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Steve14
04-11-2017, 02:12 PM
Can anyone recommend a good OTA that would suit a NEQ6 pro mount that i could use for planetary imaging? I'm going to use my modified canon dslr, a televue powermate and backyard EOS to capture. My budget would be around $1500 if i can sell my beloved 12inch dob...(i was contemplating to somehow use the dob on the mount but i think it would be too heavy)
:thanx:

Wavytone
04-11-2017, 03:22 PM
You want focal length, lots of it.

Secondhand you should be able to find a Skywatcher 180mm f/15 Mak, Celestron C9.25 or Meade 10" ACF in your budget.

Looks like you just missed a 10” http://www.iceinspace.com.au/forum/showthread.php?t=162439

Shiraz
04-11-2017, 03:45 PM
I had great fun doing planetary using a 12 inch dob on an NEQ6 - it is just doable if you have strong tube rings and a Losmandy style mounting.

won't work in wind though.

Camelopardalis
04-11-2017, 08:16 PM
Consider motorising or getting an equatorial platform for your Dob. Alternatively, a C11 rides well enough on a NEQ6.

Steve14
11-11-2017, 03:19 PM
Hmm. As i have a 102mm f5.1 refractor, i'm wondering if something like a 5x televue powermate may give me the focal length i need? Am i being too naive? Any thoughts ?
Thanks for the replies..

xelasnave
11-11-2017, 03:23 PM
Mike years ago did planetary imaging using a 12 inch on an eq 6 and will excellent results.

Personally I would not get rid of the 12 inch.

Alex

brian nordstrom
11-11-2017, 05:18 PM
:thumbsup:
C9,25 or C11 both will sit happily on an EQ6 .

Brian.

glend
11-11-2017, 05:57 PM
I have an Edge HD8 for sale in the Classified's right now, it's a pretty good planetary scope native f10 focal length is 2032mm, and that goes out to f20 @ 4064mm with a 2x Barlow. It is light enough for an NEQ6.

I would be buying a planetary camera capable of high frame rate video, that way you do not have to worry about guiding (and long focal length guiding is a real art which requires good gear). The ASI224MC is a reasonablly priced planetary camera.

https://astronomy-imaging-camera.com/products/usb-3-0/asi224mc/

Wavytone
11-11-2017, 06:44 PM
Even better was a 12 tri-schiefspiegler that Barry Adcock built (ASV) long ago. From memory probably f/23. I can recall photos taken of the planets - on FILM - through that which were superb even compared to modern efforts.

Slawomir
11-11-2017, 07:40 PM
Small aperture will significantly limit resolution for planetarny imaging. So while a 4" scope is quite capable for long exposure astrophotography, it is not the best choice for planetary imaging if one is after sharp and detailed planetary images.

Steve14
12-11-2017, 07:53 AM
Thanks for all your help. While my dob is great, it's collapsible so the truss slides into tubes on the outside of the ota - so tube rings wont go around it to secure it to the mount.
I think the best way foward is to sell my dob and modded dslr. :screwy: I'm leaning toward a c9.25....

nicosk
14-11-2017, 10:10 PM
A C9.25" will ride comfortably on your proposed mount, and even on a Celestron AVX, both for visual and for imaging.

Using a high frame dedicated planetary camera is the best way forward to do planetary imaging (along with a good quality 1.25" Barlow to achieve the necessary long focal length).

A key benefit of the C9.25" is that it is the only one in the range with a primary having a focal ratio of f2.5 - the rest being f2. This results in the C9.25" having the reputation of consistently better optics than the rest of the bunch as figuring a f2.5 mirror is easier than a f2 mirror.

I was at a friend's house last night observing from his C9.25" actually - on the AVX and we went through about 40 objects in just under two hours. The mount performed flawlessly.

As for planetary, he has used his C9.25 lately for Neptune and Jupiter - again, no issues with the mount.

Camelopardalis
15-11-2017, 10:16 AM
The C9.25 being anything special is anecdotal. Celestron's shift in manufacturing from the USA to China is much more significant. Since that happened, there are a lot of reports of their SCTs in all sizes with good optics. Damian Peach once used a C9.25 but now uses a C14.

Regardless of what scope you use, what's most important is good collimation, good focus and good seeing :)

nicosk
15-11-2017, 04:21 PM
Damian Peach has the luxury of a permanent setup (lucky him!).

The C9.25 despite having a larger central obstruction, has been noted many times as having good optics relative to the other scopes in the range. And while many reasons have been flouted for this, the usual one is the "gentler" focal ratio of the primary mirror.

As to it's status as special - no, it's not. It will not do wonders Vs the others in the range, but it is relatively much more portable than a C11. Of course, usual rules about aperture mattering do apply, subject to proper cooling along with the other parameters you mention :)

Steve14
15-11-2017, 06:47 PM
Apologies for my ignorance here but as a dob user, I collimate with a laser collimater. Do you collimate jn the same way with a SCT such as the C9.25?

Camelopardalis
15-11-2017, 07:10 PM
Damian Peach regularly travels to Barbados(I think) for superior elevation and for better seeing than the south of England. With a C14.

But don’t be fooled into thinking the C11 is a much larger scope...the C9.25 with its slower primary is almost as long, just a little narrower.

Collocation of a SCT is effected only through adjustment of the secondary. If you’re used to a Dob, a SCT will be a piece of cake.

nicosk
15-11-2017, 08:02 PM
Actually the C14 is situated at his home. He used to take it with him but now he has another C14 at Barbados.

C9.25 Vs C11: I have seen both in the flesh plenty of times. I find the C11, well, huge Vs the C9.25 but I admit that's my perception of the scope.

Re collimating SCTs: Yep, secondary only once the scope has cooled completely and at high power, conditions permitting.

Troy
16-11-2017, 10:55 AM
Steven you collimate with a star, it's free and the best way to go. I use Metaguide to assist with the process and once you have learnt the software it's really easy and best of all Metaguide is free.

Another option is to stack the focused star images or video and then sharpen a little bit to judge which way you have to move the secondary mirror. This method probably doesn't suit beginners in my opinion.

Best of luck

p.s
Planetary imaging can be really frustrating at first, but stick with it and eventually the results will come once you overcome the steep learning curve
͡ ͜ʖ ͡

Troy

Regulus
17-11-2017, 05:11 PM
Yes. The 6" Mak by skywatcher.
It's surprisingly good for the price, and is often available around $400 S/H.
With an f12 and 1800mm, it gives good contrast, colour, and magnification.

Trev

Merlin66
17-11-2017, 06:06 PM
Coming in late....
Ive used all the Meade Lx200,8,10,12 and then moved to Celestron....
I had the C925 for a few years, then stupidly sold it!! Big mistake. It was one of the best SCT I ever used.
Replaced it and was VERY happy, until my wife bought me a C11...
I couldnt sell HER telescope so the C925 went......
The C11 meets all my needs for spectroscopy........but I still miss the C925.
No matter what is said, it definitely punches above its weight.
If I needed another SCT it would definitely be a C925.

brian nordstrom
17-11-2017, 09:37 PM
:thumbsup: Ken + 1 on the C9.25's , I sold my awesome Mewlon 210 and kept and still love my C9.25 ( very close between these 2 in what you see ) , something about these scopes that performs .

No offence to my good friend that has a C8 XLT carbon fibre ( you know who you are ) just like mine and together as good as the C8 is there is something special in that 1.25 inches ,
true . C9.25 is a planet killer .


Brian.

Steve14
04-12-2017, 02:21 PM
Ok im getting a c9.25 xlt for sure. Next question. Do i get a powermate? From what i figure, if i want to image at say .33arcseconds, then i will need a focal length of 3.9meters. That is assuming i use my existing dslr which has a pixel size of 6.25 microns. As the c9.25 has a fl of 2.35m, then a 2x powermate would hopefully do the trick. Or do i get a different imaging camera and no powermate/barlow? Decisions decisions ...

Merlin66
04-12-2017, 02:41 PM
My rule of thumb is the optimum hi-res focal ratio is 4 to 5 Times the micron pixel size, for a 5 micron pixel camera this would indicate f20 to f25.
A x2 PM would fit the bill.

Steve14
04-12-2017, 03:02 PM
Ok im getting a c9.25 xlt for sure. Next question. Do i get a powermate? From what i figure, if i want to image at say .33arcseconds, then i will need a focal length of 3.9meters. That is assuming i use my existing dslr which has a pixel size of 6.25 microns. As the c9.25 has a fl of 2.35m, then a 2x powermate would hopefully do the trick. Or do i get a different imaging camera and no powermate/barlow? Decisions decisions ...

Merlin66
04-12-2017, 04:20 PM
As you probably already know, the DSLR isnt an optimum camera choice for this type of imaging. Id look at the ZWO or QHY offerings.