Why use cradle rings AND dovetail plate?

[Buqibu]

I've seen a few setups where both are used, isn't that a bit redundat? They seem like they serve the same purpose to me. Sorry if this is a silly question, quite new to this. Thanks in advance!

[teoria_del_big_bang]

No silly questions, so do not worry on that point.

When you refer to cradle rings are you talking about Tube Rings like this, they are sometimes called cradle rings but more often in UK Tube rings.

You would then mount these rings onto a dovetail, either a Losmandy or Vixen type depending on what your mount takes.

So unless I am misunderstanding your question (which is a good possibility) you do need them both as the tube rings hold the scope and the dovetail is what connects the scope ( and anything attached to it) to the mount.

Steve

[Buqibu]

1 hour ago, teoria_del_big_bang said:

No silly questions, so do not worry on that point.

When you refer to cradle rings are you talking about Tube Rings like this, they are sometimes called cradle rings but more often in UK Tube rings.

You would then mount these rings onto a dovetail, either a Losmandy or Vixen type depending on what your mount takes.

So unless I am misunderstanding your question (which is a good possibility) you do need them both as the tube rings hold the scope and the dovetail is what connects the scope ( and anything attached to it) to the mount.

Steve

Ah ok! Yes I was refering to those rings. Now it looks obvious 😅😅. Thank you!

Now a new question if you don't mind, are rings needed if you have a long enough dovetail plate? (on the scope, not the mount). In terms of balancing, my scope's plate is simply too short, cant shift it at all to try and balance it. Thinking of getting rings like that or just a longer plate and attach it to the scope. Which would be a better option? 

[tomato]

It would be helpful if you could post what telescope you have. Most refractors and reflectors have tube rings of some description which are attached to a dovetail plate. To achieve balance on the mount you can slide the assembly on the dovetail through the mount clamp, and/or you can alter the position of the telescope tube in the tube rings.

However, some scopes have the dovetail bolted directly to the scope, as per the example shown in the photo, so this one has to be balanced by sliding the dovetail through the mount clamp.

[Buqibu]

I have an astromaster 102az. It has the plate screwed into the ota, but its too short. Would cradle rings work?

[tomato]

Yes, cradle rings would enable you to fit a longer dovetail. Alternatively there may be a longer screw in dovetail available, but it depends how much longer you need it to be, since the stability will be affected by the spacing of the fixing points to the telescope tube.

[Buqibu]

3 hours ago, tomato said:

Yes, cradle rings would enable you to fit a longer dovetail. Alternatively there may be a longer screw in dovetail available, but it depends how much longer you need it to be, since the stability will be affected by the spacing of the fixing points to the telescope tube.

Could I attach cradle rings to the plate I already have and just slide the ota like that? Or is a longer plate neccesary?

[tomato]

I guess you could, but a couple of points to be aware of:

The Celestron dovetail has a curved inner profile to match the curvature of your telescope tube. You would therefore need cradle rings with a similar radius of curvature on the outside so they make good contact with the dovetail when bolted up.

Is the existing dovetail pre-drilled to take cradle rings at either end? If not that’s another job you will need to do.

I would recommend you buy a suitable dovetail and tube ring assembly to take the  diameter of your telescope tube, then you can buy a longer one which will give you the adjustment you are looking for.

[Buqibu]

1 hour ago, tomato said:

I guess you could, but a couple of points to be aware of:

The Celestron dovetail has a curved inner profile to match the curvature of your telescope tube. You would therefore need cradle rings with a similar radius of curvature on the outside so they make good contact with the dovetail when bolted up.

Is the existing dovetail pre-drilled to take cradle rings at either end? If not that’s another job you will need to do.

I would recommend you buy a suitable dovetail and tube ring assembly to take the  diameter of your telescope tube, then you can buy a longer one which will give you the adjustment you are looking for.

Thank you!