Celestron C6 OTA

[smp]

Back before last Christmas, I purchased a Celestron C6 OTA from Highpoint Scientific because their price was outstanding, and I was afraid that the "sale" would shortly disappear. Well, I found out that it wasn't a "sale" but apparently their normal price. Then, after Christmas, and practically up to now, we have had the most dreary, cold, snowy, rainy, whatever you can think of days/nights (except when I was totally tied up with something else... SIGH.

So today, I got the OTA out of storage to give it a try for some daytime Moon viewing. I first got my mount all aligned with my TV-85 and a 40mm Plossl eyepiece, and then switched over to the C6. Even with the 40mm eyepiece, of course I wasn't on the Moon any more with the more narrow FOV. It took a bit of work, but I managed to find the Moon, and the setup is currently tracking out in my driveway.

A few observations to share - and I'd like your thoughts, as well:

1. The supplied visual back seems mediocre at best. The thumb screws have tiny heads, and it seems pretty easy to not get them tight enough. On top of that, the set screws are all there is. I would really like to have one of those inner bands that the set screws tighten against, and the band tightens around the diagonal.

2. The supplied diagonal is a disappointment for me. The end that sticks into the visual back has a completely smooth barrel. That, combined with the wimpy set screws in the visual back, and I'm constantly fearful that the diagonal will slide right our of the visual back.

3. The diagonal has better set screws to capture the eyepiece you install, but, like the visual back, the set screws are all there is. I would really like to have one of those inner bands that the set screws tighten against, and the band tightens around the eyepiece.

So, my scope is visually fine, but I have a bunch of disappointments with the visual back and diagonal.

Does anyone else also have a C6? Have you been using the same visual back and diagonal? Did I simply get the cheap stuff because Celestron is trying to hold the price down? Any suggestions for possible upgrades would be appreciated.

Thanks for listening!

smp

[Bigzmey]

I have a larger cousin of 6" which I also got as OTA from Highpoint Scientific. I believe it was supplied with the same visual back and diagonal as yours. I have immediately replaced both. Good scope, bad out of box accessories - typical story.

6" SCT does not support 2" EPs, getting 2" diagonal would be a mute point. Instead, I suggest to pick a good quality 1.25" prism:

Baader T-2 90° Prism Star Diagonal Body
https://agenaastro.com/baader-t-2-prism ... 56005.html

This is the adapter which connects the prism body straight to SCT
https://agenaastro.com/blue-fireball-sc ... -t-02.html

and this is the 1.25" EP holder

https://www.ebay.com/itm/1-25-M42x0-75- ... 2cb2d4647c

[smp]

Thanks a million, Andrey!
Greatly appreciated.

smp

[smp]

Hi again, Andrey,

Since the Blue Fireball SCT Female Thread to T/T2 Male Thread Adapter is currently out of stock, would this Baader part work properly:

https://agenaastro.com/baader-deluxe-sh ... 08160.html

I ordered the eyepiece holder from eBay, and that should arrive by the end of the month. I appreciate you trying to save me money by suggesting the Blue Fireball part, but if the Baader part will work, I may simply go with the two Baader parts.

Thanks again for all your assistance with this!

smp

[Bigzmey]

Hi again, Andrey,

Since the Blue Fireball SCT Female Thread to T/T2 Male Thread Adapter is currently out of stock, would this Baader part work properly:

https://agenaastro.com/baader-deluxe-sh ... 08160.html

I ordered the eyepiece holder from eBay, and that should arrive by the end of the month. I appreciate you trying to save me money by suggesting the Blue Fireball part, but if the Baader part will work, I may simply go with the two Baader parts.

Thanks again for all your assistance with this!

smp

I am using the Blue Fireball adapter but Baader's SCT adapter you referred will work to. You may want to give Agena a call, it could be just a few days before they restock on the Blue Fireball.

You will not be disappointed with Baader prism. Took me a few years and a few diagonals to arrive to that one, but it delivers nicely.

[smp]

... I am using the Blue Fireball adapter but Baader's SCT adapter you referred will work to. You may want to give Agena a call, it could be just a few days before they restock on the Blue Fireball.

You will not be disappointed with Baader prism. Took me a few years and a few diagonals to arrive to that one, but it delivers nicely.

Thanks again, Andrey!

I looked on the Agena Astro web site, and they have a FAQ with exactly the question I would ask, and their answer is, if they do not show any message beside the "Out of Stock" indicator, then they don't know when the item will be back in stock. Sounds fair enough to me. I signed up to get a message when they are back in stock. If it gets to the end of the month, and I receive the eyepiece holder coming from China, and they are still not in stock, at least I know I can purchase the two Baader items.

I've not had a prism diagonal before, so I'm looking forward to the new experience!

Thanks again!

smp

[smp]

All my bits arrived between yesterday and today.

They all screwed together nicely, and screwed onto the OTA nicely, too. This is a MUCH more secure situation than the visual back and diagonal provided by Celestron. I am SO happy with this setup, even before being able to try it out with observing.

Of course, clouds and possible showers are forecast for today through Friday.
I'll post back when I am able to say something about actually using this setup for some observing.

Thanks very much, Andrey, for your excellent advice.

smp

[Bigzmey]

Sure thing! Once I switched to the Baader prisms I got quite noticeable improvement in sharpness and light scatter control. The stars look much cleaner and I see more details in planets and Moon.

If you have not figure it out yet - one of the caps which came with diagonal can be used as screw-on dust cover for the EP holder.

[smp]

... If you have not figure it out yet - one of the caps which came with diagonal can be used as screw-on dust cover for the EP holder.

Yes! I wondered about that, tried it, and I have it on right now.
Thanks a million for all your advice and assistance!

smp

[AntennaGuy]

Stephen, I have one of the exact same Celestron 6" OTAs as you, purchased from the same vendor at the same great (< $400) price.
I've been pretty happy with it and haven't replaced the visual back or diagonal. But I don't have any real experience with what could be superior alternatives. There do seem to be many possible upgrades available; I wonder if I would notice the difference! For example, what do think of this diagonal? See https://www.astronomics.com/1-25-99-ref ... gonal.html

[Lady Fraktor]

You are going to like the Baader prism Stephen, I have been using one for years and it is easily my favourite.

[AntennaGuy]

Oops, I just noticed that I actually purchased my C6 OTA from OPT, not Highpoint. And I guess I shouldn't act like these vendors are interchangeable, but... sometimes I forget which vendor is which, especially when there is so much similarity in the product offerings and prices.

[smp]

... There do seem to be many possible upgrades available; I wonder if I would notice the difference! For example, what do think of this diagonal? See https://www.astronomics.com/1-25-99-ref ... gonal.html

I have a dielectric mirror diagonal in my TV-85 (original equipment supplied by TV), and it has provided me with excellent views.

This Baader prism is the first time I will be using a prism diagonal in a catadioptric scope. If I could only get some good nighttime viewing opportunities - the daylight is sooo long in NE during the summer, and my yard is surrounded by trees, and, and, and, well, you get it. One of these days, I'll get to view something besides the Sun for practice with my mount.

smp

[Bigzmey]

Stephen, I have one of the exact same Celestron 6" OTAs as you, purchased from the same vendor at the same great (< $400) price.
I've been pretty happy with it and haven't replaced the visual back or diagonal. But I don't have any real experience with what could be superior alternatives. There do seem to be many possible upgrades available; I wonder if I would notice the difference! For example, what do think of this diagonal? See https://www.astronomics.com/1-25-99-ref ... gonal.html

When I got my C8 from HPS a few years ago I upgraded to dielectric diagonal right away. It certainly an improvement over the stock diagonal, but Baader prism do outperform mid range dielectric. So, knowing what I know now I would go straight for the prism.

[AntennaGuy]

"...When I got my C8 from HPS a few years ago I upgraded to dielectric diagonal right away. It certainly an improvement over the stock diagonal, but Baader prism do outperform mid range dielectric. So, knowing what I know now I would go straight for the prism."

Is this the right/best Baader one to get, in your opinion, for a 1.25" configuration?
https://agenaastro.com/baader-t-2-90-pr ... 6005k.html

[smp]

Is this the right/best Baader one to get, in your opinion, for a 1.25" configuration?
https://agenaastro.com/baader-t-2-90-pr ... 6005k.html

Go back and look at the second post. Andrey indicates the three pieces you need - and two of the three will save you money, instead of buying the entire assembly from Baader. That's what I did.

smp

[Bigzmey]

"...When I got my C8 from HPS a few years ago I upgraded to dielectric diagonal right away. It certainly an improvement over the stock diagonal, but Baader prism do outperform mid range dielectric. So, knowing what I know now I would go straight for the prism."

Is this the right/best Baader one to get, in your opinion, for a 1.25" configuration?
https://agenaastro.com/baader-t-2-90-pr ... 6005k.html

This combo will work with original visual back, not the most secure attachment. Better way is to get SCT to T2 adapter to connect T2 prism straight to the SCT OTA. Getting T2 body and generic adapters is more economical way to go, but you can go with Baader adapter to. Look at the links in the posts above.