david_taurus83

At 1200mm focal length, guiding is a must on a Skywatcher mount. I would even say off axis guiding for this.

Should it not be done on an L channel?

Well, I think that'll do it. Slightly concerning to say the least how I missed this.

20 minutes ago, kens said:

3 minutes PA error is not a problem. PHD2 was able to keep the guide star centred in the guide camera but the image camera shows a steady drift. So  one camera is moving in relation to the other. My first guess would be that the dec blips are a result of the guide scope moving. Given the dec movement I would look at whether it is rotating slightly where the guide scope is attached to the main scope. We are talking microns here.

Irrespective of that, you also appear to have backlash or stiction issues.

I had the cables routed under the carry handle. Probably the cause? I'm going to put a longer dovetail on the bottom, the short one on the top and then the carry handle to that. Should add more rigidity. Will try to route cables under the scope. I like to have them fixed along the dec axis so they aren't hanging off the back of the imaging train. Didn't think routing them through the handle would be an issue!

Yes, it has some dec backlash but I've reduced it as much as I can. It calibrates in North almost instantly and returns South in 3 or 4 steps but if I run the GA it can never seem to measure the backlash. Not enough movement detected or so.

1 hour ago, kens said:

If the guiding was OK (a guide log would be helpful), then it would be differential flexure of some sort. The "blips in dec" may offer a clue.

There you go. Looks like my polar alignment was out after all, over 3 minues error. It was excellent in Sharpcap but I must have disturbed it somehow. I tried to rotate the imaging train by 90° but after testing, the filterwheel would have likely hit the tripod near the meridian so I rotated back. Pretty sure I done this after polar aligning, I think. I done 10 minute subs a few nights ago and the PA error was 0.5 minutes and the stars were pretty good. Hopefully its an easy fix.  Rebalance, careful PA and recalibrate PHD next night out. The guidescope is the William Optics slide base type btw so I hope theres no flexure either! Feels pretty solid.

PHD2_GuideLog_2020-10-09_194811.txt

No dither at all!

2 minutes ago, PeterCPC said:

Have you checked the balance?

Yes its not bad at all. Its on the CEM25 so very difficult to balance perfectly without adding off axis weights etc. I've not noticed anything like this before. How would balance cause it btw?

Whats your first thoughts? Pretty much consistent direction in Dec. This is 22 x 900s subs from last night so a period of over 5 hours. Guiding was ok (or so it seemed) with some blips in dec every now and again. Polar aligned in Sharpcap so pretty good.

Why not get the 120MC and save the hassle of filters?

How are you cooling it?

Turn the scope so the focuser is facing up.

If you buy something online you have 14 days from receipt to return the item for a refund.

I cant get a decent picture of it outside but this arrived today.

Its nice to be shooting mono narrowband again 🙂

Surely not???

When I seen that a certain popular guide camera and a couple of filters were the last in stock, I was quick to snap them up! Many thanks FLO! Otherwise I might have waited and be left disappointed!

The guide scope is an achromat by the looks so it will have lots of bloat. I added a cheap IR/UV cut filter to my last guide camera and it tightened up the focus nicely.

Your star shapes don't look too bad either for a DSLR. You could try experiment with spacers etc but that way, madness lies..

Great image BTW!

Is that a galaxy in the background? Top left.

It doesn't look like the one on the website.

Can you thread a 2" filter inside it?

On 04/10/2020 at 11:08, souls33k3r said:

I hope I'm not going off topic here but I used to have Astronomik 6nm filters and I live in Bortle 8 skies. No halos, pure class. I never tried imaging OIII during full moon but Ha had no issues. Just putting this out there so that you do not give them a miss when considering. 

Ive got both Astronomiks 6nm Ha and Oiii being delivered tomorrow and Ollys comments gave me a bit of concern but you have reassured me slightly!

7 minutes ago, gajjer said:

Not sure that is true. When a hair drier blowing, it blows in a concentrated stream of air. If you reversed the motor, I don't think it would suck in the same concentrated flow.

 

It does such it in, from the back of the hair drier.

^^^I had forgotten about the Altair 26C. Its a few hundred quid cheaper than the ASI2600 and QHY268C. Its available to order now for October/November delivery.

https://www.altairastro.com/altair-hypercam-26c-aps-c-colour-camera-16bit-6451-p.asp

What about a different scope? Flat field quad 70mm at f5 and a camera? Depends on your budget really.

I thought my phone kept scrolling back up the page!

Have you selected On-Camera in the mount selection tab? Tried a different pc/laptop/cables?

I'm sure @Allinthehead had an ASI071 and produced some of the best OSC images I have ever seen so its not to be ruled out.