25" whit a 3.1" diagonal

[Hakann]

I has come to the insight in this project that f/4 is as far as I can go on height of the structure.
But a ladder is not all that bad, as it can be relaxing to.
But for portable use it's negative of course.

I has had the idea on a medium or a high power scope ‘only’ at ex 25” and f/4 and not use a coma corrector.
As I said, the idea I got last year at Jorge Peters 25” f/4.5 Sitall/Lomo at 70 mm thick and he used a 3.9” diagonal.
We used Ethos 4.7 mm ( 1 mm pupil ) and 600X.
Marvellous !

I can get away whit a 3.5” ( C-A 3.4” ) if the EP barrel stick in at 1”.
( 14% obstruction and mag-drop at 0.05 = worthless for a human eye – maybe, but WAY cool ! )

Example on Ethos EP ;
8.0 mm 317X. ( pupil = 2.0 mm ) 15X /”
6.0 mm 423X. ( pupil = 1.5 mm ) 17X /”
4.7 mm 540X. ( pupil = 1.2 mm ) 22X /”
3.7 mm 686X. ( pupil = 0.9 mm ) 27X /”
( I can add a Powermate x2 )

Coma will not be a big issue here ( as I tested it )

I think deep-sky must be around zenith, and low-sniffing is nothing for me.
Also no good sky is nothing for my astronomy.
So whit a ladder ( as I don’t like ) is actually a steady rest.
But a ladder is bad vs be portable.
But a mirror at f/4 is my guess more easy vs a f/3 etc.

I hardly believe it is as easy to see a good star-test in a f/3 @25”.
( Around 25X per inch or 2 mm pupil )

I doubt ( but this is personally ) that very fast bigger mirrors will show great stars.
After all, f/3 or faster has many issues.
Only good thing about it ( as I see it and MANY others ) is shorter trusses and one can has a 25” and not use a ladder.
But the optic quality ?

Sweden has no sky for it.
-But LaPalma has.

-What kind of mirror ?

A cast Dream cellular at 15 kg and 6;1 ratio or a CZ Quartz plano at 44 mm edge.
I think the cellular might be the winner out in field.