david_taurus83

I'm stumped as well! The other filters were shot on different nights and the blue shows a similar increase but not as obvious unless you look for it. I've looked at some early shots on the Pleiades when I first got the camera and filters and they don't show any obvious halos. I just don't get why that one star shows it so obviously buy the ones on the left don't as they are equally as bright at mag 7. Could it be the horrendous tilt I've got? 🤔

You can use the same darks for both sets of lights as long as all 3 are the same exposure length and ISO. Assuming you didn't move the camera between switching from Horsehead to Leo you can also use the same set of flats. 

Got a link? I might give it a go with my 6D.

I didn't know you could use a DSLR with Sharpcap?

Yes, here's a timeline.

10pm

11pm

12am

1am

And the last sub at 1.45am

What'ds going on with the bright star below M51 in my Luminance subs? There appears to be a gradual bloat or halo creeping in? The earlier subs from 10pm don't have it but as M51 gets near the zenith after 1am that star seems to start glowing a bright halo? It doesn't appear to affect the brighter stars on the left? I've looked at my binned RGB data and it's not as bright but it does start to creep in later in the night again on the blue. Is it dew on the scope though I run a dew heater 100% all the time? Atmospheric conditions? (Star shapes are poor as I've incorrectly set up my tilt adapter a few weeks ago)

Wow! Great image and I think this is the first picture I've noticed was taken with a Mak-Newt! Why don't more of us use this scope? It's definitely piqued my interest!

Does your phone receive GPS signal while your inside? Doesn't the app use that to determine the location and time? Have you tried the PC version of the app? Or a handset?

I get a similar effect with my 6D but I know its to do with the mirror! I would say it's a reflection of something during capture but when I get those (glare off a streetlamp lighting up one side of the dew sheild) it tends to move as the mount tracks away from the source. 

If its not in the flats then it's not anything in the light path from front of scope to sensor. So could be reflection or light leak during capture. What does a stretched dark look like?

Is the band in the flats?

5 minutes ago, Adam1234 said:

 

That would make sense.  It seems there is a tick box in PHD2 to dither in RA only, I guess it might be worth turning that on?

That or decrease the size of the dither. I actually asked on the PHD forum if they could implement a scale for both axis. So we can set RA at a large dither and Dec with a small dither. I didn't think this was an unreasonable suggestion given that most hobby mounts out there probably suffer from backlash in declination. The general response I got was "why would you want to do that" or "just dither in RA". I didn't ask again...😒

Now I just don't bother dithering at all as I can clean up any hot pixels on my Atik 460 with a bad pixel map.

Backlash in declination. It make a large movement in dec and spends the remainder of the settle time clearing backlash. The mount only then moves to the new position after APT has started the next exposure. I get this if I dither with my CEM25. RA is fine no matter how big the movement but Dec is bad if its too big.

Are they on every sub?

The Light Pollution Map info is about 6 years old now so things have probably gotten worse or, hopefully, better with the recent initiatives with LED streetlights. Though I seen a report a few months ago that suggests only 20% of light pollution comes from streetlights. 

https://www.darksky.org/tucson-street-light-experiment/

@gorann great image of the IFN btw!

Your welcome!

Are those patterns in the flats if you stretch them?

I'm not quite sure about the new CEM26 but owners of the CEM25 will be aware of the adjustable spring loading on both axis. Too tight and the worm mesh will bind and won't budge, too loose and it will slip over the ring gear. If you set it just right though, with a bit of force, unbalanced load or an accidental knock it's possible to still slip the worm over the ring gear. So far, I've not managed to accidentally knock the counterweight bar into the doorframe for example but I have had the RA axis slip the worm over the ring gear a few times due to the load being incorrect on scope side or counterweight side. Nothing too serious and it was usually because the spring load was too weak. The mount generally performs very well with an average guiding error of below 1" each session and regular spells of 0.5" RMS. Recently though, I've been getting some huge spikes in RA. Sometimes it looked periodic, sometimes it was random. I decided to strip the mount down last night and have a look.

There was some very fine swarf like material on the worm.

I cleaned up both the worm and ring gear and applied some new grease. You can see on the ring gear from side on, the marring caused by the worm sliding over the ring. I don't think this is the cause of the recent blips in guiding as it would only be in that one area of the ring. More likely to be the swarf on the worm. A marred ring gear can't be good either though. The good news is that with the CEM mounts you only ever use 180° of the RA ring gear. By installing it back on the mount turned 180° I now have the bottom half of the ring that has never been used facing the worm. So like new again.

Ouch!

"Bottom" side of the ring never been used

Heres the last hour of guiding from a few nights ago. This is the worst I've seen it. The first time I noticed it it done 3 large deviations but nothing for the remainder of the session.

So the lesson to be learned is don't let the worm slip over the ring gear, no matter how mild you think it is!

It's clear tonight hopefully so will try and get a session in. I will probably strip down the Dec axis today and have a look. Shouldn't be any issues there but a clean and regrease can only be good. I can also evaluate the condition of the ring gear should I ever need to swap out the RA one!

PHD2_GuideLog_2021-04-03_210939.txt

Hi Bruno. I'm not quite sure what exactly your asking?? You mention you have a 0.85 reducer so I'm guessing this is the Skywatcher ED80 you have? The 533 should come with all the adapters you need to get the required 55mm back spacing required for that reducer. The 16.5mm M48/M42 adapter, the 21mm M42 spacer and the 11mm female M42 spacer and the camera with 6.5mm from shoulder to sensor all add up to the required 55mm. It should be the same as using a DSLR (44mm) and T ring (11mm).

16 hours ago, Neo_uk said:

hi David..

yes I have pixinsight but not too savvy with it which process would i use ? ...

 

In Pixinsight open the process tab and select image container at the bottom. Add the files you want to convert.

Not sure if you need to after adding files but I always navigate to the same folder in Base Directory. In Output directory create a new folder somewhere for your new binned files.

Holding the little triangle at the bottom left drag it into the background to crate a new instance.

You can close the original Image Container now and you will be left with the new instance. If you click on it you will see the original files and folders are still all there. Keep it closed for the next step though.

As @vlaiv mentions, open Integer Resample.

Make sure its set to Downsample and 2x2 in this case. Again, hold the little triangle at the bottom and drag the process and drop it over the Image Container instance. PI should now software bin all your RGB data down to 2x2 and populate your new folder.

See my example. Original files on the left and downsampled on the right. The filename still says 1x1 but the actual file size has been reduced by a factor of almost 4.

8 hours ago, nephilim said:

Your right, there is no 10mm spacer, I dont suppose you have a link to one that would be suitable, preferably from a UK supplier due to all this leaving the EU nonsense. Thanks

Steve

https://www.ebay.co.uk/itm/SVBONY-M42-0-75mm-Thread-Extension-Ring-Tube-Set-5-20mm-for-Astronomy-Telescope-/283572790532?_trksid=p2349624.m46890.l49286

It's a bit expensive if all you want is a 10mm spacer but their handy to have.

Or Altair stock some decent ones with a knurled grip for a tenner each but then charge seven quid for delivery 🤔

https://www.altairastro.com/spacer-rings-extension-tubes--adaptors-13-c.asp

Yes. In Pixinsight. If you don't have it put them in a Dropbox and I'll sort it out for you 👍

The unicorn I can believe, but 3 clear nights? April 1st was 3 days ago my friend.

11 hours ago, nephilim said:

Cheers David, I think i've got all the things I need in the box, i'm also using the Astro Essentials M48 adapter that @Uranium235 developed.

 

If its like the ASI1600 then I don't think it comes with a 10mm spacer. Thr 21mm used with the 16.5 adapter and 11mm female gives you 55mm. You need the 10mm to get to 44mm from the Samyang adapter.

You need the 16.5mm M48/M42 on the Samyang, a 10mm spacer and then the female 11mm spacer that goes on the camera.

Is that image stretched? Does your light frame look the same? If so it's vignetting and the flat frame should remove it from the lights! That's the idea of flats.