10" newt on a Neq6 mount

[acarleton (Aidan)]

Hi all

I have a Neq6 mount, with a sw80 that i will use as a guidescope. My question is, will i have issues doing astrophotography if i get a 10" f4 newtonian. I know the weight is marginal at best, just windering if anyone has got this set up and whether or not they have had issues with long exposures.

Thanks

Aidan

[ZeroID (Brent)]

You will be marginal for weight. I have a 10" on an EQ6 but I rebuilt it into a lightweight Serrurier Truss configuration which nearly halved it's mass.
If yours is solid tube it will need to be very well balanced and sheilded from any breezes to be viable. Might be worth considering buying a lighter weight guidescope package, the SW80 is not the lightest beast out there. Bintel I think have the 50mm mini guider setup.

[acarleton (Aidan)]

How much does your rig weigh?

I guess i will have to go for the 8", i would just really like options that the 10" provides, especially when imaging quite faint dso's

[raymo]

From my experience weight is only half of the problem with large
Newts. Newts from 8" up fitted with standard dovetail and rings
vibrate badly at the slightest touch, making an electric focuser just
about essential. My mount is rock solid, yet tap the tube and it takes
over 4 secs to settle. Anti vibe pads make no difference. The flexure is all in the dovetail assembly; it's just not heavy duty.
raymo

[ZeroID (Brent)]

Originally Posted by acarleton

How much does your rig weigh?

I guess i will have to go for the 8", i would just really like options that the 10" provides, especially when imaging quite faint dso's

The Serrurier is just over 11 kg all up, no accessories. Total loaded on the mount is 17 kg. It is also better centre balanced than most scopes which minimises the counterweights required to keep it stable.
EQ6 is rated as 25 kg but recommended to be better at half that for photography. I'm inside a tinshed Ob so windage is not a major problem but the open structure of the OTA reduces wind effects as well.

What options does an 10" give you over an 8" ?
Long exposure and stability is the key for imaging, not so much aperture.
You can buy 8" or 10" Newts specially designed for imaging but be aware that larger apertures also introduce more coma effects from feild curvature.

I think my ideal imaging scope would be a longer focal length (f8) 6" newt. Big enough aperture to keep exposures short, long F to get decent mag and minimal curvature to correct. No refractor chroma either.
If I spot a mirror or cheap scope to convert\rebuild that will be my next build project. Would be nice and light and easy on the mount.

All that being said I'm about to remount the 10" (I'm using the LUNT at present ) and try out the ZWO camera on it.

[acarleton (Aidan)]

I am heading down to Bintel this afternoon and am still tossing up what to buy. i have been sold not to get a 10" (that saves me $300) but what you said about the F8 6" has thrown me a little. i am using a cropped DSLR to image so i believe i would need a faster scope than f8. i was thinking of an f4 8" (being aware that i will have to coma correct), but do you think that the f5 would be better? a bit more magnification and a little less coma.

[Marios (Marios)]

hi Buddy

I went the route of the 8inch F5 Newt on the Neq6 with the Orion ST80 Autoguider. My reasoning is to reduce the weight by sticking with a 8inch, and also still having a scope that was flexible to use for visual use at F5.

Keep in mind if you really want to get deep into astrophotography in the future you will need to go the way of the refractor.
I decided to get what I needed to start out and save the dollars for a refractor in the future.

The 10inch F4 IMO, is still well within the comfort limits of the NEQ6 however it is a very fast scope requiring addtional corrector lens and very accurate colmination not to mention expensive eyepieces to deal with the F4. If you can afford to then go for the 10inch you wont regret it.



[
QUOTE=acarleton;1054824]Hi all

I have a Neq6 mount, with a sw80 that i will use as a guidescope. My question is, will i have issues doing astrophotography if i get a 10" f4 newtonian. I know the weight is marginal at best, just windering if anyone has got this set up and whether or not they have had issues with long exposures.

Thanks

Aidan[/QUOTE]

[raymo]

My 8" is f/5 and I often wish for more magnification, so I would
certainly not go f/4, although having said that, it also depends
upon what you want to image. Small planetaries, for instance
require lots of mag.
raymo

[alistairsam]

Hi,

I have a 10inch F4 and from my tests, there is significant difference to the 8inch and I sold my 8inchF4. mine is a home built serrurier similar to Brent's.

I would definitely go the 10inchF4 as the tube is not that long and coma can easily be corrected with the mpcc, and get the mpcc mark 3.
the speed of the F4 is what makes it worth it. you get so much in so less time.

8inch to 12inch F4 shows a very significant difference in details and 8inch to 10inch relatively minor but in my opinion and trials, worth it. the longer FL gets your targets a bit larger than the 8inch.

why do you want to guide with the SW80? I would keep it simple and get an off axis guider, saves so much of weight and your guiding will improve heaps as you wont have to contend with flexure that is common with the steel tubes and at f4. You do need a sensitive guide cam though. the qhy5L2-mono works very well.

Bintel claim 15kg for the 10inch F4 OTA with dovertail and rings.

I would suggest go with 10inch F4 if you are using an OAG, as you'll save weight on the SW80, or 8inch F4 if you are using the SW80 as the guidescope.

the neq6 should support the 10inchF4 with the SW80 but you'll be dealing with a fair bit of flexure.

if you do go F4, save up for a decent focuser. the moonlite's are very good, and are short profile, meaning you can reduce the width of the light cone at the focuser opening and reduce vignetting.
A good focuser is required as the focus zone for F4's is small and any focuser tilt shows up easily.

Lower profile focusers also allow for a smaller secondary as you can move the mirror down rather than up.
finally, get a cheshire for collimation. that's all you'll need.

cheers
Alistair

[Marios (Marios)]

Yep Raymo is spot on the FOV is of concern, I was imaging the sculptor galaxy and when I zoomed and crop it started to get pixelated. So a F4 at 800mm will limit your final blow up of the DSO.

What DSLR are you planning to use?

Originally Posted by raymo

My 8" is f/5 and I often wish for more magnification, so I would
certainly not go f/4, although having said that, it also depends
upon what you want to image. Small planetaries, for instance
require lots of mag.
raymo

[alistairsam]

have a look at Shiraz(Ray)'s galaxy images here. all taken with an 8inch F4.
what dslr are you using?
Galaxies will require longer FL's but you can get good results with the F4's as well.

here are some early test raw subs of mine taken with a 10inch F4. single 3 min subs. ngc300 was a 7min sub.
uncropped with a kaf8300 sensor which is smaller than a dslr.
I was still adjusting collimation, focus, spacing and tilt so stars aren't round.

[acarleton (Aidan)]

The Camera is a Canon 600D

[acarleton (Aidan)]

using an OAG, do you get issues with trying to locate a good star to guide off ? i am not attached to using the SW80 as a guidescope ... looks like it will be up for sale soon.
In reference to what i want to image, it is definitely DSOs, i am not after a solar system scope (although i will take a few pics of the planets) i am extremely interested in shooting galaxies (on a budget). i understand i will eventually have to upgrade the camera, mount and scope to improve but you all have to start somewhere.

[alistairsam]

hi,

with an OAG, you will need a sensitive guide camera for sure.
the main two contenders are the QHY5-L2mono and the Lodestar.
the lodestar is twice the cost of the 5L2.

The other option is to use a 50mm guidescope which quite a few use with success.
Justin(tillbrook) uses one with his 8inchF4 with very good results. but it may be a bit too small an image scale for the 10inchF4.

if go you 10inch, I'd suggest an OAG, else a mini guidescope for the 8inch would do.

As for FOV, the 600D is an 18MP camera in an APS-C format.
so if you do crop the image, you will still have a decent enough resolution without causing pixelation.

one thing to remember with the OAG is spacing.
you will definitely need the MPCC or similar coma corrector. if MPCC, the requirement is 55 mm to the sensor face.
the dslr has a 45mm depth. if you get the slim OAG, it will add 10mm. now you won't have room for an EOS-T2 adaptor.
so you need to get OAG's that have an EOS adaptor instead of the T2, or get a spare EOS adaptor.
that way, you'll maintain the 55mm spacing to the coma corrector.

telekskop express have some very good products that a lot of us use here including myself.
this is the 9mm Off axis guider that you can get with an EOS adaptor to maintain 55mm. also comes with a M48 telescope side adaptor which is useful with the MPCC mark 3 as you get a larger opening at the telescope side to accomodate the steep light cone of the F4.
http://www.teleskop-express.de/shop/...ial-Offer.html

if you want to maintain a T2 thread at the camera side, you could use this zero profile adaptor and your standard EOS to T2 with the OAG. this will still maintain the 55mm.
http://www.teleskop-express.de/shop/...S-Bayonet.html

These are a few galaxies taken by Ray who has done some stunning work with his 8inch F4. Point to remember is his camera is the Starlight Express CCD's using the very sensitive Sony sensor, so dslr results will be quite different.
these are crops so gives you an idea of scale.
and his chip is a lot smaller so smaller FOV than yours.

http://www.iceinspace.com.au/forum/s...92&postcount=1
http://www.iceinspace.com.au/forum/s...25&postcount=1
http://www.iceinspace.com.au/forum/s...97&postcount=1
http://www.iceinspace.com.au/forum/s...38&postcount=1

cheers
Alistair

edit: I've never had issues getting a guide star with my OAG and the qhy5L2 or the Lodestar from light polluted sites.
key is the sensitive camera. look for the QE values (Quantum efficiency. higher the better)

[acarleton (Aidan)]

Thanks for all the info guys, i am about an hour from making a purchase and it looks like i will get the 10" f4 and look at off axis guiding.

[alistairsam]

hi,

you do need to keep any eye on the overall cost. all the bits can add up pretty quick, I'd suggest shopping around with different vendors to compare prices before committing, whatever you save is money earned!!
keep an eye on the classifieds here, sometimes very good bargains come up.

good luck.

Cheers
Alistair

[Marios (Marios)]

Have a look at Andrews Communication the GSO newtonians are the same as the Bintel. The also have newer models and Carbon fiber types.

http://www.andrewscom.com.au/site-section-10.htm

[acarleton (Aidan)]

I didn't know about this place ...

Originally Posted by Marios

Have a look at Andrews Communication the GSO newtonians are the same as the Bintel. The also have newer models and Carbon fiber types.

http://www.andrewscom.com.au/site-section-10.htm

[acarleton (Aidan)]

Purchase complete, now bring on the clear skies

[alistairsam]

Congrats
Unfortunately new toys attract clouds..

How about the corrector and oag and so on.
Cloudy skies are a good time to read up on collimation with a cheshire