don4l

3 minutes ago, han59 said:

For narrow band you often need longer exposure times to get stars above the noise.  You can speedup focusing by using 1) "stay at position" and 2) dynamic focusing. 3) Limit the number of step to 7  or  8 or 9 steps .  Furthermore you can reduce the exposure time if you 4) limit the focuser steps such that your focus if going not far off.  For my setup the HFD value at focus is around 2.5. I tune the focuser steps such that the maximum HFD is around 5  maximum.  Example for H-alpha 7 nm, I'm using 4 or 5 seconds exposure for focusing.

Going to a dedicated bright star for focusing takes more time then "stay at position"

If this is abracadabra for you, ask me for more information.

Han

 

 

 

That isn't "abracadabra" at all Han!  You've mentioned all the settings that  I've been afraid to play with  in case I break it.  Every time that I change something, I seem to break it, and I have to do the initial calibration again.  This takes valuable time, so I haven't dared change anything once it is working.

I get the impression that the "Start focus HFD" is telling CCDCiel roughly how far to move for it's first sample.  Is this correct?  One problem that I had was that it seemed to move too far and the star became too faint.  I have had the same problem with the initial "File -> Calibrate focuser" routine.  The default was 20, and I had to reduce it to 15 before it would work at all.

I suppose that I do not understand if CCDCiel needs a large range to correctly calculate where it is on the V curve...  so I have been leaving this figure as high as I can.

I am also a bit confused about the "Near focus HFD".  The figure in my settings is 8.4.  The focus star needs to be about 1.2, or less at correct focus, so I don't know what the term "Near focus" actually means.

1 hour ago, alan potts said:

Makes one want a 106mm Tak, doesn't it, great image and really jumps out the screen on my setup in the basement.

Alan

Thanks Alan.

I bought it (in 2008) because I had seen fantastic images taken with it.  Maybe at last I'm getting somewhere.

I have to say, that if I were buying now, I would look very closely at the Esprit scopes.

On 04/12/2019 at 14:36, Star101 said:

Having double clicked both images to zoom in on the noise. I think that the second image is better. 

On a normal scale, on my laptop. Both images look the same. Very nice work.

Thanks for sharing.

Dave.

On 04/12/2019 at 13:49, simmo39 said:

Brilliant!  but think the first rendition is better.

Thank you both!

Clearly, I should stop looking so closely.  If the difference is open to opinion, then I am clearly worrying far too much.

2 hours ago, stash_old said:

Ok I am stumped what is NB ? 

Sorry, Narrowband.  Focusing with a 3nm narrowband filter needs 8 second exposures, rather than the 0.5s that I use for the red, green or blue filters.  I used to spend 20mins or more focusing.  When you have to re-focus several times in an evening, it soon adds up.

I like it.

Very nice - very smooth and natural looking.

Another release came out yesterday.  This release seems to focus on tidying up the user interface.  This will make it easier for new users to learn the package.

The platesolving and autofocus routines are working brilliantly.  Autofocus through broadband filters is taking 44 seconds.  NB is taking 2 mins.

I've looked at it from my work PC, and it looks noisier.  I've applied a bit of noise reduction which I think improves it.  I'm never sure about this????

2 hours ago, Sunshine said:

Yes, i would suggest not displaying what could only be a Hubble image as your own. 

Simply beautiful! it really is Hubblesque.

Thank you very much.  

I have the feeling that it is my best image so far, but I am useless at looking at my own images.

I've been playing with Starnet, and I am very impressed with it.  Unlike many processing methods/tricks/tips, this seems to work on every image that I have tried.

My problem is that I'm not very good at processing the RGB stars as a separate image.  Sometimes they come out brilliantly, and other times I just don't get much colour in them at all.  I'd really like to get some pointers about producing the stars in the first place (I'm making an RGB in CCDStack and just stretching the levels).  I could also do with some advice about recombining them with the starless image in PS or Gimp.  Currently, I'm adding them back in in either "lighten" or "screen" mode, or a mixture of both.

This image is 50m Ha, 70m OIII and 16m RGB (5,5,6).

Tak FSQ106 at F5,  G3 16200, Chroma Ha and OIII 3nm filters, EQ6

CCDCiel, Indi, CCDStack and Gimp.

Any other comments or suggestions very welcome.

Nice one Gorann.  I was wondering if this was worth imaging, it's definitely on my list now.

5 hours ago, kfox said:

I am not sure if it is sensitive to Ha. Is there a way I can figure that out? 

I would take some photos first and see what they look like.  Will you be imaging from a light polluted location?

Is the a6000 sensitive to Ha?  If it isn't, then filters may be disappointing for most nebula shots.

For processing I use Gimp - it's free, and it works in a similar way to Photoshop.  I've easily followed online PS tutorials and videos.

https://www.gimp.org/downloads/

1 hour ago, tooth_dr said:

Thanks Adrian. I’m still struggling to get smaller stars. The ED80 was giving me nicer stars. I don’t know what to try differently, as focal length and guiding accuracy hasn’t changed.  Maybe I’m over exposing at 300s

This is just a thought...

I recently changed my camera from one with 9um pixels to 6um.  The problem that I've had with bloated/fuzzy stars disappeared overnight.  I even have the feeling that the new camera is producing sharper stars when binned.  I know that doesn't make sense, but I am going to take some test shots to find out.

If you have another camera with smaller pixels, it might be worth a try???

I can get to Spain quicker, and when I get there I can understand what the locals are saying!  😉

It does look lovely though.

When I first tried the extender I was horrified by the vignetting.  However, when I examined the background ADUs around the frame I realised that a lot of the problem was just the way that CCDStack displayed the data.  Flat fields fixed the display issue, and I didn't find that exposure times were unduly long.

I'll stick by my "try it" advice, because the results will speak far louder than any predictions.  If it doesn't cost anything, other than 30 minutes,  then it is worth a go. 

I gave up in 2009 after spending a couple of months trying to image sh2-240.  At the time I felt that I had taken the best possible image given the local light pollution.  I tried to convince my wife to move house,  but with no success.

I got back into imaging last year, and I now realise that I had been wrong to stop.  I quickly realised that either the light pollution had changed, or perhaps I had simply been wrong about it back in 2009.  3nm filters have also much improved what I can do, and a new camera also seems to have made a big difference.

For the moment I am feeling highly motivated.  I suppose that as long as I can see a way of improving,  then I find it easy to put the effort in.  I'm also helped by the rubbish that features on our TV's these days.

30 minutes ago, gerardsheldon said:

I have a 130 Skywatcher pds f/5 and use a modified DSLR 1000D.  Lots of astronomical objects, like the ring nebula and many galaxies, are really small  in the sky.  when I take pictures of them, they occupy a very small area in the photograph. Magnifying them with a barlow (I have 2x televlue one) would also make them fainter and my tracking would have to be good. 

Does anyone have any advice about whether I should use a barlow or not?

Try it.

I use a "focal extender" ( a barlow) and it gives good results.

Very nice.  I was looking at this yesterday as a possible target, so it's nice to see this.  You've got some nice detail in some of the spirals, so it's definitely on my list now.  Thanks for posting.

3 hours ago, tooth_dr said:

That is nice delicate procession, and the phallic region is particularly nice.  If you get a decent methodology please share Donal!

 

Adam.

Thank you. 

I've just looked at it from work, and I'm horrified at the noise that is visible in the red.  I'm absolutely at a loss to understand when, or where, it crept in. This isn't a display issue.  This noise just wasn't there two nights ago.

Hopefully, I have saved my work at a stage that lets me see where the problem occurred and I'll be able to fix it tonight.

48 minutes ago, alan potts said:

One of the nicest Heart images I have seen, the thing that annoys me with stars is I have found plenty of tutorials to remove stars but never found one that allows me to put them back. I actually found a way to do it myself but didn't write it down and forgot what I did, so back to the drawing board. Great image.

Alan

Thank you.

I used Gimp to put them back.  I simply made sure that the background was black, and used "lighten" as the layer mode.

In the past, I've used the "Generic -> Erode" filter to remove most of the stars.  This is quick and easy, so it gives a good idea of what to expect.  For most of my images, this was more than good enough.  However, the Erode filter does damage the background.  Starnet takes 30 minutes, but it does seem to work magic.

I think that I now need to concentrate on learning to make stars look nice.

This is my first attempt at producing a long exposure decent image at my scopes native focall length - 530mm.  I usually don't have the patience to remain on the same target as new and exciting targets come into view.  I gathered 200m Ha, and 170m OIII.  I would have liked to get much more OIII but the weather really has not played ball.   I wasn't able to process the noise down to acceptable levels, so I added in a further 270m OIII data taken at 367mm.  This improved things enormously.

I've also used Starnet for the first time, and I must say that it works brilliantly.  I also processed the stars separately and then added them back in.  I really could use some advice on producing a decent star image.  I used 10m each of RG and B and combined themin CCDStack.  However I really do not understand how to produce small coloured stars - so any advice or pointers would be very welcome. 

Comments and suggestions very welcome.  I have tried to save various stages of the processing, so I should be able to go back and try different things.

Equipment: Tak FSQ106 at F5 and F3,  EQ6, Moravian G3 16200, Chroma 3nm filters

Software:  CCDCiel, CCDStack, Gimp, Starnet

Exposure Ha 200m,  OIIO 170m + 270m(367mm),  RGB about 10m each in 60s subs.

I like the colours.  It seems to give a nice 3d feel. 

How about a duck?

I won't elaborate.

3 minutes ago, Gina said:

Ubuntu Mate 16.04 as I recall on the RPi and Linux Mint 18 on my desktop where I run KStars/Ekos.

In that case you should be fine on both.  The only hassle is adding the PHD repository as a "trusted" source in /etc/apt...

The instructions are on the link that I gave above.

If you have done this before, then you shouldn't have any problem.

Once you have the "apt" security sorted, then it is a simple "sudo apt get" jobby.

4 hours ago, Gina said:

That looks straightforward enough 😀 but I'll probably try the Ekos guider first.  Do you have experience of both/either?

What flavour of Linux are you using?  I have PHD2 on Ubuntu 16.04(??) and I didn't have to compile it. 

I like PHD2 because it just works.  I did a calibration last May, and I haven't touched it since.

If you have Ubuntu, then the instructions are here :- https://launchpad.net/~pch/+archive/ubuntu/phd2