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Walking on the Moon

Connecting a DSLR - T rings, T2, extensions, flatteners, reducers

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I have just purchased a SW Evostar 80ED and want to start using it for astrophotography.  The general advice seems to be that the must-have accessory is the SW .85x Reducer/Flattener, which I hope to get once they become available again (which may be a few weeks/months away).

In the meantime I'd like to get started with some AP, so that I can gain some experience. However I am a little confused as to what additional equipment I need / want, and how it all slots together.

I have a Canon 550D DSLR, with a T-ring adapter, and a 1.25" T mount camera adapter. These are straightforward enough and there is only one way to put them together.  I have used these with my 150PL by using this combination in place of an eyepiece. I have also used the DSLR ring directly on the focuser of the 150PL as that has a T adapter.

Now I have the 80ED I am a little lost.  This also came with a T adapter - which appears to be a short extension (male one end, female the other).

My understanding is that I should not use the diagonal, but I don't know what goes between the DSLR and the scope. I believe that I will need some sort of extension tube to make sure the camera's CCD is in the right place, but how long and what fittings it should it have?

I have looked at the usual suppliers' websites, but they seem to assume you know what you want and what to do with it. They talk about T rings, M48 adapters, prime focus camera adapters, T-2 spacers, M48 to T2 adapters, and various other tubes. Do I need any/all of these? If so which? How do they fit together and to the scope?

Once I get the SW .85x Reducer/Flattener, how does that fit into the light path?  Will I still need extension tube(s)?  There is also the FLO Adapter for Skywatcher Focal Reducers - do I need one of these as well?

I'm happy to spend money if I need to, but I also don't want to waste money on something that I don't need.

It should be clear that I'm confused by the range of connector standards that seem to be involved (T, T-2, M48, etc.) and the basics of how the components fit together. The supplier websites have a great range of components and between them I'm sure they solve almost any problem for someone who knows what they want, but there seems to be very little information for n00bs like me.

Perhaps there is a dummies guide to this stuff, but I haven't found it yet. I do have a copy of Making Every Photon Count, and that is an excellent book which will help me considerably with AP, but I couldn't find the information I'm currently looking for in there.


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You need a T ring and a T adapter to connect the DSLR to the scope.

If you get a focal reducer that normally takes the place of the T adapter.  However it is important to get the spacing right I think if my memory serves me right the DSLR can fit direct to the reducer.  I have the same scope and I use the WO Focal reducer on it as I already had one for my WO scope and it works just fine on the ED80. 

The one advantage of the SW FR is that it will screw directly to the draw tube thus making your camera much more secure and also reduces/eliminates flex, however I have bought an adapter which will do that too, so you might not need to wait for the Sky watcher FR if you want to investigate this.

The different threads can be a right PITA (T2 M48 etc etc, why they can't standardise them I don't know, I have a box full of various spacers and adapters).  If you speak to one of the reputable dealers like FLO they will sell you the right thing for your needs.

I see you live in the Thames Valley, so if you're light polluted you'll need a CLS filter, though I am not upto date on whether this will have any effect on LED street light. 



Edited by carastro
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 just to add to what Carole has stated , the  FLO Adapter for Skywatcher Focal Reducers  will allow you use a 2" filter that screws into the front of the adapter, unfortunately this will remove the option for you to screw the F/R /FF directly onto the ED80 draw tube, you will have to insert the nose piece into the draw  tube as you would an eye piece  

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