New 10" Dob

[DJVege]

Hey guys,

Seeing as the weekly (if not monthly) forecast was for cloudy weather, I figured I probably wouldn't hurt anyone's seeing by getting some new equipment!

So, I am now the proud owner of a brand new (2nd hand :)) 10" GSO Dob! Sure is bigger than I imagined it would be. Makes my 5" look like a baby!!

My question is, "Can I mount this on my HEQ5"? I read somewhere that a good limit on the HEQ5 was 15kg, and the 10" OTA weighs around 13Kg...without EPs or the finder. Would I be overloading the mount?

Not a biggy, because I'll be using the 10" as a visual scope for now, but just wondering about upgrades... ;)

[§AB]

congratulations dude, you'll love it :) When I first saw mine, it's size surprised me aswell!

Btw, the tube is actually closer to 16kg "clean".

[rmcpb]

Congrats on the "new" scope.

As for the mount, the HEQ5 would be marginal for visual but work. Forget about any serious astrophotography on it though except for some lunar stuff possibly.

Now the wait for some clear weather :)

[DJVege]

Ok. Thanks guys.

I have one more question, though. Supposedly coma is apparent in these scopes. Besides a paracorr, is there a way to decrease the amount of coma in a scope? Not a real biggy, though.

Also, in my 5" scope, there are little "ripple-like" ridges inside the scope,about halfway down. What are they for? My 10" doesn't have them...

Thanks!

[§AB]

^^ at F/5, coma does become a problem. For example, using my TV 32mm plossl in my scope is like looking out the window of the "Enterprise" at warp speed :P

You can always buy high end eyepieces, such as Naglars, Panoptics and Vixen LVws which have better edge correction. My Vixen LVWs have noticably better images than my plossls in my 10" F/5.

Those "ripples" you descibe in your 5" are probably baffles inside the tube to combat stray light. Maybe post a pic so we can be certain?

[DJVege]

Hmm....yeah, I think that must be it. Do I need them in my 10"?

I'll post a pic when I get home tonight.

Cheers!

[§AB]

I think it's really noticable only at lower powers. With premium eyepices, it'll still be noticable, but not to the same extent. It really depends on your personal tastes - if you can live with it then that's fine but if you find the coma obtrustive then I suggest you invest in a paracorr.

[Phil]

great stuff DJ
Phil

[rmcpb]

I would not worry about the coma till you give the scope a try as see if it really bugs you. I am changing to more premium eyepieces after quite a while but I have been able to cope with the coma even in my 13" which is f4.5, it has not been nice but at least I could use it.

The ripple in the tube would be a baffle which is not necessary for your 10". To try and increase contrast some people flock their tubes, others set up baffles and others do both its your choice. It is more important in areas of light pollution.

I would recommend you use your scope as it is for a while before you start any mods or accessory purchases except for some collimation tools.

Keep looking up :)

[GrahamL]

Coma for me in my 10 ";) was never an issue with a 13mm or 7mm nagler
On nights of average to poor seeing the 7 mm was sometimes a little to much power..At low power my 27 panoptic is a fantastic eyepiece that gives pinpoint stars over nearlly all of the fov .. A while back I happened to purchase a 28 mm pretoria eyepiece which corrects for coma at f 4 I think..this is one likeable piece of glass..even at f 5 its pinpoint views right to the edge ..so stupidly I now have 2 low power eyepieces that are both great :)

As suggested I'd look through your scope before shelling out for a CC
my recollection of a 5 " view of omeg cent compared to the 10" is just
more than a little differant coma or not :thumbsup:

[DJVege]

:)

Thanks guys! Will do!

However looking up and looking up through a scope are two different things! Absolutely no point in observing because my scope doens't seem to look thru clouds!!!! :(

Very impatiently waiting.....

[duncan]

Hi DJVege,
I posted about this sort of thing not long back. The title was "Astigmatism" but upon reviewing through the eyepieces it was only annoying through my cheap 32mm eyepiece. The higher power ones nowhere near as bad. My problem up here is not to many people with gear to try other eyepices before buying. So i'll probably splurge on at least one soon enough. It's just deciding which one,LOL:lol:
Cheers

[edwardsdj]

Great scope :)

You must be pleased with your purchase.

Did you get collimation tools?

[DJVege]

Thanks Duncan, Thanks Doug!

Yeah, I've already got collimation tools (for my 5"). I've got:

* a Cheshire
* A skywatcher newtonian collimation tool
* an Astrosystems barlowed laser collimator

:)

[edwardsdj]

Great set of tools.

When you use the laser, does the collimation change between pointing the telescope horizontally and vertically?

[vash]

Seeing as how I've had experience with your mount I can say that the 10" scope can go onto it and you can get some nice photo's using it. Though the set up might be better if you use it for planetary imaging with a high power barlow,

[DJVege]

Yeah? Thanks Vash! I'll probably buy some rings in a few months time and test it out. At least I'll test out the planetary stuff...

Doug, I'll test that tonight and let you know. I've never tested it both horizontally and vertically. Didn't think it would need it.

So, you want me to collimate it horizontally, then check if the collimation holds for the laser in a vertical position?

[erick]

Just swing it up in alt and watch the dot in the laser window. It doesn't move on my 8" and, last night, it appeared to move about a mm on my 12".

edit: in your case, of course, the return shadow on the white surface of the barlowed laser.

[edwardsdj]

I was just wondering if the primary mirror springs were strong enough to accomodate all viewing altitudes.

If they aren't, collimate at approximately the angle you will use most frequently.

[erick]

Yes, in my case the 12" has had stronger springs inserted. The 8" is the original GSO springs but the mirror is relatively light so they seem to be working OK. A 10" with standard GSO springs - perhaps there will be some "give" moving from vertical to horizontal.

[DJVege]

Hey guys,

Just letting you know I got out for a 3 minute view of Mars tonight! Yay! :) Horrible seeing, and it was between clouds, but I can finally say I've used my 10" Dob!!

However, I think I've been spoilt by my HEQ5! When I've got the Dob pointed at a target, how do I lock it in that position so that I can change EPs without it moving? I changed from my 2" 30mm to my 7mm, and the whole thing moved 20cm!!! Is there some sort of mod I can make to lock the Dob in place? If not, I can see myself buying 10" rings for the HEQ5 very soon. ;)

Doug and Eric, the collimation moves about a mm when moving from horizontal to vertical, however, keep in mind I didn't have the set screws locked. It was more of a rushed collimation in order to get the scope outside before the clouds covered Mars.

I also can't comment on Coma just yet, cause I'm sure the collimation was nudged when I moved the scope outside. However the view is much crisper in my 7mm nagler, than my 30mm 2" Andrews EP.

All in all, love the increase in aperture!!!!!!!!!!!!!!! :)

[duncan]

Get the rings.
You lucky fella.
I need an EQ mount!!!!!!!!!!!!!!!!!
Cheers,
Duncan:lol:

[Phil]

Any photos yet DJ love to see sum mate.
Phil

[erick]

Change eyepieces?? You should be so excited that the only movement is finderscope <==> eyepiece! :lol: I presume you mean it moved in Alt. Have you got the tension springs on? Pull them tighter - don't put the "cloth" loop over the screw - pull the spring over it! Other approach is to balance with weight. Two options:- 1) weights of some sort (lead?) wrapped up and attached with velcro to various places at the top or bottom of the scope. 2) magnets (chopped out of speakers are good) wrapped in a bit of felt. They can be placed anywhere on the tube and fine adjusted to get balance depending on eyepiece weight and elevation. But watch the angle of elevation. As you increase, the magnet can be inclined to slip. A worrying sound is the THUNK as the magnet hits the lip of the mirror cell mount and falls off into the dirt! :scared:



I never tighten the three "lock" screws when I am in the field, only during transport. That's the way I was shown for my 8" and I guess I've always worried they would push the mirror out of collimation. I must experiment on the 12" - they might prevent that small change I did see??

[DJVege]

LOL! Thanks Duncan!

Phil, sorry, will take some photos tonight and post them here. :)

Eric, yeah, sorry. I meant the dob moves in altitude to easily when I change EPs. I'm also keen to check if the mirror moves as much when if the set screws are locked in.

My argo navis should arrive in a couple of weeks. Jealous? ;) It's for my HEQ5 though. Yay!

[DJVege]

Hey Phil,

Sorry for the tardiness in getting these photos up. Had a crazy Australia Day weekend on the Goldy!

Anyway, here are the 2 scopes I have now! I think you'll recognise the Intes! :)