Imaging with the 130pds

[Adam J]

1 minute ago, al-alami said:

I do, I found several links to it (using the three little grub screws)... but every time I correct it one way, it shift almost the exact opposite when I return, and it sort of seems like its not rotating properly, hard to describe, but its almost like its elliptical and not round.

Yes its tricky. If you place polaris onto the center cross and then rotate the RA axis until it moves to about the maximum distance from the center cross then adjust the reticle so that the star moves back 50% of the way towards the center cross. If you mean that the large circle around the center cross is not round then yes thats not normal. You may have taken the adjustment grub out too far and the reticle may have slipped.

[Stub Mandrel]

16 minutes ago, al-alami said:

Finally fixed my extra diffraction spike issue! I have confirmed the cause as focuser tube ingress into the light path. So for future reference both this and twisted spider vanes can cause the problem. The fix was to move the primary up the tube hence moving the focus out.

Hmm . .. I had an extra spike on Monday, turned out to be the clothesline...  DOH!

[Adam J]

4 minutes ago, al-alami said:

am using astro baby's one .. 

http://www.astro-baby.com/HEQ5/HEQ5-1.htm

Yes that is a good method. You can do all of this during the day if you move the polar scope horizontal and point it at a distant object. Its easier than mucking about in the dark.

Edited November 30, 2016 by Adam J

[al-alami]

1 minute ago, Adam J said:

Yes that is a good method. You can do all of this during the day if you move the polar scope horizontal and point it at a distant object. Its easier than mucking about during the day.

I plan to give it one more go, before taking it to the next level  .. maybe this weekend I will have some time during daylight ... I can feel the potential of the beautiful scope ... I hate that my mount is letting me down

[alacant]

16 minutes ago, Stub Mandrel said:

Finally fixed my extra diffraction spike issue! I have confirmed the cause as focuser tube ingress into the light path.

Ah. OK. Is this with the sw cc? I was getting D shaped stars to one side of the frame when the camera was aligned with the focuser knobs. On my reflector, it takes the focus tube 1cm further into the main tube and so interferes with the light path. Moving the mirror caused vignetting so I cut the end off the focuser. Am I correct in believing that the gso cc allows focus at the normal position and so negates the ingress? TIA.

[sagramore]

Had the 130-PDS out last night for my first ever attempt at imaging one target over multiple sessions!!

M45 - it's a classic, and everyone's done it to death, but you've got to try yourself haven't you??

Full details (and a bit more back story) found in the main thread here:

 

 

 

I also managed a quick 1hr on the Double Cluster. Full thread with more details at:

 

Thanks for looking! Damn, I love this little scope

 

Edited November 30, 2016 by sagramore

[dyfiastro]

Well the mount is back and I have had a chance over the last two nights to get setup again and give everything a test since putting it all back together.
I also got a 600D that I modified over the last week or so and was the first chance to try that as well.
I am still working out a few small issues but getting there slowly.

15x300s subs at ISO800

 

10x300s subs at ISO800

15x300s subs at ISO800

10x300s subs at ISO800 + 5x60s at ISO800 blended for the core

With a modified DSLR is a custom white balance the way to go or can someone suggest something else?
Hoping that my latest attempt at collimation has also sorted my slight issue with my spider vanes and also coma due to focuser tilt (the next clear night will tell).

[Adam J]

1 hour ago, dyfiastro said:

Well the mount is back and I have had a chance over the last two nights to get setup again and give everything a test since putting it all back together.
I also got a 600D that I modified over the last week or so and was the first chance to try that as well.
I am still working out a few small issues but getting there slowly.

15x300s subs at ISO800

 

10x300s subs at ISO800

15x300s subs at ISO800

10x300s subs at ISO800 + 5x60s at ISO800 blended for the core

With a modified DSLR is a custom white balance the way to go or can someone suggest something else?
Hoping that my latest attempt at collimation has also sorted my slight issue with my spider vanes and also coma due to focuser tilt (the next clear night will tell).

Those look like a reflection, when you modified the 600D did you remove both of the filters or just the rear filter? You look to have a little purple haloing too. Custom white balance is what i do. I would be surprised if its coma or tilt though as your stars are still nicely round at the edges of the image.

Edited December 1, 2016 by Adam J

[Adam J]

2 hours ago, alacant said:

Ah. OK. Is this with the sw cc? I was getting D shaped stars to one side of the frame when the camera was aligned with the focuser knobs. On my reflector, it takes the focus tube 1cm further into the main tube and so interferes with the light path. Moving the mirror caused vignetting so I cut the end off the focuser. Am I correct in believing that the gso cc allows focus at the normal position and so negates the ingress? TIA.

I use the Baader MPCC MKIII, yes it does not change the focal length. When Skywatcher made my 130pds they set the mirror right to the very rear of its possible travel. I have never used the GSO one.

Edited December 1, 2016 by Adam J

[dyfiastro]

51 minutes ago, Adam J said:

Those look like a reflection, when you modified the 600D did you remove both of the filters or just the rear filter? You look to have a little purple haloing too. Custom white balance is what i do. I would be surprised if its coma or tilt though as your stars are still nicely round at the edges of the image.

Thanks for the reply. I will be shooting a custom white balance tomorrow as long as its clear enough.
I only removed the rear filter and left the front UV/IR in place. Given that I am in a pretty dark location I decided against using a separate light pollution filter and IR filter. Do you think that the reflections could be due to IR transmission then? It is only since getting the canon that I have seen this in my images. are the feathery tails in between the diffraction spike to do with this as well then? I know I had a small issue with one set of the spike being slightly bent which I have now corrected.

The coma in these are not as bad as it was at the start of the session, I managed to get most of it out and I am hoping now I have aligned the focuser it will help even further (a photo of the offending corner).

Thanks for the advise

[al-alami]

15 hours ago, dyfiastro said:

Well the mount is back and I have had a chance over the last two nights to get setup again and give everything a test since putting it all back together.
I also got a 600D that I modified over the last week or so and was the first chance to try that as well.
I am still working out a few small issues but getting there slowly.

15x300s subs at ISO800

 

10x300s subs at ISO800

15x300s subs at ISO800

10x300s subs at ISO800 + 5x60s at ISO800 blended for the core

With a modified DSLR is a custom white balance the way to go or can someone suggest something else?
Hoping that my latest attempt at collimation has also sorted my slight issue with my spider vanes and also coma due to focuser tilt (the next clear night will tell).

absolutely amazing

 

[Susaron]

Very useful tool for astroimaging

 

http://www.blackwaterskies.co.uk/p/imagingtoolbox.html

 

Cheers

[Stub Mandrel]

Excuse the double posting (I gave this its own thread), this is the best 60% of 100 x 120s at ISO800:

 

[dyfiastro]

Hi everyone

Sorry about posting this in here as well but I thought there may be someone here that has had the same issue and can shed some light on the subject.

I realigned the focuser yesterday after having a different issue (which is still to be resolved) however since doing so I have encountered a new issue.
There seems to be uneven illumination across the frame (visible in flats) and this changes from one side to the other as I rack out the focuser.

Am I correct in understanding this is due to incorrect offset and how do I go about correcting this?

The original issue was regarding this and if anyone can suggest anything about this at the same time it would be great

 

[Stub Mandrel]

24 minutes ago, dyfiastro said:

I realigned the focuser yesterday after having a different issue (which is still to be resolved) however since doing so I have encountered a new issue.
There seems to be uneven illumination across the frame (visible in flats) and this changes from one side to the other as I rack out the focuser.

At the risk of teaching granny to suck eggs, did you realign the secondary and re-collimate the scope afterwards?

[dyfiastro]

10 minutes ago, Stub Mandrel said:

At the risk of teaching granny to suck eggs, did you realign the secondary and re-collimate the scope afterwards?

Thanks for the reply. Yes from what I can tell everything seemed good.

I was going to have another look at the astrobaby website in regards to the offset but it seems to be down. I am going to have another look at it this evening with a clearer and fresher head

[Adam J]

4 hours ago, dyfiastro said:

Thanks for the reply. Yes from what I can tell everything seemed good.

I was going to have another look at the astrobaby website in regards to the offset but it seems to be down. I am going to have another look at it this evening with a clearer and fresher head

That would happen with tilt.

[dyfiastro]

Hi everyone

I have spent the last 3 days going over this multiple times and getting the same result.
The scope has been collimated multiple times (as far as I can tell from the guides) and I cannot seem to get the illumination even through the whole travel of the focuser.

I have limited the amount of tilt by counting the turns on each of the three grub screws and checked to make sure that the secondary is round, central and the three holders for the primary are all in view.

The illumination still uneven and travels from one side to the other, I have tried allsorts and always seem to get the same result at various different amounts. This is the latest result (Flat frames taken and equalised in photoshop)

Here is the focuser all the way in

And all the way out

Any suggestions and advise would be great, I am sure its something simple but its really starting to frustrate me now.

Thanks in advance

[Thalestris24]

16 minutes ago, dyfiastro said:

Hi everyone

I have spent the last 3 days going over this multiple times and getting the same result.
The scope has been collimated multiple times (as far as I can tell from the guides) and I cannot seem to get the illumination even through the whole travel of the focuser.

I have limited the amount of tilt by counting the turns on each of the three grub screws and checked to make sure that the secondary is round, central and the three holders for the primary are all in view.

The illumination still uneven and travels from one side to the other, I have tried allsorts and always seem to get the same result at various different amounts. This is the latest result (Flat frames taken and equalised in photoshop)

Here is the focuser all the way in

And all the way out

Any suggestions and advise would be great, I am sure its something simple but its really starting to frustrate me now.

Thanks in advance

Hi

Is that using the XT2 + mpcc with m48 t-ring? Also, I'm just thinking - it shouldn't matter too much and you'd be using it at a particular point of the focusser all the time anyway? Rob's (uranium235) mod of adding a third thumscrew to the focus tube is probably a good idea - if you havn't already done it. Getting any tilt (if you have any) out of the focusser is quite a major operation.

Louise

[dyfiastro]

Just now, Thalestris24 said:

Hi

Is that using the XT2 + mpcc with m48 t-ring? Also, I'm just thinking - it shouldn't matter too much and you'd be using it at a particular point of the focusser all the time anyway? Rob's (uranium235) mod of adding a third thumscrew to the focus tube is probably a good idea - if you havn't already done it. Getting any tilt (if you have any) out of the focusser is quite a major operation.

Louise

Thanks for the reply.
No this is using my new Canon 600D, MPCC attached via a standard T2 Adaptor.
I have already done the third screw modification as well.
Yes I tend to use the scope at a set point but also use it a various other points when doing planetary and lunar imaging etc...

The illumination is currently way off at the point that I would normally use as well so need to figure out what is happening so I can at least correct it in the right direction.

[Thalestris24]

An M48 adapter should reduce the vignetting, I think. Hope you can improve things.

Louise

[dyfiastro]

Thanks, I am more concerned about the uneven illumination at present than the overall vignetting.
 

[richyrich_one]

Worth checking if the focuser travel is square.

With a laser, see if the spot moves when you move the focuser in and out.

[richyrich_one]

Actually, thinking about it, I don't think that would prove anything.

[alacant]

9 hours ago, dyfiastro said:

Any suggestions and advise would be great

Hi. Do your flats clear the problem? Unless the issue is affecting your photos and the flats are doing their job, I'd forget it. I think the procedure is to centre the secondary then displace it 3mm both toward the primary and away from the focuser. But life is short... HTH.

Edited December 10, 2016 by alacant