Telescope Reviews: Re: Rony's Binocular Sketches--Check this out

Phil and Ed,

Thank you both for the kind words on these observations.

The sketches are created as follows.

I start with a pencil on paper sketch. The form that I use has a circle to represent the field of view. This circle measures about 19cm, the largest I can put on a letter format paper. I always start with an empty circle, no stars preprinted. The stars are drawn as seen. First the bright anchor stars. Then come the fainter ones. I label each star with a number (15 is like Vega, 2 is the faintest averted star, 1 is not used, as it could be seen as a glitch). Sometimes, the pencil is replaced by a ultra fine pigment liner. The liner is easier to read in the dark. This eyepiece sketch is created in 30 minutes to 90 minutes, depending on the complexity of the starfield. It takes more time and a lot of averted vision to detect the fainter stars. Here is were the mirror mount comes to value. I can sit relaxed and take deep breaths to support my vision, without having to support the bino's.
On an average night, I make 2 to 5 of these pencil sketches.

The digital rendering happens indoors. Again I start from scratch and build up the sketch in the same order as I did with the pencil sketch. The labels next to the stars help me to draw the dots according to the observed brightness. Star positions are compared with Sky Charts and corrected if needed. I use multiple layers to render the sketch. Stars, nebulae, halo's, glare, they all have a separate layer. The digital sketch is finished in about 90 minutes.

Ed, to answer your question on My M44 observation:

It is my experience that the 8x56 on the sky window offers me a gain of 4 to 4.5 mags over the estimated NELM. These estimates are rough. I am not good at estimating NELM. So the value might be off with 0.5 mag. If my readings are correct, the faintest star in the sketch is about mag 9.9 or mag 10 (according to Sky Charts). Thus the Nelm would be about 5.5 instead of 5?
Photographs are nice to compare with, but they do not represent the visual impression in the eyepiece.

The faintest binocular stars I have ever noticed have mag 10.5. Again, these are values that I found in Sky Charts, not from a callibrated star chart.

Thank you, Ed, for bringing it under my attention.

In the future, I should put the values like : Nelm = 5.2 to 5.5.

Clear skies,

--------------------
Rony

My Astronomical Sketches

My Binocular Sketches

Callibrate your Monitor with this little strip.

Edited by rodelaet (06/17/08 10:25 AM)

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