Odd Canon video lens

[Dave92F1]

I just picked up this Canon video lens on eBay.  It's a YH17x7KRS12U model.  But what kind of mount is on it? 

I (foolishly) expected a C-mount or CS-mount lens, but this is some kind of bayonet mount I'm not familiar with (it's not EOS that's for sure).

See pix.  There's a marking '1/2" F.B' near the mount.  The back focus distance (flange to image plane) is about 20mm (I measured it).

Can anybody identify this mount?  Is there a way to convert this to a C-mount?  The image circle is meant for a 1/2" CCD so it's way too small for a APS-C sensor, but I was thinking of putting it on a Nikon V1....if I can figure out how.

[DavidRiesenberg]

A quick search of the model item seems to indicate it is a 1/2" JVC mount.

[Dave92F1]

Thanks - that's very helpful.

Can I ask where you looked that up?  Any info I can find about the lens might be useful.

Any idea if the 1/2" JVC mount can be converted to C-mount (or really anything more popular that I could get onto a Nikon V1)?

[DavidRiesenberg]

Oddly enough, also eBay : http://www.ebay.com/itm/Canon-YH17X7KRS12U-17X1-SERVO-ZOOM-LENS-/370279084009#ht_897wt_1396

where it states that it fits the JVC KY-19U and GYX2.

[Jon Gilchrist]

I've got two lenses sitting here next to me with the same mount and I'm facing the same problem.  They look like quality glass, but I can't find any information about them or a way to mount them on anything.

The lenses I have are a Canon J15x9.5B4 KRE 9.5-143mm 1:1.8 and a Panasonic QT1612SHGB 10-120 1:1.6.  As these are lenses made for video I would expect them to be parfocal, and they have stepless apertures that go all the way to black/solid/closed/whatever.  They came off some older studio style video cameras.

Any info about these would be greatly appreciated.

[DavidRiesenberg]

Well, that Canon 9.5-143mm is a B4 mount and there are quite a few adapters for it - for different systems. Probably the most common modern use is on M43 cameras.

edit: That Panasonic lens also appears to be B4.

[Dave92F1]

Wow - that guy is asking $1750 for that lens.  I paid $50 for mine.  Somehow I don't think he's going to get the $1750.

I've been googling on this.  It seems the market for these broadcast video lenses has collapsed because nobody wants lenses that aren't designed for HD. 

But I'll bet the better ones still work pretty well at HD, depending on the pixel pitch of the sensor.  At $50 it's a toy I can experiment with.

Jon - here's what I've learned so far:

1 - The flange focal distance (flange to image plane, aka 'register') is supposed to be 20mm, which matches what I measured.  To mount it on a camera with an adapter, you need a camera with a flange distance shorter than that, to allow some room for an adapter. 

20mm rules out all standard DSLR bodies.  According to http://en.wikipedia.org/wiki/Flange_focal_distance, the only mounts with a flange distance less than 20 mm are:

Micro 4/3, 19.25mm
Sony E-mount (Sony NEX), 18mm
Fuji X-mount (Fuji X10), 17.7mm
C-mount (video/cine), 17.52mm
Nikon CX (Nikon 1) mount, 17mm
Pentax Q mount, 9.2mm

2 - The image circle is designed for a 1/2 inch CCD (4:3), which is 8mm diagonal.  See the attached spreadsheet I made (info collected online) - according to that, the ONLY modern interchangable lens digital camera that won't vignette with that lens (because the sensor is < 8mm diagonal) is the Pentax Q.  (Which I think is a crappy camera.)

So the compromise I'm thinking of is to mount it on a Nikon V1 or J1.  It'll still vignette like crazy, but I can crop afterwards.   Micro 4/3 should work too, but the pixels are so big and the sensor is so large compared to the image circle, that I think there won't be many pixels left after cropping.

3 - There do seem to be a few adapters out there.  But they are incredibly expensive:

Here's one to adapt the JVC 1/2" bayonet to Nikon - it's $590 (!!):
http://www.bhphotovideo.com/c/product/77577-REG/Century_Precision_Optics_0LA_N120_00_LA_N120_Nikon_to_1_2.html

And here's one to adapt it to C-mount - $424:
http://www.bhphotovideo.com/c/product/77584-REG/Century_Precision_Optics_0LA_12BC_00_LA_12BC_1_2_Bayonet_to.html

(C-mount adapters for cameras are easy to find and cheap on eBay.)

Those are the best prices I found.

Since I only paid $50 for the lens, I'm not going to even consider those.

The mount is attached by 8 screws.  I think I'll try to take it off and see if I can jerry-rig something...