I've recently come back from 2 weeks in France. I didn't take a scope with me but I took the Sony A7S with a couple of lenses and my iOptron SkyTracker.
Here is a "work in progress".
(http://www.markshelley.co.uk/Astronomy/2015/cygnus20150715small.jpg)
One hour of data taken in 30sec subs to avoid the (now) infamous Sony bulb mode Star Eater issue - made infamous by me ;) 50mm Nikon lens at F8 - it's a bad lens so I had to stop it right down. Ambient temperature was 23C at 1am - during the day it had reached 100F, more or less. There are a few dust bunnies and there is a green diagonal "splodge" at the lower left caused by an internal Infra-Red light leak which I documented here:
http://stargazerslounge.com/topic/243671-review-of-the-sony-a7s/?p=2714347
Full size version is here:
http://www.markshelley.co.uk/Astronomy/2015/cygnus20150715.jpg
Look carefully and you can find the Crescent Nebula, the Veil Complex (pretty faint) and the Dumbbell. The Dumbbell is actually quite interesting - it is surrounded by "stuff". You don't often see images of the Dumbbell surrounded by "stuff". So next time you see an image of the Dumbbell Nebula against an inky black background, you know it's completely wrong ;)
In many ways, this Sony A7S is driving me to my wits end. It's the last time I jump onto the "bleeding edge" of technology. I blame Robert :)
This image is just one of many - I have Cassiopeia as well. In fact I have the whole Milky Way from Sagittarius to Perseus. Goodness only knows when I'll find the chance to process that lot! Sorting out dust bunnies and green splodges in a vast mosaic of the Milky Way will be a nightmare :( Come Winter, I'll do the Perseus to Orion section - at least that's the plan. I must be stark raving bonkers.
Mark
Nice Mark,
Cant believe all those 'warts & crap' that you have to process out - full frame dslr processing is 'so' difficult...
Anyway image is looking good - like you said m27 looks lost in all those stars.. reminded me of when I used to look at 'Where's Wally' books with kids...
John
Amazing image Mark. The Crescent is difficult to spot among all those stars and nebulosity but I think I have it. The Veil Nebula complex has come out nicely as well. Didn't realised the dumbbell was orientated sideways on.
How do you find the ioptron Skytracker?
Carole
Quote from: MarkS on Jul 30, 2015, 23:29:13
In many ways, this Sony A7S is driving me to my wits end. It's the last time I jump onto the "bleeding edge" of technology. I blame Robert :)
Why Mark?
Great image. So much in there! You can even see the little Tulip Nebula.
Yeah Carole, but it must have taken a while to process 120x subs and it's only an hours data.
QuoteYeah Carole,
Sorry what are you referring to, or did you mean to say John?
Carole
So are you blaming me for this image ;)
F/8 is really slow but even so the camera has done really well to capture so much and you've processed it well too.
Robert
Quote from: Carole on Jul 31, 2015, 17:59:25
QuoteYeah Carole,
Sorry what are you referring to, or did you mean to say John?
Carole
your right Carole, sorry, I was replying to John's warts comment.
I saved the image and zoomed in on a few of those bright stars, they all seem to have 14 spokes of light emanating from them, is it always this number or do different lenses and optics give more or less ??? :undecided:
Roger
Quote from: Apophis on Jul 31, 2015, 23:00:15
I saved the image and zoomed in on a few of those bright stars, they all seem to have 14 spokes of light emanating from them, is it always this number or do different lenses and optics give more or less ??? :undecided:
Roger
Hi Roger,
It's caused by the vanes of the aperture iris in a photographic lens. Different lenses have different numbers of vanes and they cause diffraction. One way to avoid it and stop down the lens is to make an aperture mask with a smooth circular hole and stick it on the front.
Quote from: The Thing
Hi Roger,
It's caused by the vanes of the aperture iris in a photographic lens. Different lenses have different numbers of vanes and they cause diffraction. One way to avoid it and stop down the lens is to make an aperture mask with a smooth circular hole and stick it on the front.
7 vanes in the case of this particular lens
Mark
Quote from: Mike on Jul 31, 2015, 14:47:56
Quote from: MarkS on Jul 30, 2015, 23:29:13
In many ways, this Sony A7S is driving me to my wits end. It's the last time I jump onto the "bleeding edge" of technology. I blame Robert :)
Why Mark?
Problem after problem - here's the list:
1) The "raw" file uses lossy compression
2) Sony advertise it as a 14 bit camera but only 12 bits are available and those are compressed
3) There is virtually no software support for tethering to a PC. As far as I know only PHDMax allows it and this uses a kludgy interface to Sony's software. PHDMax is not very stable because of this kludge but Sony provide no other programmable interface for long exposures.
4) The camera exhibits "star eater" behaviour for all bulb mode exposures i.e. all exposures > 30sec are affected
5) The lens adaptors available for lenses other than Sony all have reflective internal surfaces. In my case it caused weird crescents in the image until I spayed the interior with matt black paint.
6) IR light leaks from the shutter unit which causes potential problems for modified cameras.
So why persevere? Because it has the highest QE and lowest noise of any consumer camera out there at the moment. To see the Milky Way and even the North American Nebula in live-view has to be seen to be believed.
Why blame Robert? Because he showed me a camera with such incredible performance that I just had to have one ;)
Mark
Mark,
isn't a raw file by definition untouched data straight out the camera. surely if Sony compress it using a lossy algorithm it cant be a raw file... also, have you complained to Sony about their false advertising 14 bit data....
Would love to see milky way on live view though....
Yes, Sony are certainly stretching the definition of "raw"
13 bits are actually written to the "raw" in most camera modes but most astro-processing software cannot access the 13th bit due to a technical issue in DCRaw, upon which PixInisght, Iris, DSS and probably many others rely. Maybe there is some mode where 14 bits are actually used. It just hasn't been found.
Don't get me wrong - I think this camera contains the best sensor available to the amateur community at the present time (QE believed to be around 65%). Read noise is around 1e at usual imaging ISOs and thermal noise extremely low. However, I know that if Nikon had this sensor in one of their cameras they would have implemented without all the Sony shortcuts.
It makes OSC CCD cameras almost redundant
It's just that I seem to have spent most of my free time recently, tracking down the various "issues".
Mark