Ken Mitchell

Thanks a lot for the help!

Last question(for now), even if the Star Adventurer doesn't guide in dec it is still important to enter the correct dec degrees? Will these values be taken into account when correcting for RA?

Would you happen to have some information on how this operates, just to have an idea what phd is doing.

Ken 

Ok gotcha. I understand now.

I assume you can consult the dec degrees with Stellarium or similar SF? So for every target I image it is best to change the dec degrees in phd2?

Ken

9 hours ago, kens said:

When you are connecting click the settings button as shown and you'll get the options for 8bit and 16bit

NGC7822 is at dec 67 which is not very extreme although PHD2 recommends against it. At that declination the RA pulses need to be 2.5x longer than at the equator for a given movement. In the step size calculator make sure all the values are correct and enter the maximum 60 degrees declination. Then manually add 25-30% to the calculated value.

When you are very close to the pole (say > 85 degrees) you can turn off RA guiding 

You'll also want your guide star to be close to your target as the relative motion difference between the two will be greater if they are at different declinations. You also want to be sure not to chase the seeing as your mount will be making large movements in RA to correct for small star movements on the sensor.

These are the default values, I only changed the FL. What values should I change here?

Do you suggest I try to turn of guiding for that target and see how well it performs?

Ken

16 hours ago, kens said:

If you are not guiding in Dec then you do need very good PA. As a guide the amount of drift you get will be equivalent to the PA error over a period of 6 hours. If you want less than 1 arcsecond of drift on a 5 minute exposure your PA needs to be in the order of 1 arcminute. You can use PHD2s drift alignment tool to adjust your PA.

Getting a good focus on the guidescope will help a lot. Is there a focus ring near the objective lens you can use? Also, since you have the ASI120 you may be able to use a threaded connection. Then you can use spacers to adjust the focus.

To choose a guide star you can either let PHD2 choose one (Tools > Auto select star) or if you do it manually, display the star profile and ensure that it does not have a flat top. You can adjust the camera gain if there are no suitable stars. Also, when you connect the camera, select 16 bit mode. It tends to give better profiles for guiding.

Since you are not guiding in Dec the guide star does not need to be very close to where you are imaging. Obviously not pointing 90 degrees away or anything like that but within a few degrees wont make much difference. 

Thanks for the information. Where do I choose 16bit mode? Can't seem to find it.

Would you happen to have any advice on guiding while imaging targets close to the celestial pole? Obviously you can't choose Polaris but even stars in the vicinity don't work. Calibration fails because the star didn't move enough. And when I choose a star somewhat off axis from where the main scope is aiming I get startrails. I don't think it's because "bad" PA but rather because the guide doesn't compensate correctly for the guidestar is off axis. Could that be?

My target is ngc 7822  if that helps.

Ken

New one from the last 2 nights and second time using guiding with the SA.

All went well except for the winds on night 2 which gave some vibration to some of the frames and didn't include 50 minutes into the total integration. Might put a heavier load on the tripod and see if it will changes things.

First night got 39 frames of each 5 min and second night 38 frames of each 5 min. A total of around 6hrs and 20min.

TS72 APO + TS flat72 with Nikon d610

77 x 5 min guided

Tracked with the SA and guided with TS 50mm mini guidescope with asi zwo 120mc-s

Stacking was done in DSS and processing in Photoshop.

Ken

On 11/11/2018 at 21:50, kens said:

Looks like the Star Adventurer will only accept guide commands whilst in celestial tracking mode so you can't test it in daylight.

PHD2 will start calibrating automatically when you start guiding. For RA only guiding you need to turn off Dec guiding as shown below. Also, you can find the PHD2 manual at https://openphdguiding.org/manual/?section=Introduction.htm

Personally I would not recommend using PHD1 as it has not been supported for many years now

Managed to get it up and running and had some decent guiding results I believe.

Got up to 5 min without startrails. Did a few tests yesterday night to see how well it reacted to a good or bad PA. I've heard people say you can do a rough PA and still get good guiding. Maybe that's true for a mount that guides in both axis? but from what I've tested it seems that it's pretty important you have a good PA with the SA as it doesn't guide in dec. 

My PA was slightly off and got trails even with 2 minutes. I could see the guidestar drifting, as with a good PA the guidestar stays in the middle. Probably because the SA can't compensate for dec.

The things that are most difficult in the guide process is locking onto a guidestar and getting focus right with that particular scope. I now wish I'd payed 50$ more and get the one with the microfocuser. The one I have now is push and pull and find it a bit hard to operate. 

Any tips on choosing/acquiring a good guidestar? It seems like it's not always the best option to choose the brightest in the sky, or am I wrong? 

How important is it to choose a star in roughly the same area you're imaging in?

Ken

6 hours ago, 8472 said:

That's impressive.

What are your skies like on the Bortle scale?

22 hours ago, Thalestris24 said:

Wow! Awesome! Must have been dark skies...

Louise

A decent bortle 4 sky in my backyard. 21.20sqm

First night out with guidesetup on the SA was a succes. 

41x 5min with TS72 f6 iso 800 with Nikon d610

TS50mm guidescope with zwo asi120mc-s

Thanks Dave,  now I know everything is connected correctly.

I will try with phd1 to see if it changes things when testing at daytime.

Ken

5 hours ago, kens said:

If you use ST4 you need to set the mount to On Camera. The further away the easier it will be to focus.

To test during  the day aim at anything you can get into focus on the camera. Turn on the cross hairs or grid  (View > Bullseye or View > Fine Grid). Set the manual guiding Guide Pulse Duration to its maximum (5000). Tools > Manual Guide to get the popup dialogue.

Click the various buttons and you should see the image move a small amount. The grid/bullseye makes it easier to detect the movement.

When I set the mount to On Camera, it says mount connected. But no matter what direction I click in the Manual guide screen, it doesn't move.

Should it work with the SA as it only guides in RA?

What else can I do to make it work? When I try to use calibrate functions in the tools menu it says, no calibration data available. Does this mean something?

Ken

Hi,

Couple weeks ago I've received my guide setup for the SA. Bad weather here didn't give me the chance yet to test it in the field. Next week there will be a (couple) of clear nights so hope to give it a go soon. I want to be sure that I have everything set up correct though.

This is what I did until now, I hooked up everything and launched the software. I can get a capture image on screen through the software so I believe it's recognizing the camera. I'm not sure if it is recognizing the SA mount as I can't find a way to test it. I tried to move the RA by the use of 'manual guiding' in phd2 but nothing happens. 

Is there a way to test this during the day and see if the SA is connected correct?

Do I need to connect the SA with USB to the laptop or just connect the SA-ST4-CAMERA and CAMERA-USB-LAPTOP?

I know there are members here that uses the SA with guiding so I'm hoping they could share their setup.

Thanks in advance.

Ken

PS.  my gear if it would help. TS72 with nikon ff, TS 50mm guidescope with zwo asi120mcs

I just debayered the sensor of my old camera, I believe all went ok. There are still some small parts left that I will clean next time.

My question is why are the images pink/blue and not black and white like in the OP? Do I need to convert it? I tried changing the wb but it always stays one color.

Thanks in advance.

Ken

Hi Louise,

Just read this post adn couple weeks ago I also decided to open up the SA and found exactly the same backlash on the gears as yours in the video.

Tried to adjust the gears and I believe it now has less backlash but it is still there. It also looks from your video that the smallest gear is "bad aligned" . Mine was positioned more on the inside. Not aligned with the gear next to it. I had to take out the motor to change the 2 screws holding the little gear. 

Tests showed that it didn't change much and still had the same accuracy as before. Did you managed to get rid of the backlash somehow?

Ken

22 minutes ago, Thalestris24 said:

That's quite darkish. I'd say I'm Bortle 9  

Didn't knew that existed ?

This is my last one taken with the TS72 on the SA

1 minute ago, Thalestris24 said:

Dark skies?

SQM 21.10 if that helps? I believe that is Bortle 4.

Ken

Thanks Louise!

This was with a Nikon d610, 120sec subs with total of 1,5hrs.

Ken

One from early summer with the SA and 200mm lens