Αυτό θα πει γρήγορο τηλεσκόπιο

[Μανούσος]

14,5" f/2.55 έχετε ξαναδεί; Εγώ όχι...

Το τηλεσκόπιο γονατίζει ακόμη και τον Paracorr με Nagler μαζί ενώ η κεντρική παρεμπόδιση είναι 30%. Μου κάνει εντύπωση ότι ο τύπος το ευθυγραμμίζει εύκολα. Τι να πω. Πάντως μη μου πει κανείς ότι με f/4 έχει γρήγορο τηλεσκόπιο...

 

http://www.loptics.com/fast14p5.html

[Fred Ley]

Hi,

 

The image of the instrument that you posted reminds of an interesting view that I had of M45 (Pleiades) back in 1984 through an 8-inch Sky Research Newtonian.

 

A friend of mine who still has that same Sky Research 8-inch f/2.9 (589.28 mm) Newtonian telescope had it pointed at M45 and I placed my 13mm Nagler in the focuser to get 45.33x and a true field of view of 1-degree 44-minutes and 32-seconds. The amount of nebulosity shown made me momentarily look away from the eyepiece and look up at the sky to see just how much cloud coverage was rolling in. The sky above me completly clear, I just didn't expect to be treated to a view like that.

 

Below is literature on that particular instrument.

 

-Fred

[Μανούσος]

Fred these scopes are the absolute portable instruments, but what about the coma and obstruction by the secondary? I know that central obstruction above 20% is observable.

[eliasg2004]

http://starizona.com/acb/articles/Telescope%20Optics%20Myths.pdf

 

Myth #2: "You Can’t Get Good Planetary Images with a Large Central Obstruction"

 

Central obstruction has to be > 40% (in other words > 12% by area) to practically - and not theoretically - compromise high power visual use. Such scopes are RCs, excellent for high resolution deep sky astrophotogaphy, totally useless for visual...

CO in typical SCTs is about 30%, a bit less in newtonians. Good, well aligned optics and a CO of 20% - as in many MCTs - will get you very close to apo-like performance

[kkokkolis]

Cheaper than a Nagler?

[Μανούσος]

Τελικά παντού υπάρχει ένας μύθος.

Finally myths are exists also in astronomy.

[Fred Ley]

Hi,

 

I can not exactly recall the view, but I do remember that it was a positive one. I am certain that if I was using a 40mm or longer focal length, I would have flocks of seagulls on the edge of the field. With the 13mm Nagler I do not recall that being the case.I guess when I am back in California, I will have to repeat the observation in order to absolutely know.

 

-Fred