On Mar 24, 4:20 pm, Doug Jewell <a...@[EMAIL PROTECTED]
> wrote:
> Pete D wrote:
> > "Doug Jewell" <a...@[EMAIL PROTECTED]
> wrote in message
> >news:47e7034b$0$17341$5a62ac22@[EMAIL PROTECTED]
> >> Cryptopixel wrote:
> >>>http://www.clocksnprints.com/bugsat200mm.htm
> >> Clicked send on my other reply before I was ready. oops. Anyway, as I
said
> >> before, nice pic doug.
> >>> Sigma and other after market lens makers have some exceptional
lenses
> >>> in their ranges. The patented nature of lens based image
stabilization
> >>> means that these smaller makers are at a substancial disadvantage...
> >>> Until the likes of Pentax and Sony (to name just two) catch up with
> >>> camera body technology.
>
> >>> The latest Pentax K20D is one example of where serious photographers
> >>> can save thousands of dollars and not sacrifice anything, compared
to
> >>> buying Canon and Nikon kits. In-camera image stabilization saves
> >>> photographers serious money when buying excellent quality lenses.
>
> >>> The Sigma 70 -200 F/2.8 (macro) that took this picture costs less
than
> >>> half of what a VR Nikon equivalent costs. Almost enough price
> >>> difference to pay for a Pentax K20D body!
> >> Was this shot with a K20D? - I thought you were using S5's and D300s.
> >>> It's hard to justify the weight and cost of in-lens gyros when
cameras
> >>> with sensor based IS are now every bit as good as their Canon and
> >>> Nikon rivals.
> >> Most tests tend to show that lens based IS is better than body based,
and
> >> that's probably right. But we survived so long without any IS at all,
that
> >> surely there are more im****tant things to rate a system on than the
> >> performance of IS with one or two particular lenses. Canon & Nikon
> >> definitely have a better range of fast telephoto lenses than Pentax
do -
> >> this makes In-Body or In-Lens IS irrelevant if it is hard to even
find a
> >> suitable lens for the body. But certainly for someone who mostly
needs
> >> wide through to moderate-telephoto the Pentax system represents
> >> exceptional value.
>
> > Not sure what lenses you need in Pentax mount but their 200mm F2.8
looks
> > pretty good and their soon to be released 300mm F4 will probably be
good as
> > well. If you really need big glass though I would suggest that Pentax
is not
> > for you.
>
> Pentax certainly offers all that I need, and then some! But
> for some of the s****ts and wildlife nuts, the lack of fast
> 300+ glass is a compelling reason not to go pentax.
>
> > If you are shooting with a K20D it would seem that faster long lenses
while
> > normally desirable may not be quite as needed as they once were
because the
> > high ISO performance is getting to be so good.
>
> True, but regardless of how high you can go in ISO, if you
> have fast glass you will always have an advantage over slow
> glass. Yes, the high ISO performance of the K20 will mean a
> K20 & 5.6 lens will do what would need a 2.8 lens on the
> K10, but a K20 & 2.8 lens will be better again. Whether that
> translates into faster shutters for better frozen motion, or
> whether it translates into lower light shooting is up to the
> owner, but regardless, they are still better off with the
> fast glass.
>
>
There seems to be a presumption here that having a F2.8 lens you will
use the wide aperture for taking photographs. That goes to show me,
none of you have a long, fast lens. A telephoto lens with F2.8 gives
you brighter images in the viewfinder and more precise auto focus. At
200 mm FL the depth of field is minuscule and unless you have a reason
for wanting a face out of focus either side of the point of focus, it
has little practical use.
The edge of one of the insect's shells is the point of focus. There
is more DOF past the focus point than there is in front of it. About 5
mm range before the OOF starts to be obvious. Certainly not enough to
photograph a person's face side on and have usable images. The Sigma,
120 - 300 F2.8 I sold before Christmas never took a shot in
seriousness at F/2.8 for that very reason.
The camera used was a Canon 10D belonging to the buyer of the lens and
some other Canon stuff I had left over from the change to Nikon. She
wanted to satisfy herself that the lens was indeed a viable rival for
Canon's own 70 - 200, F2.8. She used her partner's Canon lens to
compare shots with on my computer. My comments were aimed at those
people seeking decent glass and not having the means to shell out a
few grand to get it.
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