T2 mounts and the thread pitch conudrum?

[Cumbrianwolf]

Can anyone advise what pitch is used by Skywatcher on their included M42 camera mount, is it the common 0.75 or the new 1.0?

The reason being is that I have just made a discovery when collimating and setting up my new telescope ready for imaging when the weather and time allows. Therefore, I cannot mount my camera as I bought the M48 T mount and forgot that I needed the M42 T mount on this occasion as I do not have any focal reducers or field flatteners to contend with!

Good job, I found out before I started to set it up outside. 🙂

[Cumbrianwolf]

All sorted with a few days of research and all is in good order. Now to await delivery of the new connector and hopefully clear skies. It was 0.75 as the standard pitch for anyone interested.

[Cumbrianwolf]

Well the parts arrived, and it all fits together nicely now as in I can now fit the camera as expected. Also bought a quality dew shield made by Farpoint and darn it puts my own homemade versions to shame. Fully flocked, ABS plastic and a foam cushion where it sits on the scope so no marking and a great grip, and it stays firmly circular. This time around is yet another learning game with a new and modern setup. Now, will the weather and work please cooperate with me!

Edited January 27, 2023 by Cumbrianwolf

[Lloyd-ss]

On 1/24/2023 at 12:33 PM, Cumbrianwolf said:

All sorted with a few days of research and all is in good order. Now to await delivery of the new connector and hopefully clear skies. It was 0.75 as the standard pitch for anyone interested.

 

I realize this is an old thread but I ran into a similar situation myself and it left me scratching my head. I am a total newbie to astronomy, but was checking out various lenses that I had from cameras and spotting scopes, etc, to see what might be compatible. I actually was not very surprised by the confusion (mess?). I had 2 pieces that should have mated with, I guess, reading this thread, an M42 diameter. But checking with some thread pitch gauges, one was 0.75 mm pitch and the other was 1.0 mm pitch. Then I got curious and starting measuring some more and it looks like what is called a normal  "one and a quarter thread" isn't really that. A 1.250" round will fit into the threaded hole, but the threaded part might be more like might be M32x0.75.  It's not a big deal and these names and conventions are what everyone has used forever, but seeing that I do some machining also, and I know that there is a special place where engineers who mix Imperial and metric in the same threaded part are sent, in the end, .... forever.

 

But so far, everything looks metric to me, and there are no mixed inch-metric?

Is that correct? Kinda?

Edited January 10 by Lloyd-ss

[Nightspore]

Filter thread compatibility in amateur astronomy is not understood by anybody, on Earth or elsewhere.  In my experience filter threads are just weird. I have 'Celestron' filters in a 'Celestron' kit that aren't compatible with most of the 'Celestron' eyepieces in the same kit. The really odd thing is that they may have all been manufactured in the same Chinese factory. 

 

 

Baader 1.25" filters have a M28.5 male (and M28.5 front female) thread  their 2" filters have a M48 male (and M48 front female) thread.

 

 

Then there's thread compatibility issues between filters and instruments themselves (diagonals, eyepieces etc).

 

 

Baader and GSO M28.5 threads seem to be pretty universal and will thread into most things. 

 

 

 

Don't get me started about Tele Vue threads ... we may be here for a long time ...

 

[Lloyd-ss]

Hmm, Its worse than I thought.

[Nightspore]

1 hour ago, Lloyd-ss said:

Hmm, Its worse than I thought.

 

... and then some!