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Can Vixen GP2 be autoguided

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#26 vineyard

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Posted 15 December 2019 - 10:21 AM

That's a good tip Don, thanks.  I did just that to adjust & tighten the RA belt a bit more.  Cheers!



#27 Don Taylor

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Posted 15 December 2019 - 06:15 PM

Yuo are very welcome.  But now i'm reminded that I have to fix that one screw.........smirk.gif



#28 vineyard

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Posted 26 January 2020 - 05:25 PM

Happy New Year! (I think I can still say that in January). I finally had time to try some astrophotography w the modded GP2.  (I'm a complete beginner to AP).  Pointed it at M42 in Orion, and took 20 lights of 20s (no guiding, only tracking).  My focus really needs to get better, but anyway here's the image.  I'm still liking the EQStar EQ5 mod - I find its sensitive to having your scope well-balanced but that may also be the total weight - I'm also going to try it with longer exposures with a lighter scope.  Cheers!

 

R Pp M42 Light debayed stacked

 


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#29 Der_Pit

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Posted 27 January 2020 - 07:01 AM

Nice start, and have fun on the road ahead!


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#30 vineyard

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Posted 21 February 2020 - 04:46 AM

Hello,

 

Hope this finds you all well.  Can you believe 2020 is almost 1/6th over already?!

 

Don, this may be a Q mostly for you since you also have an EQStar EQ5 (but it may also be a more general Q about tracking & mounts too - as you'll see I don't know what the cause might be).

 

Attached is a processed image I took of M36 last night.  Not great (conditions were so-so, but my main objective was to take advantage of the absence of rain, and some stars being visible, to test out the "Mount Model" tool on EKOS w the EQStar - it worked smile.gif ).

 

As the lights were being taken, I noticed that the image shifts a bit in the FITS viewer from light to light.  I did rough polar alignment, did the Mount Model alignment (3 stars), and it plate solves and slews to target correctly.  So far all good.  So is this image shift the mount not quite tracking right (do you get something like this Don, or have you found some workarounds?), is it a periodic correction error (I'm not sure what that means tbh!), or is it inevitable with tracking and is what would be improved with a guide camera also set up?

 

I have noticed this shift in other attempts I've done, but in those cases I only plate solved so I was expecting field rotation in images.  This time I was hoping that it would be much less?

 

All tips gratefully received as ever!

 

Cheers,

 

Vin

 

M36

Edited by vineyard, 21 February 2020 - 10:06 AM.


#31 Geo.

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Posted 21 February 2020 - 02:48 PM

This is a goto replacement controller for the DMDs designed for the MT-1 drives.

 

P1016598.jpg

 

It is built with a OnStep MiniPCB2. The MiniPCB2 is one of several designs supported by the OnStep freeware.  https://onstep.group.../main/wiki/home

 

OnStep tends to be DIY and requires user particiapation, but there's lots of help from the group.

 

Depending how you purchase the parts the cost can run for $35 to $50. There are "kits" with a all the parts available from members of the Google OnStep group. Sky Safari, Stellarium Mobil and other scope control software can be used to serve the controller with a Android phone, tablet, a Linux/Windows PC, a simple handbox or the Smart Handbox designed by group members. 

 

To get the full goto slew speeds the MT-1s should be replaced with contemporary 400 step/revolution motors. The motors used by Vixen are 48 step/revolution and geared down 120:1. I set the slew speed for MT-1s at 0.3°/second. They may max out at 1°/second.   For the GP type mount the 400 steppers are usually run with 3:1 reduction.and can achieve 6°/second slews.

 

I usually budget $50 for 2 NEMA 17 steppers, mounting brackets, belts and pulleys. There are printable brackets for many mounts. 

 

 



#32 Don Taylor

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Posted 21 February 2020 - 11:25 PM

Hello,

 

Hope this finds you all well.  Can you believe 2020 is almost 1/6th over already?!

 

Don, this may be a Q mostly for you since you also have an EQStar EQ5 (but it may also be a more general Q about tracking & mounts too - as you'll see I don't know what the cause might be).

 

Attached is a processed image I took of M36 last night.  Not great (conditions were so-so, but my main objective was to take advantage of the absence of rain, and some stars being visible, to test out the "Mount Model" tool on EKOS w the EQStar - it worked smile.gif ).

 

As the lights were being taken, I noticed that the image shifts a bit in the FITS viewer from light to light.  I did rough polar alignment, did the Mount Model alignment (3 stars), and it plate solves and slews to target correctly.  So far all good.  So is this image shift the mount not quite tracking right (do you get something like this Don, or have you found some workarounds?), is it a periodic correction error (I'm not sure what that means tbh!), or is it inevitable with tracking and is what would be improved with a guide camera also set up?

 

I have noticed this shift in other attempts I've done, but in those cases I only plate solved so I was expecting field rotation in images.  This time I was hoping that it would be much less?

 

All tips gratefully received as ever!

 

Cheers,

 

Vin

 

Vin; Unfortunately, I am visual only. I did my last astrophotography with really big scopes but never had the bug to do AP since the early '90s  So, I'm afraid I'm not much help here.  Perhaps the AP forum might provide some help - or at least help you identify the most likely causes.  


Edited by Don Taylor, 21 February 2020 - 11:26 PM.

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#33 vineyard

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Posted 23 February 2020 - 03:39 AM

Thanks Don.  Will try that.  Do you find in your visual that the object stays in FOV or does it drift (if so, how fast - I'm trying to see if its the mount or the motors (or just something fundamental like still insufficient polar alignment!)).

 

George, thanks for those pointers.  My DIY electronics capabilities are non-existent.  Which is why I went with the EQStar EQ5 mod which I think does the same thing (based on limited understanding!).

 

Cheers all.



#34 Don Taylor

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Posted 23 February 2020 - 09:53 PM

Vin:

 

I've mainly used the drive for short ~ 1hr visual sessions from the city so I only do a very rough polar alignment. I've not noticed any peculiar tracking or jumps etc. only drift at higher magnification - likely caused by far from perfect polar alignment. 


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