On 10/6/2014 9:33 PM, Bruce Walker wrote:
On Mon, Oct 6, 2014 at 9:23 PM, Stanley Halpin
<s...@stans-photography.info> wrote:
On Oct 6, 2014, at 4:26 PM, Larry Colen <l...@red4est.com> wrote:
P.J. Alling wrote:
and wonder of wonders it's got some interesting information for free.
http://www.luminous-landscape.com/techniques/pentax_645z_astrophotography.shtml
Excellent link, though I'm afraid that if I were to spend $10K on a 645Z, I
wouldn't have any money left over for the $500 astro mount.
I was surprised to find that there don't seem any lenses faster than f/2.8
available for the 645. Doing some quick web search, there don't even seem to
be any manual focus lenses faster than f/2.8 available.
There are adapters that support the use of Hassleblad etc. on the 645. Maybe
you can find the faster glass you need by going that route?
I always assumed that there isn't faster glass because there doesn't
need to be. The DoF on medium format is already razor thin compared to
35mm and APS-C and perhaps a 1.4 on a 645z would create a serious
focusing problem? Or ridiculously OOF portraits?
In other words, we have what's practical to sell, as with other
formats. Or am I way off base?
Not just DOF, but an f2.0 135mm would be quite large and heavy if built
to cover the 645 format, yet it would be the equivalent of a Portrait
lens say 85mm on 35mm, (75mm actually). Fast glass makes in any focal
length on 645 need a tripod, whereas Pentax build a system to be equally
good as a hand held field camera, as well as at home on a tripod in a
studio. Traditionally medium format lenses have been fairly slow.
There are exceptions, but they are exceptions.
--
I don't want to achieve immortality through my work; I want to achieve
immortality through not dying.
-- Woody Allen
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