My first image with the auto-guiding working

[Starwiz]

NGC 7000 'Mexico region', 10 x 3 minute exposures taken from my garden last night and stacked in DSS.  

I didn't use any darks, but took 20 flats using the white T-shirt and powerful torch method.

The sky looked great last night and I wish I could have stayed out longer, but I only managed 4 hours sleep as it was  

John

[kendg]

Looking good.

[tomato]

Nice image, auto guiding is the way to go.

Hats off to anyone out there guiding manually, that is what killed my enthusiasm for this hobby first time around back in the mid 1980s.......

[Starwiz]

28 minutes ago, tomato said:

Nice image, auto guiding is the way to go.

Hats off to anyone out there guiding manually, that is what killed my enthusiasm for this hobby first time around back in the mid 1980s.......

Yes I agree, I think I'd be a twitching nervous wreck after 30 minutes of manual guiding!  

John

[tomato]

Yes indeed John, coupled with fact that you didn't get to find out if all that effort was worthwhile until you developed the film the next day or so.

Those were the days!

Steve

[Starwiz]

Ha ha, to be honest, I wasn't sure if my efforts last night were going to be worthwhile, but it's given me a bit more confidence now.

I can imagine the same anticipation though, in the dark room, as you finally find out what you've got.  

John

[wimvb]

Very nice first result!

On the left side, you have some blue streaks, which I doubt are part of the nebula. Is this from processing or light pollution/reflections???

[Starwiz]

1 hour ago, wimvb said:

Very nice first result!

On the left side, you have some blue streaks, which I doubt are part of the nebula. Is this from processing or light pollution/reflections???

Thanks.

I think the streaks are stray light getting in somewhere.  The streaks are on the raw images, and on looking at some of the earlier test frames, I can see them but in different places so I think altering the position of the telescope changes where the streaks appear against the stars.  I'm fairly close to a street lamp, so perhaps I'm getting reflection off the dew shield.  

John

[Waldemar]

On 9-8-2016 at 22:22, tomato said:

Nice image, auto guiding is the way to go.

Hats off to anyone out there guiding manually, that is what killed my enthusiasm for this hobby first time around back in the mid 1980s.......

Yes, that did it for me too back in the eighties. Took me months to recover from  a couple of hours of manual guiding. When I think of it, my neck starts hurting again...
The digital age is a blessing for astro photographers, with it's own pittfalls, though. I doubt if there will be anybody still doing manual guiding... if so:  chapeau! must be a die hard!

Waldemar

[Waldemar]

Well John, you got it working, I would say !!
Which camera did you use? There seem to be some amp glow in the right side, more so at the bottom right corner?

Why not make a dark library during day time?

Maybe some treflecting screws in your scope somewhere (blue streaks in the left bottom corner)?

Waldemar

 

[Starwiz]

On 8/11/2016 at 09:34, Waldemar said:

Well John, you got it working, I would say !!
Which camera did you use? There seem to be some amp glow in the right side, more so at the bottom right corner?

Why not make a dark library during day time?

Maybe some treflecting screws in your scope somewhere (blue streaks in the left bottom corner)?

Waldemar

 

I used the EOS1200d.  

Making a dark library in the daytime sounds like a great idea.  Do I need to be careful with temperatures (i.e. try to match what I get at night), or not? 

Thanks 

John 

[Waldemar]

Yes, John, you have to match the temperatures and the exposure times. I did not quite realise you are using a DSLR camera. 
No doubt there are tips and tricks to do this, but since I am using only cooled astro camera's, I am not familiar how to do this with a not cooled DSLR.
I am sure your results will be better even with darks which temperature does not exactly match the temperature of your lights.

I hope somebody else with the experience and knowledge how to do this efficiently with a DSLR will help you out,

No doubt you will find a lot of help in the book: "Making every photon count", as well.

Sorry for 'misleading' you... 

Waldemar

 

[Starwiz]

2 hours ago, Waldemar said:

Yes, John, you have to match the temperatures and the exposure times. I did not quite realise you are using a DSLR camera. 
No doubt there are tips and tricks to do this, but since I am using only cooled astro camera's, I am not familiar how to do this with a not cooled DSLR.
I am sure your results will be better even with darks which temperature does not exactly match the temperature of your lights.

I hope somebody else with the experience and knowledge how to do this efficiently with a DSLR will help you out,

No doubt you will find a lot of help in the book: "Making every photon count", as well.

Sorry for 'misleading' you... 

Waldemar

 

Thanks Waldemar,

You've given me a few ideas.  I can look at the temperature forecast and get close to temperatures on the night of imaging.  Probably the best time to do it is when it's cloudy or around full moon, so it wouldn't be optimum dso imaging time anyway.

John

[Starwiz]

Here's the image again, with 10 darks used, re-processing done and cropped to get rid of the streaks.  I like it better now.  

John

 

[Waldemar]

me too!!!

[ollypenrice]

Darks with uncooled DSLRs are probably bad news. Have a look at this thread 

...and maybe many others on all sorts of forums. Check out what Tony Hallas has to say. There is a tired old orthodoxy concerning darks but you won't find that the best astrophographers think much of it.

Bias and dither will kick darks off the pitch.

Olly

[Ouroboros]

Lovely  image and guiding is definitely working for you. Those stars are nice and round. 

I'm collecting a darks library. Everytime I image I take some darks which I copy to one of a group of folders folder labelled 400 ISO 300s, 800 ISO 300s etc depending on the camera settings.  Because I use Backyard EOS, the temperature is saved as part of the file name. Also the dark files are listed in temperature ranges.  So in Deep Sky Stacker I can select darks in the  same temperature range, ISO and exposure time as that of my images. 

[Starwiz]

57 minutes ago, ollypenrice said:

Darks with uncooled DSLRs are probably bad news. Have a look at this thread 

...and maybe many others on all sorts of forums. Check out what Tony Hallas has to say. There is a tired old orthodoxy concerning darks but you won't find that the best astrophographers think much of it.

Bias and dither will kick darks off the pitch.

Olly

Thanks Olly, that's interesting.  I haven't worked out what bias and dither is yet, so have some more reading to do. 

John

[Starwiz]

52 minutes ago, Ouroboros said:

Lovely  image and guiding is definitely working for you. Those stars are nice and round. 

I'm collecting a darks library. Everytime I image I take some darks which I copy to one of a group of folders folder labelled 400 ISO 300s, 800 ISO 300s etc depending on the camera settings.  Because I use Backyard EOS, the temperature is saved as part of the file name. Also the dark files are listed in temperature ranges.  So in Deep Sky Stacker I can select darks in the  same temperature range, ISO and exposure time as that of my images. 

Thanks.  I was ecstatic when the guiding actually worked and I could see the graph lines converging.  

John

[ollypenrice]

A bias is just the shortest dark frame that your camera can take. It contains the non-thermal noise, or the noise not related to heat build-up.

Dither means moving the scope-camera by a small amount between sub exposures so that the target does not land on exactly the same camera pixels each time. If you can get your camera software to talk to your guiding software this can be done automatically.

Olly

[Starwiz]

4 minutes ago, ollypenrice said:

A bias is just the shortest dark frame that your camera can take. It contains the non-thermal noise, or the noise not related to heat build-up.

Dither means moving the scope-camera by a small amount between sub exposures so that the target does not land on exactly the same camera pixels each time. If you can get your camera software to talk to your guiding software this can be done automatically.

Olly

Thanks again Olly.  

John

[Ouroboros]

34 minutes ago, ollypenrice said:

A bias is just the shortest dark frame that your camera can take. It contains the non-thermal noise, or the noise not related to heat build-up.

Dither means moving the scope-camera by a small amount between sub exposures so that the target does not land on exactly the same camera pixels each time. If you can get your camera software to talk to your guiding software this can be done automatically.

Olly

That's a very clear explanation, Olly.  I mean to look at this now I'm exploring getting my PC to control my mount via EQMOD. I hate wasting time taking darks instead of lights. 

[wimvb]

Here's an example of dithering. (This is my first time uploading a video; hope it shows)

dither.mp4

It's a stack of images that have been registered, but not stacked yet. As such, the stars are in the same position, but hot pixels move around.

When you take the images, the stars will be on different positions on the sensor, and the hot pixels will be stationary.

You can also see the benefits of dithering here:

http://wimvberlo.blogspot.se/2016/07/dithering-in-hardware_7.html

[Starwiz]

26 minutes ago, wimvb said:

Here's an example of dithering. (This is my first time uploading a video; hope it shows)

dither.mp4

It's a stack of images that have been registered, but not stacked yet. As such, the stars are in the same position, but hot pixels move around.

When you take the images, the stars will be on different positions on the sensor, and the hot pixels will be stationary.

You can also see the benefits of dithering here:

http://wimvberlo.blogspot.se/2016/07/dithering-in-hardware_7.html

Looks like the way to go.  I just have to work out how to make the mount do it now.  I'm currently controlling the camera exposures with an intervalometer attached to the camera.  

John

[wimvb]

If you have a goto mount, and don't guide, you just push the ra/dec buttons long enough for the camera to move 12 or 15 pixels. You will have to do some math, and program the intervalometer to take this time into account. My sequence was

Exp . ra+ . exp . dec+ . exp . ra- . exp . ra- . exp . dec- . exp . dec- . exp . ra+. Etc in an outward spiral.

Nowadays I have my ditherbox doing this for me.

If you use guiding, the software will probably have dithering capability built in.