6" vs. 8"

[dhumpie]

Hi Guys,

I know this question has been rehashed a thousand and one times but I will still go ahead and ask anyway. I currently own a C6 Celestron/Vixen 6" f/5. It has a rather good mirror and I have been getting great views (major globs beautifully resolved...and this scope does not have diffraction spikes : ) But I have the aperture itch and may have an opportunity to get an 8" dob from Andrew's (if I sell my 4"ST OTA...any takers :) Now I know some of you may say go to a local club and compare. I have looked though a couple of 8" (not that many...there seems to be an overabundance of 10" and 12" dobs but not that many 6" and 8") but not enough to make an informed judgement since they were very brief views. So the question is will it be worth the upgrade????? Can you also give me specific examples of objects and how they look through an 8" in comparison to say a 6". Do you think it will be wiser of me to save a little bit more (might be about a year before I can get the 10") and go for the 10"

Help me decide if i should just stick with my C6 for now and upgrade later (and in the process keep my 4" ST as well :)

Thanks guys.

Darren

[davidpretorius]

Sorry for my ignorance?

What type (reflector or refractor) is a C6 Celestron/Vixen 6" f/5.

For what it is worth. I compared my 1250 fl 10" to Ken's 1500 fl 12" and saturn was 10 - 15% bigger and clearer. This is only a rough guide.

I also look thru a 6" reflector at eta carina and my 10" blew it away.

The 8" is 1250 fl from memory, so magnification will be similiar to the 10" if i am correct???

I would go the 8", you can always sell it 2nd hand in a years time for close to what you pay now if it is in good nick!

[beren]

Hey Darren , tough decision Ive been through it each time Ive upgraded :) From what Ive gathered your a proficient and experienced observer so any gain in aperture is going to be easily noticed . I wish i had kept a log of my thoughts when i went from 8" to 10" but its hard with the differing FLs of the scopes to, but overall my impressions where more of a subtle nature then a sudden wow feeling .I think the common take on going from 6" to 8" is appreciable but from 6" to 10" would be outstanding , the higher resolution with your skill level opens many more doors to your observing regime if the bigger scope fits your lifestyle though.

[Starkler]

I have heard many times that going up one step produces a subtle improvement, but you need to go up two sizes to call the improvement significant.

[ving]

I honestly think that my 8" in some circumstance has offered better views than some 9" and 10" scopes... maybe those werent properly collimated... I cant really add to this.
is there a quallity difference?

[davidpretorius]

Actually ving, good point. Steve H's 8" was collimated and all concentric circles from the mirrors, the centre spot was beautiful. It is a f6 scope. Go to my 10" and we had to offset it slightly. Apparently there is a difference. When collimated, the 10" did not look as neat and tidy as 8".

[xrekcor]

I agree with Geoff, moving from 6" to 8" will not give you a wow! factor in improvement
of the views. But that being said you can pick out quite allot of object with a good 8"
enough to keep you going for a lifetime.

If I were you darren I'd wait and go for a 12" dob, the 6" and 4"ST OTA will be great
for the Balcony. I think you would like the 12" better

Regards,CS

[dhumpie]

Hey Guys,

Thanks for the thoughts! I will wait for more responses and see if anyone has other suggestions. But my sentiments tell me that going from a 6" (its a newtonian reflector Dave ;) to an 8" is not going to give me the wow factor I will be looking for. As for the balcony Rob, we are shifting to a townhouse come 14th of November (the current owner wants the apartment back for his daughter) and this time I will have a small courtyard to observe from in addition to the second story balcony hence the decision to upgrade.

Keep the post coming guys....

Darren

[dhumpie]

I do like Andrew's 12.5" truss ;) But it is a pretty big scope at f/6. Will wait I guess....maybe put the money into a good mid powered ep...say a 13T6 nagler ;)

Darren

[asimov]

A hard call Darren. I built an 8" reflector & within weeks I caught the 'fever'. After using the 12.5" for a couple of years I have'nt found myself thinking 'I want a bigger scope'!!

Jumping straight from 8 to 12 there was certainly plenty of WOW! factor!

Cut to the chase Darren & to solve ALL aperture fever problems wait for the 16"!!

Seriously though, I think a 12" is the optimum size for anyone...unless one has issues with portability/not big enough viewing area etc. etc.

[davidpretorius]

hmmmm, a 12" would look great on my dob buggy!!!

[asimov]

A 16" would look even more impressive Dave.

[davidpretorius]

any pics of this 16" yet???

[asimov]

Not that I've found or seen. Andrews must be getting close to showing us something though....http://www.andrewscom.com.au/site-section-10.htm

[dhumpie]

If the 16" is going to be solid tube, it is going to be a major backbreaker. I have used David's (westsky) 10" f/5 GS dob and I really like the feel of that scope. It has enough aperture to satisfy my craving to go deep and it is really quite portable (fits in small cars too :) Andrew's (astro_south) 12.5" truss is a great scope but is getting a bit too large to be deemed portable....transportable is more like it. Plus I like to get down and observe without having to setup and collimate everytime I want to observe so maybe I should stick to solid tubes. The 10" f/5 might just be my sweet spot. from memory there wasn't a very big difference in views between the 10" and the 12.5".

Anyway I think I have more or less made up my mind "not" to get the 8" and save up for the 10" or maybe even the 12". It may take a while but I will get the wow factor when I do get it. The C6 is still seeing plenty of action in any case.

Darren

[asimov]

Yep. The 10" should give you years of pleasant viewing without the 'I wanna bigger scope!' syndrome setting in! (you hope. lol) Never looked thru a 10" so I can't really say.

Good luck with whatever you decide on Darren.

[xrekcor]

Darren,

It is my understanding that the 16" will be a truss dob. Unless they have changed it.
Meade are releasing tree truss style dob's but there isn't a 16" inch in there.

I think the reason I'm still cool with my 8" is that I live unless dark skies, I'm pretty
sure if I was in an urban area I would of upped the aperture by now. That's not to
say I'm not graving for aperture more that the 8" still doing it for me 2yrs down the
track. I figure once I do upgrade it will be to 16" either look at the GSO or perhaps
have a mirror made and build the rest. And since comparing my 8" to the 10" and 12"
versions the 8" compares very well, well enough for me not to go out and get one.
By the time I do get the upgade my eye's will be better trained and I'll be sick of star
hopping and get an Argo-Narvis lol

regards,CS

[dhumpie]

I have looked through Pete Robbin's 30" at the recent QLD Astrofest. WOW. M27 and M57 came screaming out of the ep. And there was even no filter!!!!! The central stars were as plain as daylight. But I had to get on a tall stepladder to get to the ep, one thing I would not like to do. Since I am 5 feet 7 inches tall, my optimal scope would be a 14" f/4.5 :) But I think the 10" f/5 would do nicely. I will leave the big scope setup to those who have the patience...

Darren

[xrekcor]

Yeah! Pete's 30"er was incredible but the size of the thing boy!! that was
impressive too! plus the fact the workmanship was beautiful. I think for me
a 18" to 20" + samll step ladder will be the final aim. That plus a nice imaging
setup that can sit to the side and click away : )))) oh yeah complete set of
XW's the odd Nagler I like, A good CCD or Digital...etc...etc... boy the list
could go on and on lol

regards,CS

[janoskiss]

Instead of a ladder, how about a motorised ride-on OTA? :D

[frogman]

guys guys guys.... your missing the point..... its not how big it is ...its how you use it! :)

Am i wrong ????? :)

[xrekcor]

Being a rigger and having worked in the film industry swinging cameramen
around on booms, I have often thought about this, Actually it was a twin 24"
bino setup where the observer would sit in a cradle between the two and
move in unison with each other. Using a joystick the observer could scan the
sky.

Darren picture two of Pete's scopes side by side and an observer on a boom
in the middle. This would be mounted on a trailer with outriggers. There a bit
more to the concept than whats stated here

aaaarh!!! it's nice to dream.

regards,CS

[xrekcor]

:rofl: like I said I'm comfortable with my 8"s :ashamed:

[RAJAH235]

Darren, from the owner of a Meade 10" f4.5 dob, I would recommend the 10" over the 8". Give you around 2 mags more than the 6", + they are easy to transport & you don't need a step ladder at zenith.
Just mho. :D L.

[slice of heaven]

I'd say go as large as your wallet will allow as long as it's still within your limits for portability.
I started with a 12.5" 10yrs ago and still enjoy it's capabilities, though I do hunger for something larger at times.
I have an 8" as well, same brand, same quality and same makeup as the 12.5".
The 12" out performs the 8" all round, except for portability.
The larger you go now, the longer it will be before ap fever sets in again.

[dhumpie]

Ha! Ha! Fun post Rob. Pete's scope was great. I particularly liked his motorised focuser. But like I mentioned I love observing but hate the setup. I want to get out there and observe with minimal fuss so I can spend more quality time at the ep. Therefore I might be sticking with a 10" (or 12") solid tube dob if I can. But I am not ruling out the Starmaster 14.5" hybrid (F/4.5???) or a clone of that. That will be the sweetest setup for me as I don't need no stepladder. My ultimate aim is to have a large dob and a large pair of binoculars 25x100's would do nicely for comet sweeping :) But I can dream for now...

Darren