possible daft question

[Tony Leece]

I hope this question won't get me laughed at, but i see posts where people have made excellent images using hours of data.
Is there an upper limit to this?
Can you make unlimited subs of the same object? oh i don't know, say a thousand hours as opposed to tens of hours?
Would this make a more detailed image, more light equals more detail?
Or am i missing something blindingly obvious 😁😁
Thanks for any responses
Tony

[JA]

Originally Posted by Tony Leece

I hope this question won't get me laughed at,

I hope the answer doesn't get me laughed at

There are no silly questions, just opportunities for learning & growth.

Originally Posted by Tony Leece

but i see posts where people have made excellent images using hours of data.
Is there an upper limit to this?

Every little bit helps, but it's a matter of diminishing returns for your effort, some sort of inverse exponential function might describe it.

I've heard it suggested that if your are using sky-limited subexposures then, perhaps there's not much point in going beyond 30 such subexposures, as there will be little improvement in the perceivable signal to noise ratio beyond that point, pixel peeing aside. It would be good to put that to the test on a high-end rig in good conditions, perhaps comparing 1 subexposure, to 2, 4, 8, 16, 32, 64... sky limited stacked subexposures and compare the result visually and also with Signal-to-Noise Ratio measurement. Out of interest, I don't think it's a coincidence that 30 is considered a useful minimum sample size when describing/estimating a normal/Gaussian distribution as I believe the image noise is distributed in a similar fashion.

Best
JA

[billdan (Bill)]

Hi Tony,

Short answer is yes, more hours of data acquisition equals more information captured. Not more detail (resolution), that is determined by the the telescopes aperture size and local seeing conditions.

Consider the Hubble deep field image that was taken in 1995, For 10 consecutive days (240 hours) they took approx 350sub exposures of a random patch of sky, and after stacking revealed over 3000 distant galaxies going back billions of light years.

The Dragonfly array of 48 cameras and lens', for every 1 hour of capture time they collect 48 hours worth of data, in doing so they have discovered heaps of new and remote galaxies that nobody knew ever existed.

For most of us amateurs living in the suburbs we are limited by light pollution so more hours of capture time, just increases the background sky noise and swamps any faint objects..

Cheers

[Stonius (Markus)]

I think it was a good question :-)

In the end, it really comes down to the limit of how dark your skies are. :-)

Markus

[Tony Leece]

Thanks for the responses guys, cleared things up for me, cheers