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good polar alignment without expensive equipment


red dwalf
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If you have a guide scope, ideally something around 200mm focal length and a reasonable guide camera it is possible to get very good polar alignment with just these and the new edition of sharpcap 2.9, very easy to do and the software is free.

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I'll add a bit morr to my post above,  very easy to use, download sharpcap 2.9, run it, select your guide camera, now with the mount in the home position I.e. pointing at Polaris, select tools, polar alignment and set exposure to 4 - 5 seconds so it can see a number of stars, and then follow the instructions at the bottom of the screen, after it has solved it will tell you to rotate the mount 90 degrees in RA then it will solve again and as you to adjust the alt azimuth and the rotation which is easy to do as it will show an arrow on th screen so you know your adjusting in the correct direction.

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Questions Rob - How did you make sure that the guide is parallel to the imaginary celestial line of your mount ( that a polar alignment scope is supposed to be on)  - if that makes sense? - or doesnt it matter

 

What guide scope were you using ?

 

And what were you using to measure the error or is this done via Sharpcap

 

Got to be cheaper than £250 for a polar cam !

Edited by stash
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I had a fairly good polar alignment with my mount in the first place but my guiding graph still jumped about a little, also me being a little ocd I had aligned my guide scope with the imaging scope which is easily done on a bright star, but according to sharpcap instructions the guide scope and camera only needs to be within 5 degrees of Polaris, I'm using an altair astro 60 mm guide scope with a zwo asi 120 camera, once all aligned it doesn't matter what the axis of the mount is pointing at, as you say it's a lot cheaper than a pole master and just as easy to use.

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2 minutes ago, red dwalf said:

I had a fairly good polar alignment with my mount in the first place but my guiding graph still jumped about a little, also me being a little ocd I had aligned my guide scope with the imaging scope which is easily done on a bright star, but according to sharpcap instructions the guide scope and camera only needs to be within 5 degrees of Polaris, I'm using an altair astro 60 mm guide scope with a zwo asi 120 camera, once all aligned it doesn't matter what the axis of the mount is pointing at, as you say it's a lot cheaper than a pole master and just as easy to use.

Many thanks Rob for the info !!  I don't use guiding but rely on 3 point alignment in EQMOD so I am perhaps a bit lazy on Polar Alignment - just using a rough EQmod Polar scope aligment. But I think I will give a try so improve my mounts alignment.

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I used the eqmod method myself, but get a guide scope and a camera, something like a qhy5L ii and you'll be able to guide for ages and no more 3 point alignment

Edited by red dwalf
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12 hours ago, red dwalf said:

I used the eqmod method myself, but get a guide scope and a camera, something like a qhy5L ii and you'll be able to guide for ages and no more 3 point alignment

I would if I was "into" Astrophotography and I get why you guide but I am going down a different path but thanks for the info Rob. As I said before on another thread you have given me some very useful solutions e.g. Platesolving , which has made my armchair Astro work a joy.:2thumbsup:

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OK had a go last night - a bit of a fiasco. Was using my old ST80 to align via ZWO 120mm cam. First of all forgot ,due to long period of non use, that the tube doesn't draw out enough to focus the ZWO without the 90 degree diag so that wasted 1-2hrs :facepalm: Then when I remembered why and put the 90 diag my tablet just wouldn't get on with the ZWO even using a 6ft cable (power problem to ZWO I think). So I resorted to my laptop to connect to the ZWO - trouble is I use that remotely so people watching would have thought I was mad going back and forth from the laptop to the scope. After further playing with the settings of the ZWO using the moon as target I finally got the alignment in Sharpcap to resolve the stars when the scope was in the park position and it then asked to move 90 degree's - so I move it in RA and moved it and moved it but it wouldn't resolve the second frame. In the end I move the scope in RA manually CCW and it resolved the frame and said i was 3.0 something out and suggested I move right and down. I assumed it meant move the Alt bolt(Down) and RA bolts to move the head right - well thats what I thought. At this point it said it couldn't resolve the image (even though it was clear outside!!). The info did change - move down became up and right became ????? . In the end I went back to my marks on the pillar and gave up.

 

Frustrating night but I will give it one more go as most of the problems were me :wacko: - plus I have used a few bits and bobs to make a straight thru screwed tube extension which I have tried during the day and locked the focus as it worked.

 

Question

1. Can I move the mount using the EQMOD RA controls to rotate the "90 degrees" - I assumed I could but it seemed to have problems resolving the image.

2. Does having a full moon give this tool a problem as obviously the ZWO will pick up less stars even when playing with gain etc

3. Which way is right - is that CW or CCW . Right can be two ways depending which way you are facing the mount :facepalm2:

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40 minutes ago, catman161 said:

I recommend just getting a QHY pole master. So simple and so fast with great results.


Sent from my iPhone using Tapatalk

Thanks Felix but I have better uses for the £250 - would have to come out of my Hyperstar fund - so no way.;)  Its not crucial just hate being beat by something so simple. :laugh3:

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6 minutes ago, StuartJPP said:

I did a comparison of the PoleMaster software and SharpCap over on SGL...for the money SharpCap can't be beat :)

 

https://stargazerslounge.com/topic/280702-comparing-polemaster-and-sharpcapphotopolaralign-mount-polar-alignment-routines/

 

 

Literally just been reading your thread on SGL before you posted and discovered my error - forgot to press "next" when at step 2 - I just started using the Alt/Dec bolts - Dooh:facepalm2:

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Pressing next button should belp L.O.L

I personally wouldn't use eqmod to move the mount, it needs to be in the home position when started, I found moving the alt, azimuth bolts plus the left right easy to do but you only need to move them a small amount, I had a 2 inch extension on the back if my st 80 which alllowed the t2 thread on the camera to screw to it and then screws onto the back of the st 80 focuser, worked at treat, I may still have it somewhere as I don't have the st 80 anymore but I bet Graham from astrotec could make one easy enough.

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2 hours ago, red dwalf said:

Pressing next button should belp L.O.L

I personally wouldn't use eqmod to move the mount, it needs to be in the home position when started, I found moving the alt, azimuth bolts plus the left right easy to do but you only need to move them a small amount, I had a 2 inch extension on the back if my st 80 which alllowed the t2 thread on the camera to screw to it and then screws onto the back of the st 80 focuser, worked at treat, I may still have it somewhere as I don't have the st 80 anymore but I bet Graham from astrotec could make one easy enough.

I only used the Eqmod to move in RA at first then did it all manually!

Yes I think  perhaps I moved the Alt/Alt bolts a bit aggressively - more "slowly slowly catchy monkey" needed.

I have a 2inch extention but it will not replace the Std 1.25 part that screws into the focusing tube on the ST80 as the thread on the Focusing tube is not T-thread(M42x0.75) so I screw the 2 inch extn onto the std 1.25inch(which screws into the focusing tube) which came with my ST80. Anyway I have got round that problem and it doesn't account for the idiot/Gorilla (me!) who didn't read the instructions (old habit).

Just waiting for some clear skies to give it another try!

 

P.S. I was not going to be running this routine every time I use my kit as the mount is perm - unless someone comes up with a valid reason too! 

 

Thanks for the feed back folks and Stuarts pictorial for Gorilla's like me.

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I'm permanently mounted as well so I hope I don't need to do it every time L.O.L I shouldn't think you would need to as you are moving the mount and locking it off so should be a once in a while operation for us.

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Well just had another go - got past next this time :facepalm: However up/down right/left  seems to refer to the camera orientation not the up/down of the Alt or right/left of the AZ - if you follow that logic the errors become bigger . Second problem seems to be maybe I am asking to much to use the ST80 which has a smaller FOV than a Finder scope - got down to 0.0.50 than the camera seemed to stop. Plus it may be obvious to many but sadly me that going right or left (up/down) also alters the other value. And lastly I dont get any colours on the  degree lines (should be green ) 

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had another go when sky darker and clearer - managed to get down to 00.00.06 but this kept fluctuating to 00.00.25 and back to 00.00.06 - strange. Live and learn + practice makes perfect !!!!!!

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If I got down to 00.00.06 I'd count that as perfect, I got down to 00.00.20 and my guiding improvement was much better, no big spikes in the phd graph, I too will have another go and use the phd2 guiding helper to verify the results, also sharpcap does say a 200 mm guide scope with a camera sensor rougly that of a zwo 120 is ideal, says something about needed 5 degrees of view for best results or something like that, more on the sharpcap website.

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I used PHD2 to test the alignment  but found it had spikes that got bigger and bigger against time. At this stage I pulled out what little hair I had left - then when I was packing away I found that I had not locked off the AZ lock on my AZEQ6 (stop laughing :facepalm:) so I guess until I remember to get thinks right I wont know. This may (hope) have also caused the fluctuating Alignment Error given by Sharpcap.

I still find the ZWO a pain especially as there are two drivers available from within Sharpcap and the speed rating is crap at anything above 320x320 even allowing for Gain and Exposure times . Maybe I shouldn't pay so much attention to the stars shown on screen and just check the number of stars have been found by Sharpcap Alignment routine.

 However having said all that I think I am a convert to the Alignment routine.

 

I am thinking of using the C mount of the ZWO to attach and an old Canon 50mm f2 lens (already have a C to SLR mount lying about) and then making an adapter(might have to get Graham to quote on this or mod a Polemaster adapter) to fit the polar scope "Hole" as per Polemaster - reasoning smaller, lighter and less complicated(extn tubes etc) than my ST80 and can keep it in place if required and it reuses some old bits.


 In short your statement about " Good Polar Alignment without expensive equipment " seems to be bang on - why buy a Polemaster !!!!:2thumbsup::ph34r:

 

 

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I had the same usb frame rate problem with my zwo camera, did not like a powered usb hub or a single 5 meter active cable, so I bought a 5 meter normal usb cable of ebay, cost less than £2 and it flies, big frame rates, almost those specified on the website, I even have a 2 foot printer cable attached to the 5 meter cable, so just over 5 1/2 meters in total, worth trying. 

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42 minutes ago, red dwalf said:

I had the same usb frame rate problem with my zwo camera, did not like a powered usb hub or a single 5 meter active cable, so I bought a 5 meter normal usb cable of ebay, cost less than £2 and it flies, big frame rates, almost those specified on the website, I even have a 2 foot printer cable attached to the 5 meter cable, so just over 5 1/2 meters in total, worth trying. 

Even using the cable they sent and connected to a USB3 connected port it never gets the rates as advertised when doing high gain/longer exposures. Yes I can get 150fps when i am doing 1/1000 exp and low gain but I have found that the higher the gain and/or longer exposure the FPS drops to 1.2 approx even unless i do 320x240. I have tried all sorts of cables/hubs. I note this was a complaint by many hence the USB3 version I guess.  Not to worry it works for this job !

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Ok Seeing is believing a out of focus shot of m31 after 1200 secs exposure - looks pretty good to me so seems like the Sharpcap alignment was correct - 

 

https://drive.google.com/open?id=0B9aHac2P5RgVZWg4NFBLb3RUODA

 

One 300 secs and better focused

 

https://drive.google.com/open?id=0B9aHac2P5RgVTWFQTjEtdkp4ZE0

 

both Unguided

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  • 2 weeks later...

Update - using an old 50mm canon lens(1.8) attached to c-mount on the asi 120mm and home "made" polar hole attachment using rubber bung(35mm) rectangluar washer on the bottom to allow insertion through the polar hole. Another washer on top of the bung all connected with a m8 bolt and some nuts. The tightened nuts makes the bung expand and makes the whole thing rigid.

A bit(no alot) "Heath Robinson" but ,after some focusing issues ,last night it was all done in 2mins (about 30secs for the plate solving - on both legs - fast).

 

Cheap and seems to be as good as the commercial versions.

Mine will be staying on the mount permanently as I can swap the 50mm lens for the  wide view(Meteor) lens that came with the ASI to watch the weather and see "other" things". The only thing I would prefer is to be able to swap the Camera but you could do as others did and use a guide scope etc - i just wanted to see if there is a difference doing the polar align on the polar axis and there doesn't seem to be any difference in accuracy !

 

If I can do it anyone can - spend the savings on a new Nagler eye piece or something.

Edited by stash
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