Will an Auto-guider fix these star trails?

[Tropo-Bob]

I took this 2 min shot last night with my 115mm Vixen at ISO 2500.

Star trails can be seen. My mount is a 15 years old EQ5. If I upgrade to a mount with an auto-guider, will that fix this?

I don't really understand: Does an auto-guider control both motors to correct drift in both directions or only in RA? Also, besides having to buy an actually guide scope and autoguider, do I also need a laptop for this to function or does it do so without an external computer.

I think that the camera may have a tiny slip during the imaging. I currently use a 1.25" connection to the scope. Would I be better of using a 2" connection?

Help please!


PS: Image is The Helix Nebula.

[AdamJL]

Hi there Bob.

To guide, you're going to need a guide scope of some kind (and a mount that will accept guide pulses, as you say... I don't know much about that EQ5, but I believe it has an ST4 port which means it should be capable of guiding already.. but again this is on the current EQ5, I don't know if you have one without the ST4 port).

Your guide scope options are either a second smaller scope with a second camera, or to use "off axis guiding" which places a guide scope between your main scope and main camera at 90 degrees. it uses a small prism to deflect light from the main scope to the second camera so it can control guiding. Either way, you're going to need a second camera (thankfully, guide cameras are fairly cheap)

The "main" guiding is usually in RA because that is the part that moves. Dec is more of a pointer and in theory should be perfectly locked onto your target, but it can drift due to a few issues, like poor polar alignment for example. So a good mount will allow guiding in both RA and Dec.

You don't need a laptop, but you'll need some sort of compute platform to control the guiding software (PHD2 is the king here). You can of course buy a laptop, but I find them a bit cumbersome, personally, having used one for a couple of years.
One option would be to get a mini-PC and mount it on or near your mount. You can remote into the PC from the comfort of your house :)
Or another option is the ASI Air platform, which has guiding built in (based off PHD2). If you're using a dedicated astronomy camera, you'll need ZWO cameras for this to work as it doesn't accept other brands cameras. DSLRs should work on ASI Air (though I have never tried)

As for slipping, well yes, the beefier connection, the better! When I shot with a DSLR, I used M42 connections.

and PS, your shot isn't that bad. I was expecting more trailing.

[AstroJunk]

The biggest issue in that image was the slip causing two disinict star images and it may even have contributed to the slight elongation. Fix that issue first and have another go.

A well polar aligned scope can do suprisingly well without guiding when exposures are reasonably short. Up your gain to ISO 6400 and try at 30s, 1m, 2m and 5m exposures and compare the results.

[bojan]

"Double" star image could be because of scope imbalance.. It should always work against tracking direction, and only slightly so.

[multiweb]

Yep. Get a small guider second hand from the classifieds along with a pick up prism and you'll never look back. :thumbsup:

[Tropo-Bob]

Thanks, I had seen a Utube video that said the opposite. So because the 115mm was a load for the 115mm, I followed that. Thanks for the tip.

Astrojunk: I have had slippage issues, so I will change over to 2" connectors. That way, I take out an unnecessary step of a 1.25" adaptor to fit the camera.
Hopefully, this will make it more secure.

Adam: Thanks for the info. Unfortunately, my EQ5 does not have a ST4 port.

I am treating your info as useful in the longer term. However, I now realise that I need to perfect a few more basics before deciding if I will go down that path.

[xelasnave]

Bob I have yet to get into auto guiding seriously...for various reason ( quick setcups and poor polar alignment) I would go for short subs to avoid star trails..which worked..however I found some advantage over seeing with shorts subs ( 30 seconds) and high gain.
All my recent posts are 30 second subs and high gain...it isn't not perfect but it really is working for me...my recent helix I said was three hours but it was actually 2 hours ( I made a mistake) ....the last trifid was 600 subs at 30 seconds...I have three guide scopes and cameras and sure soon I will incorporate them.
The other advantage of no auto guide is you will get to know your mount much better...note which way yourctrails go..most likely East West ie RA and so you adjust balance which can e tedious but very worthwhile...if it is North South almost certainly it will be poor polar alignment...
But I suggest seeing you are doing so well with your images so far to try shorter exposes, better balance and spot on polar alignment....with 30 seconds it is easier to throw out not so good subs, which I believe is the key...and you will notice how things change over just 30 seconds.

The number of subs you take should only be limited by what your computer refuses to stack...pick a number higher than usual and each night try to go higher ... the more you get the move chances of 3nding up with a near perfect batch.

Good luck and keep posting I love watching your progress.

Alex

[Tropo-Bob]

Thanks Alex.

What program do U use to do your stacking?

[xelasnave]

There is only one isn't there.;).Deep Sky Stacker.:thumbsup:...the free version.


Alex

[Tropo-Bob]

Well, I have muffed some images together and ended up with a way too big file, so I have shrunk it, way too much. I am using Deep Sky Tracker for the first time.

Also, when I tried to edit the photo in Paint and load into Pictures, it still has the Microsoft-Photo-Viewer Frame around it. I tried to load the image onto this post, but it is a TIFF File; what ever that is.

Ha, progress at a snails pace.

It was fun taking the images, but the stacking and processing has me :confused2:.

Oh well, tomorrow is a new day ....

[xelasnave]

Don't give up... once you get it going it will be easy.

Start by stacking only say five subs...you should get a result which you save and then work on it is a processing program.

But do five and if it does not work tell us and we should be able to advice what needs fixing.

Alex

[Tropo-Bob]

Thanks Alex,

I will give that ago.

Its been great weather here, so I was out again last night.

This time, I used my 100mm Tak. My EQ5 mount seemed to handle that far better than the prior, heavier scopes. Even so, I can see some inconsistencies in the tracking. I can do a few images of the same exposure, yet they can be quite different.

On the positive side, yda I attached an app to smartphone which allows me to activate and close the camera shutter remotely. Also, my new way of connecting the camera to the scope was a great success.