Skywatcher Quattro f/4 - How much faster than f/5?

[Macavity]

As with so many things, there is no substitute for the "background (random? pointless?) knowledge" of experience AGE - And not in a derisory way! LOL. I'm sure some of you remember "photographic calculators" - Circular slide-rule things, with "teeth" - Gave exposure times, depth of field etc. - BUT Instantly, we knew the duifferences between F4, F 2.8 etc. back then!

One can say many things on these topics. For me: http://web.telia.com...olli/kolli.html says most of it. The "sweet spot" size (1.4mm) seems inherently unachievable for budget / default / £400 F4 (GSO?) Newts. I sense the typical *F5* Skywatcher Newts (2.8mm) are on the (fortuitous) hairy edge too...

It's clear one can achieve significant improvements to budget scopes with modest effort. Not of "classical imager" standards. But I see some (honest?) dealer are "hip to the trip" re. £400 F4 Newts as VIDEO astronomy "light buckets". Somehow I suspect that is their BEST use... On the other hand, mine has caused me to review my whole "philosophy of collimation". The main axes may coincide, laser-wise, but my F4 Newt still "Squints like Quasimodo". LOL. But then I have a few more idea on that one too...

[Jessun]

I now know for certain (being quite old) that I would rather double my speed by adding another fast refractor and CCD than by trying to get one of these manic Ferrari astrographs to work.

These are not wise words at all..... these are worrying words, albeit seriously money saving.... :embarrassed:

Back to the drawing board...

/Jesper

[Gib007]

Interesting note - I already have and use Skywatcher's Coma Corrector, which FLO advertise as 0.9x. Turns out my f/5 is therefore performing at f/4.5!

I guess me wanting to move to a better telescope is simply to get better quality optics and a better tube. I quite like Newtonian Reflectors for their inherent dew shielding (mine has never dewed!) and their price to performance ratio. Sure, the Takahashi FSQ-106ED is legendary but damn, have you seen the price?

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[Astroscot2]

Sure, the Takahashi FSQ-106ED is legendary but damn, have you seen the price?

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Unhelss you buy a second hand flourite version, ahem ;-)

[Gib007]

I'm just thinking, is the Skywatcher Coma Corrector really 0.9x? They only make two as far as I'm aware, the one I have (pictured here in FLO's website: http://www.firstlightoptics.com/coma-correctors/skywatcher-coma-corrector.html) and the new Aplanatic f/4 one (pictured here: http://www.firstlightoptics.com/coma-correctors/skywatcher-f4-aplanatic-coma-corrector.html). Everywhere else I look up the former Skywatcher Coma Corrector, it says magnification remains unaltered, which implies it's simply 1.0x, not 0.9x. Have I missed something here?

In terms of telescopes, I'm still unsure as to what to get in the future. I will deliberate on the options available but it looks like a small refractor for wide-field and an astrograph Newtonian reflector for more narrow-field.

[laser_jock99]

Most of us end up with a selection of scopes to cover all eventualities. I even brought a Skywatcher ED80 in January since everybody raves about them! So far it has only been used a guide scope- working at F4 or even F2.9 is just far too tempting!

[Gib007]

Yeah, I'm thinking of getting these two in a few months:

- Skywatcher Evostar 80ED DS-Pro

- Skywatcher Quattro 250 CF

The former allows me to do nice wide-field work and the latter allows me to do more narrow-field work. Quite importantly as well, both are priced nicely. I would however feel compelled to buy a Moonlite focuser for the 80ED as well, as I currently have a Moonlite focuser for Newtonian Reflectors, which would be fit on to the Quattro (removed from my Explorer 150PDS). Add up the prices of these two telescopes, the Moonlite focuser for the 80ED, Skywatcher's f/4 coma corrector and the Catseye Collimation Kit and I'm in for a sting.