T-mount cap / blank ?

AndrewC · Post by **AndrewC** » Thu Aug 27, 2009 2:36 am

Anyone know of a source for a T-mount cap ? Basically I want to make some test mounts for some lenses to fit onto a T-mount.

I want the equivalent of a camera body cap so I can drill an appropriate hole and mount the lenses on the cap

Andrew

Charles Krebs · Post by **Charles Krebs** » Thu Aug 27, 2009 1:26 pm

That would be nice wouldn't it. But I've never seen one. Pieces with male T-threads are not that common.

Although it's a kludge, if the lens is really light weight you can often get by with a cheap Pentax (M42) T-mount. Although the thread pitch is different (1.0 vs 0.75) the cheap M42 T-mounts can screw in quite a ways before things "snug up". Put a disk with the appropriate size hole on the front. You can epoxy the disk on. Better yet you could remove the T-threaded insert (via the three set screws) and insert in it's place an appropriately sized disk with the proper hole size.

Edmund Optics (among others) sells short T-mount extension tubes and adapters with male T-threads on each side. Either of these can be adapted for this purpose if you want a proper male T-thread to work with.

Another option is to make up a male T-thread to, say, a 52mm (female) filter thread adapter. Then you can use readily available (an inexpensive) metal screw in lens caps.

AndrewC · Post by **AndrewC** » Fri Aug 28, 2009 12:42 am

I want to standardize my lens mounts to T-mounts but, as I already need to use a Nikon to T-mount adapter, for this exercise I think I'll just grab a few cheapo Nikon body caps and chop them up.

I'll keep hunting for the male T-mount "blank" and post it here if I find one.

rgds, Andrew

Joseph S. Wisniewski · Fri Aug 28, 2009 7:09 pm

I've always found the best source for male T-mounts are old, no-name T-mount lenses from the bargin bins at a camera show, or perhaps eBay.

Seriously, you can often get a servicable male T-thread, a focusing helicoid, an iris, and some lens elements for $5.

ChrisR · Post by **ChrisR** » Sat Aug 29, 2009 4:29 am

One of the ebay step-up/down adaptor sellers does one with a 42/0.75 Tmount male thread, stepped from normal filter sizes. I'll post a link if I find it again.

I've recently bought some of the cheap Chinese extension tubes which have screw connections in the middle. I believe they're 55mm, but not sure if they're the same pitch as a 55mm filter, - I have none that size.

Edit sorry 57mm, as best I can measure.

Harold Gough · Post by **Harold Gough** » Sat Aug 29, 2009 9:31 am

Take a look here:

http://www.srb-griturn.com/t-mounts-and ... -331-c.asp

Harold

ChrisR · Post by **ChrisR** » Sun Aug 30, 2009 3:52 pm

SRB look useful but they are a bit expensive for some of their bits.
This ebay seller:- "heavystar "
sells a variety of cheaper "stack caps", ie metal caps with male/female threads, also body caps.

A T2 female thread is 42 x 0.75 iirc, whereas the old Pentax/Praktica camera mount was 42 x 1. In practice by the time the thread has jammed, if you use the wrong pitch, it's a turn or so in, and gripping well enough.
(Edit Sorry, Charles had already written this )

It's quite possible that a 39 or 42mm cap pair would go into the T2 mount in place of the rotating collar and suit your purpose?

Harold Gough · Post by **Harold Gough** » Sun Aug 30, 2009 10:55 pm

ChrisR wrote:In practice by the time the thread has jammed, if you use the wrong pitch, it's a turn or so in, and gripping well enough.

I can confirm that from experience with T-Mounts incorrectly sold as M42 adapters. This is a problem where infinity focus is required, but not for close-up/macro.

Harold

AndrewC · Post by **AndrewC** » Mon Aug 31, 2009 1:44 am

I've got an aversion to jamming unmatched threads (though you can accomplish all sorts of bad things with SS bolts and a strong hex key) - I don't want to progressively knacker my T-mount to Nikon adapter !

Andrew

ChrisR · Post by **ChrisR** » Mon Aug 31, 2009 5:12 am

Perhaps your best bet:
ebay 120310982244 T2 male to 52 female.

AndrewC · Post by **AndrewC** » Mon Aug 31, 2009 5:35 am

But these are only GBP1 each

370224189639

I'm sure they won't be as secure lock onto the bellows as a screw fit, but for something sacrifical to drill holes in and mount odd fitting lens, seems a good way forward.

If I can find a T-mount to filter adapter with the right hole size that would be nice.

Andrew

ChrisR · Post by **ChrisR** » Mon Aug 31, 2009 6:06 am

What "right hole size"?
I'm sure we've all done it, Andrew,

I have a cone cutter for the purpose. Double sided thin tape comes in useful too

.

I reckecked the Chinese Extension tubes. The threads appear to be 57mm x 0.72mm, as best I can measure. That's probably 57 x 0.75. Is that the same as 57mm filter?
If so, though a bit unusual, with more adapters it would give a cheap screw connection between different lenses and bodies.

Charles Krebs · Post by **Charles Krebs** » Mon Aug 31, 2009 8:19 am

Seems like the piece Chris located (120310982244) plus a bunch of cheap 52mm metal screw in lens caps would give a solid mount. Quick enough for a lens test, but solid enough for a permanent solution if desired.

ChrisR · Post by **ChrisR** » Mon Aug 31, 2009 8:53 am

Any suggestions for how to hold a Fluor Apo Plan Epi Dic Ph SULWD 400x/2 objective into it?
Hot-melt glue in the threads is the best I can think of. It isn't very hot, comes off easily when needed but holds, over a large area, quite well.

Harold Gough · Post by **Harold Gough** » Mon Aug 31, 2009 9:16 am

ChrisR wrote:a Fluor Apo Plan Epi Dic Ph SULWD 400x/2 objective

The "fluor" drew my attention. If this is fluorite, beware of degration on old lenses.

Harold