2026-10-09 APP 2.0.0-beta48 has been released !
This is mainly a bug fix release for the reported bugs in beta47. In addition it has a significant User Interface performance improvement noticable when you need to process 1000s of images in APP.
2026-10-03 APP 2.0.0-beta47 has been released !
This is a very big release... many code optimizations/rewrites, many parts of APP are much faster and more precise, especially star analysis and registration are much faster ! Big mosaics will go much faster 🙂
And we introduce a new preview filter, which includes the new Adaptive Deep Sky Stretch and a General Levels Stretch, this has been long over due. The old preview filter (the panel on the right side to stretch and preview your data) has not been updated for a couple of years and it is a critical part of any APP session.
Adaptive Deep Sky Stretch or ADSS is a much more intuitive stretch algorithm. It is also color preserving (which is a great new addition in itself ! ) which means that the highlights are no longer bleached, color is maintained from the linear data while stretching. You can simply stretch your data using the sky background level and signal width sliders which work much easier and more intuitive. You no longer need to fiddle with the old complicated sliders with zoom buttons. All the zoom buttons for the sliders are made redundant. And you can enter slider values in the slider value fields yourself. I will make a youtube video in the coming days to explain and fully introduce ADSS. Once the video is ready, it will be highlighted on the forum.
RGB Combine upgrade !. The RGB Combine Tool has been rewritten mostly. The tool is faster and easier to use and most importantly, the Luminance slider to inject a luminance channel or channels into the RGB composite is now working correctly. It no longer bleaches the RGB colors. Combined with the new ADSS preview, you will get much better and easier great composites with great color! I will also explain this in a new youtube video.
A total of 19 x 180s Light frames captured using BYEOS with my modded Canon EOS750D & wedge mounted Celestron CPC9.25 and attached 0.63 Focal Reducer.
Processed in APP with Darks, Flats & Bias with the diffraction spikes for the two main stars HD75700 & HD75638 added in PS.
![M67 (NGC2682) [2019.02.25][FLICKR]](https://i0.wp.com/www.astropixelprocessor.com/wp-content/uploads/wpforo/attachments/892/1801-M67-NGC2682-20190225FLICKR.jpg?ssl=1 "M67 (NGC2682) [2019.02.25][FLICKR]")
Thanks for looking..,
Kirk
Beautiful image! I love the colours of the stars.
If I may ask one (possibly sensitive) question: are you sure the back focus between the focal reducer and the camera is correct? The stars in the corners look a bit elongated which suggests the back focus is too small at the moment.
Beautiful image! I love the colours of the stars.
If I may ask one (possibly sensitive) question: are you sure the back focus between the focal reducer and the camera is correct? The stars in the corners look a bit elongated which suggests the back focus is too small at the moment.
Thank you for the kind words @wvreeven
No, your question is not sensitive at all. I am always looking for ways to improve what I am doing and am open to suggestion and tips.
So, if I give you my setup details please do check if I have things done correctly.
First off I use this formula to calculate my Focal Length & Focal Ratio: http://www.wilmslowastro.com/software/formulae.htm#FR_b
EQUIPMENT
Celestron CPC9.25 SCT
Celestron f/6.3 Focal Reducer
SX OAG & Filter Wheel
Canon EOS 750D
CURRENT SPACINGS
From my SCT to the Focal Reducer 49.25mm (via Baader SCT > 2" Click-Lock & 2" > SCT Nose Piece)
From Focal Reducer to DSLR 53mm (via 3mm Rubber Gasket as Focal Reducer fouls OAG Prism > SX OAG & Filter Wheel > 7.5mm Spacer Tube)
From 7.5mm Spacer to DSLR Image Plane 55mm (via Baader Protective T-Ring 298550 & Canon EOS750D)
Regards..,
Kirk
Beautiful image! I love the colours of the stars.
If I may ask one (possibly sensitive) question: are you sure the back focus between the focal reducer and the camera is correct? The stars in the corners look a bit elongated which suggests the back focus is too small at the moment.
Thank you for the kind words @wvreeven
No, your question is not sensitive at all. I am always looking for ways to improve what I am doing and am open to suggestion and tips.
So, if I give you my setup details please do check if I have things done correctly.
First off I use this formula to calculate my Focal Length & Focal Ratio: http://www.wilmslowastro.com/software/formulae.htm#FR_b
EQUIPMENT
Celestron CPC9.25 SCT
Celestron f/6.3 Focal Reducer
SX OAG & Filter Wheel
Canon EOS 750D
CURRENT SPACINGS
From my SCT to the Focal Reducer 49.25mm (via Baader SCT > 2" Click-Lock & 2" > SCT Nose Piece)
From Focal Reducer to DSLR 53mm (via 3mm Rubber Gasket as Focal Reducer fouls OAG Prism > SX OAG & Filter Wheel > 7.5mm Spacer Tube)
From 7.5mm Spacer to DSLR Image Plane 55mm (via Baader Protective T-Ring 298550 & Canon EOS750D)
Regards..,
Kirk
This got me wondering if in fact I had an error somewhere in my calculations so I uploaded a single raw frame from this set of data to Astrometry.net and was given a PixelScale of 0.536 arcsec/pixel
Using the formula:
fRatio = (pixel size [um] x 206.3) / (aperture [mm] x arcsecPixel)
fRatio = (3.7 x 206.3) / (235 x 0.536)
fRatio = 763.31 / 125.96
fRatio = 6.1 rounded with an effective Focal Length of 1424mm
This is obviously below the f/6.3 that using the website formula in the above post gave me, so I have slightly too much space between the Focal Reducer & my camera's image plane than is ideal.
I cannot say if the website I used for calculations has incorrect values or if it is in fact a slight variation in my actual Focal Reducer.
I am more inclined to trust the arcsec/pixel value produced by Astrometry.net
With this in mind I have calculated that I was over spaced by 6.25mm and have now rectified this by placing an order for some very fine spacer rings and I will be able to reduce the spacing by around 6.3mm.
When the items arrive & the first available time to image after that, I will upload to Astrometry.net again to check.
Overall though I do not think that I will get a true flat field across the whole frame as this is a limitation of the Focal Reducer not being a true Flattener.
Regards..,
Kirk
I agree that trusting the value given by astrometry.net is a sensible thing to do. I have come across slightly erroneous specs too often (and sometimes very erroneous specs!) and have developed a mistrust for them. My advise would be to take the specs as a guideline and play with the spacing until it is right. The only way to do that is to painstakingly take pics and adjust the spacing until the stars are to your satisfaction 🙁
