I have Canon R5 II converted to full spectrum, planning to use it with 720nm, 820nm, and Kolari IRChrome, but possibly the less-deep filters as well (e.g., 665nm). In my experience in the past, hot spot, while important, is only one of many characteristics making a lens suitable for IR work. Other key factors I have found to matter tremendously include:
- veiling flare (VIS vs. IR can behave very differently)
- sharpness wide open (can be abysmal in IR in lenses that are quite good in VIS)
- APO, i.e., the ability of the lens to focus all wavelengths at the same plane
Surprisingly, these are almost never discussed in all the knowledge bases of lens suitability for IR work, with majority of the information fixated on hot spots.
If you have any experience with any of the top Canon RF primes in infrared, especially used wide open, please comment.
I am particularly interested in the performance of:
- RF 50/1.4
- RF 50/1.2
- RF 85/1.2
- RF 135/1.8
- RF 35/1.4
- RF 14/1.4
- RF 24/1.4
Allegedly, the following zooms work quite well:
RF 24-240
RF 100-400
RF 100-500
1. Did you get yours converted at PetaPixel? I have been looking into IR conversion and would be interested in your experience.
2. I use the website Kolari as a reference and will share their data here.
RF 85 f1.2: Good. It handles IR without significant hotspot issues
RF 50mm f1.2: Bad. It has a distinct center hotspot that becomes visible beyond f4. It can be useable wide open.
RF35mm f1.4, RF 24mm f1.4, RF 50mm f1.4 and RF 135mm f1.8, I haven't seen any testing for the hyrid VCM primes. I would expect the 135 to be hotspot prone as telephoto primes can struggle.
RF 100-400mm: Great. Performs great in all conditions with no hotspots.
RF 100-500mm: Great. Only starts to show center issues past f11.
RF 24-240mm: Mixed. A hotspot develops early on the 24mm end and gets bad by f8. 100mm and on, it performs solidly with no significant hotspot issues.
If you perform any testing I would also be very interested in seeing your results. I think you are in a small category of people with a full spectrum R5ii with a nice lineup of RF primes.
Thank you for the data, Sir! Kolari is indeed where I have done the FS conversion.
Their data on lenses (and most other sites' as well) is sadly mainly limited to hot spots, which, important as it is, is far from the only important IR performance aspect. I have found that extreme softness wide-open (felling like extreme form of spherical aberrations), peripheral CA (translating to blur in B&W), and veiling flare to be at least as intrusive, and often much more so, than (especially mild) hot spots. It is precisely these aspects that I am hoping to gather evidence about.
Maybe PM @burningheart for his thoughts? I believe he has a FS conversion R5 and has a pretty significant collection of lenses in RF, EF, ZE/ZF, FD, Leica M, etc.,
I didn't post this sooner because I thought he might see this and am kind of surprised he hasn't commented already...
I ran tests against many lens with my R5 modded for full spectrum using the B+W 092, B+W 093 and Heliopan 1000. But I was mainly interested in hots spots.
