hi,
i have some qns regarding deep sky photography using a dslr.
i refer to dso that are relatively bright...
1)
will the a stacked image of 10 x 1min look just like the image of an 1 x 10min?
i believe the 1 x 10min image will be more exposed, showing more detail.
2)
will the a 3+++min image look like one taken at 1++min of red, 1+min of blue and 1min of green stacked together? (the "+" symbols meant compensation for exposure due to whatsoever reason(i.e. IR filter) so as to obtain an even exposure)
i believe the three separate exposure will produce a more accurate image in terms of colours (it is possible for me to add an "L" into my exposure?)
assume there is no noise and all other parameters being constant for the above senarios.
3)
for nikon D70:
will blooming be an issue for deep sky imaging?
a 2min exposure at iso800; will it be extremely noisy beyond "software repair"?
anyone has info on the bandwith of their IR filter and the individual colour filters?
i appreciate any other info...
thanks
dslr astrophotography
dslr astrophotography
K.L. Lee
Hi,
1) Roughly similar. Note that you may have to throw a few of your 1 mn images because of bad tracking, plane, cloud, etc... but you still have the other good ones.
A 10mn shot is lost for any single occurence of the above.
2) I would think so but note that the red channel is likely to be the noisier
3) I would comment for the Canon 300D : no blooming at all, the image will be washed by light pollution before any blooming.
Cheers
Jean-Yves
1) Roughly similar. Note that you may have to throw a few of your 1 mn images because of bad tracking, plane, cloud, etc... but you still have the other good ones.
A 10mn shot is lost for any single occurence of the above.
2) I would think so but note that the red channel is likely to be the noisier
3) I would comment for the Canon 300D : no blooming at all, the image will be washed by light pollution before any blooming.
Cheers
Jean-Yves
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tanguan2001
- Posts: 146
- Joined: Fri Oct 10, 2003 10:06 pm
- Location: Braddell
- Contact:
Kun Loong & JY,
I'm currently working on figuring out these trade-offs:
1) longer exposure vs multiple shorter exposures
2) High ISO, short exposure vs Low ISO, long exposure
At the moment just from experience, for 1), the longer exposure is better, within the limits of sky brightness. Since I have got autoguiding going, the longer exposures give me smoother, deeper images
For 2), in theory the low ISO, long exposure should be better due to more photons being captured, rather than just an amplifier gain being applied, but in practice read-out noise limits this effect. By experience 400ISO seems for me to be about optimal. Have done some tests on this with the Cone Nebula a few nights ago - will report back when I have processed these images.
TG
I'm currently working on figuring out these trade-offs:
1) longer exposure vs multiple shorter exposures
2) High ISO, short exposure vs Low ISO, long exposure
At the moment just from experience, for 1), the longer exposure is better, within the limits of sky brightness. Since I have got autoguiding going, the longer exposures give me smoother, deeper images
For 2), in theory the low ISO, long exposure should be better due to more photons being captured, rather than just an amplifier gain being applied, but in practice read-out noise limits this effect. By experience 400ISO seems for me to be about optimal. Have done some tests on this with the Cone Nebula a few nights ago - will report back when I have processed these images.
TG