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Exposure Timings


gazzastone

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So probably a stupid question but here goes

I have seen an image that was taken with the following exposure times  L: 5x5 min, R:5x5 min, G:5x5 min, B5x5 min

Now assuming similar scope and sky's etc. what exposure subs would be required to achieve a similar image using a OSC canon camera

I suspect that a set of 5 * 5 min would not achieve the same result

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If the exposure time is 5 minutes then it is almost a certainty that it has been guided.

So unless you have a guide set up for the similar scope then a different frame of reference.

The DSLR will not deliver the same results as a mono ccd, which I assume the other image was taken with.

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yes the mount has a guide camera and is tracking to allow for long exposures the only difference is the OSC v Mono ccd  yes I appreciate the DSLR will not deliver the same result but the question is, is there a correlation between the subs required for a mono ccd and the subs required for a DSLR to achieve an image of a similar quality

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So probably a stupid question but here goes

I have seen an image that was taken with the following exposure times  L: 5x5 min, R:5x5 min, G:5x5 min, B5x5 min

Now assuming similar scope and sky's etc. what exposure subs would be required to achieve a similar image using a OSC canon camera

I suspect that a set of 5 * 5 min would not achieve the same result

The image you are talking about was taken using a mono ccd.  A mono ccd is at least  twice more sensitive than an OSC for the same level of signal. The problem with a DSLR is that if you increase the sub length to lets say 1200s, depending on the target, you may saturate the sensor well before you acquire enough signal so the alternative is to go for 600s subs but a lot of them to build the signal and decrease the noise. A lot also depends on the darkness of your sky and the type of the target.

A.G

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The image you are talking about was taken using a mono ccd.  A mono ccd is at least  twice more sensitive than an OSC for the same level of signal. The problem with a DSLR is that if you increase the sub length to lets say 1200s, depending on the target, you may saturate the sensor well before you acquire enough signal so the alternative is to go for 600s subs but a lot of them to build the signal and decrease the noise. A lot also depends on the darkness of your sky and the type of the target.

A.G

yes that seems reasonable, I have a canon 450d and the longest sub I have taken is 300s assuming good tracking what do you think the maximum sub length is acheivable

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yes that seems reasonable, I have a canon 450d and the longest sub I have taken is 300s assuming good tracking what do you think the maximum sub length is acheivable

I have done 1200s subs with a modded 1100d but with an Ha filter, the mount was guided with very good PA . With a decent LP filter and reasonable dark skies 600s should be achievable at the least. With 300s and around 50 subs you should at least have a clean image so the stretching can be a bit more aggressive.

A.G

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I have done 1200s subs with a modded 1100d but with an Ha filter, the mount was guided with very good PA . With a decent LP filter and reasonable dark skies 600s should be achievable at the least. With 300s and around 50 subs you should at least have a clean image so the stretching can be a bit more aggressive.

A.G

Great I have the astronomik EOS  CLS clip  will have a go with some extended subs will let you know how I get on cheers

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