Jim Smith

4 hours ago, barbulo said:

Might be wrong but I'd say it is a bit out of focus: the four long diffraction spikes should be thinner.

I used a Bahtinov mask but focus may have slipped afterwards.

6 hours ago, Rallemikken said:

Seen this on my own newt sometimes. Comes and goes. Only a minor annoyance. Is the direction consistent? Can it be moonlight or other stray light entering over and into the top of the tube? Maybe a long dew shield? If your scope isn't flocked, I'd start with that.

There was no moon and no dew shield. Yes, maybe it's some sort of internal reflection in the tube. I don't have much experience with the 130pds yet so I will see how future sessions go to see if there is a pattern to it.

Off Centre Diffraction Spikes.

Some of the brighter stars seem to have off centre diffraction spikes. Any ideas?

130pds - drawtube shortened - mirror clips removed - ZWO ASI 533 MCP - Baader MPCC

60x30s - gain100 - APP - Affinity Photo - Astroflat Pro - Topaz deNoise AI

Thanks. I took a look. I don't think they do a Z-mount one.

Does anyone know of a way of attaching Nikon Z-mount lenses on an astro camera?

Celestron 150mm SCT on AZ-EQ5 in AZ mode
Nikon Z50   1500mm   f/10   ISO400  25x1/250s

2 hours ago, rotatux said:

Very nice already (esp. star colors around Crab Neb.)

Thank you. When processing I left the colours alone and trusted the camera to have got it right on "direct sunlight" white balance.

Two images from a couple of days ago. Darks only with relatively short exposure time. Skymax 127 on AZ-EQ5 in alt-az mode.

The Crab Nebula. Nikon Z50 1500mm f/12 ISO3200 33x30s

 

I think this is pretty close to the live view through a small telescope...

1 hour ago, adyj1 said:

but here is a simple description of the process I used

I will give it a try. Thanks.

2 minutes ago, barbulo said:

If you are going to plate solve, there is no need to do the star alignment. 

I might save plate solving for "phase 2". For now I suppose I will need to do some sort of star alignment at least once.

My Lynx Astro FTDI EQDIR USB Adapter for Sky-Watcher Mounts cable arrived along with a USB splitter cable. (My laptop has only one USB port). 

I installed ASCOM, EQMOD and APT on my laptop and connected my camera and mount...and...it worked first time! I slewed the mount around, turned tracking on and off and took a series of images of a tree all controlled from my laptop. OK, I know that there is plenty more to sort out once I get dark, clear skies but that's a great first step. Thank you everyone!

One question...I suppose I still need to do some sort of star alignment. Now I don't have the handset connected how do I do that? Is it done in EQMOD?

Thanks everyone. This is all very helpful. I'm going to take a look at APT first and see how I get on.

I'm a bit stuck knowing what to try next for my DSO set-up.

I have a SW 130pds Newtonian mounted on a SW AZ-EQ5 GT. I use a Nikon Z50.

My current method is to start siderial tracking on the mount, find objects with the red dot finder by slewing with the mount handset. I focus with a Bahtinov mask, take a test shot then use the camera's intervalometer to take many 30s exposures. I'm quite happy with the results.

But I find the mount handset awkward and difficult to use. Also my ancient body is finding it more challenging to position itself so that I can see through the finder. So I am looking for an improved method.

I want to use a laptop to control the mount and camera directly. I imagine using my existing Windows 10 laptop with a USB lead going to the mount and another going to the camera. I would like to point and control the mount from my laptop and see the camera's live view on the screen. Perhaps the laptop could do plate solving and point the scope at the required object?

I have started reading about various bits of software that might do some or all of these things but it all sounds rather complicated. I don't mind a reasonable amount of complexity but I would like to start off on the right track.

Can somebody point me in the direction of a relatively straightforward solution? Thanks in advance, Jim

Capturing Copernicus...

1 hour ago, jambouk said:

Possibly. You could be the first lunar imager who has been thwarted by periodic error

 

Well, I'm going to train my mount even though that sounds a bit equestrian. Interesting to see if it makes a difference.

2 hours ago, jambouk said:

With your DSO images, do you have the first sub and the last sub of a DSO imaging run and flick between those and see if the stars move.

You've reminded me of a video I made a few months ago of the periodic error of my mount. https://ishoo.co.uk/video/mounterrorlow.mp4

I think the cycles are about 15 minutes long. Bearing in mind that the above video is of an APS-C sensor rather than the small sensor of my lunar set-up, periodic error might well be the real problem.

7 hours ago, jambouk said:

polar alignment not tight enough

Thanks, Of your suggestions, I think the polar alignment might be the most likely. Although I don't notice problems with dso imaging, I do that with only 30s exposures at about 1/4 of the focal length, so it might not be obvious. I will check it again.

13 minutes ago, Gfamily said:

Can you tell whether the incorrect tracking is in RA or Declination?.

Thanks. Looks like Right Ascension to me.

7 minutes ago, malc-c said:

No expert, but how good was the polar alignment ?

To be honest drift whilst using a video camera shouldn't be a problem as you typically stack the individual frames, and the registration of each frame is handled by the stacking software.

Thanks. Polar alignment is good. The mount lives on a permanent pier. Yes, I do stack the frames but the stackable area gets smaller as time passes. I suppose it isn't a big deal...but it would be nice if it worked.

My SkyWatcher AZ-EQ5 GT tracks the stars pretty well but when I come to do lunar imaging I can never seem to get the lunar tracking working. See how far Copernicus drifts in 3.5 minutes...

First frame from video...

Last frame from video...

Here is the set-up...

2,400mm focal length. Altair GPCAM 178C using whole sensor.

I actually get less drift for the moon when using sidereal tracking mode. I balance the scope on the mount quite carefully. This lunar drifting always happens. It's not just a one-off.

Does anyone have any ideas? Thanks in advance, Jim

Messier 78

Nikon Z50  55x30s  ISO800

...and finally a clear night.

I removed the primary clips entirely and fixed the mirror with silicone sealant. I recollimated.

So here is my modified "no triangular stars" 130pds in action. Nikon Z50, Baader mpcc III, extra 1mm spacer ring, shortened draw tube, no mirror clips, no mirror edge baffle.

One 30s exposure, ISO800, +3ev in Lightroom, uncropped...

Progress! 

I searched back through Lightroom and found a shot from before when I fitted the mirror edge baffle. (Also before I shortened the draw tube.)

The stars, in the centre at least, are circular! I'm pretty sure loosening those clip screws is going to be the fix. I have ordered some silicone sealant in case I decide to remove the clips.

I have a feeling that with everyone's help I am going to end up with decent stars across 90% of the field...which I think is a reasonable goal. Thanks again for all the helpful suggestions.

54 minutes ago, bottletopburly said:

siliconed the primary to holder using a few blobs of low modulus silicone

Why did you do this? Will the mirror be loose if I loosen the clip screws? I suppose I'll find out when I take another look at the mirror cell! I wonder if the 130pds mirror cell is the same design as the 200.