Had some fun with my new 200mm Lens. Starting to process some of the shots. This one is centered on the prawn. You can also see various clusters including NGC6231 in the field and also the dark tower at the top right of the frame. There are two panels slightly overlapping from two different nights. Approx. 20x5min each panel so a total of a bit more than 3h.
I stopped the lens 1 stop. I'm getting some funny stars, only on the very bright ones on each side of the prawn. I'm not sure what it is. Is this related to the lens aperture? I mean should I stop it further? The field shows very little curvature and colimation is also good according to CCDIS so I'm not sure what this is.
Thanks Trev. Actually the lens was fully opened . Just checked it now I've pulled the rig apart back in its boxes. Got square eyes and need some sleep.
Another thing I found corrected odd star shapes was binning the camera 2x2. You have so much FOV binning doesn't lose anything in detail but seems to round the stars up quite a bit. So stopping down a few stops and 2x2 seems to be the go. At least for my setup where the 16803 is very hard on lenses.
Good one Marc!! It was interesting to see the context and relative luminosity of the Dark Tower vs The Prawn. Looks like there may be other parts of the larger neb complex worthy of closer attention too!
Another thing I found corrected odd star shapes was binning the camera 2x2. You have so much FOV binning doesn't lose anything in detail but seem to round the stars up quite a bit. So stopping down a few stops and 2x2 seems to be the go. At least for my setup where the 16803 is very hard on lenses.
Greg.
Thanks Greg. Binning's not really an option for me as my image scale is already borderline. I'll have to try stopping it. I found it odd that only bright stars showed it. But then again I have only started using lenses for widefield and still have a lot to learn and work around things.
Quote:
Originally Posted by marc4darkskies
Good one Marc!! It was interesting to see the context and relative luminosity of the Dark Tower vs The Prawn. Looks like there may be other parts of the larger neb complex worthy of closer attention too!
Cheers, Marcus
Thanks Marcus. Yeah it is interesting to see all the surroundings.There is a very interesting arch on the right of the field with enough details to be imaged at longer FL on its own as well as a faint cloud at 8 o'clock. I was also surprised to see how faint the dark tower was even at that FL in relation to all the surrounding nebulosity. Really puts into perspective the amount of subs and work you did to extract the details in your shot, especially those blues.
[QUOTE=multiweb;734060]Thanks Greg. Binning's not really an option for me as my image scale is already borderline. I'll have to try stopping it. I found it odd that only bright stars showed it. But then again I have only started using lenses for widefield and still have a lot to learn and work around things.
I don't know why either binning would work only that it does. It seems to average out the errors a bit.
I don't know why either binning would work only that it does. It seems to average out the errors a bit.
Greg.
If I bin I get a lof of noise when doing NB from the red and green for Ha for example beacuse of the OSC. I get a clearer data by debayering to red only. There's only a lot of noise in the two others. I actually took the picture with the lens fully open. Figured it out afterwards that I didn't stop it. So I'll try that next. I got a Pentax SMC-M 100mm since then too. Twice the FOV.
Nice one Marc. I love the idea of the lens and QHY9 combo. Will be watching your exploits with great interest!
Thanks Rob. You can pick some cheap good ones from eBay. All you need is an adaptor for your camera. I got one ages ago. It's a K-mount to M42. You can also pick them up on eBay.
I like those widefields because you can pick up a lot of the faint stuff that you don't see at longer FL. Once you platesolve and get the RA/DEC you then can go back with bigger aperture. I'm making a list for the hyperstar.
Yeah, I love the way it puts things in context for the long FL work you've done or might do. I wondered what sort of adaptors you had. Any particular part of ebay you looked at? I'd be happy just to get my nifty 50 on the qhy9 for staters, but seems fairly complicated
Yeah, I love the way it puts things in context for the long FL work you've done or might do. I wondered what sort of adaptors you had. Any particular part of ebay you looked at? I'd be happy just to get my nifty 50 on the qhy9 for staters, but seems fairly complicated
With your new lenses and your skills, some amazing photos are on the way.
Thanks.
Ross.
Too kind Ross. See what you've started?
Quote:
Originally Posted by peter_4059
Nice wide fields Marc. What lens are you using?
Thanks Peter. For those close up shots I used a 200mm Pentax lens. I've got a *istD with a K-mount and originaly a 18-35mm, so I got a couple of other lenses from eBay, 200mm and 100mm.
. Just checked it now I've pulled the rig apart back in its boxes. Got square eyes and need some sleep. 
