Hey,

I've finally gotten parts from Thor Labs together with a new F-mount from an F-to-C mount adapter I'd purchased from B&H. The problem, though, is that the F-mount has internal threading, as does the Thor Labs 2" tubing.

Does anyone know of a coupler that will join the two pieces? Unfortunately for me, the internal threading at the back of the F-mount is of a slightly smaller diameter than the threading at the front of the Thor part.

I've been in contact with Thor in the hopes that they might be able to custom make a step-down coupler for me, but things are running a bit short so far as I don't have the proper tools/knowledge to measure the diameter and size of the threading.

Any help would be much appreciated.

- jim

If I remember correctly Richard Mellor had to remove the back part of the cmount (Screws off I believe) and then glued that on to the end of the tube. Said it fit perfectly.

I've written Century Optics since ThorLabs has come up dry. I'll probably call them today, as well. If/once I get this custom coupler made, I'll have them keep the specs or get them myself for future orders.

At least, that's the hope...

"If I could just get these two parts..." :D

edit: Success!

I ordered a Thor Labs 2"-to-2" tubing coupler a while back that I'd forgotten about because it proved innitially useless -- now I've fit it to the back of the f-mount -- it slides in but doesn't screw in -- and there are three very small screws that screw toward the center of the f-mount to hold the coupler in place. It's kind of like how you screw bolts into the trunk of an Xmas tree to keep it in the stand.

I'm not certain this will prove field-worthy, so in the near future I'll probably add some glue to the mix, but for now, here's some images:

http://ideaspora.net/35mmadapt/f-mount.jpg

http://ideaspora.net/35mmadapt/off-camera.jpg

http://ideaspora.net/35mmadapt/assembly-detail.jpg

http://ideaspora.net/35mmadapt/achromat-stepdown.jpg

http://ideaspora.net/35mmadapt/side.jpg

http://ideaspora.net/35mmadapt/topside.jpg

http://ideaspora.net/35mmadapt/front.jpg

- jim

Wow! That looks great Jim - very pro looking!

EDIT: Jim where did you find that coupling ring?

Here's the complete parts list:

Century Optics +7 achromatic diopter (http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=77546&is=REG) -- $220

58mm-52mm generic brand stepdown ring (http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=98916&is=REG) -- $7

2" diameter, 2" deep Thor Labs optical tube (http://www.thorlabs.com/ProductDetail.cfm?DID=6&ObjectGroup_ID=213&Product_ID=1481) -- $30

Thor Labs 2" to 2" coupler, external threads (http://www.thorlabs.com/ProductDetail.cfm?DID=6&ObjectGroup_ID=848&Product_ID=1485) -- $31

Century Optics LA-NICJ Nikon F-to-C mount adapter (http://www.bhphotovideo.com/bnh/controller/home?O=&A=ShowProduct&Q=&sku=77558&is=REG&bi=E15) -- $65 (be forwarned this part looks different than it had a year ago when I first bought them. call B&H and ask to speak to someone who can describe it to you -- it should look like it does in my picture above, and not like it appears on B&H's site...)

49mm Hoya UV Filters for grinding or use with micro wax techniques (http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=23714&is=REG) -- $12ea.

- jim