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Old 20-09-2018, 07:18 PM
nsavage (Nick)
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Astrophotography Reflector Setup

Hi all,

New to the hobby, have been lurking on the forum but this is my first post. Currently have a 8 inch f/6 dob and looking to add an Astrophotography setup in to the mix.

I have a couple of fairly basic questions, have been hunting around on forums but struggle to find a definitive answer so I am going ask here. Apologies if anyone feels that these questions have been asked before.

Based upon my budget I have settled on a Skywatcher HEQ-5 Pro Mount. The hard part is deciding which reflector to put on it. Selection is down to a 6 inch f/5 or an 8 inch f/5.

Will the mount handle the 8 inch? Will it’s ability to handle the 8 inch be dependent upon conditions and wind etc. Is the mount going to struggle with the 8 inch reflector most of the time? For Astrophotography is there much difference between a 6 and 8 anyway? I have the feeling that the 6 inch is going to be the most suitable option. Also I intend to use a Guidescope which will of course add additional weight.

Also is there a big difference between the GSO and Skywatcher Astrophotography reflectors in regards to quality? Do both have good focusers? Would either of the focusers be up to the weight of a coma corrector, extension tubes and a 400-500 gram CCD?

Thanks in advance for the assistance.

Last edited by nsavage; 20-09-2018 at 08:08 PM.
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Old 20-09-2018, 08:14 PM
Startrek (Martin)
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Hi Nick
Im a newbie as well ( 2.5 years into the hobby)
My main visual scope is a Bintel GSO 10 dob and my imaging scope is a Bintel GSO 6 f6 reflector on a HEQ5 Pro Mount. I use my wifes old Canon 600D DSLR which takes great images
My advice is to start with a 6 f5 or 6 f6 reflector as they are both great visual scopes and beginner Astro scopes, easy to collimate, light weight, cheap ( mine was around $300 )
After a few years of experience under your belt you could upgrade to an 8 f5 with a EQ6 Mount ( an 8 will struggle on a HEQ5 mount with your imaging and guiding gear plus dew control , cable drag etc etc) or spend a lot more money and go down the refractor path
I cant fault my 6 f6 its a great all round scope
Attached are some of my images this year
Good luck with your decision
Cheers
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Old 21-09-2018, 04:57 PM
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doppler (Rick)
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Hi Nick, the Heq5 pro is a great start out mount and very underrated as far as far as its load carrying capabilities. 8" f5 newt is an easy load, the struggle is getting good balance and the big tube will be susceptible to wind vibrations. I would see if your 8" dob will focus on the moon with a camera and if so get some tube rings and try that out on your new Heq5. If you are serious and your budget allows go straight to the Eq6 R pro mount, it's a lot dearer but a good mount makes imaging much easier.

Breaking all the "rules" I have a 10" f4.8 skywatcher dob mounted on a Heq5 pro mount on a pier (I wouldn't feel confident with it on a tripod, although some do). The standard single speed dob focuser on mine handles a DSLR, coma corrector and off axis guide camera.


Some differences between GSO and Skywatcher, Skywatchers use pyrex glass vs Bk7 and their OTA's are lighter than GSO's, focusers are probably on par quality wise.
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Old 21-09-2018, 06:17 PM
nsavage (Nick)
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Thanks for the responses so far

Some great pictures there Martin, makes me even more impatient to make a start!

Rick, it looks like you have a reasonable amount of wind shielding around that scope, I would assume that this helps.

I have read about the wind susceptibility issues with the 8" and the HEQ5 Pro but there seems to be some mixed comments.

Is there really that much of a difference between the 6" and the 8" for photography anyway? Many say no. I realise that more aperture is better and the jump from 6" to 8" is considerable but I guess you can just take longer exposures is that correct? My understanding is that mount accuracy and OTA stability is the main key to achieving good results, am I correct?
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Old 21-09-2018, 08:02 PM
Startrek (Martin)
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Nick,
Ask anyone who has a 6 its capable of imaging most DSOs but this of course is dependant on atmospheric seeing conditions , polar alignment, tracking error, your location ( light pollution ), imaging camera type , auto guiding, exposure time and other technical parameters .....

My 6 is currently imaging 47 Tucanae a really good globular cluster while Im inside watching the footy
My polar alignment error is 8 arc seconds using the Synscan PA routine and just a 2 Star alignment and my exposures are 60 seconds with tight stars ( no autoguiding set up tonight )

Its your decision,but if you decide on the 8 I would strongly recommend the EQ6-R mount for future proofing ( I raised the same issue about the 6 and 8 over 2 years ago and ive been very happy with the 6 - no regrets )

Good Luck !!
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Old 21-09-2018, 08:10 PM
nsavage (Nick)
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Thanks Martin

This is really helping me solidify my decision.
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Old 21-09-2018, 08:56 PM
47Tucanae (Helen)
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Quote:
Originally Posted by nsavage View Post
Thanks Martin

This is really helping me solidify my decision.
I've found it worthwhile too. Interesting advice about the smaller scope - I suspect I'd be inclined to throw too much money at it - not that we can afford to, but 'go big or go home' and end up with too much scope and running into problems. Starting with something a little more manageable sounds wise. I think 'future proofing' is a concept I'm keen on though, as I really can't deal with the hassle of onselling.
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Old 21-09-2018, 09:02 PM
nsavage (Nick)
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Originally Posted by 47Tucanae View Post
I've found it worthwhile too. Interesting advice about the smaller scope - I suspect I'd be inclined to throw too much money at it - not that we can afford to, but 'go big or go home' and end up with too much scope and running into problems. Starting with something a little more manageable sounds wise. I think 'future proofing' is a concept I'm keen on though, as I really can't deal with the hassle of onselling.
One of the reasons I would like to try and get it right the first time as well Helen. I want something to last me a good 2 years and would prefer not to lose money from making poor decisions.
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Old 21-09-2018, 09:36 PM
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doppler (Rick)
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Another thing to be aware of is the difference between focal ratio's. A fast short focal length f4 newt will allow for shorter exposures and easier guiding but will need a coma corrector and very precise collimation. If you go the other way with a long focal length scope (like an f8 RC or cassegrain) you will need long exposures and a well set up mount as any errors in the system will be very apparent. The sweet spot for easy to manage newts is around f5 or f6.
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Old 24-09-2018, 09:17 AM
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sil (Steve)
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There are trade offs everywhere in astronomy and though on paper the dollar figures and spec numbers imply suitability or even overkill for use. Reality is you need Rock Solid stability plus high precision construction for good use of gear and possible future proofing. The EQ5 is a good start but its nowehere near an end game tripod mount. you cant put anything on it that negates its limitations. So if you accept that then fine. Otherwise EQ6 or 8 may be where you need to be aiming if you want to avoid the upgrade stepping stones in the long run. There's work in setting up and maintaining whatever you get. A seemingly overkill mount now with whatever OTA you have will be great and give you room to save for bigger better OTAs down the track you can swap on. Maybe you'll want two mounted side by side for visual and photo use. If you get a mount that does the job now but maybe at a struggle wont have room to grow when you're ready to. Get the mount right and you have a solid accurate foundation to add gear onto. No need to get everything at once.
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Old 27-09-2018, 05:56 AM
nsavage (Nick)
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Quote:
Originally Posted by sil View Post
There are trade offs everywhere in astronomy and though on paper the dollar figures and spec numbers imply suitability or even overkill for use. Reality is you need Rock Solid stability plus high precision construction for good use of gear and possible future proofing. The EQ5 is a good start but its nowehere near an end game tripod mount. you cant put anything on it that negates its limitations. So if you accept that then fine. Otherwise EQ6 or 8 may be where you need to be aiming if you want to avoid the upgrade stepping stones in the long run. There's work in setting up and maintaining whatever you get. A seemingly overkill mount now with whatever OTA you have will be great and give you room to save for bigger better OTAs down the track you can swap on. Maybe you'll want two mounted side by side for visual and photo use. If you get a mount that does the job now but maybe at a struggle wont have room to grow when you're ready to. Get the mount right and you have a solid accurate foundation to add gear onto. No need to get everything at once.
Thanks Sil

Coming in to this I am aware of and accepting of the limitations of the HEQ5 mount. I would love to just grab the EQ6 mount and possibly the 8 inch scope but unfortunately that is out of the question for now. Having read the comments here and elsewhere I have settled on the 6 inch f/5 with the HEQ5 mount. I know I will have to look to upgrade in the future but for now this seems like a great starting setup and should suit me for a couple of years at least.
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Old 27-09-2018, 10:05 AM
raymo
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Take note of Nick's remarks, the HEQ5 carries an 8" f/5 easily; a few people
use them with a 10", and I know of one who uses a 12". The limiting factor
with most mounts is not a strength one, it is the power of the motors.
Mine carried my 8" f/5 happily for seven years, until I had to give up. Just balance properly[slightly against the drive direction] and all will be well.
raymo
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Old 27-09-2018, 04:40 PM
nsavage (Nick)
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Originally Posted by raymo View Post
Take note of Nick's remarks, the HEQ5 carries an 8" f/5 easily; a few people
use them with a 10", and I know of one who uses a 12". The limiting factor
with most mounts is not a strength one, it is the power of the motors.
Mine carried my 8" f/5 happily for seven years, until I had to give up. Just balance properly[slightly against the drive direction] and all will be well.
raymo
Thanks for the input Raymo.

I would love to go with the 8 inch instead if it will work. You didn't find that you had issues with wind etc.? I have noted elsewhere regarding the balance against the drive direction.

Last edited by nsavage; 27-09-2018 at 05:11 PM.
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Old 27-09-2018, 06:11 PM
raymo
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You need to balance slightly against the drive or it will flop backwards
and forwards because there is always some gear backlash.
Yes, wind does affect an 8", but also affects a 6", although of course a bit less.
The extra aperture is worth the occasional wind problem for my money.
Portable wind shields are not that difficult to make, especially if you are
on grass.
raymo
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Old 27-09-2018, 06:18 PM
nsavage (Nick)
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Originally Posted by raymo View Post
You need to balance slightly against the drive or it will flop backwards
and forwards because there is always some gear backlash.
Yes, wind does affect an 8", but also affects a 6", although of course a bit less.
The extra aperture is worth the occasional wind problem for my money.
Portable wind shields are not that difficult to make, especially if you are
on grass.
raymo
Thanks Raymo appreciate the feedback. When I started looking into the options I immediately wanted an 8 inch. Having an 8 inch dob already it seemed like I would be "missing out" by getting a smaller astrophotography newt. I realise that aperture is not as important for astrophotography but I also understand that you can never have too much . Looks like I might switch to the 8 inch now. Also as I am going to go straight to an OAG I assume that helps reduce the wind impact slightly.
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Old 27-09-2018, 09:24 PM
raymo
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Aperture is important for objects that show lots of detail; the larger scope will resolve more of it. For example an 8" will show far smaller craters on the moon than a 3 or 4" will.
raymo
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Old 28-09-2018, 11:49 AM
nsavage (Nick)
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Thanks everyone for all the help.

Bit the bullet on an 8 inch f/5 and bumped up to the NEQ6 Mount. Small wait for stock to come from SkyWatcher unfortunately.
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