Imaging with the 130pds

[RolandKol]

1 hour ago, Stub Mandrel said:

That made me curious, here are my counts since January 2014. I only really started regularly in 2015, and many of my early attempts went undated.

2014  - 3 (actually quite a few more)

2015 - 40

2016 - 43

2017 - 42

2018 - 66 (12 nights in June alone!)

2019 - 41

2020 - 18 to date

There's  tendency for me to push my luck if things have been thin (so I might  a short hour or two's window for some planetary or lunar) , and to run out of steam if there are long periods of good conditions. My only blank month is February 2017.

But on the whole, a consistent 40 days a year of actual imaging (not opportunities).

I am only 3 years in a hobby,

never ever managed to get more than 20  

I added 5 just in case  as I am not keeping any diary, - just dated folder names 

Location Location Location....

My Bortle 8-9, probably shine much brighter even if a slight thin cloud line is in the way.

You actually made me a bit more optimistic... 

Edited July 30, 2020 by RolandKol

[BrendanC]

Hi all,

I have a problem with my 130PDS (I think - or it could be the mount, the software, or any number of things, but it's probably the optics).

I've posted elsewhere about this (see https://stargazerslounge.com/topic/358322-what-on-earth-has-happened-here/) but was advised that the resident 130PDS experts (that's you!) might be able to help. So, apologies if this counts as a double post, I'm just doing what I was told...!

So, the problem is, I'm getting subs that look like this (zooming in to show the details at the corners and middle - these are all from one, unprocessed sub, at actual size):

Top left

 

Bottom left

 

Bottom right

 

Top right

 

And finally, middle

 

There are several things going on, as you can see. The directions of the blurring changes. Some stars are out of focus. And none of them look at all right to me.

A previous similar problem seemed to be fixed by making the mount east-heavy, but as you can see, it's far from fixed the problem.

The latest thinking is that it could be the focuser impinging on the image?  This is what someone has found when zooming in:

For comparison, here's a sub I took a couple of months ago, exact same setup except that I've disassembled the kit a couple of times during bad weather, I'm now using EQMOD directly connected to my mount, and I'm also trying to improve my polar alignment by using Sharpcap (click image to see larger version then save that to see original, albeit jpg). The problem doesn't seem to be here?

You can see my kit list in my signature.

I'm tearing my hair out (or at least what's left of it) to figure this one out. If anyone has any ideas, I'd really appreciate it.

Thanks, Brendan

 

Edited July 30, 2020 by BrendanC

[MartynB85]

I'm new to this hobby but I came across this thread while looking into my next purchase. I have a Celestron Inspire 80AZ at the moment that I have tried to take photo's with using my old Nikon D3100 but the results were very poor, it just doesn't seem to focus correctly.

I'm looking at the Skywatcher PDS range, first question is will the 150 and 200 versions make much improvements over the 130? I'm planning to couple the scope with the Skywatcher EQM35 mount (looked at the EQ3 GOTO but I think the payload capacity is too little?) and of course my D3100 for deep sky images. 

Would I notice the difference in the larger diameter once I become a little more experienced? 

Thanks

 

[si717]

hi all and another newcomer to the 130 club,i have spent some time reading this thread ,or alot of it and made the purchase of a 130pds

my thoughts or questions would be will it perform out of the box

or collimate straight away ive ordered a collimator

ive ordered the baddar coma corrector to go with it

and a dslr adaptor anything else i will need a mount ofcourse im looking into buying the skywatcher eq5 pro ?

i dont want to start modding the tube straight away 😂

anyway my main question was how are you guys going about taking your Dark Bios and flat files ?

i intend using a dslr i have a canon 650d unmodified and a 450d modified for imaging

so i was wondering do you take these frames on the same night or on cloudy nights when nothing else to do ?

is that possible and how about flat files how would one acheive that any advice really helpfull and im looking forward to getting going with the new scope thanks and a really nice thread and read on this scope some amazing pictures too  👍

Edited July 30, 2020 by si717

[RolandKol]

12 hours ago, si717 said:

hi all and another newcomer to the 130 club,i have spent some time reading this thread ,or alot of it and made the purchase of a 130pds

my thoughts or questions would be will it perform out of the box

or collimate straight away ive ordered a collimator

ive ordered the baddar coma corrector to go with it

and a dslr adaptor anything else i will need a mount ofcourse im looking into buying the skywatcher eq5 pro ?

i dont want to start modding the tube straight away 😂

anyway my main question was how are you guys going about taking your Dark Bios and flat files ?

i intend using a dslr i have a canon 650d unmodified and a 450d modified for imaging

so i was wondering do you take these frames on the same night or on cloudy nights when nothing else to do ?

is that possible and how about flat files how would one acheive that any advice really helpfull and im looking forward to getting going with the new scope thanks and a really nice thread and read on this scope some amazing pictures too  👍

Welcome to the dark side!
Once you get all, - check youtube, - it has nice vids about collimation, just one mistake (on all videos), they offer to adjust secondary (the small mirror), - I strongly suggest do not touch any bolts of the secondary at the start as it is quite sensitive and difficult to adjust...

To collimate the primary (large mirror) is very easy and you can be confident, - you will not ruin anything.

as per Baader CC, - most likely you will not need to shorten the Focuser's drawtube as it has no Focal Length reduction as Skywatcher's cc has (which is 0.9 reducer).

Bias,  - you can take any time, as these are the shortest exposures of Darks (Canon probably has 1/4000sec exposure in the fasted mode). Bias are done at the same ISO as Lights, you can build library and re-use Master Bias (stacked version) in the future.

Darks, - currently is quite a big tendency to use Dither strongly instead of Dark (Dither every sub or every second sub). Dither is slight shift of the target between subs, - it is usually done via Astro imaging software like APT, SGP and etc while Guiding (some even able to it manually...... O_o )

Of course,  try the procedure with Darks also, - in ideal they should be taken even at the same temperature as Lights, - it will not be possible with Canon, so just simply try to get the temperature close (and of course, the rest of the settings like ISO and Exposure - have to be the same as Lights). Thats why darks on Canons are hated... Especially if you do Long exposure lights, - you will waste a lot of time on Darks also... 

Flats, - depends on the software you will use, APT has ant option for Canon Flats, - easy as 123. If no software is used, - it is quite a poem to write about it.....

Keep in mind, - Flats is not only for vignette reduction , but Mainly to remove dust shadows from images (you cannot avoid them completely... dust will pop out from time to time in different places), so if you moved any toy one your optical train (for example camera... or reducer or Light Pollution filter and etc), - you will not be able to produce Flats which will match your Lighs, as optics will shift and dust shadows on Flats will not match their location on the Light images.

Edited July 31, 2020 by RolandKol

[si717]

6 minutes ago, RolandKol said:

Welcome to the dark side!
Once you get all, - check youtube, - it has nice vids about collimation, just one mistake (on all videos), they offer to adjust secondary (the small mirror), - I strongly suggest do not touch any bolts of the secondary at the start as it is quite sensitive and difficult to adjust...

To collimate the primary (large mirror) is very easy and you can be confident, - you will not ruin anything.

as per Baader CC, - most likely you will not need to shorten the Focuser's drawtube as it has no Focal Length reduction as Skywatcher's cc has (which is 0.9 reducer).

Bias,  - you can take any time, as these the shortest exposure Darks, 1/4000sec, done at the same ISO as Lights, you can build library and re-use Master Bias (stacked version) in the future.

Darks, - currently is quite a big tendency to use Dither strongly instead of Dark (Dither every sub or every second sub). Dither is slight shift of the target between subs, - it usually done via Astro imaging software like APT, SGP and etc (some even able to it manually...... O_o )

Of course try procedure with Darks also, - in ideal they should be taken even at the same temperature as Lights, - it will not be possible with Canon, so try least to get the temperature close (and of course, the rest of the settings like ISO, exposure - have to be the same as Lights).

Flats, - depends on software you will use, APT has ant option for Canon Flats, - easy as 123. If no software is used, - it is quite a poem to write about it.....

Keep in mind, - Flats is not only for vignette reduction , but Mainly to remove dust shadows from images (you cannot avoid them completely... dust will pop out from time to time in different places), so if you moved any toy one your optical train (for example camera... or reducer or Light Pollution filter and etc), - you will not be able to produce Flats which will match your Lighs, as optics will shift and dust shadows on Flats will not match their location on the Light images.

Thankyou for your in depth guide this is very helpfull

im unsure as to shorten the draw tube would that be shorten the inner end or the outer end and by how much

so i take it i wont reach focus ? i was advised the baddar cc was a good one to have by the retailer ?

thing being its a new tube so to start cutting straight away i wasnt wanting to do but if its going to require it

then i suppose it has too be done are there any guides on this job available or here on the site 

will it involve removing all the focuser housing ?

i can try and get this matter sorted while i get my order in on my mount

many thanks for your help

[alacant]

Hi

13 hours ago, si717 said:

will it perform out of the box

I doubt that it will be much use out of the box. Remember that this is a low budget Skywatcher telescope. Collimation is easy, but before you have a go, be sure too read the collimation myths

 

26 minutes ago, si717 said:

unsure as to shorten the draw tube would that be shorten the inner end or the outer end and by how much

Unless you use the gso coma corrector, your dslrs will give you distorted stars. You would shorten the end which protrudes into the telescope by 10mm.

 

26 minutes ago, si717 said:

will it involve removing all the focuser housing ?

Yes. It's a case of removing 4 bolts. Preferably without dropping the nuts down the tube! The focus barrel is soft aluminium. A fine tooth hacksaw eats through it like butter.

 

13 hours ago, si717 said:

Dark Bios and flat files

I'm with @RolandKol on this. dark frames will introduce more noise rather than help remove it. so: bias and flat frames applied to your images with a dither between each frame and stack with a clipping algorithm.

 

If you're apprehensive, you may want to go along to an astro club meeting. It's far easier to learn collimation by watching someone do it. it's likely the primary mirror cell will need attention as well as the secondary spider. They'll do that for you too. They also have hacksaws; they do the work. You buy the drinks. Easy!

Good luck and HTH

 

Edited July 31, 2020 by alacant

[RolandKol]

14 minutes ago, si717 said:

Thankyou for your in depth guide this is very helpfull

im unsure as to shorten the draw tube would that be shorten the inner end or the outer end and by how much

so i take it i wont reach focus ? i was advised the baddar cc was a good one to have by the retailer ?

thing being its a new tube so to start cutting straight away i wasnt wanting to do but if its going to require it

then i suppose it has too be done are there any guides on this job available or here on the site 

will it involve removing all the focuser housing ?

i can try and get this matter sorted while i get my order in on my mount

many thanks for your help

Don't Cut if you use Baader CC, -  try all out first.

If you will notice any problems (most likely not), - think of chopping 10mm off first, simply with hacksaw, - aluminum gives up easy, 5min job...

Test test Test... If problem remains, 5mm more (not more, otherwise drawtube will not stay on the internal rollers). The inner side which protrudes into the scope is chopped, as other side has threads which are used for camera holders

As I mentioned, usually that problem happens with Coma Correct for Skywatcher Brand.

[RolandKol]

16 hours ago, BrendanC said:

Hi all,

I have a problem with my 130PDS (I think - or it could be the mount, the software, or any number of things, but it's probably the optics).

I've posted elsewhere about this (see https://stargazerslounge.com/topic/358322-what-on-earth-has-happened-here/) but was advised that the resident 130PDS experts (that's you!) might be able to help. So, apologies if this counts as a double post, I'm just doing what I was told...!

So, the problem is, I'm getting subs that look like this (zooming in to show the details at the corners and middle - these are all from one, unprocessed sub, at actual size):

There are several things going on, as you can see. The directions of the blurring changes. Some stars are out of focus. And none of them look at all right to me.

A previous similar problem seemed to be fixed by making the mount east-heavy, but as you can see, it's far from fixed the problem.

The latest thinking is that it could be the focuser impinging on the image?  This is what someone has found when zooming in:

For comparison, here's a sub I took a couple of months ago, exact same setup except that I've disassembled the kit a couple of times during bad weather, I'm now using EQMOD directly connected to my mount, and I'm also trying to improve my polar alignment by using Sharpcap (click image to see larger version then save that to see original, albeit jpg). The problem doesn't seem to be here?

You can see my kit list in my signature.

I'm tearing my hair out (or at least what's left of it) to figure this one out. If anyone has any ideas, I'd really appreciate it.

Thanks, Brendan

Hi Brendan,

Very sad story...

I see 2 problems:
1) Guiding issue 100%, - after SharpCap polar alignment, Calibrate PHD properly and run drift alignment to check your PA. You should be quite close or actually even Spot On after Sharpcap PA procedure. If guiding is still in trouble even with good PA, check your balancing again (RA and DEC) and check cabling, - maybe some cables are able to catch mount bolts or something.

2) Spacing -  which causes coma.
I do not use Canon for last 2 years, - but as I recall it has 2 different types of adapters.... I hope someone will correct me if I am wrong... But one of them, actually had incorrect spacing which produced coma (or in other words, - does not eliminate coma completely even if CC is used).

Can you please drop us the link of Canon Adapter you use?

However, in your case, stars distorted quite heavily... I suspect the Primary mirror holder bolts can be over-tightened a bit, but I am not sure... have you bought your PDS from the shop or it was used?

 

Edited July 31, 2020 by RolandKol

[alacant]

4 minutes ago, RolandKol said:

Baader CC

The focus position (the same distance as without a cc) with a dslr protrudes into the light path.

Cheers 

Edited July 31, 2020 by alacant

[si717]

thanks all for the advise i will get it setup and take a look before anything

there always seems to be something haha

and dithering between frames sounds another thing to look into

but thankyou

[alacant]

17 hours ago, BrendanC said:

There are several things going on

Hi

Let's do the collimation first. If you can't get along to an astro club for them to check it...

Post a photo through your Cheshire collimator. If it has cross hairs, so much the better. Post another with a simple cap; one with just a hole in the centre to ensure you are central.

There's astigmatism so this looks like the Baader cc but you could confirm that too. if so, which connection method for the cc are you using?

Cheers

 

 

Edited July 31, 2020 by alacant

[RolandKol]

25 minutes ago, alacant said:

The focus position (the same distance as without a cc) with a dslr protrudes into the light path.

Cheers 

I used my Canon without any SW CC first and have not noticed any drawtube  protrusion issues...

SW CC actually caused problems...
However, it can be written off, - as I had completely no experience at that time and did not know what to look for.

[Stub Mandrel]

22 hours ago, RolandKol said:

Location Location Location....

My Bortle 8-9, probably shine much brighter even if a slight thin cloud line is in the way.

I can see that being an issue.

Planets and the Moon are always a good standby when conditions are tricky.

[Stub Mandrel]

20 hours ago, BrendanC said:

Hi all,

I have a problem with my 130PDS (I think - or it could be the mount, the software, or any number of things, but it's probably the optics).

I've posted elsewhere about this (see https://stargazerslounge.com/topic/358322-what-on-earth-has-happened-here/) but was advised that the resident 130PDS experts (that's you!) might be able to help. So, apologies if this counts as a double post, I'm just doing what I was told...!

So, the problem is, I'm getting subs that look like this (zooming in to show the details at the corners and middle - these are all from one, unprocessed sub, at actual size):

Top left

 

Bottom left

 

Bottom right

 

Top right

 

And finally, middle

 

There are several things going on, as you can see. The directions of the blurring changes. Some stars are out of focus. And none of them look at all right to me.

A previous similar problem seemed to be fixed by making the mount east-heavy, but as you can see, it's far from fixed the problem.

The latest thinking is that it could be the focuser impinging on the image?  This is what someone has found when zooming in:

For comparison, here's a sub I took a couple of months ago, exact same setup except that I've disassembled the kit a couple of times during bad weather, I'm now using EQMOD directly connected to my mount, and I'm also trying to improve my polar alignment by using Sharpcap (click image to see larger version then save that to see original, albeit jpg). The problem doesn't seem to be he

You can see my kit list in my signature.

I'm tearing my hair out (or at least what's left of it) to figure this one out. If anyone has any ideas, I'd really appreciate it.

Thanks, Brendan

 

Those shapes are definitely coma, shaped like the reflection of light slanting into a mug of tea! Exacerbated by poor collimation which is probably why they all point pretty much the same way..

Have you got a coma corrector?

[Stub Mandrel]

I found this, which is rather unfair on the MPCC as increasing the back focus should bring it to the same as the others (which are all possibly spaced a bit too far):

[BrendanC]

@Stub Mandrel Yes, I am using a coma corrector. Thanks for posting those images, but I'm not sure what they're telling me? 

[Stub Mandrel]

On 31/07/2020 at 14:06, BrendanC said:

@Stub Mandrel Yes, I am using a coma corrector. Thanks for posting those images, but I'm not sure what they're telling me? 

Your examples are all pretty much like the Baader example. This suggests you need to increase the spacing. Is it the Baader MPCC - this is much fussier about spacing than the skywatcher one.

It's not clear but there appears to be some tilt or the collimation may be out as well. Try adding a 1mm spacer (card will do for a trial) and recollimating and see if it improves.

Once you get the spacing right you can get a permanent spacer (or look on amazon they have some spacer sets that are cheap).

[alacant]

On 31/07/2020 at 14:39, Stub Mandrel said:

found this, which is rather unfair on the MPCC as increasing the back focus should bring it to the same as the others

Hi. 

Mmm. Not sure; what you see in the Baader example is mainly astigmatism, not coma.

i'm not sure what camera the OP is using, but I never got the Baader to cover aps-c; get the corners right and you're greeted with fat stars centre. You can't win:(

The 2 element sw 0.9 cc does better and is not as fussy on spacing. However to be able to take the cc out of the equation, IMHO you need the 4 element GPU or better. 

The closest i got was with the Baader (without the bodge of the m42 adapter) was a 4mm low profile filter ring screwed directly onto its m48 thread with a proper wide throat t ring. Remember that the correct spacing on the Baader cc is 57.5mm.

A good way of narrowing down the issue is to borrow and so substitute suspect components. Try the local astro club?

HTH and clear skies.

 

 

Edited August 2, 2020 by alacant

[barkingsteve]

8 minutes ago, alacant said:

i'm not sure what camera the OP is using, but I never got the Baader to cover aps-c

Hi Alacant / Stub, I was trying to help the OP and advised he ask for help here from the other post:

 

Brendan is using a Canon EOS1000D with an unstated cc. He says he has only had this problem since changing mount but i think he must of 'knocked' something while changing mount. It looks like a combination of problems and i advised him to do a star test and go from there, here is the star test with shows poor collimation and focuser intrusion, along with coma/tilt and/or poor tracking could this cause the issue shown ?

 

I am sure he appreciates the help  

[alacant]

20 minutes ago, barkingsteve said:

advised he ask for help here

Hi. Ah, OK. I thought that this seemed familiar.

The problem here is that this isn't a dedicated one topic thread, which makes it difficult to decipher the interspersed postings.

But that's nothing; many of us here do astrophotography;)

Cheers

[BrendanC]

Thanks for the advice everyone. I've identified a set of problems which I hope to address in order over the next few days, so no need for me to hijack this thread any more! 

[Jamgood]

My first shot of the Moon with the 130PDS. I was just playing around with settings and trying things out as this is all new to me as yet. 

[si717]

first clear night and first ever shots with the 130pds only 20 40s lights darks an bios of M13

im pleased could of done more

but happy with my first attempt at photography next to move onto guiding and more subjects 😀

Edited August 11, 2020 by si717

[sagramore]

Hello 130PDSers!

Having just learned about plate solving (and how to do it properly in APT, which I use for capture) I have revitalised my interest in imaging. I was having real trouble locating targets and centring them but since getting plate solving working I feel WAY more ready to move up in the world.

I've been having some problems with my Canon 550D disconnecting from my laptop during imaging and it's really starting to bug me. I've tried troubleshooting in lots of different ways and this has included a complete update of the laptop software, drivers, etc and re-install of all the guiding and capture software. Sadly the problem (while improved tonight, compared to normal) is still present and I am wondering if it's likely to just be the fact that my camera's USB connection is dodgy. 

Alas, on top of this I have always wondered how well my NEQ6 is functioning. PHD2 guiding is usually OK and in the 0.5-1" total RMS range, but it sometimes goes higher, and there's a fair whack of backlash in certain directions.

 

So, two-part question:

• Has anyone here belt-modded their NEQ6, did it go well and was it worth it? I've been considering it for a while but been put off by the worry that some of the hex bolts are REALLY REALLY tight and I might buy the kit and find myself unable to actually install the mod. I'm also just a little worried about screwing up my expensive mount....
• Considering I live in the middle of a medium-sized town and LP is reasonably strong near me, do you think I'd see significant upgrades moving to something like a ZWO ASI1600MM-pro with narrowband filters? I *love* the look of hubble pallet images but so far have never really dabbled in nebulae imaging because of my light pollution and camera. I'm assuming LRGB will be affected by LP as badly as OSC, but narrowband would help a lot?

 

I'm just looking for excuses to spend some inheritance but I don't want to waste my cash

 

PS. Sorry for anyone in here who's already seen another post I made with similar questions but I wanted to hone in specifically on the 130PDS community as that's the scope I have and have so far really enjoyed using.