get excess IR registered into all channels not just red. This needs to be taken care of in the psot processing stages.

Thank you! One more thing that has always annoyed me about my IR results: Soft focus/blurriness on foliage. While not unbearable, a consistent annoyance for 10+ years. So related, do you find that the more expensive filters from reputable names make a difference in this regard? I got my entry-level 590nm from a Chinese vendor on eBay for about $24US. Do you recommend paying more? Does it make a difference?

Link to comment

Blurriness + IR make me think of diffraction. What are your usual apertures? If you go below f/8 it is likely that you see diffraction in the image. One way to test for this is to photograph a point source of (infrared) light (it can be a reflection of sunlight from crumbled tinfoil, for example) and see if you see rings around it. Those are Airy disks, and are visible when the aperture is too narrow and they become bigger than a pixel on the sensor.

 

(I must say that if you have been doing IR for 10+ years, you probably already know about this issue).

 

Also, it's odd that you see this blurriness on foliage only. I can't think of a filter that blurs the foliage and leaves everything else sharp.

Link to comment

I wasn't getting sharp images with my full spectrum E510, but never really figured it out until just a couple years ago. It was converted without any glass on the sensor. So wasn't focusing to infinity. Its possible you may not be getting infinity focus depending on your camera or conversion.

A way to test with your filter and the Sony is to get a slim m42 adapter and a helicoid and adjust the distance manually with a lens and your filter.

 

Adding 3mm of glass behind my Peleng 8mm fisheye was needed on my E510 to get sharp image with a long pass 760nm filter.

 

For filters the recent Zomie glass filters have been good. But I do like just a Zwb3 filter.

Link to comment

Blurriness on foliage can be due to a bigger focal shift by the lens at longer wavelengths.

As foliage is highly reflective over a very wide wavelength range even the longest wavelengths contribute to the image.

If my guess is correct adding a KG-type filter will attenuate the longer wavelengths.

 

That was one of the filter components used in a more ambitious project for AIR-emulation, to tame the IR-components.

Link to comment
Andy Perrin
Or just use a lens with less drastic IR focal shift. My Sony Zeiss 55mm/1.8 lens is normally a great lens but unusable in IR due to the focal shift problems. Using an EL Nikkor of any focal length solves the problem.
Link to comment
digitalhecht
This pic was shot at f/8, 1/400, ISO 100 with a vintage 55mm f1.4 Pentax Asahi (M42) lens. The filter used was a (LifePixel) 490nm "Hyper Color" filter. Using focus peaking, everything appears to be in focus. AM I asking for too much that the trees beyond the wires be clearer? (Just because I have been doing this for 10 years, doesn't mean I have learned anything. :tongue: )

post-355-0-99331900-1621197174.jpg

Link to comment
You may simply not have enough depth of field. The problem is that stopping down even more can blur the images because of diffraction. Did you focus to infinity? Maybe you can't reach infinity with your camera + lens?
Link to comment
digitalhecht
Thanks, all. I am continuing experimenting with wider apertures, per Robert Reiser's diffraction points. Again, I claim complete ignorance here. But using wider apertures reduces the depth of field, making some elements out of focus seemingly unavoidable. However, a few more tests seems to show that, at least with this camera+lens combo, f/4.8 (top photo)-f/5.6 (bottom photo) seems to be the sweet spot(s). To clarify the setup, it's the aforementioned 55mm Pentax Asahi f1.4 M42 on a Sony A7R II (full spectrum) using a generic M42-FE (Sony) adapter. Recommendations are welcome for other adapters. Thoughts? Again, HUGELY grateful for all the feedback/advice here!

post-355-0-56987200-1621205505.jpg

post-355-0-64639500-1621205520.jpg

Link to comment
digitalhecht

The Nikon O-56 kind is the one I use these days. In the days of IE, Wratten 12 did the trick, but this class of yellow filters leads to colour balancing troubles later so not recommended for digital. Any filter cutting just below 600 nm should be fine, however.

 

Do note that, depending on your actual system, you can get excess IR registered into all channels not just red. This needs to be taken care of in the psot processing stages.

Thanks again for this recommendation. I bought a nice Nikon 52mm O-56 (chrome finish!) on eBay. Tried it out today and am SUPER happy with the results! I may have to grab another at 72mm as they seem to be pretty scarce!

Link to comment

Soft focus/blurriness on foliage. While not unbearable, a consistent annoyance for 10+ years. So related, do you find that the more expensive filters from reputable names make a difference in this regard?

 

IR wavelengths are longer and they partly penetrate some substances and do not reveal the surface details that shorter wavelengths reveal, thus there will always be an inherent "softness" in IR photos due to decreased fine detail. There is no getting around that. However, you can test for the best stopped down aperture before diffraction begins to blur by running an aperture series with each combination of lens and filter.

 

In general, you would find that IR diffraction softens 1-2 stops before visible. And visible diffraction softens 1-2 stops before UV. And you would find that diffraction aside, IR has less fine detail than visible. And visible has less fine detail than UV.

 

Additionally, best practices in IR usually include some enhancements in the converter/editor for increased local contrast while at the same time avoiding induced noise or sharpening artifacts. Increasing accutance cannot, of course, re-create detail lost from long wavelengths, but it provide a good illusion of edge sharpness to mitigate diffraction blurring.

 

*******

 

Some of the chinese filters are not good quality, some are ok. There is no way to know whose are good and whose are not because the vendors change constantly. Many have striations or wavy flaws. If you get a good Schott glass filter from UVIR*Optics on Ebay or get the Hoya brand or B+W brand from a store like B&H, then you have assurance that the glass is of excellent quality.

 

******

 

I was running a Sony A7R for a while. I was using Novoflex (woo expensive!!) and Fotodiox adapters, both types good.

 

Generic adapters usually work out OK. Just make sure there is no warp against the camera mount side and no light leaks. Also check that if there is any black paint, it doesn't wear off in the form of fine powder which can grit up your sensor or lens elements. (I've mostly had that happen with step rings and not with lens mounts though.)

Link to comment
Andy Perrin

Soft focus/blurriness on foliage. While not unbearable, a consistent annoyance for 10+ years. So related, do you find that the more expensive filters from reputable names make a difference in this regard?

 

IR wavelengths are longer and they partly penetrate some substances and do not reveal the surface details that shorter wavelengths reveal, thus there will always be an inherent "softness" in IR photos due to decreased fine detail. There is no getting around that. However, you can test for the best stopped down aperture before diffraction begins to blur by running an aperture series with each combination of lens and filter.

 

The above is correct buuuuut, there is one other thing you could be seeing: I have found that many lenses have significant IR focal shift, so if you are shooting over a wide range of wavelengths (say, from 550nm to 850nm), the focal point will be different for something reflecting mostly 800nm vs. something in the same photo reflecting mostly 600nm. That means two objects at the same physical distance from the camera can blurred by different amounts. The effect was most obvious in a photo I took one night a bunch of years ago in full spectrum mode using a Sony Zeiss 55mm/1.8 ZA, a very nice lens but not at all good for full spectrum photography! Here it is:

post-94-0-98083900-1621918935.jpg

In this case you have two different light sources with quite different IR:visible ratio and in one case it's in focus and the other is not. (There is also some blur from hand movement in both - night photos handheld are difficult.)

Link to comment
.....but wouldn't you simply refocus when you switched from, say, the 550 nm filter to the 850 nm filter??
Link to comment

oh, now I get what Andy meant !!

 

I seem to have been thinking of focus shift only in conjunction with changing filters or changing apertures at which time one might have to refocus with certain lenses.

 

Having two kinds of IR reflectivity within one photo could also cause a kind of "focus shift". But wouldn't it be more of an axial aberration?

 

I don't think I've ever seen that happen in any IR I've photographed.

Either I've been just lucky or I haven't photographed enough IR. La!! :lol:

Probably both.

Link to comment

Yes, a kind of axial colour aberration or longitudinal chromatic aberration. Which, in fact, is the most unpleasant kind as the colour fringing will differ front and rear of the focused plane thus making later correction difficult., if not downright impossible. We see a lot of such wave-length dependent focus shifts just outside the visible range for many lenses, in particular when entering the UV range.

 

However we ought to keep in mind that blaming a lens not designed for use outside the visible spectrum for its behaviour when (ab)used in that manner, is not fair.

Link to comment
Andy Perrin

I defer to you all on the proper terminology, but yes, two different wavelengths of light in the same image (from different light sources) will end up focusing at two different planes even if they are the same physical distance from the camera. Meaning that there is no way to adjust the lens to deal with it and no way to fix it in post processing either. The only solution is to find a different lens which is corrected for the range of wavelengths we are interested in.

 

Andrea, it’s entirely possible that the lenses you use are well-corrected enough in IR that you didn’t see it, or you just never encountered the kind of mixed lighting situation that makes the effect most obvious (hint: nighttime IR photos have that a lot...).

 

Anyway, back to the original question, leaves reflect IR so well that if you had a filter with a shorter cutoff like a 550nm on there, it’s possible you would see some leaf blur relative to other objects in the scene if they were reflecting mostly shorter wavelengths.

Link to comment

Andy, you are likely spot on that the lenses I use most often do not have any serious IR-aberrations.

And also, it is true that I have not made many night IR photos.

 

On a side note: Here I don't have much to shoot at night unless I go into town. Must do this. And I would love to have an IR critter camera to see all the rodents around here who have wonderful parties at night, lots of dancing and hijinks.

 

So your example was *very* instructive to me. Good !!! :grin: (...and thanks, as always....)

 

The leaf problem, to me, is probably just the typical lack of fine detail in IR because most leafy foliage does not differ greatly in its IR reflectivity. We should look up that value. I used to know it, but it escapes me at the moment. :rolleyes:

Link to comment

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now
×
×
  • Create New...