astronomy & imaging ?

[Dazraz]

Hi can someone explain to me when you see one of these glossy very good pictures on the internet of galaxies etc - is that what the telescope is actually seeing or does the imager only see these great pictures once they have recorded the image and stacked it etc. I hope i am making sense

Regards Daren

[Andrew*]

Hi can someone explain to me when you see one of these glossy very good pictures on the internet of galaxies etc - is that what the telescope is actually seeing or does the imager only see these great pictures once they have recorded the image and stacked it etc. I hope i am making sense

Regards Daren

Perfect sense! The latter applies.

The level of detail in an image depends largely on the exposure length. Typically, images are exposed for over an hour and sometimes many many hours. This means lots of light falling onto the chip and lots of detail. Visually, you don't have a "long exposure" function, so the level of detail visible is much more restricted.

Furthermore, digital images are subjected to complex processing to bring out as much detail in the final image as possible from the data.

Andrew

[SteveL]

Andrew is spot on. What you can visually see is nowhere near the level of the smooth and colourful images posted in the imaging section here and in the magazines. The final images are culmination of many hours of photon collection, which are stacked and post processed to bring out the really dim sections without saturating the bright areas. White and black points are edited, curves are applied to increase the dim sections, colour saturation and contrast levels are often bumped up to provide a more dramatic image. Selective sharpening and/or deconvolution are applied to some sections, selective smoothing is applied to the noisier areas. And each image requires a different set of processes.... I often spend as long image processing as I did actually taking the sequence in the first place, especially for color image (mono are slightly easier)

[ashenlight]

be warned - astrophotography is even more expensive than astronomy alone

[John]

One of the interesting challenges for newcomers to the hobby, who want to start off observing rather than imaging, is that there are very few images around which accurately represent what we can see visually through a scope - it's probably best to look at drawings done at the eyepiece for that and even then the contrast of an astro object can be exaggerated a little to produce an interesting drawing.

There are a few notorious objects for this - M1, the Crab Nebula is one of these IMHO - in images and drawings it looks a well defined object but visually it's much, much more subtle, even in large scopes.

John

[Deneb]

Enter the Dark Side if you Dare

[Dazraz]

Hmmmmm thats the second warning i have had telling me its expensive i will certainly take that on board but then again christmas is on its way time to suck up to the mrs - cheers for advice

[Dazraz]

Andrew is spot on. What you can visually see is nowhere near the level of the smooth and colourful images posted in the imaging section here and in the magazines. The final images are culmination of many hours of photon collection, which are stacked and post processed to bring out the really dim sections without saturating the bright areas. White and black points are edited, curves are applied to increase the dim sections, colour saturation and contrast levels are often bumped up to provide a more dramatic image. Selective sharpening and/or deconvolution are applied to some sections, selective smoothing is applied to the noisier areas. And each image requires a different set of processes.... I often spend as long image processing as I did actually taking the sequence in the first place, especially for color image (mono are slightly easier)

Just visted your website and must say you have a stunning collection of pictures brilliant !!!

[SteveL]

thats the second warning i have had telling me its expensive i will certainly take that on board but then again christmas is on its way time to suck up to the mrs - cheers for advice

The imaging bug is a never ending draw on finances... you just cant stop, there is always just one more (expensive) item that could really help... and then another... and another! You may need to suck up to the Mrs all the time, not just at Christmas.

Just visted your website and must say you have a stunning collection of pictures brilliant !!!

Thank you, thats very kind of you to say.