OTA for planetary imaging?

[thercman]

Hey guys...

I have a SkyWatcher EQ6R-Pro mount and looking to get a scope for planetary imaging. The max load of the mount is about 20kg. My budget for the scope is $3k... What do you suggest I get?

Cheers,
Greg

EDIT: changed $2k US to $3k AUD :-)

[Tulloch]

Hi Greg, I have a 2nd hand C9.25" SCT, bought off the IIS classifieds. They cost about $2.5k at Bintel new
https://www.bintel.com.au/product/celestron-c9-25-xlt-sct-optical-tubes/?v=6cc98ba2045f

They are cheaper 2nd hand (in fact you just missed one!)
http://www.iceinspace.com.au/forum/showthread.php?t=179155

I was able to get this shot of Saturn a few months ago using my 9.25. It should meet your needs.

Andrew

[Merlin66]

+1 for the C9.25.
One of the best scopes I ever used.

[thercman]

Thanks guys... I edited the amount to $3k AUD. The $2k was in US dollars. Whoops... :-)

Do you think the mount will handle the C11? Also, with the 9.25 or 11 will I need to add a focuser and lock the primary?

[Merlin66]

The NEQ6 and C9.25 was a marriage made in heaven!!!
No need for mirror locks, but the Feathertouch 10:1 micro focuser worked well for me.

I upgraded to the C11 (long story...) and it now sits happily on the NEQ6 for spectroscopy. I think it works for me but serious AP may be pushing it.

[mental4astro]

The Skywatcher 7" Mak I would say for a mass production instrument the best optically I have seen. Their quality has been increasing over the years, yet from the very start their standard quality has been outstanding and consistent. The first I looked through was an original gold coloured OTA. That instrument showed the Encke Division in Saturn's rings, though it struggled with average seeing. I've looked through two of the current model, with the second one being better than the gold scope, and the last and newest one I looked through rivaled my 7" Intes Mak. You can find the occasional outstanding SCT, but you really do need to test these units as optical quality does vary greatly. I do know of one particularly outstanding SCT in the Blue Mountains. SCT or Skywatcher Mak sight unseen? I'd go the Mak.

Now, if you want top shelf, then you can make a look for a Russian made 7" or 8" Mak like from Intes, or a Questar, but the Questar is very expensive. A star test I did with my own 715 Deluxe Mak showed me 5 diffraction rings around Arcturus, with glimpses of a sixth. The 9" Santel Mak I've just picked up, now that's the big brother of the Intes, with the same outstanding optics but larger aperture. Rare as hen's teeth, but ooh, so nice!

Alex.

[Wavytone]

Hi Greg, The 7" f/15 maks from skywatcher (sold as celestron in the US) are readily available. These are a bargain and will do better than 8" SCTs. You'd have to look at a C11 Edge to do significantly better.

As Alex indicated there are other exquisite maks - notably from Intes, Santel, AP, TEC or APM/Wirth, but they're seriously rare and won't be within your budget, even secondhand.

Other alternatives:
- a long-focus Newtonian eg an 8" f/9 or 10" f/7, sheer size and mount will be a pain;
- classical cassegrains with small secondaries (ie not the fast RC ones from GSO).

[Startrek]

I use a $300 6” f6 GSO newt and a second hand Canon 600D DSLR for planetary and lunar imaging
Here’s some of my images

[doppler]

Nice pics Martin, but the big difference here is, where your 6" is maxed out with barlows the fore mentioned cassegrains are just starting out at prime focus.
Rick

[Startrek]

My 6” scope $300

C9’s $2,500 + ( 8 times the cost of mine )
C11’s $3,500 + ( 11 times the cost of mine )

My HEQ5 mount $1200

Celestron mounts $ 3000 to $5000

I think for a budget low cost rig , my images are pretty darn good considering the above cost differences ( first time I’ve given myself a pat on the back )

Cheers

[Camelopardalis]

On an EQ6, a C11 takes a lot of beating and comfortably within the payload capacity.

The only way to get better resolution is with larger aperture...

[Tulloch]

There is no doubt that a 6" OTA can produce good planetary images, I myself recently upgraded from a 6" SCT to the 9.25" SCT. For planetary, an OTA with larger aperture and longer focal length can really bring out the details in a planet like Jupiter and Saturn. Bigger is better, but comes at a price.

With the original poster's specs of a A$3k budget, a C9.25 OTA, ZWO ASI224MC camera and 2x Barlow should come to around $3k new, and should be more than capable of producing high quality images of the planets. Given that he appears to be posting from the USA, an ADC would also be recommended as the planets are so low there.

Hope this helps,

Andrew

[thercman]

Thanks for all the replies everyone.

I reviewed all of your suggestions and then checked images produced by each on Astrobin. At this point the minimal resolving power I would settle on would be 9.25" and really prefer 11"....

There is a guy on Astrobin using the C11 on the EQ6 mount and capturing great lunar detail. I just wonder if that combo is taxing the mount a bit.

At this point I am leaning towards the C11 or something similar. If anyone has any other suggestions I am all ears. :-)

[Camelopardalis]

Why would a C11 be taxing the mount?

[Tulloch]

Well, if you are looking for 2nd hand in the US, C11's go for about US$600-$1000 here...

https://www.cloudynights.com/classifieds/category/7-cats-casses/?sort_key=date_added&sort_order=desc

[thercman]

Hey... :hi:

It has been my understanding that it is ideal to run the mount around 50% of the rated capacity. So with the tube weighing in at 27.5lbs, add another 5-10lbs for gear, the total will be around 38lbs. The rated load is for 44lbs. I'm not sure how the counter weights are calculated in. They are another 22lbs. So if they are also supposed to be added in then I'm quickly at 60lbs.

Am I of track here? :shrug:

[Tulloch]

Well, I just had a quick look at the manual for your mount - it specifically says:

Payload (Counterweights excluded) - 20kg (for Astrophotography).

I would hope that the rated payload would be more than able to be handled appropriately by the mount when properly balanced, with a bit extra for a safety margin.

Andrew

[Tulloch]

By the way, if you want to see what a C11 is capable of in excellent viewing for the gas giants, have a look here.

https://www.astrobin.com/users/DMach/

Best I've ever seen from a scope of that size...

[Merlin66]

My C11 fully loaded.....four cameras, spectrograph etc, five 5Kg counterweights sits OK on the NEQ6PRO.
I can easily work with 10 min subs on a 20 micron Slit gap.

[Camelopardalis]

Just in case you’re still in doubt, a C11 is well within the payload of an EQ6 ;)

[thercman]

Awesome guys thanks! :D

Well it looks like the C11 is on my purchase list.

Do you guys recommend putting say a Moonlite focuser on it and locking the mirror in place?

Now I just need to figure how to explain to the wife what the big tube in the living room is. lol

[Camelopardalis]

Personally, I've found the large focuser knob on the C11 perfectly adequate for visual and planetary work.

For DSO...note the mirror locks only exist on the Edge HD series, not the conventional SCT/XLT series.

There is a technique with Celestron SCTs whereby your final focuser knob movement should be anti-clockwise. This apparently takes advantage of gravity and leave the mirror in a settled position. Note that for large changes in pointing direction, it may be worth checking your focus again until you observe how much shift you may or may not have. It varies from scope to scope (often due to distribution of the grease on the baffle tube) and has no bearing on the optical quality of the scope.

FWIW, a C11 is not a particularly large tube...when compared with, say, a 12" Dobsonian :lol:

[Tulloch]

For focussing, I'm still using the standard focuser, but I put some thick pipe insulation rubber foam over it to reduce vibrations
https://www.clarkrubber.com.au/products/33887p-pipe-insulation

However, I have my eye on this ...
https://www.celestron.com/products/focus-motor-for-sct-and-edgehd

[thercman]

Very true... Compared to my 4" refractor it's big though. :-)

My 12.5" truss tube dob sits in the garage. Some day I'll buy a mirror for it...

[thercman]

I put the ASI EAF on my refractor and love it...

[The_bluester]

I have one of the Celestron focusers on my C9.25 for photographic work and it is a godsend. I am not sure if they would be as useful for visual work but anything that keeps you from having to touch the tube is a good thing. The only thing it is missing is a temperature sensor.

For manual focus or automated, you always want the final focus move to have the mirror going up the tube against gravity, as Dunk mentioned.

[Tulloch]

Thanks for the tip, Paul.

To the OP (Greg), when you get your new scope, post a picture of it here!

Andrew

[thercman]

Hey Andrew!

I will do! In the mean time here is my current rig. :-)

[Tulloch]

Geez, I thought I had a lot of cables! Is there a scope in there somewhere amongst the spaghetti? :lol:

[thercman]

I think so. ;)

[thercman]

Update: I ordered the C11 yesterday along with an Astrozap heated dew shield and a set of Bob's knobs. The next few days are going to be so loooong...

[Tulloch]

Cool, looking forward to the results :thumbsup:

[thercman]

I just received a Celestron C11 in the mail yesterday and I'm excited to begin lunar & planetary imaging. At this point I need to order either the QHY 290 or the ASI 290 and a MoomLite focuser.... Although the QHY is more expensive the cooling will be beneficial when capturing deep sky objects such as the ring nebula. I also need to add another counter weight...
https://scontent-sea1-1.xx.fbcdn.net/v/t1.0-9/s960x960/78066442_10221539123527023_91997322 0185014272_o.jpg?_nc_cat=105&_nc_ohc=8DbmkvN1v_wAQkjpiMNA-wKVNj8tte-6dpgZZJNEsYGLk7E7IUWnOapxg&_nc_ht=scontent-sea1-1.xx&oh=7771b9c513c8c1a3253bdb9c9c272f05&oe=5E6E93E9
https://scontent-sea1-1.xx.fbcdn.net/v/t1.0-9/s960x960/79201123_10221539123167014_21780722 89117995008_o.jpg?_nc_cat=102&_nc_ohc=ULJWukDaTNIAQlRT9QS6IjxNYXq VtjEHdoTDNEViAZyn9-OdYEWZ3C_7Q&_nc_ht=scontent-sea1-1.xx&oh=8cbe3c80c43a6c39053e42ccd71e643a&oe=5E6D25F3
https://scontent-sea1-1.xx.fbcdn.net/v/t1.0-9/s960x960/79998476_10221539123007010_20564347 05011572736_o.jpg?_nc_cat=108&_nc_ohc=CVsEzv1k99IAQmlhcTp8m61Zp9L fcPnkKfmWu26MfmHI7HlK5-f7KR5Pg&_nc_ht=scontent-sea1-1.xx&oh=1188a6135396d71e1b401248fc958909&oe=5E743CF5

[Merlin66]

Very nice set-up!
I have the C11 mounted on a NEQ6 with a Losmandy dovetail.
To make it easier and safer while setting the scope onto the mount I added a safety clamp to the dovetail.
You can then lift the OTA onto the dovetail held from slipping by the clamp while tightening the dovetail holding screws.

The clamp was supplied by Astrodevelopments in the UK, but I can't seem to find their website - may be gone out of business?
You can see the clamp (black colour) at the left of the Orange dovetail saddle.