tornado33
27-02-2006, 06:08 PM
Hi all
heres a bit of an interesting comparison
both images taken with 50mm lens on modded 350D with 2inch uhcs filter on front of lens.
First one is 2x 300 sec shots @ISO 400 lens at F4 with in camera n/r off and darks subtracted in Iris by strictly following the instructions. In the original result before jpeg compression theres small green pixels all over, seems that because theres so many stars it for some reason didnt optomise the dark subtraction properly. But worse, the colours lack the richness of the originals as they appear on the canon software.
2nd pic is a SINGLE 250 sec pic with in camera n/r on (taking another 250 secs to do the DF. Lens at f4.5 Total down time for the image 500 secs. I think its time well spent, as the colours are far richer then I get by turning them to CFA monochrome and turning them back in IRIS after dark subtraction. Its a bit "rougher" because its only a single 250 sec shot, and that was through some high cloud! If I can do several more of these shots with n/r on and stack them, I will get a much smoother result with the richer colours. I will try the same comparison with galaxies. If the same results then I will exclusively use in camera n/r. The taking of the darks gives me a break from the manual guiding anyway, what I normally do is take a 1 or 2 min pic with no n/r just to see ive got the object framed properly and that focus and tracking is okay, then turn on the n/r and do the longer shots. (Wouldnt it be great if the camera could store a dark and subtract it to every image of same length and ISO)
One thing, I wish the camera would "beep" when the dark is finished. I set a timer for the length of the light exposure and start it again when the camera starts taking the dark to get around that.
What do Images Plus users think? Personally, (most of the time) Iris does a good job of df subtraction, with its "optomise dark" function where a dark of unequal length and/or temperature will be accurately subtracted leaving very little noise, but the colours I can get are rarely as good as using the canon software to extract the Raws (n\r on) as tiffs and using Iris to just do the stacking
Scott
heres a bit of an interesting comparison
both images taken with 50mm lens on modded 350D with 2inch uhcs filter on front of lens.
First one is 2x 300 sec shots @ISO 400 lens at F4 with in camera n/r off and darks subtracted in Iris by strictly following the instructions. In the original result before jpeg compression theres small green pixels all over, seems that because theres so many stars it for some reason didnt optomise the dark subtraction properly. But worse, the colours lack the richness of the originals as they appear on the canon software.
2nd pic is a SINGLE 250 sec pic with in camera n/r on (taking another 250 secs to do the DF. Lens at f4.5 Total down time for the image 500 secs. I think its time well spent, as the colours are far richer then I get by turning them to CFA monochrome and turning them back in IRIS after dark subtraction. Its a bit "rougher" because its only a single 250 sec shot, and that was through some high cloud! If I can do several more of these shots with n/r on and stack them, I will get a much smoother result with the richer colours. I will try the same comparison with galaxies. If the same results then I will exclusively use in camera n/r. The taking of the darks gives me a break from the manual guiding anyway, what I normally do is take a 1 or 2 min pic with no n/r just to see ive got the object framed properly and that focus and tracking is okay, then turn on the n/r and do the longer shots. (Wouldnt it be great if the camera could store a dark and subtract it to every image of same length and ISO)
One thing, I wish the camera would "beep" when the dark is finished. I set a timer for the length of the light exposure and start it again when the camera starts taking the dark to get around that.
What do Images Plus users think? Personally, (most of the time) Iris does a good job of df subtraction, with its "optomise dark" function where a dark of unequal length and/or temperature will be accurately subtracted leaving very little noise, but the colours I can get are rarely as good as using the canon software to extract the Raws (n\r on) as tiffs and using Iris to just do the stacking
Scott