Guiding trouble!

[Andreas]

After the frustration of not being able to get more than one - minute - exposures I decided to buy a guide scope and a guide camera.

Last night I had the chance to try it out, but I got disappointed when I still couldn't have much longer exposures than before.

I'm probably just doing wrong, but It's still frustrating when things never works!

This is how I did:

I polar aligned my mount, enabled sidereal, started the PHD software and selected a star for my guide camera to follow.

It seemed to work at first since I could hear small adjustments being made from the gear, but the results from the picture didn't show the same.

This is a 4 min exposure with guiding:

Also, I can't balance the DEC axis properly with my guide scope mounted on top of my main scope for some reason.

Do anyone know what I might have done wrong?

Could the balance of the scope affect the pictures?

Do I need to drift align as well when I'm using a guide camera?

All help is appreciated!

// Andreas

[Andreas]

Sorry for the extremely large picture btw

[Tinker1947]

If you could post the Auto Guider make and the Scopes/Mount used people will offer cures ...

Opphs its properly the kit in your Sig,,,,

[Andreas]

If you could post the Auto Guider make and the Scopes/Mount used people will offer cures ...

Opphs its properly the kit in your Sig,,,,

Yeah, It's in my sign

Qcam5 guidecamera and Celestron 80mm Guidescope.

[rfdesigner]

Firstly it's worth taking a screenshot of the Phd guide in action. Then we can all see what's happening a bit better.

Secondly, do you know which way is north in your image?.. i.e. are the stars not guiding in RA or DEC. Failing on just one axis is frustratingly common, Dec especially.. more so if it isn't balanced.

Just looking at the star wiggles I'd suggest you either have too much or too little gain. Possibly it just needs to settle down, so a second shot might look better.

If Phd can get past the 'calibrate' stage then it should all be working.. how did it fair with calibration?

Edit: Drift alignment is advisable even with guiding. If you don't you will end up with image rotation. However it is much slower than the drift in DEC you get without guiding.

Derek

[kookoo_gr]

for balancing your scope see thiw video

Other possibilities for your guide issues are major issues of flexure. the most likely are the following.

1. The focuser of the main scope is sloppy when you place the camera. make sure that when it is focused the focuser is locked into position

2. The rings of the main tube are not properly tightened at the dovetail bar, also the dovetail is not properly secure at the mount (even though it is a lognshot since your gear would have fallen). Make sure that these are thight, also make sure that when you place the scope at its rings they are tight so it doesn't slip inside the rings

3. the guidescope is not properly placed at the rings of the main scope, also the guidescope may not be securely placed at the guide rings, make sure they are tight.

4. the focuser of the guide scope has flexure as the main scope, also make sure that it is well focused for guiding.

5. the optics of teh main scope are not properly locked. e.g. the main mirror may be a bit loose or the the secondray (it's a longshot but check it)

6. your mount is not propelry tuned, if you know someone that knows how to do it tune it, if not make sure that you have elliminates all teh other problems

for your questions balance does make a huge impact at imaging along with drift alignment

[Andreas]

Firstly it's worth taking a screenshot of the Phd guide in action. Then we can all see what's happening a bit better.

Secondly, do you know which way is north in your image?.. i.e. are the stars not guiding in RA or DEC. Failing on just one axis is frustratingly common, Dec especially.. more so if it isn't balanced.

Just looking at the star wiggles I'd suggest you either have too much or too little gain. Possibly it just needs to settle down, so a second shot might look better.

If Phd can get past the 'calibrate' stage then it should all be working.. how did it fair with calibration?

Edit: Drift alignment is advisable even with guiding. If you don't you will end up with image rotation. However it is much slower than the drift in DEC you get without guiding.

Derek

Hi Derek!

Yea, I will enable logging and take some screen shots next time!

I'm not sure which way is north, but I think it's the DEC axis, which also is most reasonable since DEC axis was badly unbalanced.

When it comes to the wiggle, It could have been the dew on the mirror?

I'm not sure what you mean with the calibration, but the program told me it was guiding and I could hear small adjustments being done from the mount.

Btw, does the guide scope need to be aligned to the main scope, like the finder scope is?

// Andreas

[Andreas]

for balancing your scope see thiw video

Other possibilities for your guide issues are major issues of flexure. the most likely are the following.

1. The focuser of the main scope is sloppy when you place the camera. make sure that when it is focused the focuser is locked into position

2. The rings of the main tube are not properly tightened at the dovetail bar, also the dovetail is not properly secure at the mount (even though it is a lognshot since your gear would have fallen). Make sure that these are thight, also make sure that when you place the scope at its rings they are tight so it doesn't slip inside the rings

3. the guidescope is not properly placed at the rings of the main scope, also the guidescope may not be securely placed at the guide rings, make sure they are tight.

4. the focuser of the guide scope has flexure as the main scope, also make sure that it is well focused for guiding.

5. the optics of teh main scope are not properly locked. e.g. the main mirror may be a bit loose or the the secondray (it's a longshot but check it)

6. your mount is not propelry tuned, if you know someone that knows how to do it tune it, if not make sure that you have elliminates all teh other problems

for your questions balance does make a huge impact at imaging along with drift alignment

Hello and thanks for the great tips!

I will try them all when I get clear skies.

After the video I can now balance the DEC axis roughly, but It's hard to get it perfect since my guide scope is placed on the left side of the main scope which means that I have to put a lot of weight on the other side. (pretty hard to explain - I'll take a picture).

// Andreas

[rfdesigner]

When it comes to the wiggle, It could have been the dew on the mirror?

No. wiggle means the scope stopped pointing in the right direction. Blur is the result of dew.

I'm not sure what you mean with the calibration, but the program told me it was guiding and I could hear small adjustments being done from the mount.

Btw, does the guide scope need to be aligned to the main scope, like the finder scope is?

// Andreas

In Phd guide first you turn on the camera, then you ask it to 'calibrate' where it pushes the mount North, then South, then East then West. It watches which direction the star moves in the guide cam, then you can start guiding. If you didn't do this then you may not have been guiding at all (i.e. it might have been watching the star move east, then it ask the mount to move north... i.e. it simply isn't guiding)

Re scope alignment.. no, perfection is not required for guide scopes, but the nearer your guide star is to your image, i.e. the better they are aligned, the smaller the resulting errors. (from field rotation) Your primary requirement on a guide scope is that is absolutly never ever ever ever moves compared to the imaging scope.. I went over to an off axis guider specifically to elminate this kind of problem.

Derek

[earth titan]

I have to say, the guiding problems look more like a vibration problem. Their doesn't appear to be any consistency to the direction.

What have you got the mount stood on? Were you walking around a lot near the mount?

[rfdesigner]

I have to say, the guiding problems look more like a vibration problem. Their doesn't appear to be any consistency to the direction.

What have you got the mount stood on? Were you walking around a lot near the mount?

I have some shots just like this. They were a combination of incorrect polar alignement and no autoguiding, I think if it were wobble then you'd see a bright core and thin streaks (I have a few shots like that too), the point is the shot is quite long, so to have 'fat' wobble lines means it was pointing in the wrong direction for many seconds at a time, which leads me to point the finger at lack of guiding.

Derek

[Andreas]

I have to say, the guiding problems look more like a vibration problem. Their doesn't appear to be any consistency to the direction.

What have you got the mount stood on? Were you walking around a lot near the mount?

Hello!

The mount stood on my lawn as usual, so I don't know where vibrations would come from.

// Andreas

[kookoo_gr]

was it windy? newtons are sensitive to windy conditions even at a small breeze, also like earth titan asked were you near your mount/walking around it?

[Andreas]

was it windy? newtons are sensitive to windy conditions even at a small breeze, also like earth titan asked were you near your mount/walking around it?

Hello

Yeah, it might have been a bit windy..

But when have my mount standing on my lawn, isn't it safe to walk around then?

// Andreas

[Dave S]

That looks exactly like images i've got because the camera was way too heavy and I got the balance wrong.

Dave...

[earth titan]

Hello

Yeah, it might have been a bit windy..

But when have my mount standing on my lawn, isn't it safe to walk around then?

// Andreas

To my eternal embarrassment, one of my most common #### ups when I used to have a mobile set up, was to forget to tighten up the mount bolt after polar alignment. When I walked around, the top of the mount used to wobble (obviously) and I got images such as yours.

[Daniel-K]

that looks like phd hasnt finished calibrating did it say guiding in the bottom corner?

[paler31]

Hi one time when I was using PHD the dec alignment failed and so it switched it of then everytime i tried to guide it seemed to to calibrate ok but would not guide as the dec guide mode was switched of. It took me ages to figure out I had to go into PHD settings and switch it back to auto. DOHHHHH.

John

[Andreas]

Hello and thanks for your great answers!

After a try without walking around during the exposure it seemed to work pretty well at 5 min. However, next night it didn't work at all, so I tried to enable the DEC guiding option which made it better, but the stars looked like small grains at 5 min.

My last try was tonight, and now it was even worse! So I looked at the graph, and noticed that the RA was okay, but the DEC looked very strange.

So my thoughts is that I was just lucky with the PA so that the guiding worked well first night without DEC guiding. But why doesn't the DEC guiding work?

The reason to why I bought the guidekit was to escape from doing the drift alignment. I know its necessary for longer exposures, but for 2 minutes?

[rfdesigner]

Loss of DEC is not uncommon. It's best to always have the graph going and turn on logging... always.

I've had loss of DEC due to mechanical, electronic and software issues. Mechanical failings have been due to imbalance, and loose grub screws on my worms.. all solved now, electrical errors have been water getting into the electronics and broken wires, and software isn't really software problems.. it's me and fat fingers.

Your guider won't mean you don't need to polar align. But it will make you less sensitive to polar alignment errors, and by watching the guide trace with the DEC guide turned off you can quickly drift align.

So we know what scale your graph is on, what's the guide camera and what's the scope?

Derek

[Andreas]

Loss of DEC is not uncommon. It's best to always have the graph going and turn on logging... always.

I've had loss of DEC due to mechanical, electronic and software issues. Mechanical failings have been due to imbalance, and loose grub screws on my worms.. all solved now, electrical errors have been water getting into the electronics and broken wires, and software isn't really software problems.. it's me and fat fingers.

Your guider won't mean you don't need to polar align. But it will make you less sensitive to polar alignment errors, and by watching the guide trace with the DEC guide turned off you can quickly drift align.

So we know what scale your graph is on, what's the guide camera and what's the scope?

Derek

Hi Derek!

Yes I'm aware of that guiding doesn't solve bad polar alignment, but I thought that I could get at least a 5 min exposure by just doing a roughly polar alignment trough the polarscope.

The guide equipment that I use:

Qcam5 Guidecamera, (pretty much the same as the QHY5).

Celestron 80mm Guidescope - Focal Length (mm) 600 mm

[rfdesigner]

Guiding will allow sloppier alignment than plain tracking which of course can't cope with any error, but you will need the dec guiding working to get the benefit... of course if your polar alignment is too far out then a max DEC setting that's quite low (normally a good thing) could prevent the DEC from being able to hold onto the guide star.

Looking up the numbers, your guide scale is 1.78 arc seconds per pixel, so to get 0.2 pixels rms error (0.35 arc seconds rms, or 0.78" FWHM guide error) that's not going to show on the imaging camera. (I'd be very pleased with a result like that)

You could try increaseing "max dec" to several hundred and see if that gets it to hang on.

Derek

[Andreas]

Alright, I'll try it out when the skies are clear again. Seems to be cloudy for the next 5 days however..

// Andreas