ASI1600mm cool

[piprees]

1 hour ago, David_L said:

Thanks guys - I've got the next script for "Yes, Minister" LOL!

(don't be offended - I mean that in a good humour way - the terminology vs. translation to layperson terms is hilariously difficult :-)

David

 

 

Not only do I like this I actually laughed out load, so much so that my wife asked, "what are you laughing at?" .

 

[piprees]

Wouldn't it be great if someone could work out a program that gave the optimum settings for various tasks that then changed by entering different cameras/scopes etc..

P.

[Filroden]

25 minutes ago, piprees said:

Wouldn't it be great if someone could work out a program that gave the optimum settings for various tasks that then changed by entering different cameras/scopes etc..

P.

I think the problem is that this is fine for combinations of equipment but no software can work out best exposure/gain/offset settings because it can't measure your sky darkness, nor take account the target brightness, etc. That's why I'd like to see a simpler decision tree that helps us optimise the settings based on something we can see (i.e. the actual image we take). I guess software could analyse the image and, knowing your initial settings, suggest how to optimise, e.g. it sees your mean/median value being close to zero ==> increase exposure (if possible) or increase gain (if not); it sees the min = 0, so increase exposure and/or decrease offset. I think the problem is that there are more variables at play which sometimes work together and sometimes work against each other.

[Gina]

Thanks to IanL for a great explanation of offset   I had a feeling that was what it meant but wasn't sure so I haven't altered it from the default of 10 as yet.  Now I know what is happening I can examine my subs and adjust offset as well as gain and exposure to get the best fit of the dynamic range into the A/D range available.

One thing that puzzles me about the ZWO graphs (as reproduced above) is that they only go up to 300 in gain whereas the camera goes up to a gain of 600.  As might be expected, the read noise continues to decrease as the gain is increased - it doesn't stop at 300.  The read noise graph is linear whereas it would be more informative if it were logarithmic.  This is a logarithmic function.

For faint DSOs I have found a gain of 600 very useful in combination with shorter exposures and many more of them.  The total imaging time may be the same but with a higher gain the camera is more sensitive.  The greater number of subs counteracts the relatively small dynamic range of the A/D.  After using a CCD sensor for several years it takes a "leap in the dark" to deal with a CMOS sensor as they are so very different.

[Guest]

8 hours ago, Gina said:

After using a CCD sensor for several years it takes a "leap in the dark" to deal with a CMOS sensor as they are so very different.

I have to admit I'm so nervous about losing an imaging session due to my messing up the basic settings that I still stand here...at the edge of the abyss...watching as the rest of you soar into the unknown :-)

It's thanks to all of you doing this investigation, and sharing it, that slackers like me will one day know what this camera can really do :-)

Thanks again

David

[Guest]

17 hours ago, Filroden said:

This bit I can understand  I just find that terminology tends to be driven by the engineers that develop the kit and not for the customers who use it.

I like simple things. If my image can only contain values from 0 to 4096, I only want to see values ranging from 1 to 4095 (so I know I'm not clipping). I want to turn the two dials (currently called gain and offset) to expand my image so it occupies the most values without clipping. I think I get confused because of the whole ADU element of the process. To me, that just needs to be a black box and all I see in my image summary is the min/max pixel values in my image. I need to adjust my exposure length (first preference but not always possible because of mount limitations) and my gain/offset to spread this range as much as possible. I just want to know which way to change my dial depending on what I see in the min/max pixel summary. Gain seems intuitive, offset seems counter intuitive!

Thanks for your efforts on this guys - it would be great if you guys started a shared document that combined the tech stuff with the explanations you've created - you could put it up on Google Drive or something similar, limit editing rights, let us dedicated 1600er's (have to come up with something catchier LOL) have access and in the end publish it?

Just a thought as I was copying and pasting the threads to read during coffee breaks :-)

David

[Guest]

I had two nights of fun using 3 ZWO cameras - 2 x ASI120MC and 1 x ASI1600MM-Cool on the Moon

There's some notes and pictures in my blog here :-)

David

p.s. all 3 cameras are running simultaneously off a Startech hub - no fps/download issues :-)

 

[Notty]

Had the thing for 3 months now sat in its boxes and finally got the time to put it together with a view to having a go tonight, but does anyone have any ideas how on earth I can balance this thing in DEC?  It's so tail heavy I can't see how it's possible, but I can't be the only one with a setup like this can I?  

 

[RayD]

15 minutes ago, Notty said:

Had the thing for 3 months now sat in its boxes and finally got the time to put it together with a view to having a go tonight, but does anyone have any ideas how on earth I can balance this thing in DEC?  It's so tail heavy I can't see how it's possible, but I can't be the only one with a setup like this can I?  

No you're most definitely not the only one.  You can either fit a longer dovetail or add weights to the front of your current one.  I fitted a longer Losmandy on my ES 80 to overcome this problem with my Atik stuff.

[SkyBound]

Looks like he has the dovetail right at the end of possible travel anyway, the OTA thins out after that...!

[Guest]

27 minutes ago, Notty said:

Had the thing for 3 months now sat in its boxes and finally got the time to put it together with a view to having a go tonight, but does anyone have any ideas how on earth I can balance this thing in DEC?  It's so tail heavy I can't see how it's possible, but I can't be the only one with a setup like this can I?  

 

This works great for my rig - same problem

https://www.firstlightoptics.com/adm-counterweight-kits/adm-dovetail-counterweight-kit-d-series.html

 

[RayD]

Sorry my fault there I wasn't very clear.  I meant a longer dovetail bar, which on my ES80 let me shove the whole thing forward.  You just need to have the filter wheel cables to the side or at the top.

[Notty]

7 minutes ago, David_L said:

This works great for my rig - same problem

https://www.firstlightoptics.com/adm-counterweight-kits/adm-dovetail-counterweight-kit-d-series.html

 

Thank you David.  I don't suppose you know if these adapters work around a Skywatcher dovetail do you?  

[RayD]

21 minutes ago, Notty said:

Thank you David.  I don't suppose you know if these adapters work around a Skywatcher dovetail do you?  

Not wanting to answer for others, but I believe SW is just a Vixen type dovetail, so you would just get the one with this dovetail adaptor.  ADM do them for all types.

[Magnus_e]

I'm sooo happy I asked the question about Uniity gain.

This discussion has thought me a lot of useful insight on gain and offset, that I did not realize was missing!

I also think all of you has managed to explain this non trivial system in a very readable format.

Thanks a lot

 

Also @RayD That ES80 looks so nice! And it would fit in my obsy

How are you liking the AVX? Do you re balance it after the meridian flip? I wonder if I should install something in my obsy to keep it east heavy balanced, but I'm not sure it's needed?

Clear night forcasted on sunday, so I'll try to balance it neutral and see if it still guides well.

 

// Edit: SW dovetail is Vixen style. It's what I use.

[Guest]

1 hour ago, Notty said:

Thank you David.  I don't suppose you know if these adapters work around a Skywatcher dovetail do you?  

Yep - I just grabbed the first link on First Light Optics website that looked like this counter weight - they have all types there - and two different weights

David

[Guest]

13 hours ago, David_L said:

Thanks for your efforts on this guys - it would be great if you guys started a shared document that combined the tech stuff with the explanations you've created - you could put it up on Google Drive or something similar, limit editing rights, let us dedicated 1600er's (have to come up with something catchier LOL) have access and in the end publish it?

Just a thought as I was copying and pasting the threads to read during coffee breaks :-)

David

....and of course if you don't ....I might :-)

[Magnus_e]

Yay! A clear night, and I can image with the moon

As it's sort of on topic here is my first sub with this camera, and my first nb (ha) sub.

 

The stars looks like they are a little out of focus, but I think it's amplified by the massive stretch.

It's one sub @ Unity gain, offset 21 and 5 minutes. Looks like It will be clear tomorrow too, so I might actually get some data on this

[AKB]

On 13/01/2017 at 07:21, David_L said:

dedicated 1600er's (have to come up with something catchier LOL) 

1.6e3ers ?

 

[Notty]

First Light for me too with this camera 3 nights ago after only DSLR use to date.  Had it for months but hadn't had the chance to even open the boxes until recently.  Same as above, big moon=time to try narrowband and see if this new setup works.  Lots of first for me including Mono, Filter wheel, Narrowband, SG Pro camera control.  First sequence was half way through when I realised that I hadn't configured the right cooling setting in SG pro so it wasn't cooling at all.  I restarted it after sorting that out cooling, but I can only think that clouds must have come in during my sequence with the cooler running because my DSS output from the data taken then was worse than dreadful. Still, uncooled or not, I got a capture from it so I'm off the blocks.

90 x 30s, gain 300, offset 10, unguided HEQ5 SWED80 DS, all Ha.  No calibration frames.  No idea why I chose those, just wanted to try something - and I guess I'm still shooting for the holy grail of unguided short subs.  I think I'll try a higher gain next time with MAX cooling (as opposed to none!).  V.rough curves/levels in Photoshop.

Use of SG Pro was on recommendation from people here, and I even downloaded the Plate solving database but didn't get to use it in anger. There was a lot of switching from one bit of software to another, my goto is Stellarium, Astrotortilla for plate solving, which only interfaces to APT for capture, but I had to use SGPro for focus as nothing else (APT, Firecapture etc) gave me anything like a decent enough live view to focus with, but I know some of you use it so I'd be pleased to hear how to get it usable in Firecapture.

I'm assuming the bright band along the top is "amp glow"?  What's the best way to get rid of that?

[Andyb90]

21 hours ago, Magnus_e said:

Yay! A clear night, and I can image with the moon

As it's sort of on topic here is my first sub with this camera, and my first nb (ha) sub.

 

The stars looks like they are a little out of focus, but I think it's amplified by the massive stretch.

It's one sub @ Unity gain, offset 21 and 5 minutes. Looks like It will be clear tomorrow too, so I might actually get some data on this

Are you using a bahtinov mask for focusing? With the 1600 you can increase the gain and take short exposures with the mask for focusing. I've found you can get a really clear diffraction pattern which is great for focusing. This has been a revelation for me coming from a dslr. 

Andy.

[Magnus_e]

12 minutes ago, Andyb90 said:

Are you using a bahtinov mask for focusing? With the 1600 you can increase the gain and take short exposures with the mask for focusing. I've found you can get a really clear diffraction pattern which is great for focusing. This has been a revelation for me coming from a dslr. 

Andy.

Hi. I'm at the conclution that I did everything wrong yesterday. I started a thread on it, and got a lot of help. Thankfully it's clear tonight too

For those of you with the asi1600 thats new to mono imaging, there are some useful tips in that thread.

[alcol620]

I see that we are on version 3 of the camera already!

 

see http://zwoug.org/viewtopic.php?f=21&t=6727&start=10

[alcol620]

On 1/14/2017 at 23:03, Magnus_e said:

Yay! A clear night, and I can image with the moon

As it's sort of on topic here is my first sub with this camera, and my first nb (ha) sub.

 

The stars looks like they are a little out of focus, but I think it's amplified by the massive stretch.

It's one sub @ Unity gain, offset 21 and 5 minutes. Looks like It will be clear tomorrow too, so I might actually get some data on this

Hi Magnus

One thing I learnt after ALREADY taking hundreds of subs is to spend time on achieving a good focus. I know there is great pressure to just start taking images, but if you don't make time at the start of the imaging session to achieve good focus then the final results will be well below what is achievable.  

Regards

Alec

[Magnus_e]

1 hour ago, alcol620 said:

Hi Magnus

One thing I learnt after ALREADY taking hundreds of subs is to spend time on achieving a good focus. I know there is great pressure to just start taking images, but if you don't make time at the start of the imaging session to achieve good focus then the final results will be well below what is achievable.  

Regards

Alec

Well this was the time I learned the importantcy of focus

I got a chance with a clear night the follow night, and took good focus subs. I did a process on it yesterday, and I'm very pleased!

By miles my best image so far.