First light for my Sigma Art 85mm and QHY163M combination. I had originally planned on getting 3 hours of data but due to my STUPID mistake of leaving the Subframe selected my first two hours (Blue and Red both with different subframe regions for focusing) had tiny crops so I just did a quick mockup before I had to pack up to go to work.
The lens was set at F/3.5
So I ended up with just under an hour of subs. Below is a link to the higher resolution but be aware, the Full Resolution image is 65.59 megapixels of pure unadulterated resolution.
Nice one. Working on this one at the moment. Gives me an idea as to what to look for when completed.
There's a surprising amount of hydrogen alpha in this region, though, I don't think I'm going to get time to capture more than I have due to competing projects. I'll do what I can. It will be a bit of a hassle to get it to blend naturally, I suspect.
Commented on AB Colin, love it.such a dense area and so sharp!
Certainly a lot going on. The lens in insanely sharp in the centre but it falls off a bit off-axis. Some of it I think is tilt that may be introduced by my rings and the mounting but I’m not sure. Might even try F/4 at some point.
Quote:
Originally Posted by Octane
Nice one. Working on this one at the moment. Gives me an idea as to what to look for when completed.
There's a surprising amount of hydrogen alpha in this region, though, I don't think I'm going to get time to capture more than I have due to competing projects. I'll do what I can. It will be a bit of a hassle to get it to blend naturally, I suspect.
H
That’s quite interesting H, I may have to see if I can get some time to go Ha around here; see what shows up.
Always a good target Colin and you've done it well. Nice to see RCW71 poking out in the coal sack
Steve
Thanks Steve. I had no idea what that object was but figured I was going to have to image it with a longer FL than 85mm to find out.
Googled it and your image pretty much shows up at the top!
That’s a great Image, Colin. Who would have thought there would be so much Ha though?
Well done!
I images a small region of the Coal Sack near a week ago and it shows that there is streams of Ha (red emission) in that particular field so it stands to reason that there will be more around
Quote:
Originally Posted by beren
Awesome image Colin {like the unedited image best}
Thanks Beren
Quote:
Originally Posted by Ross G
A very nice wide photo Colin.
Very sharp, great detail and rich colours.
An excellent lens.
Ross.
Thanks Ross. I’m not that impressed with the top left corner, I’m pretty sure it’s the lens as when I’m using my DSLR I think the rotation puts it in the bottom left as that corner looks worse than the other three.
I keep feeling tempted to get a 135mm because those lens’ are amazing and it gives a big increase in resolution.
Before you blame the lens, check the adapter you are using to mount the lens on the ccd.
I have used a variety of lenses ranging from 35mm to 300mm on QHY and ZWO cameras and I have found even the very smallest play in the mount results in bad corners and edges.
I am currently using a 300mm Nikon lens on a ZWO asi 1600 and I went through 3 different mount adapters.
A great field Colin.
I love these widerields.
I second the idea about adapter sensitivity.
My Sigma Art 14mm gets better results with one adapter over another.
Greg
Before you blame the lens, check the adapter you are using to mount the lens on the ccd.
I have used a variety of lenses ranging from 35mm to 300mm on QHY and ZWO cameras and I have found even the very smallest play in the mount results in bad corners and edges.
I am currently using a 300mm Nikon lens on a ZWO asi 1600 and I went through 3 different mount adapters.
Ross
Quote:
Originally Posted by gregbradley
A great field Colin.
I love these widerields.
I second the idea about adapter sensitivity.
My Sigma Art 14mm gets better results with one adapter over another.
Greg
Thanks for the thoughts Ross & Greg. I went through some images that I took earlier on in the night, some luminance images around the LMC looking at galactic cirrus and those two stacked images, although showing off-axis astigmatism, aren't really any worse in one corner than the other.
This has me thinking that the problem may be with the stiffness of my mounting. I have a ring on the Sigma lens and a ring on the QHY163M and they're mounted to a Losmandy D plate. It would take very little flex due to gravity to show its ugly head.
Not sure how I'd go in changing lens adapters though. The only Nikon lens adapter that I can use is the QHY one as no other company that I can find makes a M54 threaded Nikon adapter. They're all M48, T2 or C-Mount.
My only real reservation with the lens is blue bloat as can be see in the attached 1:1 crop around the Jewel Box. Granted, a monochrome blue sensitive camera with small pixels isn't going to do it justice. The blue halo's show up worse with the QHY163M at F/3.5 than they do with my D7200 at F/2.8 so it's not all bad. Still considering getting the Sigma Art 135mm F/1.8
Unless of course you mean that it was shot on one side of meriaint than the other 
