SkyWatcher Black Diamond 180/2700 Mak-Cassegrain Assesories

[bluesilver]

Hi,  sorry for yet another post in regards to this telescope  ( SkyWatcher Black Diamond 180/2700 Mak-Cassegrain )

I am not far from making the jump at putting in an order for this Telescope.

But firstly i have read that there are a few recommended assessors to replace on this scope.

I have read that a lot of people are swapping out the original diagonal for a better unit and also the focuser.

So i was hoping that someone that has got one of these SkyWatcher Black Diamond 180/2700 Mak-Cassegrains  might be able to help out with a recommendations

1.  What diagonal should i be looking at for this setup,  i would like something fairly decent as i have read the optics are very good to start with.

2.  What focuser should i be looking at,  or is the original one fine?

3.  What mount should i be looking at,  AZ-EQ5 goto or AZ-EG6 goto

4.   I have read that someone went with tube rings and handle for mounting the scope instead of the original mounts,  is this a good idea and if so where do i get them from as i have yet been unable to find anything to suit this scope.

5.   I have also read that you can get something called,  Celestron Starsense Autoalign for Skywatcher and Saxon mounts,   is this also a worth while thing to look into or not?

 Sorry again for all the questions,  i am hoping i have asked all in this one first up.

Any information would be greatly appreciated.

Thanks.

 

 

 

 

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Edited July 22, 2019 by bluesilver

[johninderby]

Hi

I replced the diagonal with a William Optics SCT diagonal but any decent 2” dielectric diagonal will do and often for sale second hand.

I originally fitted a Badder crayford focuser but removed it as it made the scope very back heavy. Have now fitted a Skywatcher Autofocus motor. No vibration when focusing.

Recommend changing the stock dovetail saddle for a decent one such as the Primaluce one. You’ll need the mounting puck as well. Link is to the AZ-EQ5 puck but they do an AZ-EQ6 puck as well.

https://www.firstlightoptics.com/dovetails-saddles-clamps/primaluce-lab-plus-big-dovetail-clamp-for-vixen-losmandy.html

https://www.firstlightoptics.com/dovetails-saddles-clamps/primaluce-lab-az-eq5-plus-puck-adapter-plate.html

The tube rings can be ordered from Orion Optics UK. Rolled tube rings 216mm. I fitted a handle from WDS Ltd. There is a bit of DIY involved in drilling mounting holes in the rings but nothing difficult. So much easier to fit the scope to the mount when you can hold the scope one handed and tigthen the saddle bolts with the other hand. 

https://www.orionoptics.co.uk/ACCESSORIES/tuberingsa.html

I’m using an AZ-EQ5 GT mount and it handles it fine. I use it mostly in Alt-Az mode which is fine for lunar / planetary imaging as it’s all short exposures.  

Yes you can get the Starsense unit for the Skywatcher mount but note that it will only work with the expensive Celestron  GPS acessory not the Skywatcher one. Not really needed but convieient.

I replaced the stock straight through finder with the right angled version. Also don’t forget to get a dew shield. 

Edited July 22, 2019 by johninderby

[Sunshine]

Tube rings are a great idea, I found I can focus it no problem as it came, a quality diagonal is a must have.

[bluesilver]

Thanks for the replies, appreciated.

Pretty much answered all questions in one go.

Did you have to get the belt and the two belt cogs separate,  or do they come with the kit?

I was looking at this Skywatcher starsense unit,  So to make this unit work i would also need a gps unit also?

https://www.bintel.com.au/product/starsense-autoalign-skywatcher-telescopes/?v=6cc98ba2045f

Appreciate all the replies.

 

[johninderby]

The pulleys and belts have to be bought seperately but are easily available from eBay or Amazon as they are also used for 3D printers. The details are in my thread.

You don’t need the GPS unit to make the Starsense work as all it does is enter your position and time for you instead of having to manually enter them with the hand control every time you turn on the scope. A convenience rather than a necessity.

Edited July 23, 2019 by johninderby

[bluesilver]

Thanks again for the reply,  appreciated.

I didn't see you thread the first time i read through the post,  sorry about that.

Found it now and answered the questions i re asked.

Some very good information there,  appreciated.

 

[Alan64]

https://www.harrisontelescopes.co.uk/acatalog/altair-2-prism.html#SID=566

 

 

 

 

[Captain Scarlet]

2 hours ago, Alan64 said:

https://www.harrisontelescopes.co.uk/acatalog/altair-2-prism.html#SID=566

Interesting, I hadn't been aware of the potential for prisms to be noticeably better than even expensive mirrors. See here

https://www.cloudynights.com/articles/cat/articles/mirror-vs-dielectric-vs-prism-diagonal-comparison-r2877

key quote "... As more and more field observations were conducted with the 80mm APO on Jupiter, it became apparent that the prisms were providing another level of performance that the mirrors were not."

[johninderby]

It very much depends on the particular scope and in particular it’s focal length. Some scopes do work better with a top quality prism and some don’t. Not something to worry about really and it’s more important that the diagonal be accurately made. 

Lots of arguments on CN on this issue.

[Alan White]

I think like many things in Astronomy, the arguments go both ways and it's a very personal choice.
We are all choosing differing eyepieces for differing expectations, finances and perceived presentation.
The same I believe applies for most diagonals, yes quality and indeed price do make a difference to a point,
but substrate or type?

Edited July 23, 2019 by Alan White

[johninderby]

Good little read on diagonals from someone who knows a thing or two about optics. 👍🏻

https://www.cloudynights.com/articles/cat/articles/optical-theory/diagonals-prisms-vs-mirrors-r79

[Captain Scarlet]

Yes thinking about it it makes sense, fast scope will have much more oblique angle of attack, not good in a prism. I wonder if anyone's ever built a scope with a prism secondary?

[Captain Scarlet]

1 hour ago, Captain Magenta said:

... I wonder if anyone's ever built a scope with a prism secondary?

a bit of reading comes up with this "Prisms used to be the standard for the secondary in telescopes back in Russel Porter's day, [early 1900s] but they are never used today."

[Alan64]

A diagonal should behave as though it not there, at all.  It is a convenience, to save the neck and back.  Would that we had an extra set of eyes at chest level, or lower.

Mirrors scatter light.  What might be the advantage of adding a third mirror to a reflector with two already?

Light-scattering...

Mirrored diagonals proliferate in the marketplace, as they are cheaper to produce; not for some imagined optical advantage.  Mirrored diagonals are also more apt to arrive mis-collimated.

Incidentally, in fitting a 2" diagonal onto a telescope with a 2700mm focal-length, what sort of low-power wide-field views are to be anticipated...

https://www.teleskop-express.de/shop/product_info.php/info/p604_T2-diagonal-prism-90----T2---1-25--connection-on-both-sides.html

A Maksutov, regardless of aperture and a 2" visual-back, is , after all, the utter antithesis of a rich-field refractor.

[johninderby]

Zero problems with light scattering with my Skymax 180 and a good mirror diagonal. Just not a problem. I use a 2” SCT diagonal as I already had one. Never use 2” eyepieces in it. 

I have one of the Baader T2 prisms but find no advantage to using it on the 180. I use on my little 127 mak where I want to keep the weight down.

Edited July 23, 2019 by johninderby

[Alan64]

The scattering is certainly not to that extent within that image.  Why, I see scattering with a refractor and a star-prism, although not that much.  But I know that a star-mirror would simply make it worse.  The background sky would tend more towards grey-black rather than jet-black.  One or the other, it may either make or break a critical observation.  However, true, the effect may not be noticed during general observations.

[johninderby]

I have flocked my 180 which does make things a bit blacker though.

 

[John]

I have a Baader T2 Zeiss prism diagonal that I use with an F/9 apo refractor. I also have dielectric mirror diagonals by Tele Vue and Astro Physics and can't in all honesty see any difference in optical performance when I've compared them with the prism

The Baader T2 prims suits the F/9 Takahashi well though so I'm glad I've got it.

 

[Alan64]

Yes, the flocking, along with ultra-flat black paint for those areas within where it isn't practical to flock, makes for a most welcome improvement...

[John]

To flock a mak-cassegrain ( the subject of this thread) you need to remove the meniscus lens.

How would the OP's warranty stand (if bought new) ?

 

 

 

[Alan64]

I haven't touched my wee, 127mm Maksutov, yet...

It's a Jinghua. and with a one-year warranty.  Within, it has micro-baffling.

No, you do not want to take the telescope apart whilst under warranty.  A keeper, or no?  As for my own, that determination will be made this coming fall and winter.

[bluesilver]

Some good information there,  not sure i would dismantle a new scope myself though.

Was looking at the Tele Vue Star Diagonals Everbrite 1.25inch

Seam to look like a reasonable Diagonal,  but i am also guessing that you would need some sort of adaptor to get the two to connect together.

 

[John]

The Everbrights are expensive but wonderfully made. Both the 1.25" and the 2" are machined from a single block of aluminum so hold heavy eyepieces very securely even when the scope is at an angle because it's all one piece - nothing to unscrew.

In terms of performance, also excellent although to be fair I've not noticed any differences optically between my Tele Vue Everbrights and lower cost units by William Optics, GSO etc.

 

[Cosmic Geoff]

A heads-up on the nominal aperture of these scopes - I read somewhere that the earlier ones (gold?) had an effective aperture smaller than the claimed 180mm, but the later ones (black?) have a larger mirror and so are close to the claimed aperture. 

[John]

5 minutes ago, Cosmic Geoff said:

A heads-up on the nominal aperture of these scopes - I read somewhere that the earlier ones (gold?) had an effective aperture smaller than the claimed 180mm, but the later ones (black?) have a larger mirror and so are close to the claimed aperture. 

I think the effective aperture is limited by the primary not being over-sized as it needs to be with this type of mak-cassegrain design. I'm not sure that this has actually changed with later models ?

It would be good if it has but that would require a pretty major redesign of the primary cell and the tube diameter would increase a bit as well I would think.