1 hour Ha subs

[ChrisLX200]

57 minutes ago, Rodd said:

The questions is --how far off is my focus.  Is teh B mask really that bad.  TV makes a digital focuser--not motorized as they stopped making there focus mate driver.  But there digital focuser measures movements to 1 micron.  I am thinking of getting that.  The problem is I do not know what focuser will be compatible with the  scope.  What would you recommend? I use Maxim so I do have the potential for autofocus at least with the TV

Re: How far off is my focus? - I can't really answer that question definitively but you are working at 545mm f/l whilst I'm using 660mm f/l - not so different. Also, since the image scale will be similar so you should be recording similar detail and star sizes if your NP101is is focussed correctly. I'm using a camera with small pixels (3.69uM) which is over-sampling compared to my [usually poor] seeing. So just compare the detail, I think most of that difference is due to focus accuracy.

As I said I use a SkarpSky motor and they will supply a simple bracket, there are many others - Lakeside (in the UK http://www.iankingimaging.com/show_products.php?category=168 ) but there must be a manufacturer more local to you offering similar products.

ChrisH

[ChrisLX200]

15 minutes ago, Rodd said:

The other thing I don't get is if you have to check focus every 30 minutes or so--(or after every sub ideally), how can you program in a 20 sub run and use dither for drizzle integration?  If you have to move to a star to focus after every couple of subs--you might as well do it 1 sub at a time, which means why have a software package that can be programmed to capture full imaging runs?

I check focus (triggering a manual autofocus run manually) only whilst the scope is cooling fast, and from experience I know that after midnight (or ~3hrs imaging when the temperatures have stopped dropping) I can then leave it to the external temperature probe to track the temperature changes which trigger an automatic/programmed autofocus run. There is facility within SGPro to also set a time delay (every 60mins for example) which would trigger a run in combination with temperature changes. It can be made totally automanous.

SGPro (and Maxim I believe) can monitor temperature change and use it to trigger an autofocus run, so I have my system to autofocus every 1degC change. However, the problem I mentioned means that even though the probe has stabilised and is tracking external temperatures the internals of the OTA have not - whilst it is still stabilising over the first 2-3hours. That means I have to manually trigger an autofocus run even though probe suggests temperature has not dropped a further 1degC. I will continue to do that as I said until about midnight when it seems to be OK.

For SGPro I don't use just one star to focus, the program measures the HFR (half flux radius) for many stars across the whole FOV. A program like FocusMax will just use a single star like you suggest. For myself I autofocus on the FOV I'm actually imaging so no scope movement is required for an autofocus run. Further, as I noted above, I autofocus using the actual filter in use at the time, so even narrow band focus is achieved without calculating an offset from a Luminance filter. This is necessarily much slower - maybe 5mins for an autofocus run, but to my mind it is worth the delay knowing I will get the best focus possible.

ChrisH

PS. If folk are taking the time to answer your questions, and you find the answer useful, there is a 'like' button you can press... Just saying...

[Rodd]

34 minutes ago, ChrisLX200 said:

I check focus (triggering a manual autofocus run manually) only whilst the scope is cooling fast, and from experience I know that after midnight (or ~3hrs imaging when the temperatures have stopped dropping) I can then leave it to the external temperature probe to track the temperature changes which trigger an automatic/programmed autofocus run. There is facility within SGPro to also set a time delay (every 60mins for example) which would trigger a run in combination with temperature changes. It can be made totally automanous.

SGPro (and Maxim I believe) can monitor temperature change and use it to trigger an autofocus run, so I have my system to autofocus every 1degC change. However, the problem I mentioned means that even though the probe has stabilised and is tracking external temperatures the internals of the OTA have not - whilst it is still stabilising over the first 2-3hours. That means I have to manually trigger an autofocus run even though probe suggests temperature has not dropped a further 1degC. I will continue to do that as I said until about midnight when it seems to be OK.

For SGPro I don't use just one star to focus, the program measures the HFR (half flux radius) for many stars across the whole FOV. A program like FocusMax will just use a single star like you suggest. For myself I autofocus on the FOV I'm actually imaging so no scope movement is required for an autofocus run. Further, as I noted above, I autofocus using the actual filter in use at the time, so even narrow band focus is achieved without calculating an offset from a Luminance filter. This is necessarily much slower - maybe 5mins for an autofocus run, but to my mind it is worth the delay knowing I will get the best focus possible.

ChrisH

PS. If folk are taking the time to answer your questions, and you find the answer useful, there is a 'like' button you can press... Just saying...

I like---so--in short, with maxim and the TV np101is, what do I need to focus on the FOV like your do?  

[ChrisLX200]

5 minutes ago, Rodd said:

I like---so--in short, with maxim and the TV np101is, what do I need to focus on the FOV like your do?  

I haven't used FocusMax in anger but it only uses a single star from what I recall when I last looked at it, so just choose one star within your current FOV. Best to read their user instructions I think but some say FocusMax is better than SGPro's autofocus system - I know for a fact that it's much quicker.

ChrisH

[ollypenrice]

On 18/06/2016 at 19:07, Astroboy239 said:

I never knew if a target was circumpolar it would be effected by field rotation!. New for me☺

Varad 

Sorry, I missed this post earlier. Well, this looks like field rotation to me!! http://www.mauricetoet.nl/Nightscapes/i-DSXjQvj/A Image by Maurice Toet, placing the apex of the roof of my house at Polaris (...a charactersitically stylish touch from Maurice!  )

 

Manual focus won't hack it? Awe, it's all I have and all I ever use!! 

 

Olly

[Davey-T]

Haven't got round to using Focus Max yet, it's in the works, thought I read somewhere it uses Pinpoint in some way which would seem to infer it used more than one star ?

Dave

[ChrisLX200]

36 minutes ago, ollypenrice said:

Sorry, I missed this post earlier. Well, this looks like field rotation to me!! http://www.mauricetoet.nl/Nightscapes/i-DSXjQvj/A Image by Maurice Toet, placing the apex of the roof of my house at Polaris (...a charactersitically stylish touch from Maurice!  )

 

Manual focus won't hack it? Awe, it's all I have and all I ever use!! 

 

Olly

LOL, then again - you don't have a TV refractor that needs focussing every half hour Olly :-)   - and how do you manage to focus using a mask with narrowband filters if there are no bright stars in the FOV? Sounds much harder than pushing 'Autofocus' button, for sure in my case that means it wouldn't get done as often as needed (being terminally lazy! )

ChrisH

[Rodd]

55 minutes ago, ollypenrice said:

Sorry, I missed this post earlier. Well, this looks like field rotation to me!! http://www.mauricetoet.nl/Nightscapes/i-DSXjQvj/A Image by Maurice Toet, placing the apex of the roof of my house at Polaris (...a charactersitically stylish touch from Maurice!  )

 

Manual focus won't hack it? Awe, it's all I have and all I ever use!! 

 

Olly

Olly--am I reading this right?  You use manual focus?  Or are you being facetious? By manual do you mean you manually chose a star and manually press teh button to initiate a software assisted focus, or do you actually use a B mask or something similar and focus by hand and eye?

[Rodd]

1 hour ago, ChrisLX200 said:

I haven't used FocusMax in anger but it only uses a single star from what I recall when I last looked at it, so just choose one star within your current FOV. Best to read their user instructions I think but some say FocusMax is better than SGPro's autofocus system - I know for a fact that it's much quicker.

ChrisH

Chris--pardon my ignorance, but is Focus Max part of Maxim?  

[ChrisLX200]

57 minutes ago, Rodd said:

Chris--pardon my ignorance, but is Focus Max part of Maxim?  

At one time it was a free add-on for MaximDL, then I think it went commercial and was usable with a wider range of programs (or as a stand-alone program). I;ve not kept up with developments because although I wanted to try it some time ago I didn't have MaximDL to use it with.

ChrisH

[ChrisLX200]

1 hour ago, Rodd said:

Olly--am I reading this right?  You use manual focus?  Or are you being facetious? By manual do you mean you manually chose a star and manually press teh button to initiate a software assisted focus, or do you actually use a B mask or something similar and focus by hand and eye?

It's just Olly laughing at me saying 'Manual focusing won't hack it' when he knows (and I know) he produces some of the best astrophotos ever - but he doesn't use an autofocuser :-)   Olly likes steam-driven mounts and brass telescopes and hates computers (apart from photoshop) :-)

ChrisH

[johnrt]

Goodness knows how us manual focusing types cope, what with topping up the coal in my steam powered mount there's barely time for anything else! ?

[Davey-T]

Now at the same location as CCD Inspector etc.

Dave

 

[Rodd]

42 minutes ago, ChrisLX200 said:

It's just Olly laughing at me saying 'Manual focusing won't hack it' when he knows (and I know) he produces some of the best astrophotos ever - but he doesn't use an autofocuser :-)   Olly likes steam-driven mounts and brass telescopes and hates computers (apart from photoshop) :-)

ChrisH

Then I am in good company.  I have grown accustomed to the B-Mask.  However, I do see focus deteriorate through a 10 sub run.  So, I don't mind refocusing every sub (30 min subs).  However, how then would dithering be accomplished and drizzle integration.  I used to dither manually, but have found automated dithering much better.  

[Rodd]

43 minutes ago, Davey-T said:

Now at the same location as CCD Inspector etc.

Dave

 

Thanks Dave--I saw this, then I learned that Maxim DL actually has its own focus routine apart from Focus Max, which is a 3rd party for purchase program.  My big question is what would be best for the np101is.  I already own a boss II kit that O got for the Celestron--I use it for manual hands free focus on planets and the moon.  I could use it if I got a stepper motor for the np101is.  

[ollypenrice]

15 hours ago, Rodd said:

Olly--am I reading this right?  You use manual focus?  Or are you being facetious? By manual do you mean you manually chose a star and manually press teh button to initiate a software assisted focus, or do you actually use a B mask or something similar and focus by hand and eye?

I do! I use my fingers. Zanier still, one of the dual Taks has a home made microfocuser on it, simply because when it arrived (second hand) it was missing a bit from its dual speed knob so it only had single speed working. I made this simple device and like it so much that, when the missing bit arrived, I never bothered to fit it.

When doing my one star alignment at the start of the night I use a B mask to focus both scopes at that stage. During the run I then use FWHM about every 1.5 hours or so to check for drift. The Mesu is so stiff that I can manually focus one scope while the other is shooting without this showing up on the guide trace. Seriously! On my other rig, TEC 140 with original Feathertouch, I again just do a manual refocus between sets of subs, though I find the TEC drifts even less than the Taks. Two small notes: these are Fluorite FSQ106Ns which seem far less drift-prone than the later ED versions. And I run heater tapes throughout the night to slow down the cooling process.

I'm not averse to robotic focus but I don't feel I have much of a problem so I've not tried to solve it. Also, buying three decent electric focusers would be quite expensive. The nearest I got was when collaborating with Yves and doing the capture side of things here with his 14 Inch. It had a motor focus but controlled only by a handset. On that scope FWHM proved useless so I had no choice but to use a B mask. It suffered minimal focus drift though. Sometimes it held fast all night.

So there you go, a stone age imager gives you a tour of his cave!

Olly

[Rodd]

42 minutes ago, ollypenrice said:

I do! I use my fingers. Zanier still, one of the dual Taks has a home made microfocuser on it, simply because when it arrived (second hand) it was missing a bit from its dual speed knob so it only had single speed working. I made this simple device and like it so much that, when the missing bit arrived, I never bothered to fit it.

When doing my one star alignment at the start of the night I use a B mask to focus both scopes at that stage. During the run I then use FWHM about every 1.5 hours or so to check for drift. The Mesu is so stiff that I can manually focus one scope while the other is shooting without this showing up on the guide trace. Seriously! On my other rig, TEC 140 with original Feathertouch, I again just do a manual refocus between sets of subs, though I find the TEC drifts even less than the Taks. Two small notes: these are Fluorite FSQ106Ns which seem far less drift-prone than the later ED versions. And I run heater tapes throughout the night to slow down the cooling process.

I'm not averse to robotic focus but I don't feel I have much of a problem so I've not tried to solve it. Also, buying three decent electric focusers would be quite expensive. The nearest I got was when collaborating with Yves and doing the capture side of things here with his 14 Inch. It had a motor focus but controlled only by a handset. On that scope FWHM proved useless so I had no choice but to use a B mask. It suffered minimal focus drift though. Sometimes it held fast all night.

So there you go, a stone age imager gives you a tour of his cave!

Olly

So good focus is possible with a B-Mask.  Ever hear of the Goldfocus system (Goldastro.com)?  It has a software package that analyzes the Mask image geometry and identifies the ideal focus (Collimation too).  I have been told numerous times that my focus may be the issue (or one of the issues) causing lack of sharpness/clarity in my images, so I am hunting for the best solution.  When I take an image with the B-mask I save the image and open it with my processing software and zoom in.  Tiny increments are possible.  How far off could mt focus be if I take care to center the spike?  Also, how do you differentiate between drift caused by temperature and drift caused by changing seeing conditions?

[swag72]

Why no download the free Bahtinov grabber software .... it's brilliant and will really nail the focus for sure.

[Rodd]

1 minute ago, swag72 said:

Why no download the free Bahtinov grabber software .... it's brilliant and will really nail the focus for sure.

I was looking at this, and could not find a site fro which to download it.  I did find the Gold Focus software system, but I think I need to get the Gold Mask right?  I don't think it will work with my B mask.  Wasn't sure if changing my focus system to a Mask from a Mask was the best thing.  I have heard so many different opinions.  Purchasing a focus system is not trivial--.  My limited understanding is the best way would be to automate focus so that the software would analyze focus on the FOV between subs and tweek it without input from me.  That way I can program a 10-15 sub sequence (or 6-8 30 min sub sequence) and maximize imaging time.  I suppose I don't mind fumbling along with a mask as long as the focus is really spot on.  Trial and error is not the best approach for this.  Do you use automated focus?  or do you use mask based focus?

[swag72]

I use automated focus with a Lakeside focuser and using SGP auto focus routine. Prior to that I used to use manual focus, with Grabber and the bahtinov mask. I found that focus would wander during the night and I had to check focus every 2 hours otherwise I was ditching a load of out of focus subs.

I think that focus can make or break an image....... get the focus wrong and you may as well throw the lot away as there's nothing that can be done to resolve it. 

With SGP I have it set to refocus at ever 1 degree drop in temperature.

[ollypenrice]

If I test a B mask focus against FWHM I get a very close accord. I just look at the B mask image - but very carefully. I always see a slight assymetry on either side and use that as my final arbiter. If I have a choice between a software solution and a human or physical one I avoid the software - but that's me. I did try Bahtinov Grabber but could make no sense of it. Again, that's me.

Olly

[Rodd]

5 minutes ago, swag72 said:

I use automated focus with a Lakeside focuser and using SGP auto focus routine. Prior to that I used to use manual focus, with Grabber and the bahtinov mask. I found that focus would wander during the night and I had to check focus every 2 hours otherwise I was ditching a load of out of focus subs.

I think that focus can make or break an image....... get the focus wrong and you may as well throw the lot away as there's nothing that can be done to resolve it. 

With SGP I have it set to refocus at ever 1 degree drop in temperature.

Back to deciding which focuser would be best for my scope.  Maxim has a focus program that I can start with--friends tell me it works.  I can go to focus Max if I don;t like it.  But the first step is getting the right system.  I can cannibalize the Boss II kit from the Celestron if I can get the starlight instruments stepper motor to work on the Televue.

[Rodd]

53 minutes ago, ollypenrice said:

If I test a B mask focus against FWHM I get a very close accord. I just look at the B mask image - but very carefully. I always see a slight assymetry on either side and use that as my final arbiter. If I have a choice between a software solution and a human or physical one I avoid the software - but that's me. I did try Bahtinov Grabber but could make no sense of it. Again, that's me.

Olly

Olly--here is a crop of one of my focus shots that I called "in focus"  How far off can this be?  Its a FITs, as the JPEG compression really screwed with the geometry of the spikes

1.fit

[ollypenrice]

 

48 minutes ago, Rodd said:

Olly--here is a crop of one of my focus shots that I called "in focus"  How far off can this be?  Its a FITs, as the JPEG compression really screwed with the geometry of the spikes

1.fit

Looks pretty good to me but, to be sure, I'd give it a good bit more exposure, maybe binned, so that you get clear and continuous spikes rather than dots. A screen stretch could help in that respect.

Olly

[Rodd]

2 minutes ago, ollypenrice said:

 

Looks pretty good to me but, to be sure, I'd give it a good bit more exposure, maybe binned, so that you get clear and continuous spikes rather than dots. A screen stretch could help in that respect.

Olly

This is Ha Olly--Ha always looks dotty to me--does that change anything?