Skywatcher Evostar ED80 with a Skywatcher ST80 as a guiding telescope

[stevewanstall]

I had a bash at imaging a couple of years ago, but found that an 8inch reflector with ST80 was too big for my Celestron CG5-GT mount.  The trials and tribulations of that are here : I thought I would tell you what has happened now that I have swapped the reflector for a Skywatcher Evostar ED80. 

Basically, it now tracks! I am using a QHY5II- C camera in a ST80 as the autoguider.  I have a Nikon 5300 attached to the ED80 and the ST80 is piggy backed. My routine is:

1. Polar align the Celestron CG5-GT mount

2. Align it using 3 stars (e.g. at the moment, Arcturus, Mizar and Deneb)

3. Using a bahtinov mask to focus.

4. On the laptop, use ASCOM to link the scopes/cameras to Cartes du Ciel and PHD (the autoguiding software)

5. Choose a guding star, spend around 60 seconds calibrating PHD.

6. Start imaging!

7. Take darks, flats (i use a white screen app on a tablet) and bias.

 

I know the quality is no where near what people get with cooled CCD's and filters, but I do feel I am finally making progress. This is last nights effort, before the clouds rolled in (so, 9 x 180 seconds, with UHC filter):

 

 

[PESKYWAABBIT]

Im loving this image, great progress Steve.

I also have a 8" reflector for DSO photography and am considering going down the refractor route instead, my main reason is that I can't seem to get my calibration frames (at least the flat frames) sorted till the next day due to the size of the OTA I have not sorted a light source out that big yet.

I will be following this closely as I may end up doing what you are doing too! What would you say have been the benefits of moving to a refractor for DSO imaging?

Cheers,

Tom

[gnomus]

Your 'journey' so far is almost identical to mine.  I started off trying a C8" on a CGEM (and guiding via the finder/guider!!).  It was .... shall we say ... 'testing'.....   Things started to pick up for me when I took the C8 off, and bought an ED80.  You are at the start of a very slippery slope.    The image is great (although to my eyes, upside down)  Clearly at only 27 minutes it is going to be very noisy, but you know what you can do about that.

In your signature you impy that you have the 8", the ED80 and the ST80 all loaded onto the mount simultaneously.  If this is what you are doing then I would counsel against it - I doubt the mount could cope.  There is some slight trailing in the image and overloading might account for that.

I found polar alignment to be a real nuisance when setting up and tearing down every night, and if I was still doing that I would be tempted to invest in one of those Polemaster things (indeed I have one).

Finally, I wonder if you have thought about trying SGP.  Using this program, my routine is a bit simpler than yours.  It is:

1) Fire up computer and connect SGP to equipment

2) Press 'Run'

SGP comes with a relatively easy to set up plate-solving feature.  As such, when I press 'Run' SGP will slew to my target object.  It will take a 5 second exposure and determine how close I got to target - it then makes small corrections to get me to within (usually) less than 10 pixels of the target.  Each time it does the platesolving it sends a 'Sync' to the mount.  Once it is happy that I am close enough it will start off PHD2 and start the 'sequence' I have set up.  The great joy of platesolving is that (asuming you have the camera on the scope in the same orientation - and I would suggest one of the orthogonals is best) it makes it very easy to image the same target night after night, thus building up a decent amount of data.  Processing becomes much easier when you have lots of subs.

Great effort and good luck.

Steve  

PS: There is a box that you can tick within PHD2 that allows you to reload a previous night's calibration.  So as long as things are pretty much as they were last time (same scope, camera and so forth) PHD does not need to calibrate each and every time.  If you are calibrating PHD2 within 60 seconds then you are doing very well.  It normally takes me ~48 x 4-5 seconds = 3-4 minutes.  You should be aiming for at least 12 steps forward and back in each axis, and don't make the mistake of using short PHD exposures - that way you are 'chasing the seeing'.  Guide camera exposures of 3-5 seconds are usually what you are looking for.

[RayD]

Really good start, particularly with relatively limited data.  Well done.

[Firas]

On 8/29/2017 at 12:50, gnomus said:

Your 'journey' so far is almost identical to mine.  I started off trying a C8" on a CGEM (and guiding via the finder/guider!!).  It was .... shall we say ... 'testing'.....   Things started to pick up for me when I took the C8 off, and bought an ED80.  You are at the start of a very slippery slope.    The image is great (although to my eyes, upside down)  Clearly at only 27 minutes it is going to be very noisy, but you know what you can do about that.

In your signature you impy that you have the 8", the ED80 and the ST80 all loaded onto the mount simultaneously.  If this is what you are doing then I would counsel against it - I doubt the mount could cope.  There is some slight trailing in the image and overloading might account for that.

I found polar alignment to be a real nuisance when setting up and tearing down every night, and if I was still doing that I would be tempted to invest in one of those Polemaster things (indeed I have one).

Finally, I wonder if you have thought about trying SGP.  Using this program, my routine is a bit simpler than yours.  It is:

1) Fire up computer and connect SGP to equipment

2) Press 'Run'

SGP comes with a relatively easy to set up plate-solving feature.  As such, when I press 'Run' SGP will slew to my target object.  It will take a 5 second exposure and determine how close I got to target - it then makes small corrections to get me to within (usually) less than 10 pixels of the target.  Each time it does the platesolving it sends a 'Sync' to the mount.  Once it is happy that I am close enough it will start off PHD2 and start the 'sequence' I have set up.  The great joy of platesolving is that (asuming you have the camera on the scope in the same orientation - and I would suggest one of the orthogonals is best) it makes it very easy to image the same target night after night, thus building up a decent amount of data.  Processing becomes much easier when you have lots of subs.

Great effort and good luck.

Steve  

PS: There is a box that you can tick within PHD2 that allows you to reload a previous night's calibration.  So as long as things are pretty much as they were last time (same scope, camera and so forth) PHD does not need to calibrate each and every time.  If you are calibrating PHD2 within 60 seconds then you are doing very well.  It normally takes me ~48 x 4-5 seconds = 3-4 minutes.  You should be aiming for at least 12 steps forward and back in each axis, and don't make the mistake of using short PHD exposures - that way you are 'chasing the seeing'.  Guide camera exposures of 3-5 seconds are usually what you are looking for.

This was very informative description of plate-solving!

I'm going to be using it as soon as my G2 8300 arrives next week. But I need to ask you Gnomus, unfortunately Polaris isn't visible from my balcony and thus a precise polar alignment is not doable unless if I Drift align which I haven't tried yet. My solution was to be dependent on my SBIG SG-4 auto guider. I do a rough alignment to north and then I guide. this allowed me to get 15 minutes subs with no apparent trailing although I fear some field rotation but I only saw it once in the background where noise looked like a Van Gough clouds in its circular shape. My question is, will I be able to plate solve successfully going this path? 

Thanks 

Firas 

[gnomus]

1 minute ago, Firas said:

This was very informative description of plate-solving!

I'm going to be using it as soon as my G2 8300 arrives next week. But I need to ask you Gnomus, unfortunately Polaris isn't visible from my balcony and thus a precise polar alignment is not doable unless if I Drift align which I haven't tried yet. My solution was to be dependent on my SBIG SG-4 auto guider. I do a rough alignment to north and then I guide. this allowed me to get 15 minutes subs with no apparent trailing although I fear some field rotation but I only saw it once in the background where noise looked like a Van Gough clouds in its circular shape. My question is, will I be able to plate solve successfully going this path? 

Thanks 

Firas 

There is a Drift Align tool within PHD2.  It is very easy to use.  Just remember to leave the thing running for a minute (or two) before making an adustment (otherwise you end up chasing periodic error).

 

[Firas]

1 minute ago, gnomus said:

There is a Drift Align tool within PHD2.  It is very easy to use.  Just remember to leave the thing running for a minute (or two) before making an adustment (otherwise you end up chasing periodic error).

 

Oh, you probably don't know that the SBIG SG-4 is a standalone auto guider. I don't use PHD! My question was whether it will be possible to do plate-solving with a rough polar alignment. 

/Firas

[TareqPhoto]

One day i will have another scope then i can put my ST80 as a guide scope, i bought one guide scope to go with my ST80, but i can't put much hope on that setup, but i have no choice now but to use my ST80.

I wanted to use one of my Canon lenses but piggyback Canon lens is something i need to know.

I try to get tools one by one so i can do guiding and imaging with their own tools, also i got Ha filter finally, which means i have to find DSO that depends on Ha more.