Purpose of black disc on skywatcher tube rings

[Edward Dewolf]

Does anyone know what the purpose is of the black round disc on the screw of the back tube ring on skywatcher reflectors?

Thank you?

 

[michael.h.f.wilkinson]

I think the top screw is a piggy-back mount for a camera with lens (1/4" thread). The black ring acts as a locking ring to keep the camera pointed in the desired direction

[Phillips6549]

It's to allow you to mount a camera 'piggy-back' on your scope.

 

Mark 

[Edward Dewolf]

Quote

thank you, will be taking them off

 

[Edward Dewolf]

Would anyone know what holder shoes would best fit on those tube rings?  not just flat ones, but holder shoes that clamp around the tube rings preferably?

[Craney]

You can use these to attach a dovetail bar between the rings to mount a larger guider etc...  or use as a carry handle for the Newt.

[joe aguiar]

Yep for a camera almost every scope here comes with that ring.

Its 1/20 thread

Joejaguar 

[Edward Dewolf]

8 hours ago, Craney said:

You can use these to attach a dovetail bar between the rings to mount a larger guider etc...  or use as a carry handle for the Newt.

That is what I am looking for.  I have the guidescope and the rings for it on a plate and the dovetail bar.  I guess all that is left is getting a second one of those discs to go on the second tube ring, and then drill holes in the dovetail bar to attache the plate with the rings 🙂 Thx! 

[Craney]

Some  dovetail bars have a central slot,  which gives you more flexibility in terms  of spacing may mean you might not need to drill.   Make sure that you have enough thread though to get a washer and a nut on it.

[Edward Dewolf]

Would anyone know what those black discs are called?  trying to find where to buy one ...

[discardedastro]

7 minutes ago, Edward Dewolf said:

Would anyone know what those black discs are called?  trying to find where to buy one ...

The top thread for a camera is a 1/4" Whitworth (yep, really) thread. I don't know what the SW top plate is threaded but I think it's a standard metric thread (or imperial, what with the US market still existing, sadly). But searching along those lines should yield something. 1/4"-20 UNC thread will also work, though the official standard is Whitworth.

[Edward Dewolf]

last question Is there a way to figure out (besides guessing) if a clamp will fit on a dovetail bar?  I would like to fit the following https://www.astroshop.eu/mounting-plates-and-rails/artesky-prismenklemme-vixen-style-150mm/p,61514 on a Skywatcher HEQ5 dovetail bar, but I do not see how to make sure it will fit

thx

[discardedastro]

13 hours ago, Edward Dewolf said:

last question Is there a way to figure out (besides guessing) if a clamp will fit on a dovetail bar?  I would like to fit the following https://www.astroshop.eu/mounting-plates-and-rails/artesky-prismenklemme-vixen-style-150mm/p,61514 on a Skywatcher HEQ5 dovetail bar, but I do not see how to make sure it will fit

thx

Do you mean fitting into the saddle (i.e. the clamp on the mount that holds the dovetail which your tube rings mount to) or on top of your tube rings? If the latter, length is the critical factor as it needs to be long enough to cover both tube rings (or you'll only get one screw for mounting, which is no good).

"Vixen style" and "Losmandy style" are the two widths/profiles you'll find for dovetails, and most (large-ish) SW mounts are dual Los/Vixen saddles. But what you've got there is a clamp for Vixen style rather than a dovetail in and of itself - so you could mount that (if long enough) either onto the tube rings and then clamp a Vixen-dovetailed component on top. Or you could mount it on another slotted dovetail using some suitable nuts/bolts.

It might be easier if you explain what you want to achieve?

[johninderby]

Besides the dovetail saddle you need an adapter puck to allow the saddle to fit to the HEQ5 mount As mentioned above you can get saddles that accept Vixen or Losmany dovetail bars or you can get a dual,fit type that takes both types of dovetails. The saddle you have linked to is a bit weak and undersized for an HEQ5. something that is stronger is recommended.

https://www.firstlightoptics.com/search/for/primaluce+heq5/

Edited January 9, 2020 by johninderby