Infrared with the M system

)Having heard that vintage lenses often work well for IR, I decided to take a couple of vintage lenses I recently got with a large set off Craigs list. The whole set was someone's 'junk' lenses they couldn't sell on eBay - some had loose barrels, most were pretty dirty, a few have some fungus on glass inside the lens. Projects for another day!

I cleaned up the two best ones as much as I could to try them out with my full-spectrum M200, with various filters.

I chose a Star-D 28mm f2.8 lens in Minolta MD mount, which looks like a lot of 28mm lenses such as Albinar, Promaster, etc, I've had pretty good luck with this type of lens in the past, stopped down a bit. This copy had something smudged on the front element which I mostly got rid of, a few tiny scratches, and a bit of haze inside.

I also chose a Montgomery Ward 60-300mm f4-5.6 lens in Nikon F mount. A little haze in the lens but otherwise not too bad.

I shot the Tampa city skyline from an observing platform at McKay Bay, in bright sunlight on a clear morning. Here are the results:

Star-D 28mm f2.8 vintage lens results

Unconverted Canon M6ii, f8

Full-spectrum Canon M200, no filters (full-spectrum), f8

Full-spectrum Canon M200, Spencer camera Visible + H-alpha filter, f2.8 (forgot to stop down!) - this filter is very similar to the TIffen Hot Mirror filter more widely available (amazon.com)

Full-spectrum Canon M200, Visible + H-alpha filter plus Hoya Red 25A filter, f8 - Two filters make this a very narrow-bandpass monochromatic image from ~590 nm to ~680 nm in the deep red.  The V+Ha filter is similar to the TIffen Hot Mirror filter more widely available (amazon.com)

Full-spectrum M200, Spencer camera 590mm filter, f8, red/blue color channels swapped in post

Full-spectrum Canon M200, Hoya Red 25A filter, f8, red/blue color channels swapped in post

Full-spectrum Canon M200, Hoya R72 IR filter, f8, red/blue color channels swapped in post

Full-spectrum Canon M200, $6 Neewer 950 nm filter off eBay, f8. Very deep infrared

For the visible + H-alpha shot I forgot to stop down to f8, but you get to see the lens' poor performance wide open.

Interestingly the major flaw with the lens appears to be chromatic aberration, and in the narrow-bandwidth shots, especially the super-narrow 590-680 nm shot, the lens is quite sharp. There isn't much of a range of wavelengths for the CA to 'spread out' into the classic CA blur.

In post, images were processed as similarly as possible using DxO PL5 given that they are at different wavelengths. Similar sharpness settings were used, all downsampled to 2160 pixels high. The M200 has its sensor filters removed, including the anti-aliasing filter, which helps the lens sharpness, but moire shows on the square windows of the building, even with the anti-moire-setting in DxO PL5 maxed out.

I also shot directly into the sun just after sunrise, expecting the image to be the unusable 'mess' of glare & internal reflections all my Canon EF-M zooms all produce in IR with the sun in the frame. I was quite surprised to see this vintage lens do a far better job with only a few ghosts!! This is a great lens for IR photography, with little to no hot spots.

Full-spectrum Canon M200, Hoya R72 filter, shotting straight into the morning Sun at f8

Montgomery Ward 60-300mm f4-5.6 vintage lens results

Unconverted Canon M6ii, 60mm, f8

Full-spectrum Canon M200, 60mm, f8, Spencer camera 590 nm filter, red/blue color channels swapped in post

Unconverted Canon M6ii, 300mm, f8 (as marked on the lens which was probably f11)

Full-spectrum Canon M200, 300mm, f8 (as marked on lens), Spencer camera 590 nm filter, red/blue color channels swapped in post

In visible light this lens does pretty well stopped down to f8. I do not show wide-open images here, they weren't nearly as sharp - nothing to write home about.

The 60-300mm obviously does much better with IR at the short end of its range. At both the short and long ends of the zoom range, the foliage is blurred --- which isn't surprising as foliage reflects strongly in infrared light - so there was a lot of IR and some orange light from it, which focus at very different places behind the lens, blurring any foliage detail.