From: "Martti Koskimo" 
To: 
Reply-To: "Martti Koskimo" 


It depends on what we mean by seeing detail. It is possible to 'see'
surface detail that is smaller than resolution limit.

The dimensions of that smaller detail is magnified to the theoretical Airy
disk diameter of  telescope used.
The intensity of object is lessening due to the Area ratio (object angular
diameter/Airy disk-Diameter)**2 .
And thus the Modulation transfer is dramatically reduced bur not inevitably
'disappeared' for point or line objects.
If the object is bright enough (as stars and bright points on moon) we can
DETECT sub diameter detail but
of course it is not resolved.

Planetary detail are even from the start so low contrasted that it is very
difficult or almost impossible to catch up the theoretical limit not to
mention seeing sub diameter detail. The only exception is high contrasted
Cassini Division and probably it is possible to see it with 'sub' aperture
telescope.




Martti Koskimo



----- Original Message -----
From: "Mel Bartels" 
Cc: "ATM list" 
Sent: Thursday, January 09, 2003 11:03 PM Subject: Re: ATM Ultimate Optical
Capability


>
> >     I'm going to paste below a discussion I've had with Roger Sinnott of
> > S&T.  My question to this group is; Why is it possible to see planetary
> > detail much smaller than a telescope's theoretical resolution?  Is the
>
>
> It is not possible to see detail in a telescope that is below its
> theoretical resolution.  No exceptions.  End of story.  By definition, a
> physical impossibility.
>
>
> A 2 inch scope can almost show Cassini's Division.  Double stars separated
> by 1 arcsecond and of equal brightness and of apparent magnitude 3-5 in
> the eyepiece will require in the range of a 5 inch scope to show the two
> components.  Resolution of NGC891 takes a much larger scope.  In these and
> in many more cases, theoretical resolution varies tremendously per type
> and apparent size of object.
>
> Ask yourself, how do you see a single star at night with the unaided eye?
> The eye surely cannot resolve any of these stars, yet, there they are, to
> use an ancient Greek metaphor, peering down at us.
>
> Don't fall for the trap of believing that a 5 inch scope's resolution is 1
> arcsecond detail, as that is its theoretical resolution for only one very
> distinct category and condition of object.
>
> Mel Bartels
>
>

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