Biggest possible OTA for imaging on an EQ6

[toryglen-boy]

Howdy

Using a 200mm to good effect on an EQ6 for imaging, whats the biggest i could go before it gets unstable?

The logical part of me is saying i am already there, with a 10" borderline, and a 12" a no-no

any takers?

:)

[g__day]

I take it you mean an SCT or some sort of newt?

In a sheltered location or exposed to moderate gusting winds?

If you are imaging how challenging are our targets (i.e. how long subs do you need to take).

Personally I'd imagine you're pretty close to the limits there fella!

[DavidU]

Mike (Iceman) has a nice 12" hanging off the EQ6, and his images are awesome
http://www.mikesalway.com.au/2008/12/16/planetary-imaging-equipment

[toryglen-boy]

yeah, i thought i had answered my own Q !!

:lol:

[toryglen-boy]

Thats a good point also dave, i forgot El Capitan uses a 12"

:)

[Satchmo]

I have a 12.5" F3.5 Newt with a "no mirror cell " conical mirror and lightweight aluminium tube on the drawing board. Intention will be an `astrograph' , using an MPCC that can function well on an EQ6pro out in the open. I think the GSO F5 tubes being long and heavy would function well only in an observatory.

[Paul Haese]

10 inch newt at a pinch for imaging DSO work. Using a 12 inch is ok for planetary but the weight is going to affect the drives eventually.

You could use a folded scope up to an 11" but you would need a self guided camera to do that.

My recommendation would be an 8" with guide scope, cables and cameras would work best.

[miki63au]

G'day Duncan,
IMHO it's come down to rotational inertia. How long is the OTA,
and how much mass is in the end of the tube?

I will use the G11 for the big DK Cass. Initial try without optics is promising. The mass is 27kg for the OTA. Not for deep sky!
Now the G11 has a 6" worm wheel, in your EQ6 has a 3". Think about it!

In the old days the worm wheel should be the diameter of the primary for long exposure photography.
My 2c.

[Tandum]

I recently bought a 10" gso dob to go on my eq6. I got a set of 303mm rings 2nd hand off les and I had a 12" vixen bar here. I didn't like it like that at all, the vixen style bar felt to me like it was twisting with the weight. That big 10" newt is heavy.

I now have a losmandy replacement head coming from adm for the eq6 mount, a 15" losmandy dovetail coming from adm to mount a new set of custom dual bolted rings from honkers.

Add in the moonlight focuser which is in the mail and the coma correcting stuff I haven't bought yet and it's no longer a cheap 10" imager :)

Hi from Port Douglas :)

[peter_4059]

Robin,

Can you post a link to the new rings site?

Peter

[peter_4059]

ps - anyone here seen Eric's DSO work - 10" newt on an EQ6 from memory....

http://www.ezystyles.com.au/index.html

[Tandum]

Sorry Pete, I'm in port douglas for a wedding without my bookmarks. Does anyone else have peter tan's web site address on hand :)

Yes I've seen eric's images. He modified my 40D for me. He used a celestron 10" newt for those images and sold it in the forums not long ago.

[peter_4059]

No problem Robin - got it. How many counter weights are you going to need?

[Tandum]

I got the 10" balanced with 3 weights. I got a 4th weight from alexn in exchange for my time in making him up a lightbox and dew controller. That should cover the guidescope and camera. Real images are still a ways off for me on that scope :(

Once the eq6 head changes, so does the tak mounting. I'll then need a losmandy to tak clam adapter :doh: It never ends ....

[Hagar]

Hi Duncan, Lots you can put on an EQ6. Pro or just EQ6? There is quite a diference to the bearings ect. I would sugest the biggest possible ,I mean stable would be a 10" F5 Newt for visual work and probably the most stable for imaging with a guide scope attached would be an 8" Newt. The method of mounting the guide scope will make quite a diference to the balance. To balance well for imaging it is worth using an extra weight and keeping it up high on the counterweight shaft than to use fewer weights and hang them off the end of the shaft. The shaft is quite flexible and does impact on imaging ability of the scope which tracks and guides with stepper motors.

A Few things to think about.

[RobF]

All praise Master Eric......:bowdown:
Convinced me I could do plenty of damage with a Newt when I was first deciding which way to jump with scopes.

[DavidU]

Where is he? I used to live a few streets way from him and we both moved and had not heard a thing

[dugnsuz]

Ed80:P

[peter_4059]

Doug - have you seen anything published regarding differences in the bearings - I have it from one of the retailers that the only difference is the coat of paint (black/white). Visually the mounts are identical from the outside.

[mch62]

Hi , I have had in the past a light weight 12.5"f6 conical mirror double truss Newtonian on an EQ6 and while it was fine for Planetary video shots I did not use it for Long exposures. The complete weight was only 13 Kgs well with in the weight limits of an EQ6 .The problem was the length.To much torque on the gears and back lash became a problem.This double truss was very light in the ends as well. I think that a 12" f4-5 ish might do it in a pinch if it was kept light (conical mirror & truss or CF tube) it would also depend on the other accesories to be fitted as well and forget windy nights.
Then there is a folded design but that adds the weight of an extra mirror and the larger obstruction as well.
I currently have a 10"f3.8 Astrograph with guide scope and side by side mount and feel that I am at the limits of the EQ6 even though the main optics only weigh 10kgs.It's all the other stuff that adds up.
I have the same amount of counter weight on both 20KGs but the 10" has the weight bar not fully extended and one weight near the top.
I also found using a larger weight at the bottom reduced the total weight on the bar.


Mark

[bmitchell82]

10" stable, 12" on un windy nights. i use the 10" and its weighing in at 23kgs.

[Hagar]

I don't know about published data but I have seen them both appart and the bearing structure in the pro was significantly different and the lack of plastic spacers in the pro version was quite evident.
I think the carrying capacity is actually quoted as diferent between these mounts. (At least it used to be.)

I had an EQ6Pro and found it to be a very capable mount. I wish I had kept it as a field mount and left the G11 in the Obs.

[Don Pensack]

Load limits including camera, cables, guide scope, rings, dovetail, etc:
Celestron CG5--25 lbs (11kg)
Celestron CGEM--30 lbs (14kg)
Celestron CGE Pro--90 lbs (41kg)
Losmandy G11--60 lbs (27kg)
Losmandy Titan--100 lbs. (45kg)
Another way of putting it:
CG5--8" SCT
CGEM--9.25" SCT
Losmandy G11--11" SCT/8" newt
CGE Pro--14" SCT/10" newt

And the above presumes a piggy-backed guide scope and probably with an autoguiding camera.
And, it presumes wind protection. For photography in the open, even a Paramount ME isn't big enough for a 10" newt.

IMHO.

[MrB]

http://www.tan14.com/gears.htm