Re: I give up
- --- In firstname.lastname@example.org, "John Bambury" <jbambury@b...> wrote:
>Yeah I gathered that, but I decided to let that slide and roll it off
> I didn't call the ASGT mount garbage, I was referring to your
> statement. Matched to the correct scope the ASGT mount does a very
> good job IMO, but its not as good as the Nexstar 8 GPS.
> Clear Skies
> John Bambury
And I agree, I was thinking about the N8i, the N8GPS (on a good wedge
and with the heavy duty tripod) would perform better than the ASGT, but
at more than 2x the price!
ASGT can handle 8" SCT just fine... wait till ya see the results I will
get on film with the Hardin 8"f4 (when I get it finally) on my orion
SVP mount, which is as you know, in the similar class as the ASGT, but
with even smaller tripod legs, and no autoguide capability.
- I never thought of it as divided camps... Exposure time is
determined by f ratio, and image scale is determined by focal length.
To not think of both at the same time is alien to me, it is just a
fact of photography. Focal length and image scale need to be
considered in how stable you need to be (how accurate your guiding
needs to be in astrophotography), and the converse is, the focal
ratio needs to be considering when factoring the exposure time. I do
not expect my Nikkor 200mm f4 to show the same image as an 8"f4
reflector, but I do expect the same target to have the same density
at the same time exposure, but obviously the image scale is bigger
with the 8"f4, since it has an 800mm FL vs 200mm FL. It is just a
given to me to think of both.
now MONEY can BUY not having to think about f ratio... just have
enough MONEY to buy CCD cameras that are sensitive enough to work
with f12 scopes, and you get the best of both worlds. For the non
gaziollionares out there, we are stuck with using faster scopes, and
the more image scale we want, the bigger our scopes, and hence
mounts, need to be. 8"f4 is about as big as I can personally afford
at this time.
in email@example.com, "Kevin Dixon" <ksbtk@c...> wrote:
> Hi Joe:all
> This is one of those topics where there never is agreement among
> astrophotographers. Some are in the camp of the f/ratio; othersare in the
> camp of focal length. I have seen discussion threads on this topicgo for
> weeks, each side presenting compelling arguments for their position.standpoint
> I personally approach imaging with film and CCD cameras from the
> of emphasis on focal length because it takes into account f/ratioand
> aperture, whereas the reverse is not necessarily true. It is alsohow I
> judge the demands on a mount. The longer the focal length, thegreater the
> demand placed upon the capability of the mount. And that isgenerally
> without influence from f/ratio.I don't
> To be sure, there will always be disagreement on this topic. And,
> pretend to understand the complex math and physics behind it.Based on my
> personal experience, and on the experience of those I hold in thehighest of
> regard in the fields of astrophotography and CCD imaging, weworship
> together at the altar of focal length.should be
> Clear as mud now Joe? <g>.
> Clear skies,
> From: "Joe Fittipaldi" <j.fittipaldi@b...>
> > ---- Kevin Dixon <ksbtk@c...> wrote:
> >>And to be more accurate, it really is not the focal ratio that
> >>emphasized but, rather, focal length, when it comes tothe odd
> > Hi Kevin,
> > as a start I'm not an astrophotographer, although, I have taken
> > picture of the sun (using a filter) and moon by holding thecamera to the
> > eyepiece.in his
> > You statement above directly contradicts what Stef Cancelli said
> > post about astrophotography, he stated that the F ratio should beof the
> > emphasised not the focal length or aperture.
> > Something doesn't add up, have I missread or missunderstood any
> > statements made?please explain
> > I know you are an accomplished astrophotographer, could you
> > to me what is the most important aspect between f/ratio,f/length,
> > aperture?
> > Regards
> > Joe.