The "No EQ" DSO Challenge!

[Filroden]

5 minutes ago, The Admiral said:

The other benefit of a derotator though would surely be to allow increasing the sub exposure length, even if the total imaging time isn't extended, assuming that the mount tracking was good enough (which I know isn't the case with my mount).

Ian

Indeed, but so long as you're exceeding your read noise (which is easy with UK's light pollution), then there is minimal benefit to taking 1 x 120m subs compared to 240 x 0.5m subs. In fact, with more subs you can reduce noise more. It's one of the 'hidden' benefits we have to suffer 

Unless we went narrowband or to a 16bit CCD, I think most of us are already clipping stars with our cameras at current exposures.

Edited December 21, 2016 by Filroden

[Filroden]

I'm getting excited. It's rained this afternoon and is now clear, with a forecast that still says clear all night (though with stronger winds than I'd like). After doing some reading on exposure times with the ASI 1600, I'm going to try something new. My plan for tonight is:

a ) get auto-focus working or if not, get good focus offsets for each of my filters

b ) test even shorter exposures using the median ADU given in SGPro's statistics panel - for a unity gain I think I need an ADU reading of 850 which is much lower than I think I currently get so I may be looking at 15s exposures but I'll start with my usual 30s

c ) work on a second panel to go alongside my Flaming Star Nebula - hopefully capture 2 hours of LRGB data on the new panel and maybe 1 extra hour on the original panel

d ) figure out how to do mosaics!

Right, off to take flats...

[SteveNickolls]

4 hours ago, The Admiral said:

You might live to regret making that offer 

If I did win big Ian it would give me nothing but pleasure to order several such mounts for us all to use. 

Fingers crossed now.

Cheers,
Steve

[SteveNickolls]

Well the mount is outside and ready for later use if it all stops clear as forecast. Good luck to all able to image tonight, we are owed some good skies. 

Like Ken I'm going to do some experimentation tonight but not so adventurous as a mosaic (though I did grout some mosaic earlier today)-

1. See how BYEOS operates using just the camera on the Synscan Alt-Az mount.

2. See how a mains camera charger fares in place of a battery.

These both involve my pet hate-cables, into the imaging set up. Now what to image it has been so long...

Cheers,
Steve

 

[schmeah]

1 hour ago, SteveNickolls said:

If I did win big Ian it would give me nothing but pleasure to order several such mounts for us all to use. 

Fingers crossed now.

Cheers,
Steve

British sarcasm is way too subtle for most of us yanks to fully comprehend. Now stop making fun of me ? And Merry Christmas all!

Derek

[schmeah]

5 hours ago, Filroden said:

It's all too hypothetical still. Professional observatories all utilise alt/az but they can afford the kit needed to make it work. There are amateur alt/az mounts that can match mid-range EQ mounts for tracking but rotation remains the issue. That TSS mount can only derotate for up to 2 hours so it isn't great for long sessions. You can easily image for up to 2 hours on any EQ mount without need for a meridian flip so I don't see the benefit.

What we need is either a derotator that can manage 10+ hours at high accuracy or for the prices of large CCD/CMOS sensors to drop to the point they can fully cover the image circle so derotation can be done in software.

Until then the current equipment will give some improvements but not as much as the step up to an EQ mount.

Meade made a field derotator some years ago that never took off, because of course it was a sloppy design that never worked well. But the idea is there and if done correctly, by a premium mount company, could permit a full night of uninterupted alt-az imaging. I once thought that commercially available fork mounts could never track/guide as well as a premium GEM. But now I have one in the Avalon. So maybe it just takes a commitment from an innovative company.

Derek

[Filroden]

4 minutes ago, schmeah said:

Meade made a field derotator some years ago that never took off, because of course it was a sloppy design that never worked well. But the idea is there and if done correctly, by a premium mount company, could permit a full night of uninterupted alt-az imaging. I once thought that commercially available fork mounts could never track/guide as well as a premium GEM. But now I have one in the Avalon. So maybe it just takes a commitment from an innovative company.

Derek

Avalon is one of the mounts I have been studying because it can handle my SCT without needing to do a flip.

[SteveNickolls]

1 hour ago, schmeah said:

British sarcasm is way too subtle for most of us yanks to fully comprehend. Now stop making fun of me ? And Merry Christmas all!

Derek

No seriously Derek, it's meant in good part. Merry Christmas to you.

Cheers,
Steve

[Filroden]

3 hours ago, Filroden said:

I'm getting excited. It's rained this afternoon and is now clear, with a forecast that still says clear all night (though with stronger winds than I'd like). After doing some reading on exposure times with the ASI 1600, I'm going to try something new. My plan for tonight is:

a ) get auto-focus working or if not, get good focus offsets for each of my filters

b ) test even shorter exposures using the median ADU given in SGPro's statistics panel - for a unity gain I think I need an ADU reading of 850 which is much lower than I think I currently get so I may be looking at 15s exposures but I'll start with my usual 30s

c ) work on a second panel to go alongside my Flaming Star Nebula - hopefully capture 2 hours of LRGB data on the new panel and maybe 1 extra hour on the original panel

d ) figure out how to do mosaics!

Right, off to take flats...

Not really having a successful time in terms of my objectives so far:

a ) I can manually focus through the software but it will not autofocus. As soon as I run the autofocus routine it starts to go out of focus and then searches further and further out. Resetting to my original step does not work and I have to set a new focus point about 1500 down (out of 9000 steps) then return to my original value to get back into focus. I'm going to have to investigate this, as it seems to be software related.

b ) I'm getting the right ADU for my RGB filters at 30s but I'd have to go too short for my L so I've stuck with 30s

c ) First hour collected though I lost about 10 subs because the new SGPro beta failed to save. I've reverted to the last full version and it's all working as normal now and I'm into my second hour of data. Focus is really holding.

c + 1 ) I set up Teamviewer on my laptop and main PC and I'm now sat in the warmth remotely watching the capture! If I can get the telescope control working, I can run the whole thing from here. However, image quality of the screen isn't great so I have to rely on the statistics to know I'm holding focus, etc.

d ) A job for tomorrow!

No flats taken yet. I had a bad case of something that required a good cleaning of surfaces. I think it was condensation from cooling too quickly. I've set a slower cool down time and it worked the second time, but it was too late to mess with flats. Another job for tomorrow.

But I'm at least able to integrate all my new bias and darks I took.

Edited December 21, 2016 by Filroden

[Nigel G]

If I win the lotto I'll buy you all the camera of your choice and a big yacht for me.

Hope your promise of clear sky's is happening, bit cloudy here atm.

Cheers

Nige.

[SteveNickolls]

So where is all the clear sky? I'm all set up outside but the stars are being hidden by the cloud. Don't think I can wait much longer for clear skies although I'm going to have to of course.

Right that's it I've succumbed to the Christmas cider, first up (or rather down) is a nice bottle of Rattler at 6%.

Cheers,
Steve

Edited December 21, 2016 by SteveNickolls

[Filroden]

Mosaic of IC405 and IC410

This joins my older image of IC405 (1.5hrs L, 1.5hrs RGB at 45s g300 o50 t-20C) with a new image taken last night (1.0hrs L, 1.0hrs RGB at 30s, g139 o21 t-20C). There's something wrong with my calibration of the blue frame thanks to a very large smear I discovered after taking the flats this morning. It hasn't fully corrected so it's left a bad colour gradient in IC410 which I will have to rework. Still, as a first attempt I'm just pleased I even managed to get a join (luckily I had a slight rotation on the camera or it would only just have joined!). No sign of the tadpoles in IC410 so I think I may have to start again with this after cleaning my filters.

[Nigel G]

Great first mosaic Ken, well done. Lucky you were using Alt-AZ kit to get the rotation

I have often thought about a mosaic of 135mm images around Orion and Monoceros but keep chickening out.

You have inspired me to do it. Now do I put it at the top of the list or hmmm, I have two unfinished images Rosette and Crescent and two to image HH and Orion.

Crescent is fine as that's an early start. I have 2 of the mosaic already, but I really want to continue with Rosette and start the other 2. My mind is made.

Weatherman said clear sky's tonight  

Cheers

Nige.

[Filroden]

It was a rushed process. I developed both separately then joined them. You're suppose to join them when they are still linear so they take on the same colour, etc. So I will have to do it again in slow time and see if I can fix the blue channel with some background wipes/photoshopping.

[Nigel G]

It all seemed to go well until light cloud at 11pm as weatherman said.

Got a bunch of 30s and 60s on the Crescent nebula,  a bunch of 20s and 30s on HH &Flame, about 40 minutes on Orion but didn't get any on Rosette. 

Rosette was my 11pm target maybe get another chance tonight, but I'm not waiting to long.

Nige.

[Filroden]

I had a similar clear night but the wind was too high and I thought better of it. I'm hoping the forecast is right tonight as the wind should weaken and the skies clear around 21:00. I think I've found why auto-focus wasn't working. I need to put a very large offset into the backlash settings. I just need to work out my directions of travel to match the auto-focus routine. 

I also tried to reprocess IC410 but there is just too much wrong with the colour for my skills to fix. Thankfully it's only an hour of data but I think it's better to discard it and start again. I found I'd cropped the original IC405 a lot and by cropping just the stacking artifacts I can get a larger overlap between the two frames. If I start again, I think I can align the second frame better so I can get a clean rectangular crop once stitched together. I really need to figure out how to work goto functions on the scope from the laptop so that I can frame better using plate solving.

[Nigel G]

First image from last night.

Horsehead and Flame nebula, 45 minutes of 20s and 30s. flats and bias. modified Canon with CLS filter ISO 1600. DSS & ST. turned off hot pixel filter in DSS to try and prevent star issue.

Flats worked very well and gradients low, quite nice to process. I know I can do better, tracking was not at its best last night so I kept frames I would normally dump.

First original unmodified camera, 2nd modified camera for comparison. Similar exposure times.

Cheers

Nige.

 

[Stub Mandrel]

14 minutes ago, Nigel G said:

First image from last night.

Horsehead and Flame nebula, 45 minutes of 20s and 30s. flats and bias. modified Canon with CLS filter ISO 1600. DSS & ST. turned off hot pixel filter in DSS to try and prevent star issue.

Flats worked very well and gradients low, quite nice to process. I know I can do better, tracking was not at its best last night so I kept frames I would normally dump.

First original unmodified camera, 2nd modified camera for comparison. Similar exposure times.

Cheers

Nige.

 

Great crisp sharpness, but have you been a bit aggressive with the black point, it looks like you have clipped out loads of faint detail.?

[SteveNickolls]

Well done Nige, good images and I love your experimentation. I must have a play in DSS and see what changes it may bring.

Best Regards,
Steve

[Steve_Field]

OK so I saw this thread recently and it inspired me to start trying to image DSOs with my old Pentax K100D and Celestron Nexstar 130 SLT.  I've gotten a few images of M42 amnd M31 but the stacked images have not been all that impressive.  I had to use a barlow lens to get my dslr into focus and I kept thinking that perhaps with the focuser racked in so far and with a barlow lens in the optics train that i was not getting as much light to the senor as I could so i set about to try and remove the Barlow lens from the equation.  I built some extensions for the collimation screws and locks screw by fabricating bolt couplers out of 3/8 IN rolled steel and tapping them with 5mm x .8mm threads... that size not being readily available around me.  The whole modification cost be about $15 US and moves the primary mirror about 250mm closer to the secondary which lets me focus my DSLR without needing a barlow lens AND I still have enough backward travel in the focuser to use an EP if I want... the mod is easily removed or added and could be done in the field if necessary which was my primary design consideration.  I don't know if anyone is interested in the details of this mod but let me know and I'll post a detailed thread with pictures in the DIY section.

I did a quick test from my driveway on Wednesday night using a stack of 9 images with a 30 second exposure (no darks, flats or bias frames due to having limited time).  I keep reading that 20 seconds is the max exposure you should be able to take on an ALT AZ mount but I got 9 good frames out of the 11 at 30 seconds so I'm convinced that 30 seconds is OK and I could maybe push that a little more (and believe me I'll be figuring out where the upper limit is over the next few months).  Anyway, this is my 3rd DSO imaging attempt and while it's not great, it did make my jaw drop and I'm pretty happy with it.  Next go round I'll see what I can get with the same camera settings and maybe 50 or 60 frames plus darks, flats and bias frames to see if I can get a better image.  I also want to have a go at M31 at some point over the next few weeks.  Anyway, I thought I was limited to lunar and planetary imaging with my set up but this thread has shown me that quite a lot is possible with an ALT AZ mount...

 

[Nigel G]

42 minutes ago, Stub Mandrel said:

Great crisp sharpness, but have you been a bit aggressive with the black point, it looks like you have clipped out loads of faint detail.?

Thanks.

I may have been a little aggressive but my wife liked this one  it is my first go, many more attempts to come  

[Nigel G]

28 minutes ago, Steve_Field said:

OK so I saw this thread recently and it inspired me to start trying to image DSOs with my old Pentax K100D and Celestron Nexstar 130 SLT.  I've gotten a few images of M42 amnd M31 but the stacked images have not been all that impressive.  I had to use a barlow lens to get my dslr into focus and I kept thinking that perhaps with the focuser racked in so far and with a barlow lens in the optics train that i was not getting as much light to the senor as I could so i set about to try and remove the Barlow lens from the equation.  I built some extensions for the collimation screws and locks screw by fabricating bolt couplers out of 3/8 IN rolled steel and tapping them with 5mm x .8mm threads... that size not being readily available around me.  The whole modification cost be about $15 US and moves the primary mirror about 250mm closer to the secondary which lets me focus my DSLR without needing a barlow lens AND I still have enough backward travel in the focuser to use an EP if I want... the mod is easily removed or added and could be done in the field if necessary which was my primary design consideration.  I don't know if anyone is interested in the details of this mod but let me know and I'll post a detailed thread with pictures in the DIY section.

I did a quick test from my driveway on Wednesday night using a stack of 9 images with a 30 second exposure (no darks, flats or bias frames due to having limited time).  I keep reading that 20 seconds is the max exposure you should be able to take on an ALT AZ mount but I got 9 good frames out of the 11 at 30 seconds so I'm convinced that 30 seconds is OK and I could maybe push that a little more (and believe me I'll be figuring out where the upper limit is over the next few months).  Anyway, this is my 3rd DSO imaging attempt and while it's not great, it did make my jaw drop and I'm pretty happy with it.  Next go round I'll see what I can get with the same camera settings and maybe 50 or 60 frames plus darks, flats and bias frames to see if I can get a better image.  I also want to have a go at M31 at some point over the next few weeks.  Anyway, I thought I was limited to lunar and planetary imaging with my set up but this thread has shown me that quite a lot is possible with an ALT AZ mount...

 

Nice first stack, especially with a barlow, well done.

30s is fine, I have had up to 2 minutes with no star trails before, regularly use 60s exposures just tend to throw 50% away.

Which scope do you have, I made modifications to the focuser to get prime focus. I have a skywatcher 150p.

Nige.

Edit- just seen your text and scope.

Edited December 23, 2016 by Nigel G

[Nigel G]

Second image from last night.

Orion and the Running man. 40 minutes of 30s and 45s, flats and bias, modified canon and CLS filter, ISO 1600. 150p. DSS & ST

I love the colours but it seem's to lack some detail, the star bottom right started to over power the nebula and took some filtering to tame.

The running man is showing nice colours,

Cheers

Nige.

[Steve_Field]

Hey Nigel,

Thanks!  Actually this was taken without a barlow lens (I moved the primary so that I could remove the barlow fro the optics train).  I have a Celestron Nexstar 130 SLT which tracks pretty well when I take my time and get it properly aligned.  I love the telescope for it's ease of set up and precise go to puts the faint fuzzies dead center of a 9mm EP but to be honest the focuser leaves a lot to be desired... it's incredibly cheaply made and requires a very heavy touch making minute adjustments really difficult.  I added an Orion Accufocus which helps but I've been seriously considering dropping some cash on an after market focuser

[Steve_Field]

Also, the old Pentax K100D only allows for 30 second exposures and really lacks in features.  I've got a wealthy friend who has a camera addiction problem that just gave me his old Nikon D80 ... still an older camera and not a Canon but I think it'll work a bit better than my 10 year old Pentax.

I'm really curious how you modified your focuser... any details you can give me?

Edited December 23, 2016 by Steve_Field