Question from a wannabe imager

Campus Dweller · #1 08-06-2009, 10:16 AM

I've been looking through telescopes for more than 30 years but am placing my question in this forum because I haven't yet joined the digital imaging revolution.

There is an amazing amount of gear on offer and I've been looking into adapting my equipment, which is a 10" Dob with a Argo Navis. The telescope is an excellent visual 'scope and I love my AN

I'm thinking of buying an equatorial platform for tracking and a G-Star to do the imaging.

My question is, will this system work?

I know there are many other more sophisticated systems, but will a Dob on an Eq platform with a G-Star and a laptop enable me to be able to go out into backyard after work and enjoy some decent imaging?

Cheers
Drew

dannat (Daniel) · #2 08-06-2009, 10:55 AM

there are a few who image with 10" Newt, but its not common.Something with shorter f/l would be easier & more forgiving. Some Newts need the mirror shifted and/or low profile focuser to reach focus
I presume you are wanting to image dso's?
I think you would need to upgrade the eq5 to eq6 - the 10" will weigh a lot & guiding at that f/l is a must.
G-star is marketed as both planetary & dso but i don't think many here use one (not sure why)
THe 120mm will be a bit heavy for guidescope - most use something smaller & lighter.
For dso's i'm pretty sure you would want a coma corrector, baader is popular (mpcc) - but like my d-slr (olympus) the chip is smaller than other d-slr & coma is less problematic

IvanTheTerrible · #3 08-06-2009, 10:58 AM

Of course it will work. Will it be practicle is another question. What you want to image will decide if this is what you want. Your proposed setup will probably be good for planetary shots but not for deep sky. You also have to remeber that a DOB is not designed to be equatorially mounted and you may encounter a fair amount of flex in the tube.

Campus Dweller · #4 08-06-2009, 11:18 AM

Thanks for the replies Daniel and Ivan. There is a lot to take into consideration that I'm ignorant about.

I will want to use the G star as an all round option. It is marketed as both a planetary and DSO imager.

Will the flex in the Dob tube come into play if it's sitting on a ground based equatorial platform, rather then a mount like an EQ6?

jjjnettie (Jeanette) · #5 08-06-2009, 11:40 AM

I used to use my Gstar with a 10"Dob but I was only hand guiding.
Needless to say I didn't have much success, but I could see the possibilities.
But mount it on an eq platform and you'll be able to produce some quite excellent images.
The FOV is quite small and if you want to use a focal reducer, the ota would need to be cut down about 40mm so you achieve focus.
But you have the 120mm, you can use that if you want a wider fov.

Have you joined the Gstar Users Group? Have a look at some of the images that these guys put out. Awesome stuff. http://tech.groups.yahoo.com/group/gstar-users/

Campus Dweller · #6 08-06-2009, 12:03 PM

Thanks Jeanette.
Yes I was thinking about getting the G-Star first and trying it on my refractor set up. The EQ5 tracks excellently for visual observing and all I do when aligning is line up the mount with a line I've drawn pointing N-S.
I'll have a look at the newsgroup, too!

jjjnettie (Jeanette) · #7 08-06-2009, 01:48 PM

I use the gstar with my 120mm f5 and an ed80 f5 using mainly an alt azi mount.

Campus Dweller · #8 08-06-2009, 02:01 PM

Quote:

Originally Posted by jjjnettie

I use the gstar with my 120mm f5 and an ed80 f5 using mainly an alt azi mount.

That does make it sound a simple option to use among all the latest technology!
I have requested membership to the newsgroup as well.

bmitchell82 (Brendan) · #9 08-06-2009, 02:29 PM

If you search for some of my responses to Astrophotography and what to use i have written a lot.

-Flex isn't a issue with my dob and the Orion/Skywatcher dob are just different colours...

-You will need a EQ6 platform for the weight as a EQ5 will die in the A55.

- These dobs have not got a long focal length, they are actually the fastest dobs in Syntas range of dobsonians at F4.7 and they are affected by COMA...

- Gstar will be fine for doing Planetary work, but DSO's not so well (not to say it wont capture them)

- with 10" of love get a 5x Powermate coupled with a DMK21 and that will be a powerful one shot planetary camera

- the use of a DSLR - Canon 350 modified (can be purchased for 4-600) will produce spectacular shots.

you will also need to guide as DSO's need decent exposure times depending on your setup.

Astro isn't a easy thing to do, your best bet is to take yourself and your scope down to a astro group and find the people who have gear like yours. you will be surprized by what you see.!

Have a look at the photos i have taken that are on the website in my signature thats what a canon 40d (just more Megapixels) and a 10" can do.

Brendan

AlexN · #10 08-06-2009, 04:49 PM

Quote:

Originally Posted by bmitchell82

-You will need a EQ6 platform for the weight as a EQ5 will die in the A55.

Not if you use a round table eq platform like what Mike Salway used to use for planetary imaging.

Quote:

Originally Posted by bmitchell82

- These dobs have not got a long focal length, they are actually the fastest dobs in Syntas range of dobsonians at F4.7 and they are affected by COMA...

Despite being fast at F/4.7 and a focal length of 1250mm, with a camera like the GSTAR, the field of view will be very small, giving the illusion of long focal length.

Quote:

Originally Posted by bmitchell82

- Gstar will be fine for doing Planetary work, but DSO's not so well (not to say it wont capture them)

The Gstar will capture DSO's just fine.. Its very versatile, very sensitive and can be used to capture whatever you point it at... Its perhaps not the ultimate deep sky imaging camera, however it is quite capable.

coldspace · #11 08-06-2009, 05:11 PM

Drew,

The g-star performs very well on deep sky stuff.
Have alook at what Steve does with a g-star,
http://my.hwy.com.au/~sjquirk/index.html
To get results like this you will need to stack many 2.5 sec frames and if you want colour you will need to use filters otherwise they make a good easy way to have ago at imaging using a platform. You don't need to do a polar alignment just a good Alt/Az tracking mount as the longest exposures are about 2.5 seconds.
You will need to adjust your mirror forward up the tube to get focus.

I use the Mallincam video system which is similar just modified/cooled and is one shot colour, here are some results with the Mallincam,15 inch dob on a platform,
http://equatorialplatforms.com/malli....platform.html
the difference is you just put it in the focuser and it displays great views on the monitor or PC via a capture card and has exposures upto 56 seconds with out stacking or colour filters.

If you were/are mainly a visual astronomer like me and want to dabble abit into the imaging side and improve visual experences in the suburbs with out the time and patience of conventional imaging then a Astro video system is the way to go.
I admire the great shots many people post up here and all the hard work that goes into it, but what you are looking at will do the job with out to big learning curve.

Regards Matt.