I still ended up getting moonlight into this shot, because the clouds didn't really clear for me until around 3am. Just once I'd like to get Carina with no moon, no wind, the neighbour's searchlight out, no dew and precise focus. Oh well, one advantage with being out in the middle of the night is that you get to chat with any burglars who may come wandering down the driveway.
This one is a stack 6 x 90secs ASA1600. Canon 350D at prime-focus of LXD-75 SN-8. Camera's onboard noise reduction was On. Images aligned in MaxDSLR, processed in ImageReady and Noiseware. I think this result is a little better than my last one.
Getting correct focus is a problem for me at the moment using the Canon at prime-focus. I use a Hartmann mask but, that doesn't help a lot when attempting to focus via the Canon's very ordinary viewfinder. Even with a 2x magnifier judging focus via the viewfinder is not really a long-term proposition.
Before taking the image below an approximate focus was obtained with a Hartmann mask and then I got more accurate focus by taking a series of short starfield shots and viewing them to check when I was near focus.
Even after all that effort the focus is still not perfect. I'm thinking a Stilleto for the Canon, or some such, is in my future. I've got two Stilletos (35mm Film & CCD) and I'm underwhelmed by their usefulness. I think that maybe for the Canon that's all the choice I have. I haven't got a laptop in my equipment yet so I can't use software for focusing. Does anyone have any ideas on cheap and effective methods suitable for the Canon 350D? http://www.cloudynights.com/ubbthrea...estionicon.gif
Bill have you an image to view. I have a stelletto, they are not all that good, I find it extremely difficult to use for the pentax. I bought the 2.25 right angle finder c and find it very good to focus with.
Nice shot Bill. I bet a bit of curves adjustment would give you more contrast. But great shot all the same.
Re. focus. Try DSLRFocus. It helps a lot. Adds a few extra minutes to setup time, but it's will worth the effort. I too struggle to get tight focus, manily due to the constantly poor seeing we get here.
Cheers
Hi Bill,
I couldn't resist, so I took liberties with you image in Photoshop. I hope you don't mind....
This is what I did..
1. Minimum filter to reduce star sizes (blended 40%).
2. Curves adjustment with mask on keyhole to try & improve the contrast.
If you don't like it then I'll delete this post, but I couldn't resist having a little play.
Cheers
Robby....what do you mean by a minimum filter reducing star size..........?????
Ahhh that's my little secret..... No not really. I sumbled across it the other week. Try it. I have Pshop 7 and it is under filter-other-minimum menu.
I usually copy the image onto another layer then applly the minimum filter which pinpoints all the stars. This is a bit too much, so then I blend with the original about 40%. Try it.
Cheers
Nine Eta Carina there. At first I was a fan of not using the 350D noise reduction, but rather taking some DFs and subtracting them in IRIS but last night I used the in camera N/R again and found the results considerably better, also when using my 50MM lens for some reason the darks didnt work under Iris, because the instructions say to optomise the darks draw a small rectangle in the light image where theres no stars, but in the 50MM lens shot there were no star free areas, and I was left with green dots all over when I did the Iris processing.
Scott
...At first I was a fan of not using the 350D noise reduction, but rather taking some DFs and subtracting them in IRIS but last night I used the in camera N/R again and found the results considerably better... Scott
The in-camera noise-reduction gets bagged a bit, and just now I can see no reason why. For a newbie like me it is just so convenient. I'm sure I'll move onto Master Darks, etc. later but for now the in-camera noise reduc is working very well.
The way I see it, the in camera n/r is designed by Canon to work with that image sensor, so would have to be optomised better then any 3rd party astro processing software, Though it doubles imaging time, the lesser amount of fiddling on the pc can make up for the time lost.
Scott
for some reason the darks didnt work under Iris, because the instructions say to optomise the darks draw a small rectangle in the light image where theres no stars, but in the 50MM lens shot there were no star free areas, and I was left with green dots all over when I did the Iris processing.
Scott
you can uncheck the optimise box in IRIS and run the darf frame subtraction-this is what Jim Solomon recommends..or I have I misunderstood what you are saying?
Iris got corrupted somehow, I uninstalled and reinstalled it and it now seems ok. It seems to do better with optomise box checked resultwise. Iris is a bit more fiddly with the colour balance too, as with the CFA conversion its a linear conversion and shows green images which need to have manual colourbalance done during processing. Stacking Tiffs extracted by the canon software (that have had in camera n/r on and therefore dont need dark subtraction) is so much easier as I only need Iris for the stacking, and might be for me worth the xtra time taken imaging . As I manually guide it gives me a break between images too .
The Canon in camera noise reduction works so well for two reasons the 'dark' the camera takes is at the same temperature and there is a hardware advantage as all the 'pixels' correspond exactly not a Beyer interpolation. I think they do it at a raw level in camera. For the in camera processor to do it so quickly it is hardware wired ie not complex software simulation. If someone can tell me otherwise I am open to enlightenment. I can't think of any other reason why it works so well.
Yes some people talk of maintaining a "dark library" of darks taken at different temperatures to match up with their light images, though I wonder also, if the characteristics of the imaging sensors may change over time, eg will a dark taken now, look different from one taken in a few months time, even at same temperature?
Scott
