Why do you get more detail ?

[johnb]

Hi

I’m following the tutorial Basic widefield with a Camera and Tripod

So im sure the answer is obvious but I will ask anyway. It says

“10 exposures at these settings, as the number of individual shots increases, the more detail you get”

Why do you get more detail

Regards

John B

[jgs001]

John, It's to do with increasing the Signal to Noise Ratio, I also think the combining mechanisms are able to pull more details out when the images are combined. There are many more people on here who will be able to go into a lot of technical details about the process. You may also be able to get away with more than 10. I did about 40 odd one night. M31 was very obvious, the biggest issue was to do with field rotation, and the corners started to mush out, beyond a certain number of subs, this effect becomes more noticeable and more of the image is affected.

[arad85]

Because you increase the signal to noise ratio. The more signal you have, the more you can cancel out the noise. It's a square law I think - drop the noise floor by 2x = 4x exposure time.

[themos]

Because the detail is the part of the signal that is in every shot but the noise is random and so is not in all the shots in the same place with the same strength. The good signal piles up in brick-on-top-of-brick fashion but the random noise piles up in a higgledy-piggledy heap of bricks. That's how detail emerges from more data.

[johnb]

Thanks to all for the answers - Now I understand

John B

[Tim]

And the less noise there is, the more you can stretch a picture to pull out the details.

[ollypenrice]

...and maybe you can think of it like this; the more often you measure something (and average the results) the more accurate your measurement will be - in the absence of an unidentified systematic error.

Olly

[G4YVM]

Because the detail is the part of the signal that is in every shot but the noise is random and so is not in all the shots in the same place with the same strength. The good signal piles up in brick-on-top-of-brick fashion but the random noise piles up in a higgledy-piggledy heap of bricks. That's how detail emerges from more data.

This is one of the most succint descriptions of s:nr I have ever seen...and I've seen a few.

david

[ollypenrice]

Agreed.

Olly