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Scope Not Targeting Well


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I've always had a problem with my scope not hitting the target, but now I'm using cameras with small sensors, this has become a real problem. I polar align using Polar Finder (or something similar) and do a 2 star align (3 star can be problematic). But the 1st star is always outside the view of my 24mm EP. Quite a way out. So I use my RDF to get it into view, centre it as accurately as poss, then to the next star, which can also be out of view. I centre this and the alignment is successful. I attach my cam on this star which is bright enough to focus on. Then I slew to my target. It's off. Not by much but enough for it to be outside my ATIK or ASI cams' small sensors. My RDF isn't accurate enough to get the object in view. (I've tried a Telrad finder but couldn't get on with it with my varifocal glasses.)

I tried the other night, with my frac and ATIK, to get some nebulae in view, but none of them showed up. The stars that were in view were clear in Artemis. I tried last night to image Jupiter with my 200P, ASI and 3x TAL Barlow. Could I get Jupiter on the sensor?? Nope. Then the fog rolled in after an hour of trying. This is getting beyond a joke.

I was determined to jack it all in last night. It's hard work with not much in the way of results. I like hard work but surely this should be fun as well??  :mad:

Angry Alexxx

Hi Alex,

Is the mount permanently fixed or do you take it in and out like I do?

A.G

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The mount isn't permanently fixed. It's all over the place!

I can't say how much I'm out by. I can never picture degrees, minutes and seconds. It might only be acceptably out, but it looks quite big to me!

Doing 2x2 star aligns sounds interesting. What I do is run through the handset's set-up until the star align's finished. Then I could go into the Setup (I think!) menu and do another align on two other stars. Is that what you mean?

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The mount isn't permanently fixed. It's all over the place!

I can't say how much I'm out by. I can never picture degrees, minutes and seconds. It might only be acceptably out, but it looks quite big to me!

Doing 2x2 star aligns sounds interesting. What I do is run through the handset's set-up until the star align's finished. Then I could go into the Setup (I think!) menu and do another align on two other stars. Is that what you mean?

To set your mind at rest this is exactly what happens to me every time that I set up. When you start the mount up the handset has no idea how far out the mount is from the home position. Even though I have the place of the feet marked out, at times the 1st star is out of the view of the 9X50 finder never mind the chip of the 314. The best way is to always try and locate Polaris in the finder and then the scope and call this home position so you always start up from a known reference. I don't understand why you have problem with the 3 star align. The alignment on the 3rd star is meant to iron out the cone error of the scope and for me at least it is always out by a mile but once aligned using the handset arrow keys I test the mount accuracy by giving the mount a command to go to a star near my target and 90% of the time it puts it well within the sensor of the CCD. The trick is to always start from a fixed position or as close to it as possible. The mount does play funny buggers every once in a while but I park it, power it down and start again and more often than not all is fine. I also advise you to have the hand set flashed to the latest firmware and check the firmware of the boards that control the motors. If you don't feel confident doing this yourself as it can be tricky if things go wrong then have some one do it for you. Also do use the Polar align routine of the handset once the firmware has been up dated. Hope that you find this helpful.

Regards,

A.G

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The mount isn't permanently fixed. It's all over the place!

I can't say how much I'm out by. I can never picture degrees, minutes and seconds. It might only be acceptably out, but it looks quite big to me!

Doing 2x2 star aligns sounds interesting. What I do is run through the handset's set-up until the star align's finished. Then I could go into the Setup (I think!) menu and do another align on two other stars. Is that what you mean?

Yes.....

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To set your mind at rest this is exactly what happens to me every time that I set up. When you start the mount up the handset has no idea how far out the mount is from the home position. Even though I have the place of the feet marked out, at times the 1st star is out of the view of the 9X50 finder never mind the chip of the 314. The best way is to always try and locate Polaris in the finder and then the scope and call this home position so you always start up from a known reference. I don't understand why you have problem with the 3 star align. The alignment on the 3rd star is meant to iron out the cone error of the scope and for me at least it is always out by a mile but once aligned using the handset arrow keys I test the mount accuracy by giving the mount a command to go to a star near my target and 90% of the time it puts it well within the sensor of the CCD. The trick is to always start from a fixed position or as close to it as possible. The mount does play funny buggers every once in a while but I park it, power it down and start again and more often than not all is fine. I also advise you to have the hand set flashed to the latest firmware and check the firmware of the boards that control the motors. If you don't feel confident doing this yourself as it can be tricky if things go wrong then have some one do it for you. Also do use the Polar align routine of the handset once the firmware has been up dated. Hope that you find this helpful.

Regards,

A.G

Thank you! I'll flash the handset and see what I can do then.  I'll ask FLO about the mount's firmware.

I just kept getting 'Alignment unsuccessful' when I did the 3 star align, so gave up on it.  Some in my astro group only do a 1 star align on a star near their target. Then they use a handset command to fix on the object. I haven't got that option. Maybe it's in the upgrade.

I've marked home position in RA and Dec using Dion Heap's tutorial so it's accurately parked.

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PAE (Position Accuracy Enhancement), is a sort of PEC but it is really good for temp setups. 

If your object starts to drift, instead of just using the arrow keys you hit escape once and then again quickly and hold down until you see the words " Recenter Object" (the name of the object you are on will appear underneath), then you re-centre using the arrow keys. 

Once re-centred you hit enter and you have to go through the menu as if you were searching for another target but choose the same one again.  It will then beep and you are still on the same object.

But this time the computer in the HC has compensated for any errors in your setup for that part of the sky.  The more you do this during a session and on each object at different parts of the sky, it will become more & more accurate.

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A little caveat to above.  Try and finish the re-centring with the Up & Right arrows (this may mean bringing the object past centre one way and bringing it back again to centre).  If you finish on either the Down or Left arrow, when you choose the object again it will slew away a little and then come back to centre.  I think it does it for the motors.

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I'm wondering if you have some slippage on one ore both clutches? 

I don't agonise over polar alignment. I just get Polaris within the PA circle in the polar finder (rough I know!) and have good 3 star alignment first time, every time.

What I do though is get a good balance in both axes. That takes me longer than 3 star alignment!

Perhaps 3 star alignment isn't working for you because the handset is expecting to see ever decreasing errors as it slews to each star. If you are still yards off and having to make considerable adjustments with the arrow keys to center the third star the handset decides there must be a problem. It isn't confident of it's derived location?

If the errors don't improve with each alignment point there is a consistent error that is independent of the alignment process. That makes me think of problems with the actual driving of the axes? 

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You might be right. My mount has never been that tight. I sent it back to FLO a couple of times but I could still move the mount, when tightened, with my hands. A friend repositioned the clutch levers for me and that helped a lot, but it's still not absolutely firm. I don't think it's going to get any better to be honest. I would like an NEQ6 but it's far too heavy for me. I struggle a bit with the HEQ5! :o

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It could also be too much backlash or float.  When the clutches are on, do you get excessive rocking in either or both of the axis when you try and rock them by hand?  If so, either your gear mesh is too loose or the float produced by the worm retaining nut is too loose.

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I can't remember. I'll try that tonight and get back to you.

Hi Alex just picked up on your thread. Are you still struggling with the alignment? As you say, each to his own, but I've perfected alignment just with the Handset as there are too many variables for me when using software. I now find it a doddle to do and I refine it just with the drift align in PHD2 which is so intuitive. One thing I keep repeating on this forum is that 3 star alignment is best avoided except for general observing. Yes it corrects for cone error if you have any but it's accuracy is limited to a small portion of the sky. For higher accuracy my experience over 7 years has taught me that I should only use 2 star alignment on the same side of the meridian as my target. This works every time for me. Don't ask me why it just does. I'm happy to help at any point if I can. Don't give it up!

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Thank you! I'll flash the handset and see what I can do then.  I'll ask FLO about the mount's firmware.

I just kept getting 'Alignment unsuccessful' when I did the 3 star align, so gave up on it.  Some in my astro group only do a 1 star align on a star near their target. Then they use a handset command to fix on the object. I haven't got that option. Maybe it's in the upgrade.

I've marked home position in RA and Dec using Dion Heap's tutorial so it's accurately parked.

You have the option, after the mount slews to a target, a star, it will be off centre. There are two ways of doing this, immediately after the slew press the escape key and hold for 2 or 3 seconds the prompt changes to Centre Target or something like that then you can set the slew speed and use the arrows to centre the target and then press enter to accept the correction the other way is from the menu, Utility_PAE_PAE Align/ Enter, PAE ( Pointing Accuracy Enhancement ) so that you know. The mount will remember the correction and will apply it to about 5 degrees radius of the target. The back lash problem mentioned is really serious as if the mount backs off on itself and the back lash is excessive the targeting will be way off.

A.G

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You have the option, after the mount slews to a target, a star, it will be off centre. There are two ways of doing this, immediately after the slew press the escape key and hold for 2 or 3 seconds the prompt changes to Centre Target or something like that then you can set the slew speed and use the arrows to centre the target and then press enter to accept the correction the other way is from the menu, Utility_PAE_PAE Align/ Enter, PAE ( Pointing Accuracy Enhancement ) so that you know. The mount will remember the correction and will apply it to about 5 degrees radius of the target. The back lash problem mentioned is really serious as if the mount backs off on itself and the back lash is excessive the targeting will be way off.

A.G

Thanks A.G. I don't think the backlash is too bad. I manage to guide fine with the mount, if I've done everything OK. Mind you, Dec can be a bit twitchy sometimes. I wonder if that's more a balance issue. I'm not too good at remembering to balance!

Thanks for the PAE menu info. I certainly will try that.

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I don't think anyone has mentioned a flip mirror yet, although with a Newt, pretty sure it will not fit in the backfocus. It should work with the Mergez though I would have thought. This way, you can use a wider EP to get centered and then flip the mirror out of the way and have the errant planet it firmly on your sensor.

Cheers

Matt

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In my opinion the latest versions of the software are much better on the 3-star align then they used to be. I frequently used to get the dreaded alignment failed, but I have never got this with 3.35 or 3.36.  Now if only they would fix the restart from park which they broke in 3.36 ...

NigelM

p.s. using a reticule eyepiece does make a big difference to the final accuracy (won't help with the first star misalignment of course).

p.p.s. I see no reason why you cannot slip the clutches to do that first alignment. I do this all the time on my HEQ5 and it works fine.

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