PDA

View Full Version : 1.25" nose thread incompatible with 1.25" filter



quantumac
October 29, 2007, 02:07:54
Hello all,

I recently purchased a "DBK 41AF02.AS," and I've noticed the optional 1.25 inch nose will not seat a 1.25" IR filter, or any other 1.25" inch filter. The threading will partially catch, but it won't seat fully. I have a friend who bought the B&W version of the same camera, and his camera nose exhibits the same problem, so I'm guessing it's a generic problem.

Why isn't this thread the same thread used for all other 1.25" eyepieces and filters?

Rando
October 29, 2007, 23:08:48
Uh Oh...I just recieved my Sirius IR filter pending the arrival of my new USB monochrome DMK camera. I hope it fits.

Can you still use it if it doesn't screw all the way in?

quantumac
October 30, 2007, 00:46:29
Uh Oh...I just recieved my Sirius IR filter pending the arrival of my new USB monochrome DMK camera. I hope it fits.

Can you still use it if it doesn't screw all the way in?

Yes. Just screw it in part way, but when it stops, don't force it any further. The threads are incompatible, but you can get a couple of turns before it locks.

I'm hoping the imaging-source people comment and let us know what the deal is. Even if I had to purchase another nose with the proper threading, I'd do it.

aerodyneguy
October 30, 2007, 02:20:03
Yes. Just screw it in part way, but when it stops, don't force it any further. The threads are incompatible, but you can get a couple of turns before it locks.

I'm hoping the imaging-source people comment and let us know what the deal is. Even if I had to purchase another nose with the proper threading, I'd do it.
Rando,
I'm quantumac's friend with the DMK 41AF02.AS camera.

Be careful as it would be easy to strip the threads on the filter (and/or the nose too). Also since it is an interference fit it is possible that what is just snugg at sundown will be stuck late in the night if the temperature drops drastically.

You can side step the issue, as I have, by getting a filter wheel. Unfortunately for me, the Atik/Orion filter wheel puts the camera too far back and my current focuser doesn't have enough in-focus travel to work. So if you have a short focus Newtonian (mine is the Orion 8" @ F/4.92) it could be an issue. I have no issue with it on a F/10 SCT though.

Rando
October 31, 2007, 21:28:36
Thanks for the info. I just realized that I have a 1.25 nose on my Orion DSI and I tried the Sirius IR filter on it. It fits snug. So, when my camera arrives, I should be able to interchange the nosepieces as the IR filter on the Orion DSI sits just in front of the CCD chip, not on the nosepiece.
Thanks again!

dwsubc
October 31, 2007, 22:18:34
I just got my 21AU04 with one of the astro 1.25" nosepieces. I have 3 eyepiece filters and only one of them fits it. Luckily, it is a new IR filter that I wanted to use with the camera for moon shots. The other filters are older so maybe the thread spec has changed?

Here is a link that suggests filter threads are not standardised

http://www.televue.com/ask_al/service/0036.html

hth
Dave

quantumac
November 1, 2007, 02:20:25
I just got my 21AU04 with one of the astro 1.25" nosepieces. I have 3 eyepiece filters and only one of them fits it. Luckily, it is a new IR filter that I wanted to use with the camera for moon shots. The other filters are older so maybe the thread spec has changed?

Here is a link that suggests filter threads are not standardised

http://www.televue.com/ask_al/service/0036.html

hth
Dave

Not sure what the deal is. My Orion color filters all work with other eyepieces, but they won't seat fully on the CCD nose. Today I received shipment of a "Celestron 1.25" UV/IR blocking filter for CCD/NexImage" and that filter DID seat on the CCD nose, although I haven't tried it with other eyepieces.

I suspect there's some disagreement in the manufacturing of the thread. Aerodyneguy says he's read somewhere that the old British standard is 1/16th inch thread pitch, but the new metric standard is 0.75mm OR 1mm, depending on who you ask.

Rando
November 24, 2007, 06:13:39
Just got my USB DMK today and I can't swap the Orion DSI nosepiece with the DMK and my Sirius IR Blocking Filter will go on, but with only a two thread or so catch.
My filter wheel scrapes the filter so I rolled a rubber washer over the nospiece to create a stop and that works.
Im just a tad worried that the filter might come off, of course, in the dark!

Wonder where I/we can get another that fits the DMK as well as most 1.25" filters?

Stefan Geissler
November 26, 2007, 12:51:15
Hi,

There will be exist 3 different types of threads for filters:
1) M28,5x0,5 (e.g. Schneider Kreuznach)
2) M28,6x0,6 (e.g. Meade Astrometric)
3) An UNC thread (1 1/8 inch x 40 GpZ), used by Pentax for Oculars only i think

We used till now the M28,5 x 0,5 thread. But for the future we will release the Adapter with the M28,5x0,6 measurements because it seems to be that this threads the most common.

Rando
November 26, 2007, 18:40:31
Hello Stefan,
You make mention of the M28,5x0,6. Should that be M28,6x0,6 (Item #2)?
Can we exchange existing one that was shipped with the camera?
Can we order from you, that particular nosepiece?
Thanks in advance
Randall Krall

Rando
November 27, 2007, 18:03:47
I just ordered (locally) a Lumicon C to 1.25" nosepiece Lumicon Part No. LA1085. I read from a post somewhere, (Yahoo Imaging Source Group), that this one will support most 1.25 filters.

Update: Supplier out of Lumicon but sending a clone. Will post success or failure...stay tuned!

Stefan Geissler
November 28, 2007, 10:56:06
Hi,

I did a small error:

Wrong:
2) M28,6x0,6 (e.g. Meade Astrometric)


Correct:
2) M28,5x0,6 (e.g. Meade Astrometric)

Sorry for that.

Rando
December 2, 2007, 22:48:39
Finally got my new C-Mount to 1.25" nosepice from my local dealer and all filters now fit snug.