dazza1639

Thanks everyone, I am really nervous now about using DFO, even though they said they could do it by Christmas or New Year. Which even without seeing the reviews, I thought it was optimistic. I have also contacted Rother Valley, they said the earliest they could book it in was Mid Jan or Feb. They would need to consult the workshop and get me a price and date. This again makes me a little nervous. But as they are only in Sheffield its not too far for me to drop off & collect.

I'm looking for a bit of advice, I have an original Skywatcher EQ8 sat in my observatory and it is starting to show its age after 8 years. Guiding has always performed brilliantly with an RMS of around 0.5". However, of the last month or so, the guiding performance seems to have dropped of a cliff, RMS averaging 1.6". The stars still look pretty round but subs keep getting aborted as i get guiding spikes that are taking it over the 2.5" guide limit. 

I have, in the past, adjusted the dec & ra worm gears but i think it may be time for a thorough service by a professional who can take the time to do it properly and do a full strip, regrease and perhaps upgrade the worm gears & bearings. 

I was looking at the stellardrive upgrade by darkframe optics, however, I do not appear to be getting a respone to my emails. I have also seen some pretty negative reviews as well as some really positive ones. 

Is there any alternative to Dark Frame or are they still the best option?

love the star colours 👍

Version 2, this time I have used Starnet++ to process the nebula independently to the stars. Again the processing has been done in Affinity Photo.

I’ve had a quick play with this in Affinity Photo. I will give it a proper go later.

When you launch it, you should get a dialogue box saying there is a newer version available. 

Updated👍 I like that we can now enter x & y values for more accurate curves. Maybe someone will create arcsinh curve presets 🤞

On 19/10/2017 at 08:50, sharkmelley said:

Thanks everyone for your feedback - it's helped me to crystallise the way this should work.  To be honest I found using a gamma curve was just a bit too fierce for what I wanted. So with a bit of maths, I've now managed to find a way to actually use Arcsinh (Hyperbolic Arcsine) curves in Photoshop  

Firstly a couple of hints:

• Always perform a levels adjustment on your image to subtract as much of the background as possible otherwise you won't achieve so much stretch and the colours you see in your stretched result will be the same colours (washed out by the background) that you started with.
• If you are planning to use the colour preserving stretch frequently then it's well worth recording an action to create the layers for you.

I have worked out that it is possible to design preset curves that apply an Arcsinh curve.  However Photoshop doesn't have the granularity in the curve design to allow such a strong curve to be designed in one hit.  Therefore I have designed a curve that when applied twice in succession gives the correct Arcsinh shape.  Here's an example:

The above curve is not an Arcsinh curve of itself but will give an Arcsinh curve with a stretch factor of 300 when applied twice in succession.  Every single point on the curve has been carefully calculated in a spreadsheet to have the desired effect.  The way it is used is illustrated below:

The intermediate Levels layer is there to allow some additional subtraction of background (if necessary) between the first and second curve layers.

I have calculated and built a set of preset curves: Arcsinh10, Arcsinh30, Arcsinh100, Arcsinh300, Arcsinh1000 which give stretch factors of 10x, 30x, 100x, 300x, 1000x.  Arcsinh100 is probably the most useful one in general.  You would use the same Arcsinh100 preset curve in both layers to achieve a stretch of 100x.  It is quite possible to "mix and match" them - for instance using Arcsinh100 in one layer and Arcsinh300 in the other layer would give a stretch somewhere between 100x and 300x.

If you want to use these curve I'm making them freely available here: PS_ArcsinhCurves.zip

You need to unzip them into the relevant Photoshop folder.  On my Windows machine that is C:\Users\Mark\AppData\Roaming\Adobe\Adobe Photoshop CC 2015\Presets\Curves  but if you don't know where your own folder is, just try to save any arbitrary curve as a preset and notice which folder Photoshop is using.

Enjoy!

Mark

Mark

Now that version 1.9 of Affinity Photo has been released it is possible to place points on a curve as x & y values between 0 & 1. Would it be possible to create arcsinh preset curves in Affinity Photo?

Regards

Darren

That's a fantastic image.

What a stunning image

On 24/01/2021 at 11:54, Stub Mandrel said:

I've had a brilliant idea...

I'll just keep PS2 for combining images then edit them in something else...

There is no need to keep PS2 if it is just for combining the mono images into a colour image, if you watch my video you will see how easy it is.

To make the process a little clearer I have recorded a quick video showing how I combine mono images to create a colour image using Affinity Photo.

https://youtu.be/MBZ5W5YKVg4

The images in this video are just single 5 minute subs taken with Red, Green & Blue filters, that have been aligned using Astro Pixel Processor and saved as Tiff files.

I hope it helps.

The method I use is to paste each of my mono images into a new document as a layer, then use the colour channel adjustment layer on each of the new layers to colour them as either red, green or blue. I have set up presets for each colour to make it quick and easy. Then you just set the blend mode to add for each of the layers. This produces a colour image, if you then create a stamp layer that combines all the visible layers (ctrl, alt, shift & E) this creates a colour layer that you can further process. A good video to watch about colour is 

this explains splitting a colour image into each channel and recombining as used in my method.  
this video explains how to user the colour channel mixer

I had another go at processing the Horsehead from the same dodgy data. Is it an improvement?

Darren

Due to the bad weather and having no new data to play with, I have dug out some of my early astro imaging efforts. I wasn't expecting much as the source data is really bad. The RGB data was taken with an stick Canon EOS 1000d through my C8 with a 0.63 FR. Now the focal reducer I used at the time was one of the dodgy Chinese knock offs that means that the back focus was all wrong creating misshaped stars towards the edges and really bad vignetting, most of which has been cropped out because of the size of my Ha data.

The Ha data was my first every attempt at Ha when I first got my AtikOne 6.0. So the Ha data has issues as well. The Ha was taken using the same scope and focal reducer set up as above, so is suffering from the same issues as the RGB. But it also has the additional problem of being slightly out of focus, so some stars are little donuts.

From the above, you would think why bother, so did I, but I really wanted to try some new techniques and try to combine data from different sources and image scales. I am just starting to get used to Astro Pixel Processor, Starnet++ and Affinity Photo so thought that this would be a real test. It was, I stacked the Ha & RGB files in APP so that the resulting files where same size and orientation, I also used the batch crop and rotate tools to get the framing I wanted, and to cut out as much of the crud as possible. I also used the background / light pollution removal tools before moving the two files (RGB & Ha), on to Starnet++ where I created starless versions of each. I then did the rest of the processing in Affinity Photo.

Its not the best image I have ever produced, but from such bad data I am quite pleased. I suppose the moral of the story is never throw away any data, however bad.

Thanks

Darren

This was from my last imaging session of 2020, The Monkey Head Nebula taken on Christmas Eve.

On 26/12/2020 at 21:31, redfox1971 said:

Great image i did the same target with ha and 03 but when combined in pixinsight I'm struggling to get much blue,what camera,exposures lengths did you use?.

20x5min of Ha OIII & SII USING AN Atikone 6.0 through an Equinox 80 pro with a televiewers TRF2008 0.8x focal reducer. In Astro Pixel Processor I applied a 3x factor to both OIII & SII when combining the channels. I then used selective colour adjustments to balance the colours 

On 26/12/2020 at 20:14, Allinthehead said:

Nice one, the Monkey head has some interesting structures. Did you process in Pixinsight?

No stacked and preprocessed in Astro Pixel Processor and finished off in Affinity Photo

Nice 👍 

Nice set of images 

Christmas Eve I managed to get 5 hours on NGC2175 the Monkey Head nebula 

What an image absolutely stunning 🤩 

Nice 👍 

2020 hasn’t been a great year for anyone, but we’ve had a good comet, and some clear nights. I haven’t been the most productive, or even a very good imager this year, but I’m quite pleased with what I’ve learnt, narrowband has been a revelation . So I thought I would share a few of my images, and a video I put together or them. Thanks for all the great images and tips that have been posted. Wishing you all a happy Christmas and a great 2021.

Darren

You can minimise stars in exactly the same way as you do in photoshop, but the filter is called minimum blur under blur in the filter menu.