Upgrade mount or start autoguiding?

[Ken Mitchell]

Hi all,

Need some advice on my next step into the world of AP.

I currently(for the last 3 years) own a Star Adventurer tracking mount and use it with a ff Nikon and TS72mm refractor. I have managed to get some decent results with this. I'll add some samples at the end of the post.

I usually take subs at 60sec but with a loss in frames around +-40% or sometimes even more and more than half of the subs have startrails.

I'm very familiar with the PA on the SA and take my time to be sure I'm spot on. I count a full hour(while imaging) to get the perfect PA with every 10-15 min readjusting/finetuning the PA. Usually after that, Polaris stays at exactly in the same spot throughout the night. So I'm pretty sure that the rejections aren't because of a bad PA.

I guess 60sec at 430mm is probably at the limit of the mount. I've done up to 3 minutes with very minor trailing but than I definitely get 60% or so rejected frames.

 

Now my question is, I'm a bit tired of tossing out all those hours/frames and would like to eliminate this problem or at least reduce all the wasted frames. Reducing exposure time is an option although not so interested in with the f6 scope.  

So other options are, buy a new tracking mount, which will probably be an SW eq5 pro, or get into guiding.

As guiding option for the SA, my first choice would be the zwo 30mm f4 guidescope( I've read here it's perfect for the SA) with an ASI120MC-S camera.

What is the best thing to do? Will upgrading to an eq5 give me better results, so less frame rejections? 

Or is it more wisely to get myself into guiding and achieve better results this way? Guiding is obvious the cheapest option for now and maybe this will satisfy me enough with the SA for a while and get better in AP in general?

 

Also to add: Would guiding with the SA give me the option of starting imaging with narrowband?

 

Thanks in Advance

Ken

 

Some of the results so far with the 72mm

 

 

[jjosefsen]

First of all you can be very proud of those images!

I don't know much about the star adventurer, but I assume it has an autoguiding port, and can cope with the weight.

In terms of progressing with gear, at some point you will probably want to guide, irregardless of mount, so why not go for the guiding setup now? I think it is the smart move. And if you are going to upgrade the mount don't go for the eq5, go straight to the heq5, it is much better!

I had an eq3 which was a terribly mount for AP.. But when I bought my guiding setup I went from tossing 40-50% of my 45-60 second subs, to getting 70-80% percent keepers at 300s.. It really is one of the biggest upgrades you can get!

When you finally decide to upgrade the mount, you can just swap over the guiding gear and use it again.. But make sure the guide scope is firmly secured, it must not be able to move one iota in relation to the scope. Also look at getting sharpcap and using it for polar alignment, once you have the routine down you should have good PA in 5-10 minutes each session.

Good luck! ?

 

[Synchronicity]

I've only been doing this for a few months, having bought an Esprit 80 and an EQ5 mount before I really had enough experience to know different.  I hadn't intended to start guiding but spotted a good deal and couldn't resist.

I'd suggest thinking ahead and making your next purchases with a view to the long term.  Do you plan to get a bigger, heavier scope? Maybe want to mount two scopes... stuff like that means a bigger more capable mount
The star adventurer is quite portable, is that important to you?  If so then an bigger, heavier mount will be limiting as it's harder to move around.
I'm in a Bortle 8 area but 20 minutes away is Bortle 4, so I'm aiming to travel there as much as possible.  Because of that I've decided to keep my EQ5 and have stripped and tuned the mechanics so that it now can give me 5 minutes guided - maybe more. 
I'd suggest that guiding is a sensible next step as it should help you to keep more of your images and you will be learning skills that are relevant whatever mount/scope you end up with.

I'm wondering about where you say you are fine tuning the PA every 15 minutes or so.  I'm fairly sure that with the setup you have there should be no need to tweak it once set for the night.  Have you checked that there isn't any small movement eslewhere in your setup?  The tripod shifting a little as the weight distribution moves or as it settles into soft ground, things like that could give a bit of trailing too.

Hope this helps - or at least doesn't hinder ?

Michael

[don4l]

I'd also advise to go for the autoguiding option.

 

I have an EQ6 and I cannot keep all of my 60s subs.  I don't think that you would gain as much from a bigger mount.

 

Those are some brilliant shots.  The M33 is superb!

 

[upahill]

First, amazing shots!

I'm a beginner but personally my ease of imaging and results improved significantly with autoguiding, and if you change the mount in the future the gear will be transferable and always used so that would be where I would put my money.

I imagine even with perfect polar alignment you are going to be fighting mechanical inaccuracies etc without guiding too - for me even with perfect PA I would get trailing too above 60s - and it was spend money getting the mount perfect (not sure thats possible) or use autoguiding to compensate.

[ollypenrice]

Autoguiding is the life-blood of astrophotography. As soon as you approach telescopic resolution you need it. (Let's ignore the encoder-guided mounts which are clearly way out of an HEQ5 budget.) The trouble is that the SA is only equipped with a single axis guiding option. With perfect PA theory says that no guiding in Dec should be necessary. Experience, however, says that it is. Nevertheless, given the high standard of your images (indeed very high) single axis guiding would be surely a big bonus and you could keep the autogiuder when you move up to a larger mount. (As I suspect you will because you've clearly gone into all aspects of AP carefully in order to produce results as above.)

Autoguiding turns a £1000 mount into a £10,000 mount for most purposes. It's inexpensive, elegant, easy and effective. On top of that the best software is free. Just do it.

I'm not sure about your PA procedure. Polaris contains virtually no useful information about RA because it is so close to the pole as to describe only a tiny circle during the sidereal day. I suspêct that the DARV method might serve you well: https://ideiki.com/astro/usersguide/darv.htm

Olly

[8472]

Guiding certainly makes a difference with the SWSA, particularly with longer FL. I discard far fewer subs. But the mount has it's limits.

Some of my guided subs are now long enough to exhibit star bloat, so as a result, i now need shorter subs.

Oh, the irony.

[ollypenrice]

3 hours ago, 8472 said:

Guiding certainly makes a difference with the SWSA, particularly with longer FL. I discard far fewer subs. But the mount has it's limits.

Some of my guided subs are now long enough to exhibit star bloat, so as a result, i now need shorter subs.

Oh, the irony.

Or a filter for the guide camera?

Olly

[Ken Mitchell]

Thanks a lot for your replies, very useful information here!!

My decision is clear now and will go for the guiding option with an later upgrade of the mount.

What are your opinions on the set up I mentioned?

ZWO 30mm f4 https://www.firstlightoptics.com/zwo-accessories/zwo-mini-guide-scope.html 

with a ASI 120MC-S  https://www.firstlightoptics.com/zwo-cameras/zwo-asi120mc-s-usb-3-colour-camera.html

Should this be a nice introduction into the world of guiding? Also just another question regarding the asi120, what purpose could this camera also serve besides a guidecamera?

 

On your questions regarding the PA on the SA. 

After placing Polaris in the right spot I've encountered , on several occasions, a small "drift" of Polaris.

I place Polaris right on the middle line of the circle(red dot at 9 oclock) and after a while it moves at the position of the two other red dots. 

(the position of the dots on the hour is just a representation but the drift between the circles is correct). 

 

The polar scope itself doesn't show any signs of calibration error, so I believe that's not the source of the drift. 

I'll also say that after adjusting the position it doesn't seems to do any major difference. Well I'll have to do some more tests on that to be sure . 

Maybe the reason I do the adjustment is because I don't mind doing it and euhm well at least it gives me the feeling I'm doing something right here.

added : Forgot to mention that I can also see a small drift in the images ( probably at the same rate as Polaris), as it's just another star in the fov)  This makes it suspicious that the PA isn't perfect.

That aside.

 

So yeah thanks all for your input, much appreciated!!

If anyone wants to share their knowledge, tips, what to expect,... on guiding (and software) I'd love to read it as this is all new terrain for me.

 

Ken

[Ken Mitchell]

5 hours ago, ollypenrice said:

 

I'm not sure about your PA procedure. Polaris contains virtually no useful information about RA because it is so close to the pole as to describe only a tiny circle during the sidereal day. I suspêct that the DARV method might serve you well: https://ideiki.com/astro/usersguide/darv.htm

 

Aah yes, I've read about that method and tried it but it didn't work. I probably didn't understand it correctly or maybe it isn't possible with the SA? I exposed for 30sec pushing the left button that controls the RA and after that I pushed the right button for 30sec. It gave me a totally different pattern, and no matter how I changed PA the pattern stayed the same. 

Ken

[johngm]

I have Just recently purchased an Altair Astro 60EDF as a travel scope to accompany my SA. I made a finder guider using a skywatcher finderscope and an ASI120MM. I was imaging last week with guiding on this travel setup and was getting 5 minutes Subs with no trailing. The only wasted subs I had was from passing aircraft and satellites. So yes, by all means, definitely guide with your current rig, + it will give you an introduction into guiding.

I will soon be doing a review on this scope, which I highly recommend, and will be posting images of my setup. 

 

John

[johngm]

I forgot to mention, I use a polemaster for polar alignment

John

[kendg]

If I read your procedure  right for polar alignment, you always put Polaris at 9 o'clock and it drifts.

Remember, Polaris revolves around the pols so you need to put is at the correct position around the circle.

A good app will help you get the right position for Polaris at the current time you are doing the PA. 

I use an app called Scope Companion on Android. 

[Ken Mitchell]

16 minutes ago, kendg said:

If I read your procedure  right for polar alignment, you always put Polaris at 9 o'clock and it drifts.

Remember, Polaris revolves around the pols so you need to put is at the correct position around the circle.

A good app will help you get the right position for Polaris at the current time you are doing the PA. 

I use an app called Scope Companion on Android. 

No I must explained myself wrong. The image is just an example(to show the drift). I use the app from SW pole align for the mini SA. I align Polaris to the spot the app is telling me.

 

Ken

[oldannie]

I also use polemaster - brilliant piece of software.  Does exactly what it says with no fuss and great on-screen instructions.  I've used my ZWO asi  120 for lunar and planetary.

[oldannie]

ps.  polemaster does need the right adapter for your particular mount.

[johngm]

1 hour ago, oldannie said:

ps.  polemaster does need the right adapter for your particular mount. 

Yes I agree, I got the adaptor for the SA and actually got it to fit in the middle of the L Bracket  between the telescope and finder guider with a bit of fettling and the correct screw. Works a treat.

John 

[johngm]

My Travel Rig. Note the polemaster adaptor in the middle. Works great.

 

[ollypenrice]

5 hours ago, Ken Mitchell said:

Aah yes, I've read about that method and tried it but it didn't work. I probably didn't understand it correctly or maybe it isn't possible with the SA? I exposed for 30sec pushing the left button that controls the RA and after that I pushed the right button for 30sec. It gave me a totally different pattern, and no matter how I changed PA the pattern stayed the same. 

Ken

Essentially it has to work. It is no different from the classical drift method except that in the classical method you watch the movement of the star over time. In the DARV method you track the movement of the star over time while it is leaving an 'out and back' trace to help you be sure what's going on.

Olly

[Ken Mitchell]

52 minutes ago, johngm said:

My Travel Rig. Note the polemaster adaptor in the middle. Works great.

 

Do you balance in dec? My cam side is way much heavier, I've made some custom weight for the scope side but it adds and extra 600gr to the mount. What actual difference will it make if you balance dec on the SA? Is it worthwhile to buy an adjustable dovetail for it? What other options are there for balancing?

Ken

[johngm]

2 minutes ago, Ken Mitchell said:

Do you balance in dec? My cam side is way much heavier, I've made some custom weight for the scope side but it adds and extra 600gr to the mount. What actual difference will it make if you balance dec on the SA? Is it worthwhile to buy an adjustable dovetail for it? What other options are there for balancing?

Ken

Hi Ken,

I do, but my 60EDF balances great. Does it make a diferrence ? well, the SA doesn't move in Dec so probably not. So long as the RA is balanced, and your PA is good, it shouldn't be an issue.

John

[Ken Mitchell]

Thanks John for the advice.

Is that a mono or color camera you use for guiding? I've read it's best to use a mono for guiding as they are more sensitive? Is there any advantage? 

I will also get me an asi120 but not sure yet on color vs mono.

I'm also not sure on the scope yet, my initial idea was to get the zwo 30mm f4 but now I also have another option the TS 50 MM DELUXE MINI, f3.6 

Both are the same price range. The good thing about the zwo is that I don't need any extra accessories/adapters.  As with the TS one I'm not sure if the asi120 fits without any extras? Any advice, ideas or recommendations?

How about the connections to the ballhead?

 

Ken