ZWO ASI120MC-S

[patricmooriamnot]

Hi Guys. I am very new to this subject and would appreciate any help I can get. Orion is nice and high in the southern sky at the moment and I would love to take photo`s of the horse head nebula and the great orion nebula. I have a skywatcher 130 goto scope and a ZWO ASI120MC-S CAMERA. I don`t understand about darks and lights. I have watched a video on u tube and a guy there has explained how he gets sharp images and what settings he uses but I have had little success copying he settings. Unfornunatly I do not get very dark skies where I live so perhaps this is my problem. Any help would be most appreciated. Phil.

[MARS1960]

You and me both. Iv'e had 4-5 attempts on M42 and still come away with nothing.

Darks are easy, after you have taken your lights just put the lens cap on and take a few shots using the same settings, i have been taking around 10% darks to lights.

Are you taking long enough exposures? and enough of them.

[edjrgibbs]

Hi Phil

A few things jump out. The first is the type of mount you have. The mount is the most important part. The second is the camera itself and its suitability for DSO imaging. I'll deal with them in order:

> Mount. Do you have an AltAz or Equatorial mount? If not an equatorial then tracking DSO's will be problematic due to field rotation. That being said, its possible.

> Camera: the ASI120MC-S has a pretty small chip which might be more suited to planetary imaging. I'm not sure how it will fair on large DSO's like Orion but I guess only trying will tell. You'll need some software to run it either in DSO mode or planetary. Planetary you tend to take video in a programme like sharpcap then stack the individual frames with software like registax (both pieces are free). If doing DSO imaging you're into longer exposure territory but depending on the mount your exposure times will be limited (i.e. no Eq tracking will mean much shorter exposures, especially with the size of the imaging chip). I use APT (Astrophotography Tool) with my DSO camera's and find it a decent piece of software. You can then stack using something like Deep Sky Stacker. 

Another issue you'll likely encounter is focus. A bahtinov mask (available from most astro shops) is the best way i've found to focus. You might need spacers etc to achieve focus. 

It might be worth trying to find a local astro group or alternatively trial and error. Over the years I've found searching these forums provide a wealth of info. AP can be frustrating but don't give up!

Hope this helps. 

Ed

[PeterCPC]

@edjrgibbs

The ASI120MC is generally used for planetary imaging - that's how I have used mine (not the S) and it's good for this.

Peter

[patricmooriamnot]

20 minutes ago, MARS1960 said:

You and me both. Iv'e had 4-5 attempts on M42 and still come away with nothing.

Darks are easy, after you have taken your lights just put the lens cap on and take a few shots using the same settings, i have been taking around 10% darks to lights.

Are you taking long enough exposures? and enough of them.

Thanks for you reply Peter, I will try taking much longer videos and see how that goes. I still can`t get my head around the stacking bit I have downloaded deep sky stacker so will have to just practice using it. Dark skies. 

[patricmooriamnot]

24 minutes ago, edjrgibbs said:

Hi Phil

A few things jump out. The first is the type of mount you have. The mount is the most important part. The second is the camera itself and its suitability for DSO imaging. I'll deal with them in order:

> Mount. Do you have an AltAz or Equatorial mount? If not an equatorial then tracking DSO's will be problematic due to field rotation. That being said, its possible.

> Camera: the ASI120MC-S has a pretty small chip which might be more suited to planetary imaging. I'm not sure how it will fair on large DSO's like Orion but I guess only trying will tell. You'll need some software to run it either in DSO mode or planetary. Planetary you tend to take video in a programme like sharpcap then stack the individual frames with software like registax (both pieces are free). If doing DSO imaging you're into longer exposure territory but depending on the mount your exposure times will be limited (i.e. no Eq tracking will mean much shorter exposures, especially with the size of the imaging chip). I use APT (Astrophotography Tool) with my DSO camera's and find it a decent piece of software. You can then stack using something like Deep Sky Stacker. 

Another issue you'll likely encounter is focus. A bahtinov mask (available from most astro shops) is the best way i've found to focus. You might need spacers etc to achieve focus. 

It might be worth trying to find a local astro group or alternatively trial and error. Over the years I've found searching these forums provide a wealth of info. AP can be frustrating but don't give up!

Hope this helps. 

Ed

Thank Ed. I will keep working at it. I do have an AltAz goto scope and when aligned I thought it might track a star in the nebula. Focus is a major issue yes. again I try and focus on the star I`m tracking. I have made a cap with two holes in to place over the end of the scope and this helps. Thanks once again for your input and lets hope for more cleer skies.

[edjrgibbs]

8 minutes ago, patricmooriamnot said:

Thanks for you reply Peter, I will try taking much longer videos and see how that goes. I still can`t get my head around the stacking bit I have downloaded deep sky stacker so will have to just practice using it. Dark skies. 

Just to jump back in. If you're taking videos its very unlikely you'll get any DSO's coming out in them. Video is for planetary only where you have a really bright object that needs really short exposures but lots of them. DSO work needs much longer images. With M42 you should see something from 15+ seconds. Rotation will be the problem on an Alt Az mount as might stability. 

[patricmooriamnot]

1 minute ago, edjrgibbs said:

Just to jump back in. If you're taking videos its very unlikely you'll get any DSO's coming out in them. Video is for planetary only where you have a really bright object that needs really short exposures but lots of them. DSO work needs much longer images. With M42 you should see something from 15+ seconds. Rotation will be the problem on an Alt Az mount as might stability. 

ok thanks for that, I wonder if the software can get my zwo to take a long exposer snapshot. I will try.

[Cornelius Varley]

1 minute ago, patricmooriamnot said:

Thank Ed. I will keep working at it. I do have an AltAz goto scope and when aligned I thought it might track a star in the nebula. Focus is a major issue yes. again I try and focus on the star I`m tracking. I have made a cap with two holes in to place over the end of the scope and this helps. Thanks once again for your input and lets hope for more cleer skies.

The mount won't actually "track" a star, you need a mount with an autoguiding setup to do this. After the mount has slewed on to your chosen target the mount will then revert back to sidereal tracking. The mount doesn't have any idea if the target then starts to drift out of view. 
 

[MARS1960]

14 minutes ago, patricmooriamnot said:

Thanks for you reply Peter, I will try taking much longer videos and see how that goes. I still can`t get my head around the stacking bit I have downloaded deep sky stacker so will have to just practice using it. Dark skies. 

It's exposures you need for DSO's Phil, save the video for lunar/planetary.

[edjrgibbs]

Looking at the sharpcap pages it looks like you can take long exposure video. Maybe try 15 second frames and see where you get to.

[patricmooriamnot]

2 minutes ago, edjrgibbs said:

Looking at the sharpcap pages it looks like you can take long exposure video. Maybe try 15 second frames and see where you get to.

I think that is where I am going wrong. I think the guy on u tube said something like that. He says he can get good DSOs with his ZWO.  Great help guys Thanks

[patricmooriamnot]

12 minutes ago, Cornelius Varley said:

The mount won't actually "track" a star, you need a mount with an autoguiding setup to do this. After the mount has slewed on to your chosen target the mount will then revert back to sidereal tracking. The mount doesn't have any idea if the target then starts to drift out of view. 
 

O Dear. and I thought my mount was all singing all dancing. ( for a beginner) 

[Cornelius Varley]

3 minutes ago, patricmooriamnot said:

O Dear. and I thought my mount was all singing all dancing. ( for a beginner) 

No, they just jiggle around and hum. 

[PeterCPC]

There have been previous threads on DSO imaging with short exposures such as

 

 

 

Started by ArmyAirForce, 8 January

 

You might want to have a look through that.

 

Peter

Edited January 28, 2016 by Cornelius Varley
link added

[Astrosurf]

19 hours ago, patricmooriamnot said:

O Dear. and I thought my mount was all singing all dancing. ( for a beginner) 

You can take images of the brighter DSOs without having to autoguide as you can take shorter exposures, but as long as your polar alignment is good! Globular clusters are good, but I've never tried with that cam. I've only ever used DSLRs and now my CCD. I use my ZWO for planetary. Good luck!

 

Alexxx

[rwg]

19 hours ago, Cornelius Varley said:

The mount won't actually "track" a star, you need a mount with an autoguiding setup to do this. After the mount has slewed on to your chosen target the mount will then revert back to sidereal tracking. The mount doesn't have any idea if the target then starts to drift out of view. 
 

Strictly true, but being a goto mount the OPs mount will follow the target across the sky (how well it does this depends on the quality of initial alignment setup). This is going to be good enough for a go at deep sky video astronomy.

I'd suggest the following...

For finding the target and focusing turn the gain up high and set an exposure in the 0.5-2s range. The noise caused by high gain doesn't really matter to you - you want to see the effect of any changes you make quickly.

For actually taking the image, turn the gain *down* and set an exposure in the 2 to 15s range. The length of exposure is determined by how well the mount tracks - if the stars aren't round, turn it down.

Use SharpCap - download the latest beta version and use the live stacking option from the top toolbar. In this mode SharpCap will automatically align and stack each frame as it arrives. This will take care of any field rotation caused by the AltAz mount and movement between frames. Note that there is a bug in the latest beta that causes a crash if you try to 'Save Stack as Viewed' - will be fixed in the next version over the weekend hopefully.

cheers,

Robin

[Cornelius Varley]

6 minutes ago, rwg said:

Strictly true, but being a goto mount the OPs mount will follow the target across the sky (how well it does this depends on the quality of initial alignment setup). This is going to be good enough for a go at deep sky video astronomy.

 

The point I was making is that a goto mount won't physically follow an object in the sky. The mount will slew to an area of the sky which it believes is the location of the target and when there will return back to normal sidereal rate tracking. Whether the target stays in the field of view and centred in the eyepiece or not is down to how accurately the mount is set up.To get true tracking of a star for imaging you need an autoguider which will continually monitor any drift and send corrective actions back to the mount.

[Freddie]

True but the OP is clearly new to all this so I don't think the lack of auto guiding should be something to bring up at this stage as a tracking mount will be fine for some initial work and I wouldn't want to see the OP put off getting started.

[patricmooriamnot]

20 minutes ago, Freddie said:

True but the OP is clearly new to all this so I don't think the lack of auto guiding should be something to bring up at this stage as a tracking mount will be fine for some initial work and I wouldn't want to see the OP put off getting started.

I have just been looking through my ZWO manual and it seems it has a auto guilder built in. I have no idea how to use it. It needs other software. Will this guider control my goto mount? I imagine I would have to use the mount control first to slew to the region of sky I want and then disconnect the control and connect the camera guider. The more I look into this the more questions I have. Trial and error seems a good option at the moment. Thanks for all your input.

[PeterCPC]

It will work as a guide camera with PHD. If you do this you will need another camera for imaging. You go to the area where you want to image then you set up PHD to guide before you start imaging with your imaging camera. If you use it for planetary imaging you won't need to guide.

Peter

[Cornelius Varley]

3 minutes ago, patricmooriamnot said:

I have just been looking through my ZWO manual and it seems it has a auto guilder built in. I have no idea how to use it. It needs other software. Will this guider control my goto mount? I imagine I would have to use the mount control first to slew to the region of sky I want and then disconnect the control and connect the camera guider. The more I look into this the more questions I have. Trial and error seems a good option at the moment. Thanks for all your input.

Unfortunately the AZ-GOTO mount doesn't have the corresponding ST4 port for the autoguider to connect to. The way autoguiding works is a separate camera (guide camera) connected to a guide scope sends a continuous video feed back to some software on the computer which continually monitors any drifting of the guide star. The software then sends corrective commands back to the mount through the autoguider port on the camera. Equatorial goto mounts and some high end alt-az goto mounts have the autoguider port, but not the Skywatcher AZ-GOTO. 
Your best option is to use  the camera for lunar and planetary imaging, which is what it is best at. You can try DSO imaging with the camera but you will be limited to what can be achieved by the size of the sensor and the limitations of the mount.

[rwg]

15 minutes ago, patricmooriamnot said:

I have just been looking through my ZWO manual and it seems it has a auto guilder built in. I have no idea how to use it. It needs other software. Will this guider control my goto mount? I imagine I would have to use the mount control first to slew to the region of sky I want and then disconnect the control and connect the camera guider. The more I look into this the more questions I have. Trial and error seems a good option at the moment. Thanks for all your input.

Yes, the ZWO will work fine as a guide cam, but don't worry about that just now - as Peter points out you need a second camera for that to work *and* an EQ mount. Save that option for later and get some experience using the ZWO for imaging on your current set up for now

Robin

[patricmooriamnot]

58 minutes ago, Cornelius Varley said:

Unfortunately the AZ-GOTO mount doesn't have the corresponding ST4 port for the autoguider to connect to. The way autoguiding works is a separate camera (guide camera) connected to a guide scope sends a continuous video feed back to some software on the computer which continually monitors any drifting of the guide star. The software then sends corrective commands back to the mount through the autoguider port on the camera. Equatorial goto mounts and some high end alt-az goto mounts have the autoguider port, but not the Skywatcher AZ-GOTO. 
Your best option is to use  the camera for lunar and planetary imaging, which is what it is best at. You can try DSO imaging with the camera but you will be limited to what can be achieved by the size of the sensor and the limitations of the mount.

Thanks for the info I`m learning all the time. I won`t waste my time trying to work with auto guiding. Still its all good fun.

[AstroNebulee]

I managed to get M42 on my skywatcher exploere 150p with zwo asi120mc-s last night, i didnt know about darks or lights but getting some knowledge of it now, i have an eq3-2 mount and tracking motor for RA and got this image i took it as a ser file but later saw i had to do it in tiff single file captures but heres my image and settings text. This is an old thread i know, so this is a usb 3 version of the camera.

04_49_24.CameraSettings.txt

Edited August 31, 2020 by LeeHore7