Canon XI 100mm f1.5 lens

kymarto · Posted: Sat Dec 23, 2017 2:45 pm Post subject: Canon XI 100mm f1.5 lens

Hi folks,
I found this lens in my local secondhand store, among all the kit zooms. For $150 I thought it was worth a try. It appears that the XI lenses were x-ray lenses, but this one is a surprise. It does not have the usual soft bloom and hazy look of the x-ray kowas and heligons. I'm posting some samples. Mounting it was not easy, since the registration distance for infinity focus is 0.5mm from the mount of the Sony NEX. I have managed to modify a 65mm helicoid so that the back of the lens can get flush with the M65-to-NEX adapter I have, in which case it focuses to ~5 meters, which is perfectly OK for the use that I will put it to.

No vignetting even at that short flange distance, and quite sharp up to about 2/3 of the way out on FF. Even the corners are not bad. See what you think. And I quite like the bokeh as well Smile

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visualopsins · Expire: 2025-04-11

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#8 interesting!

Sjak · Joined: 29 Sep 2017 Posts: 696

Psychedelic! But once you get close to the subject, the character suddenly seems very different. Well done, thanks for sharing!

kds315* · Expire: 2021-03-09

Congrats, great find!!

That whole series of lenses is quite interesting. I once found this f1.3/75mm one with aperture even...
http://www.macrolenses.de/ml_detail_sl.php?ObjektiveNr=153
and some are extremely fast, like this f0.75/65mm
http://www.macrolenses.de/ml_detail_sl.php?ObjektiveNr=109
But admittedly, all not that easy to adapt!

blotafton · Joined: 08 Aug 2013 Posts: 1636 Location: Sweden

kymarto · Posted: Sun Dec 24, 2017 10:44 am Post subject:

Looks like the image circle is around 65mm on this lens, which is pretty crazy considering the registration distance. Iâ€™d love to see the optical formula of this puppy.

Nordentro · Expire: 2015-01-29

Picture of the lens?

kymarto · Posted: Wed Dec 27, 2017 2:39 pm Post subject:

stephenmcleod · Joined: 05 Jan 2018 Posts: 15

I'm curious how you managed to mount the lens on the Helicoid. Is it a permanent mount? I have a 50 f0.75 XI I am trying to find a better solution for (like a clamp) than my DIY effort.

kymarto · Posted: Thu Jan 25, 2018 1:57 am Post subject:

I use enough wraps of PVC electricianâ€™s tape so that the barrel of the lens fits snugly in the helicoid. PVC tape ages well, doesnâ€™t make everything sticky, and is elastic enough to hold the lens firmly in place. I shy away from permanent mounts whenever possible.

The problem with a clamp such as those made by Rafcamera is that you have no focusing possibility unless you screw that into a helicoid, at which point (even with a thin helicoid) you are in real macro territory. You want to get the rear element as close as possible to the sensor. What I would do is to get a thin M65 helicoid, such that when you fit the lens as far as you can down into it (until the fat part of the lens hits the front of the helicoid), the rear element is about at the bottom of the helicoid. At the rear of the helicoid then you use a M65 to M42 adapter ring, plus another M42 to NEX ring (or to whatever mount you need). If you use E mount then an M65 to NEX ring is better, because it is thinner, and with my setup at least every fraction of a millimeter counts.

If the lens barrel is considerably smaller than 65mm (actually the insides of those helicoids have some lips that bring the diameter down a few mm) then I suggest you improvise using sheet rubber and then wrapping with tape to hold that on. If you want PM me and we can discuss more in detail.