Re: STUNNING image of M51



> The so what can be seen in the blockiness of the stars in your image!

I guess you need a pair of glasses.
>

You do a lot of guessing but guessing wrongly.Zoom up your image and the
stars are composed of as few as 4 pixels, Rolfe and Roland's images have
rounder stars.

> Being well defined doesn't mean it needs to be oversampled. And even
> undersampled images can be restored, witness the Hubble.

The Hubble had 2 waves of spherical abberation. The stars were bloated
and oversampled! Detail is lost where undersampled so why do it?

> I don't seem many people packing up several 100s lbs worth of equipment
> and traveling the world around. AAs tend to stay put.

Usually they do and produce average images. Some visit large star parties
like the WSP and take advantage of dark skies and great seeing.

> I don't know about you but the people I know when want to look for
> details stay a bit closer than a yard. Yet I don't see the connection
> between magnification and quality.

It shouldn't be that hard to see the difference between a 6 Megapixel
image and a 1.4 Megapixel one.

> The point I'm trying to make is we don't know the details so how can we
> say who had the worst/best setup?


He posted that his scope is a RC AstroSib 10" f/8.
We can see it has 40% obstruction here:
http://www.kasai-trading.jp/astrosib-rc.htm

Off axis at 20mm the stars are bloated. The chip in the ST8E is offset by
a similiar amount.

> My CCD is about as sensitive as the latest ST8 (peak at about 60% QE at
>550nm). He had nearly 2 hours more with a larger scope. Even if the ST8
>was the older model there's more than plenty to tip the scale in his
>favour. And if you want to show the very faint stuff, noise might be
>the price you got to pay (or more exposure). I'm not saying it's
>perfect, mind you. For that I would need those extra 2 hours of
>luminance, if you get what I mean...
The website shows he used a ST8E. The brightness for extended objects is
determined by f/ratio. Unfortunately you choice to stack many short
exposures and hence your image has more noise.

> You might try to ignore it but that little picture (at a smaller scale)
> has more detail (i.e. information content) than the other one. Compare
> the two with Adam Block's one, which is definitively the best there is.
> You might dislike mine but that's bound to be.

I tried very hard to see it your way but his image shows fainter stars
and faint nebulousity more clearly. Your stars do look sharper except for
the blue ones which have a halo.

> Jon and Bryan Rolfe / Adam Block captured this AO guided ST10XME using
an RCOS 20 inch f/8.4 ....Program at Kitt Peak National Observatory

Of course his image is better. He used a bigger scope, higher resolution
camera at larger scale and at Kitt Peak.

I don't hate your image, it is nice for your equipment. But you said you
can produce a better image with less equipment and less exposure time.

I wish it were true but you didn't prove that,

Magnum
.

Relevant Pages

  • Re: My First Outing with a Telescope
    ... that you have the Celestron Powerseeker newtonian reflector scope, ... Center that in your finder scope and see ... Your first goal is to be able to find something specific in the night sky ... the three brightest stars in the sky above you. ...
    (sci.astro.amateur)
  • Orion 90mm AZ refractor - review, comparison, observing report
    ... Orion Explorer 90mm AZ - review, comparison, observing report ... purchase another scope. ... This time I wanted to try a refractor. ... Stars looked great - round and tack sharp. ...
    (sci.astro.amateur)
  • OR: Visiting some old friends, but now armed with more aperture (umm, long)
    ... Scope Setup Notes, DSCs ... Then it's two alignments on bright stars out of a moderate database of ... this open cluster requires aperture to ... M8, Lagoon Nebula ...
    (sci.astro.amateur)
  • Re: ST-80 maximum ideal aperture - anyone know?
    ... I have pushed the little 80mm f/5 scope to 156x. ... surrounded by a 1 minute of arc diameter faint haze which is often produced by ... On M11, I can see a large number of faint stars, ...
    (sci.astro.amateur)
  • Re: Today, I Am The Luckiest Man In The World
    ... > left of the lower of the two, and point your little scope at that... ... the surrounding forest of stars. ... If I can find Gemini with our polluted city skies, ...
    (sci.astro.amateur)