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09-08-2017, 01:01 PM   #1
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Mystery Lens Mount Identification?

I picked up a weird lens recently. Basically, it's a Tamron adaptall 2 300mm lens which seems to have had the original fitting removed and a simple tubular mount put in its place.












The protruding bit is 41mm diameter and about 19-20mm long, the bit at the end that looks like a screw fitting is actually just a groove in the tube. My guess is that it's supposed to click into some sort of quick-change mount, maybe for a cine camera or something of the sort. It'd be nice to know before I try to sell it.


Anyone got any any ideas?

09-08-2017, 01:07 PM   #2
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Interesting. Definitely a custom diy job IMO. Like you I have no idea what that mount is for.

Have you tried taking off the mount to see what he did underneath? It might be pretty simple to replace the adaptall mount using bits from a junk adaptall lens, or a nearly worthless 80-210mm. Then that SP 300mm 54B would be good to go.
09-08-2017, 01:42 PM   #3
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Are you sure it's not just missing bits? For example, I don't see an aperture ring.
09-08-2017, 02:22 PM   #4
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Sorry, the ring is right at the base of the lens, it's just turned round so it isn't visible. It stops down OK. I just risked taking off the mount, it looks like they took off the flange that links the lens body to the Adaptall mount and added a couple of brass plates. The first is a spacer, plus it's pressing on the stop-down mechanism so that the lens is manually operated, the tube part is screwed to the second. It's quite nice workmanship, so I'm guessing it was a custom job done professionally.

It would probably be possible to fit the the flange from another Adaptall lens to get it back up and running, assuming that they're all the same, but it isn't in wonderful condition - there's some internal dirt and possible fungus - so I really don't want to spend a huge amount of time or money on it. I'm really more curious about why this was done than anything else. Come to think of it, I may have the remains of a dead Adaptall lens in my parts box, I'll have a look tomorrow and see if I can find anything useful.

09-09-2017, 06:03 PM   #5
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OK, I found another Adaptall lens and tried a flange swap and it seems to work well - but it's actually a fairly nice little zoom 35-80 f2.8-3.8, and in better condition than the 300mm lens. I've got a lens adapter on order, what I'll do is try both (swapping the flanges between the two lenses) and see which gives the best results, then sell that with the Adaptall flange, the other one with the weird tube mount.
09-09-2017, 07:34 PM   #6
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You are better off finding a 60-300mm 23A it is far better than this lens and faster at the long end at f5.4 compared to the 54B f5.6
here it is wide open at 300mm

I think this one is f 8

Last edited by Sliver-Surfer; 09-09-2017 at 07:42 PM.
09-10-2017, 05:12 AM - 1 Like   #7
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Resolution wise I find the 23A and 54B to be very similar. Rendering is a bit different, 23A IMO is less prone to fringing. Close comparison shows 23A is actually a bit shy of 300mm.

QuoteOriginally posted by Marcus Rowland Quote
OK, I found another Adaptall lens and tried a flange swap and it seems to work well
Marcus I can give you the mount bits, I have several junk lenses. PM me.
09-10-2017, 11:10 AM   #8
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QuoteOriginally posted by marcusBMG Quote
Resolution wise I find the 23A and 54B to be very similar. Rendering is a bit different, 23A IMO is less prone to fringing. Close comparison shows 23A is actually a bit shy of 300mm.
The Fringing is very similar between the 2 lenses. However the 60-300mm eliminates the need for a bag full of standard to long teles and macros because it is sharp all the way through the focal range. It can also do 1:1.55 Magnification at <10cm
Here is an unsharpened crop of the first image in my other post which demonstrates the resolution of this lens at 500iso shot with 60-300mm @300mm on an apc-s camera


09-10-2017, 05:21 PM   #9
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Silver-Surfer, those are amazing photos for a lens that old! I really hadn't been thinking in terms of using the 300mm lens myself, but maybe I'll give it a try - I have an adapter on order for testing them.

MarcusBMG, many thanks - you have mail.
09-14-2017, 12:28 PM   #10
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QuoteOriginally posted by marcusBMG Quote
Marcus I can give you the mount bits, I have several junk lenses. PM me.
These arrived today and I managed to get it all put together fairly easily - having another lens to compare it to helped considerably. Many thanks indeed!

Hopefully the Adaptall mount I ordered will turn up soon - I'm also watching another lens on eBay that's currently very cheap and has a mount I can use.
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