El lenso grrande: 500/6.3 3M-6A on Canon 400D

rick_oleson

I just snagged this lens on eBay for $57. I had doubts that it would fit on my 400D but figured that I could risk that much to find out. The lens was advertised as "Pentax Mount", which I assumed would mean M42, but it arrived with a K mount bayonet on it... what mounts did they make these in? I have a K mount adapter, so I tried it ... the lens hit the prism overhang about 3mm before reaching the bayonet flange of the camera. I thought I might use it with a teleconverter, but I don't have one in K mount... my best one is in OM mount.

The mount looked a lot like the outer half of a T mount, so I pulled out the 3 set screws and pried it off, then disassembled an OM T mount and discovered that its outer half would slip onto the ring at the back of the lens ... a perfect fit, except that it was shallow and so would not go on as far as the K mount had been. But it was far enough on for the set screws to grab, so I went ahead - I can improve on it later.

Cool thing though is that now the lens WILL mount on the 400D, since the OM mount sticks out a bit too far to the rear of the lens; it clears the prism by about a millimeter and a half. But where will it focus to?

Well, it turns out that it seems to focus to infinity, maybe even a little past. I don't know if it's supposed to do this or if someone has tinkered with it, but the focus ring goes WAY past infinity on this lens, far enough to make up for the extra length I've added in to make it fit the camera.

Probably not according to Hoyle, but I seldom do things that way anyway... I'm looking forward to getting out and playing with this excellent, compact walking-around street lens......

Attila · Expire: 2025-11-18

This is a superb lens! I have it too, very sharp even if you shoot to infinity distance. Value is lot more than 57 USD only, congrats to catch this rare bird!

casualcollector · Posted: Sat Jun 13, 2009 7:57 pm Post subject:

Way cool, Rick. Is this a Russian lens?

Attila · Expire: 2025-11-18

estudleon · Joined: 15 May 2008 Posts: 3754 Location: Argentina

A beauty monster!!!

Congratulations!! (and the pics??)

Rino.

rick_oleson · Posted: Sat Jun 13, 2009 9:18 pm Post subject:

I'll admit I'm cheap (or poor, if you want to look at it that way) and I've never used a good mirror lens before, only a few of the cheap brands. But honestly, I didn't really think you could get shots like this with a mirror. The sharpness (vastly better than the cheapies I'm used to, of course) was not really a surprise, but the high contrast is. I had thought that at least a fair part of the low contrast I'm used to in mirror lenses was due to the necessary gap in the baffling between the two mirrors. These are both handheld, I boosted the ISO up to 1600 for the lily shot to get a faster shutter speed. Sharpness in the bike picture is degraded by heat waves; and the little speck in the background at the upper right in the lily shot appears to be a gnat.

rick_oleson · Posted: Sat Jun 13, 2009 9:21 pm Post subject:

Oh, and the split image prism in the focusing screen works fine, focus is spot on.

Attila · Expire: 2025-11-18

Excellent samples! Thank you for sharing them! I didn't see any better 500mm lens below 1000 USD.

rick_oleson · Posted: Sat Jun 13, 2009 9:51 pm Post subject:

of the three cheap mirror lenses that I've had, I think I paid more for at least two of them than I did for this, and I also paid more for my respectable (but definitely cheap) 400/6.3 glass Spiratone lens... I'm very pleased with the purchase.

I'm still puzzled by the Pentax K mount that it came with, though. Do you know what mounts this lens was made in? If it was modified, it must have been a lucky chance like my OM mount, it doesn't look like anyone has done any machining on the lens barrel.

Oh, and also: the focus ring goes a long way beyond the engraved markings in both directions, something which of course does not bother me in the least ... but is this normal for this lens, or has someone tinkered with that as well as possibly the mount?

Attila · Expire: 2025-11-18

I think not normal either focus ring and PK mount. I saw only two copies from this lens both have M42 mount. Orio have it too, Orio please check your focus ring.

M. Valdemar · Joined: 14 Nov 2008 Posts: 93

It's got a t-mount. You can take off the Pentax K mount and put on any mount you want.

I've got a few of them.

Attila · Expire: 2025-11-18

rick_oleson · Posted: Sat Jun 13, 2009 11:27 pm Post subject:

You mean the part that's still stuck on the back end of the lens should unscrew off of it on a normal T thread? Mine must be seized together then, it won't budge. It does make sense though, it looks just like a T mount adapter and I managed to interchange the outer half of it with one of my T mounts.

M. Valdemar · Joined: 14 Nov 2008 Posts: 93

Every one I have ever seen has just been a normal t-mount lens. Do you have a photo of the back of your lens so I can see what you're talking about?

rick_oleson · Posted: Sun Jun 14, 2009 1:49 pm Post subject:

Yeah, I can do that (not at the moment) ... it looks like it's a T mount, but the mount will not unscrew off of the lens. I changed mounts by removing the set screws from the mount and interchanging the outer part with another T mount that I had.

The most likely explanation is that the 42mm threads of the T mount are frozen onto the lens and I just can't unscrew it. I don't have any urgent interest in solving that problem, since if I get it all back to the way it should be it won't mount on my camera any more. Some day I may get some Liquid Wrench in there and take the mount off, but for my purposes it's just about perfect the way it is. I really only asked the question out of curiosity, I had not known these were T mounts and assumed it would come in a mount to fit a Russian camera.

poilu · Expire: 2019-08-29

wow! this is a big thing Shocked

great results! nice bokeh on #2