The EQ3 DSO Challenge

[Nigel G]

53 minutes ago, Filroden said:

Now you're using an EQ mount and have PHD working I would recommend trialling SGPro. It will platesolve out of the box allowing you to precisely centre on a frame taken on a previous night. It will also work if you move to a mono camera with filter wheel. It also will manage focusing if you ever decide to automate.

I shall look at that.

Cheers.

[Stub Mandrel]

M5 from last night, 30-second subs, but not enough to make it good enough for teh 'comp'. Amazed I don't appear to have tackled M56 before. Unfortunately anything lower than M10,M12,M5 is going to be a big challenge from home.

I'm wondering if I can get away with putting the scope on top of the kitchen's flat roof... as long as I'm not stomping around while it gets on with imaging?

[bobro]

2 hours ago, Stub Mandrel said:

 

M5 from last night, 30-second subs

 

No guiding with the new camera and DIY scope yet?

[Stub Mandrel]

36 minutes ago, bobro said:

No guiding with the new camera and DIY scope yet?

I have to reprogram my goto box and then wire it up ...

[mikey2000]

7 hours ago, Nigel G said:

 

Question to all- what capture software are you using and do you get any problems with it, also is it free ☺

 

I'm excluded from most of the 'proper' capture software as I have a sony A6000 camera.  Lovely APS-C sensor (no banding and v. low noise) but sadly Sony hasn't given out a camera control API for other developers to hook into my camera.  It's a canon/nikon world out there....

 

So, I bodge it up a little.  I use an ebay intervalometer to operate the shutter.  I save pics in raw+jpg to an eyefi memory card.  During capture, the previous sidecar jpg flies through the air to the computer and I can have fun with DSS Live watching the stack build up.  When done, I just put the memory card into my big computer for stacking the raw files.  If DSS Live can see something with the jpg files, then DSS Proper can definitely get a decent result from the raws.

 

For setting up and aiming I use astrotortilla.  For this, I need to physically visit the camera to change settings.  15s at ISO1600 is usually enough to get astrotortilla something good enough to plate solve.  Then I reset to Bulb mode and ISO400 directly on the camera, let it settle a for a few minutes guiding (touching the camera sends PHD2 haywire...) and press the Go button on the intervalometer and off we go!
 

I'm investigating a little hack I found for the Sony Remote Control software.  As it comes, the Sony software is limited to 30s exposures. The hack (MarksAcquisition, found on cloudynights.com) can trick the software into longer exposures. Cool!   The direct cable camera remote control is much quicker than eyefi and allows adjustmens of camera settings without touching it. 

 

All for free!  (Except the eyefi card)

[Art Gecko]

My offering from last night.... M101. 52x50s subs plus 15 darks and 35 flats.

Ever so slightly off with the focus on this one, hence the double diffraction spikes if you look very closely... My bad really as I should have kept checking it, but I'm blaming the hazy cloud while I was setting up

Still, didn't turn out too bad. Art

[bobro]

19 minutes ago, Art Gecko said:

 

My offering from last night.... M101

 

Nice capture! Although it's quite a blue target, I wonder if it's perhaps a little too blue? I'm interested in how people adjust colour balance - I usually just do it in DSS as I can't seem to successfully do it in GIMP alone.

[Art Gecko]

3 minutes ago, bobro said:

Nice capture! Although it's quite a blue target, I wonder if it's perhaps a little too blue? I'm interested in how people adjust colour balance - I usually just do it in DSS as I can't seem to successfully do it in GIMP alone.

Thanks Bob, I know what you mean about the blue.. I didn't boost the saturation at all, I heard somewhere that having focus slightly off infinity boosts the colour somehow? Might be what happened here as I really struggled to keep the saturation down with this one... But I do like the variety in the star colours!

I edit in Photoshop, I've no idea what the differences are between that and GIMP, but I'm always adjusting the levels of individual channels to keep the RGB histogram balanced, then color balance controls to adjust the hue of each colour in the highs and lows to stop any one colour from taking over... I know this shot doesn't give a particularly good example, but my M51 shot (a page or two ago) was processed more or less the same way and shows a better balance... the way I see it, if the colour is there, go with it... if it isn't, don't try and push it too far!

[mikey2000]

Clear skies here tonight!

 

but it won't be truly dark until 11pm and I have to get up for work at 5am.   Drat

[bobro]

13 minutes ago, mikey2000 said:

I have to get up for work at 5am.

I don't 

[mikey2000]

My shots from last night....  I started a bit early, so this first one was taken against a sky that wasn't completely dark.  Almost impossible to drag anything out of the data:

M81 (Bode's Nebula)

 

 

Then an easier target, an old favourite of mine - M13 The Great Cluster (just 5x2mins here).  No artficial dffraction spikes here - it's all real!

 

And last of all, M57 The Ring Nebula.  I tried a bigger set of pics, hoping to try DSS 2xDrizzle so I could crop in a bit on the ring.  In the end, I think it just makes the stars look too big...

 

[Stub Mandrel]

+point for self employment.

I can set up the scope, put the camera timer on and come in a and do a couple of hours work so i get a lie in :-0

[mikey2000]

  great idea!    Unfortunately, working at home is definitely not an option for me :-/.     Sometimes I think about setting the whole rig up, set it going then head off to bed.    I worry though about something "happening" such as rain, excessive moisture, fence jumping burglars.   And who would keep an eye on the PHD graph...

[bobro]

Great to see stars out last night - and for an extended period! First time I've managed to find M81 & M82 - thanks to nova.astrometry.net

SharpCap polar alignment works very quickly with the new AR0130 camera - makes a real difference to guiding as DEC corrections are infrequent. 23 subs @ 240 secs - cropped.

[Art Gecko]

3 hours ago, bobro said:

Great to see stars out last night - and for an extended period! First time I've managed to find M81 & M82 - thanks to nova.astrometry.net

Nice capture Bob!

[Nigel G]

3 hours ago, bobro said:

Great to see stars out last night - and for an extended period! First time I've managed to find M81 & M82 - thanks to nova.astrometry.net

SharpCap polar alignment works very quickly with the new AR0130 camera - makes a real difference to guiding as DEC corrections are infrequent. 23 subs @ 240 secs - cropped.

 

Lovely image bob, well done.

Nige.

[Nigel G]

On ‎24‎/‎05‎/‎2017 at 09:48, bobro said:

Until recently I used EOS Utility, but moved to APT (19 Euro) to allow dithering. In my limited experience I didn't have any problems with EOS Utility. A thought : enabling in-camera noise reduction results in an exposure doubling effect - could this be the problem?

Bob

Hey Bob.

Thanks for that info.

It turns out that my long exposure noise reduction was on auto so it would choose to reduce noise when it wanted to which would explain it starting halfway through a batch, disabling it has rectified the problem.

Well done and cheers

Nige.

[Art Gecko]

I might do a little experiment tonight, since I do my imaging unguided I tend to throw away a lot of my shots as they're not up to scratch... So I'm thinking I might pick a nice easy but interesting target like M51, spend an hour imaging at 45-50sec subs, then spend an hour imaging at 10-15sec subs and stack them as two separate images to see which one has the longer total integration time... Will have to make it fair though, so if I say session1: 50s subs, 10s delay... 1 hour in time, means 50 mins worth of subs. session2: 10s subs, 5s delay... 1 hour in time will give me 40 mins worth of subs, so if I spend 1 hour 15 mins I should get the same total of 50mins to compare against..... I'm simply interested to see which set will yield the longest total exposure after stacking, but also what effect the shorter/longer subs have in the final outcome in terms of signal/noise.

This is purely for my own interest really, but I'll post the results if anyone is interested.

[bobro]

1 hour ago, Nigel G said:

It turns out that my long exposure noise reduction was on auto

Glad you managed to fix it Nige - and the sky looks clear tonight!

Bob

[bobro]

1 hour ago, Art Gecko said:

I might do a little experiment tonight

Definitely interested Art - if I understand theory correctly both images should have the same overall signal/noise for the same total exposure time. However, the image with longer exposures should show more faint detail. No idea about theory regarding colour, though real images I have seen posted seem to lack colour with shorter exposures. It would help with a comparison if it's possible to use the same processing steps with both images.

Bob

[Art Gecko]

28 minutes ago, bobro said:

Definitely interested Art - if I understand theory correctly both images should have the same overall signal/noise for the same total exposure time. However, the image with longer exposures should show more faint detail. No idea about theory regarding colour, though real images I have seen posted seem to lack colour with shorter exposures. It would help with a comparison if it's possible to use the same processing steps with both images.

Bob

That's pretty much how I understand the theory as well Bob, you're right I will have to make sure it's as controlled as possible all the way through... I can use the same set of flats, but darks would have to be taken separately for each session... so do I get the same number of darks? or go for the same total time value? or sack off the darks and just do flats?.... also, as you say, the processing will have to be duplicated.. I think there's a way of saving the processing information and applying it to another image in photoshop.... I don't know how to do it yet... but I'll look into it.... otherwise I'll go for a simple stretch that I can duplicate myself and compare the difference.

Art

[Nigel G]

Now I have turned off the camera NR everything is working just fine  along with a very clear night and no dew  Perfect.

I dithered for the first time last night on a test of the Elephant trunk nebula. I wanted to see if its worth spending a few hours on the object with a small scope and DSLR.

I have not spent much time on processing this image yet, It was easy to process I guess dithering did the job.

I'm very supprised to see so much data in the image, well worth imaging even the dark dust is showing. This is 18x240s ISO800 with usual calibration frames. ED 80, EQ3 and modified 1200D.

I also took a single sub on the Veil set to see that I should just about fit both East and West in the frame, so I'm looking forward to imaging them too.

Cheers

Nige.

[Art Gecko]

6 hours ago, Nigel G said:

Now I have turned off the camera NR everything is working just fine  along with a very clear night and no dew  Perfect.

Beautiful image Nige! Good to see you got the NR sorted out!

[Art Gecko]

The results of my experiment are in!

So, as I said before, this is 2 shots... one taken with 50sec subs and one with 10sec subs, no darks, 30 flats. I gathered a total of 50 mins worth of exposures for each set. ISO1600.

Each image was processed very simply using nothing more than curves and levels (black point eye-dropper in levels to set the background luminance)... so no complicated processing techniques used at all!

1st: The set of 50sec subs came out at a total of 18.33 mins (36.6% of the total subs)

2nd: The set of 10sec subs came out at 22.66 mins (45.3% of total subs)

So, not much difference between the total time to be fair... But very different outcomes. I'm still not sure which one tips the scales?

[Art Gecko]

.... and let's face it... I was always going to do a composite of both!