Spaced Out

Hi

Just wondering if anyone is using one of these telescopes with either the dedicated StellaMira 0.8x flattener/reducer or the TS FLAT2 1x flattener on a APS-C sized sensor ? I'd be very interested to hear/see how well your stars are corrected into the corners ?

Thanks

Gary 

2 minutes ago, alacant said:

It looks as though you're too far. We use 53mm cc to sensor distance with our 130.

Unless the prescription has changed, the GPU needs the following spacing, depending upon focal length:

https://www.bintel.com.au/product/skywatcher-f4-aplanatic-coma-corrector/

 

Thanks for the info, it's useful. I was actually at 53.2mm, any movement either way and the curvature % in CCDI just got worse. 🙁

I think I'm going to try and improve the tilt (which I'm guessing may be down to slack focuser tensioning) then revisit this test again. Tbh if CCDI says 23% curvature I could live with it so long as the stars look better/rounder than they do atm !

29 minutes ago, R1k said:

Is this CC correct for your scope? My understanding is that it is only for f4 newts

Yes, the CC should work at f5, I had the TS version before the SW one and it worked great with the 130PDS, that was with the smaller ASI 1600 sensor tho, so perhaps less to correct.

TS blurb reads....

"Ideally suited for Newtonian telescopes with focal ratio f/4 - delivers very good results from f/3.5 to f/6"

17 hours ago, teoria_del_big_bang said:

I am no expert but to me I would say it has some tilt.

This camera is a fair bit heavier than the 1600 so with a stock focusser could cause tilt (not that I know you have a stock focusser).

Steve

Thanks Steve. Yeah I think maybe tilt is contributing most to those star shapes, the CCDI charts seem to support that too, both text and the colour changes (it looks a bit off centre). The ASI 2600MC setup is actually quite a bit lighter than the old 1600, but only because the 1600 imaging train included a heavy EFW/filters and OAG/guide camera etc. I think the 2600 is actually about 100g lighter than my current DSLR, so I thought the stock focuser should cope with it OK. I will have a fiddle with the focuser and see if I can tension things up a bit better to improve the tilt.

I am still concerned about the field flatness, 23% seems the best I can get, is that down to the larger sensor being more difficult to correct or could a fair chunk of that be down to tilt ? 

Hmmmm..... 🤔

Hi All

I hope someone is able to offer me some advice here. I am excited to have a new camera but I am having a bit of trouble spacing it with a coma corrector.

Equipment is:

ZWO ASI 2600MC

SW Aplanatic Coma Corrector

SW 130PDS

I was having trouble with non round stars around the edge of the frame. After lots of faffing with spacers I downloaded a 30 day trial of CCDInspector to see if that might help. The best result I managed is shown below, 0.4mm either side of this spacing seems to make the curvature worse.

Looking at the test image, it’s not terrible but you can see the star shapes are a little misshapen in the corners (worst on the left side), this is also reflected in the CCDI charts.

My old camera, the ASI 1600, spaced really easily with this coma corrector and gave nice round stars to the corners, in CCDI it showed 8% curvature, this 2600 is sitting at 23%.  

So...

I’m wondering if my star shape issues are down to the larger sensor of the 2600, maybe it is just harder to correct ? Or perhaps it is not CC spacing, maybe it is tilt as suggested in CCDI ?

Has anyone else had similar issues with the ASI 2600 and spacing coma correctors ?

Any experienced CCDI users able to tell me how bad these charts really are please, is 23% curvature very bad/visible in images ?

Thanks

On 05/04/2022 at 21:27, Bibabutzemann said:

I always thought the focuser is really stable. I would have thought flex in the tube would be a bigger concern then the focuser. 

How did you measure the weight induced tilt?

 

I had streak like stars on one edge of the frame, they moved around when I moved the mount position, it seemed to correspond with gravity. Once I’d worked this out I put a hotech laser in, put my full camera gear in a carrier bag and hung it (very carefully !) off the laser. This tilted the laser dot and as I gently moved the mount around the laser dot moved about. I tightened everything up on the focuser the best I could but couldn’t fix it. Used a lighter DSLR only and there were no issues, just when I used heavy mono gear, so I got the impression 1.3KG is too much for the stock focuser to take.

Fitted a TS V-power focuser instead and problem solved.

Just now, BrendanC said:

Quick question: what was your opinion of the TS GPU corrector? I keep hearing good things about it and am tempted.

The MPCC mk3 I was using was quite faffy with spacing and felt sort of wobbly in the focuser tube sometimes, it never gave great stars to the edge consistently for me. I thought the GPU was way better, I found it dead easy to space, it felt solid and couldn't tilt at all in the focuser tube due to its long straight edged design. It gave nice round stars to the edge with the ASI 1600.

The only (BIG) problem I had was weight, which caused focuser tilt, but this was because I had the ASI 1600, EFW, GPU CC, OAG + guide camera hanging off it, nearly 1.3kg in total and the focuser didn't like it at all. Ended up fitting a new focuser which cost more than the telescope ! 

Anyway I've just bought another 130PDS and have bought the SW aplanatic CC for it this time. This is identical to the GPU corrector except the collar is not removable on the SW. I contacted TS to ask about this and they confirmed it is the same CC from the same factory. Only got the SW aplanatic because it is a little cheaper than the GPU and much easier to source in the UK. I'm going to use it with a OSC, no EFW or OAG this time, so hopefully weight/focuser tilt won't be an issue.

6 minutes ago, BrendanC said:

Hi all,

I'm trying to get to grips with why I'm getting vignetting with my ASI1600 and 130PDS.

I'm using the 8 position EFW with 1.25 inch mounted ZWO filters, and the Sky-Watcher 0.9x coma corrector. I'm looking into various fixes, including the TS Optics non-reducing coma corrector, but if anyone has a similar (ideally identical!) optical train, and they're NOT getting vignetting, it would be good to know. It's definitely all set up correctly.

Thanks, Brendan

I used to have a 130PDS with an ASI 1600, 1.25 filters and the TS GPU (non-reducing) corrector. Got vignetting with that set up but just took flats, they sorted it out.

Hi All

I've just noticed this on the ZWO website...

https://astronomy-imaging-camera.com/news/oil-leak-issue-on-asi2600mc-pro-and-other-cameras.html

Thought I'd just throw it on here in case it is of interest or use to other ZWO camera owners.

11 hours ago, Whistlin Bob said:

Not sure of the weight, but mine can handle an asi1600, filter wheel and coma corrector without trouble.

It needed careful adjusting though.

Thanks. I used to use a similar setup on my old 130PDS. ASI 1600, ZWO EFW, ZWO OAG + camera and TS GPU CC (a little larger/heavier than a MPCC), weighed it all at just under 1.3KG in total and the focuser didn't like that at all ! I got obvious tilt that couldn't be fixed whatever I tried, ended up swapping to a better focuser and that sorted it. 

I'm back with a new 130PDS, thinking about OSC this time, maybe investing in an APS-C format tho. They are a bit heavier than the 4/3 format cameras. 🤔

Hi all

Just looking for your opinions on the maximum weight you can comfortably hang off your stock 130PDS focuser without introducing tilt ?

1 hour ago, alacant said:

Hi

Yes. No problem. We restored an old 250p. It goes fine on an -even older- eq6. With the lighter pds and a modern eq6 you're in for a pleasant surprise.

You really do notice the speed of the thing. Try side by side with a 150mm;)

We'd still recommend however spreading the tube rings on a long losmandy plate, a rigid rail to tie the same along the top, uprated springs, sealing the mirror to the cell, a dew shield, a black shower cap and an oag. It sounds a lot, but it's only around an hour's job.

Cheers and HTH

 

Thanks, useful info and reassuring ! 👍

3 hours ago, david_taurus83 said:

If you haven't bought a 250 yet then maybe consider a 200 as it's a similar focal length, F5 and will be much more manageble on an EQ6 class mount. 

I hear what your saying. I had a 200PDS and it was fairly large so I only used it in calm conditions. Figured it'll be the same scenario with the 250PDS, so if the mount can take it I'd quite like to try it just for the extra 200mm. 🙂   

6 minutes ago, iapa said:

My thought is that the carbon fibre is lighter than the other 10" models.

IF you have the 250PDS, the give it a shot, if it doesn't work for you upgrade the mount  

Only just bought the eq6-r recently, I have little money to spend on more gear tbh. 🙂

I don't have a 250PDS yet but I am thinking it might be a cost effective way of achieving greater focal length (if it will work OK with the mount).

31 minutes ago, iapa said:

Guiding was OK, but that thing is a sail and didn't like any gusts > mph 10, even worse on tripod.

 

Thanks for this, interesting. Yeah I figured a 250PDS is a huge wind sail and so that would limit the times I could use it anyway. The EQ6-R is on a pier in the garden, it's not shielded from wind as such but it does have a little protection when the wind blows from certain directions. 

Given a nice calm night, I'm wondering if the EQ6-R is up to the job, once a 250PDS is loaded up with cameras etc it won't be far off the stated payload capacity (20kg ?), this is why I was asking for other peoples experiences. I'm guessing it will need careful balancing. I've used a 200PDS on a HEQ5 in the past, close too the mounts payload capacity, sometimes it was ok but it didn't always work out well.

Just wondering if anyone has tried using a Skywatcher 250 PDS mounted on an EQ6-R Pro for DSO astrophotography... I’d be interested to hear your experiences, daft idea, or achievable ?

1 hour ago, nfotis said:

What are the hard cases for? Batteries and accessories?

N.F.

 

They have mains power running to them, 8x plugs inside and a powered USB hub which is routed back to my 'mini obs'/warm room in the shed.

Just setting up a new EQ6R on my concrete/brake disk pier.

I used to use a HEQ5 on the pier. To fit the EQ6R I’ve had to change the top disk to one with a larger central hole. Just drilled the bolt holes to fit the new disk for now. Next job is to weld a base plate underneath for screwing the mount down, then adding a peg for AZ adjustment and some paint.  🙂 

Should be sorted soon. Can't wait to start using it !

If you are considering a DSLR, Canon seems to be the popular brand for this sort of stuff. I’ve had good results with the 130PDS and an astro modified 600D and a standard 7D Mk2 in the past. I just remote controlled them from a laptop using APT.

4 hours ago, tony8690 said:

Hi All,

 

Haven't posted here for a couple years!

Recently moved to Northumberland (originally from Kent) am loving the dark sky’s !

 

Northumberland rocks ! 👍 🙂

3 hours ago, AstroNebulee said:

This stunner arrived today courtesy of RVO. Never thought I'd ever own one of these a beautiful zwo asi294mc pro but been saving up, so so excited eek! Was toying between the zwo 533 mc pro but the larger sensor swayed me.

 

Congrats ! 👍 I am in the process of saving up for one of these too, looks the biz 🙂.

Making slow but steady progress on my mission to get back imaging again ! New arrivals this last week, a shiny new SW 130 PDS from FLO, a cheapy guidescope off Amazon and a nice ebay deal on a second hand ZWO ASI 290 mini guide camera.

Imaging camera next... time to get saving again.  🙂

As mentioned above, I find starstax is good. For timelapse I use LR Timelapse but you also need adobe lightroom for that.

I use a Canon DSLR and I don't use in camera NR, I find it can soften things, with long exposures and lowish ISO and stacking I don't think its that important + you can always do NR when processing the final image if required. Not sure about your camera tbh.

Length of open shutter time, I go for as long as possible on my locked open intervalometer = 30secs for me, it doesn't matter if the stars start to trail in the individual images. Longer open shutter = lower ISO = less noise.

For ISO I just take a couple of test shots and see. For my Canon 6D I find 30 secs at 500 ISO gives pleasing trails, less than that and they are a little sparse, more than that and the sky gets busy ! Depends on the effect you are looking for I guess.

Easiest way to check all of these things is just to try a range of different settings for some short test runs and then stack them into a star trail to see what the result is. I did this and this is how I ended up with my go to settings for most star trails = 30 secs & 500-1000 ISO depending on the situation.

I have a few star trails here along with the settings used for each one

https://www.flickr.com/photos/132427272@N04/albums/72157655067298718/with/31468538285/

Good luck !

On 23/12/2021 at 18:40, Jim Smith said:

But as you can see, even with the latest modifications, the triangular stars persist!

I had a triangular star problem with my 130PDS, it was fixed by loosening the primary mirror clips a little, they were too tight.

Good luck !

Thanks everyone, some good suggestions there, really helpful. 👍