Advice needed on equipment

[RobertI]

Hi all,

I’m looking for a bit of advice about my setup for electronically assisted observing.

Just to put you in the picture I’ve had a go with lodestar live and been chuffed with the initial results. For me it has all the ‘immediacy’ of visual observing, but with super sensitivity AND a permanent record of the night’s activities to take home!! So I really want to concentrate on this over the coming season.

I’m looking to use my 66mm refractor (giving a FOV of 55 minutes with the lodestar) and possibly the C8 with a 0.63Focal Reducer (giving a FOV of 17 minutes with the lodestar).

I currently have a non-goto CG5 which is fine for wide field imaging with a DSLR but is a bit of a faff to  transport by car and set up for a quick observing session. For electronically assisted observing I thought I could use a much simpler mount, possibly alt-az to remove the need for counterweights and polar alignment. I was thinking perhaps a Nextstar SE mount which seems big enough to take a C8 and has goto which I think may be useful for finding objects on the small lodestar chip (although I am pretty adept at star hopping from 30 years of practice!).

So my questions are:

• What do you think of the proposed scopes to be used for electronically assisted observing in the field (or in a field!)?
• What are your opinions on the idea of an alt-az  mount to make setup easier? Will field rotation become an issue with an alt-az, especially when the  ‘live stacking’ feature comes along (looking forward to that!)?
• Have you any recommendations on alt-az mounts sub £500? The main alt-az candidate seems to be Celestron Nextar SE? Will it be stable enough and track accurately enough?
• Do I need GoTo? If so would the Nextstar SE have the GoTo accuracy required especially when using the C8?

Any help or thoughts really appreciated.

Cheers

Rob

[Martin Meredith]

Hi Rob

On the field rotation point, I can get away with 60s exposures on an alt-az mount with my 80mm refractor (FL 480mm). I guess Paul will chime in re the stacking feature, but I imagine it handles field rotation as he has been test stacking some of my sequences where field rotation will be present.

On GoTo, one alternative is to use an e-finder (essentially a wide-field finder such as Lodestar+camera lens) as shown in some of Nytecam's posts. But that requires a separate camera or swapping -- not good for focus. 

On GoTo accuracy, it doesn't have to be too important, at least for the larger FOVs. One of the joys of near-live viewing is that you can star-hop via the screen image. I've done this on many occasions and it is just as much fun as doing it at the eyepiece ;-) Sensor-assisted viewing goes so deep that I'm frequently looking for objects which are not in my mount's GoTo database anyway.

Looking forward to seeing some of your images! Which Lodestar model do you have?

Cheers

Martin

[RobertI]

Hi Martin,

Thanks for the response - much appreciated. Interesting to hear about viewing objects which are not in the mount's database - do mounts generally allow the input of an objects coordinates? (sorry I've never had Goto so I'm a bit ignorant!). I have the mono version of the Lodestar (not the latest X2). I have been using it as a guide cam, and often found that it was clearly showing the object I was supposed to be imaging before the DSLR had completed it's first sub!! So I'm excited to see what it can do.

Rob

[Paul81]

Hi Rob,

Glad to hear you have been enjoying Lodestar Live! 

I would say the scopes you have are a good selection for video astronomy. The real key is focal ratio, the faster the better. There is a 0.33x focal reducer which I think works with C8, and I also believe the Antares (or other popular UK retailer branded versions) 0.5x reducer works too. The nice thing about the small sensor size of the Lodestar is that you can push most of the optical trickery to its limits without optical aberrations taking over as with larger sensor sizes.

As for mounts, Alt-Az is fine. I have been doing all my VA and live stacking testing with Alt-Az images. You will get 'effects' around the edges after a while, but it doesn't spoil the main object if it is well centred. You need a mount that can track sufficient for about 30s without producing too many eggy stars. The az-eq6gt I have produces the odd eggy or failed 30s exposure in alt-az, but generally most are just fine (and thats with the big Vx10 on it). I think the NexStar SE is pretty good, but Ive not actually used one. I know the iOptron Mini Tower gets rave reviews and is really quick to setup - there is one of ABS at the mo for around 500 GBP.

GOTO is useful, I use it for VA but I might give Martin's suggestion of star hopping a go next time - funny I never really considered doing that! Bring back some of the fun of visual! 

I am hoping to have 0.9 out for release on Sunday (with live stacking).... There is one small issue I want to look at and I want to cobble together some notes on how the stacking works and how to use it etc. I still have some other things to sort out with the live stacking, but it is at the point now where I think it needs some user run-time to flush out bugs and get more confidence in the algorithms. Fingers crossed I get some time to work on it between now and Sunday (the day job has been hectic recently hence things slowed down) so watch this space...

[Tinker1947]

Why not go for a Reflector 8" and a HEQ5 , you won't need a FR but a Coma Corrector might be handy, faster scope so shorter subs, will run EQMod so finding stuff will be easy........

[RobertI]

Cheers guys,

Paul - thank YOU for creating Lodestar Live!! It's good to know that AZ is ok for this kind of work, I will definitely take a look at the Ioptron mini-tower. The 0.33 FR is a good idea I had not considered, as it's usually discounted for imaging and often visual for the reasons you mention,  but I can see how it would work with a small chip. Great to hear Live Stacking is nearly here!!

Tinker - thanks for the suggestion, what I was really after was getting maximum portability, hence looking at AZ mounts in order to dispense with counterweights and sticking with compact refractors and SCTs.

Cheers

Rob

[Peter Drew]

Rob. The 0,33 reducer works great on a SCT with a small chip camera. Not suitable for visual or DSLR cameras.    

[DoctorD]

Hi Rob

I have used the minitower with my C8 and F3.3 reducer and it worked fine upto about 30s - at 60s I began to see field rotation, however this will depend pip where in the sky you are pointed.

Very quick to set up but in the end I traded in for a HEQ5 so I could consider longer exposures and tracking as well as use for VA and shorter exposures.

Have a look at my gallery to see what is possible.

Clear skies

Paul

[RobertI]

Thanks again guys. Paul - some really good examples of what's possible in your gallery, thanks.

As a result of your excellent advice I have decided  shall to stick with my CG5 for a few more months whilst I get acquainted with electronic assisted observing - and I'll try and test drive a mini tower in the mean time. I keep looking for a reason to change my olde worlde non-goto CG5 for something more interesting but can never seem to come up with a convincing argument!