How to test for IR suitability of lenses?

[Bern]

Happy new year to all, before anything else, as this is my first post for the year.

I have been interested with IR for quite awhile now and read that there are lenses that do well with it. Also, its been said that there are a few other things that affect whether, a lens would be producing a hotspot or not. A few of these are aperture, camera model, IR filter and maybe some other shooting conditions... A number of lenses have also been labelled as excellent IR lenses such the Nikkor 35-135 among others.

I am assembling a small IR kit for my D200 IR and would like if anyone can share a test methodology to determine which other lenses would perform well in IR. I have seen a list of lenses here that have already been said as good ones already.

This site has really been a great help.

Thanks!

Bern

[Erik Lund]

Here is a link to our sister site where Andrea and Bjørn have compiled a lot of info on IR, cameras filters and lenses


http://www.ultravioletphotography.com/content/index.php/topic/712-sticky-ir-photography-cams-mods-lenses-lights-links/

[Seapy]

My 'standard' IR lens is a Nikkor 18-105VR, I have heard it can hotspot but neither of my copies do.

When I got my D1 IR I tested all my lenses on it at various apertures.  I still have the results somewhere but the 18-105 serves me well, I occasionally use my 16mm fisheye and that seems OK too but no doubt there may be circumstances where it could be troublesome given it's extreme coverage.

I also study Bjørns lens pages from time to time, he makes very helpful comments about the suitability or otherwise of lenses for IR-UV spectrum uses.  This is my trusted 'go to' site for general and IR-UV info.

http://www.naturfotograf.com/lens_surv.html#top1

This is a sample from my D200IR and 18-105mm at about mid zoom, say about 50mm?.

[Bjørn Rørslett]

The matrix of possible camera-filter-lens combinations is simply huge and the interrelationships pretty complex and convoluted. Thus, in reality only a test shoot can decide whether a given lens will perform well under the testing conditions. I added the latter phrase because there are plenty of examples of lenses doing well in some situations and fail in other.

Typically problems will be more severe when the lens is stopped well down. End at f/8 or so and some otherwise  "poor for IR" lenses might function well enough. Many lenses start to show hot-spots only when they are closed even further to f/11 or beyond. The gravity of the hot-spot issue also will depend on the light conditions, whether or not a lens hood is used, and so forth.

[MFloyd]

Herewith a database https://kolarivision.com/articles/lens-hotspot-list/ but whiteout any assessment (from me) whether this is valid or not.

[Bjørn Rørslett]

That list is a curious mix of valid and not-so-valid assessments. For example, one of the best IR lenses on my D200IR (and Fuji S3/S5 full spectrum) is the venerable 43-86 Nikkor, which is listed as "poor". There are many more of such questionable entries.

[Bern]

The matrix of possible camera-filter-lens combinations is simply huge and the interrelationships pretty complex and convoluted. Thus, in reality only a test shoot can decide whether a given lens will perform well under the testing conditions. I added the latter phrase because there are plenty of examples of lenses doing well in some situations and fail in other.

Would a "simple" test such as shooting at different aperture be sufficient? I understand that there are a lot of factors that may affect the outcome thus the reason for the initial querry of how to test. Some established IR capable lenses are not readily available where I am, so I wanted to test other alternatives.

Typically problems will be more severe when the lens is stopped well down. End at f/8 or so and some otherwise  "poor for IR" lenses might function well enough. Many lenses start to show hot-spots only when they are closed even further to f/11 or beyond. The gravity of the hot-spot issue also will depend on the light conditions, whether or not a lens hood is used, and so forth.

Just a side question, would diffraction also be an issue with shooting in IR?

Thanks for the continued answers.

Bern

[Bjørn Rørslett]

Select conditions under which you would like to shoot in IR, and test the lens by carefully going through the aperture scale. If the lens is manual and won't give any EXIF feedback, make sure you keep notes to consult later.

Diffraction occurs earlier along the aperture scale in IR than in visible light "ordinary" photography (and UV is more relaxed in terms of harmful diffraction effects). Thus it can be prudent not stopping the lens all the way down. On the other hand, by using a narrower band of the spectrum, some lenses actually increase their performance in IR. This is probably the reason why such a middle-of-the-road performer as Nikkor 35-135/3.5-4.5 becomes a great lens for IR. I could list a long array of similar cases.

[richardHaw]

very interesting. I will follow this thread

[Bern]

Aside from hotspot, is there any other issues that should be considered?

[Erik Lund]

There is focus shift for IR so Live view can come in handy for testing that,,, and since sharpness is revealing, shooting wide open can be tricky,,,
Some lenses are definitely behaving better than others in this regard.


It's quite important when you go hunting to find the exact version of the lens, since even 'siter' lenses can behave quite different - Rolands pages with Nikkor serial # are quite good for that!

It is also important to be aware that flare and reflections can be very prominent in IR - Use an adequate long lens hood if you want to avoid flare and reflections, or use it for effects