DxOMark gives sensor in the D800E with an overall rating of 96 for
quality, and the Pentax 645D an 82. The Nikon has an effective EV range
of over 14 stops the Pentax about 12. The Nikon has a 36.3mp sensor
with linear values of 7360x4912, which gives a 300dpi print size without
undue manipulation of 24 1/2" x 16 1/3". The 645D has a 40mp sensor
with linear values of 7264x5440, which gives a 300dpi print size of
roughly 24 1/5" x 18 1/10". Now the actual sensor size of the Nikon is
35.9mm x 24mm, and the Pentax is 44mm x 33mm so given that both
manufactures decided to give 100% viewfinder coverage with say 90%
magnification the Pentax would win out, but since neither manufacture
decided to do that and I haven't actually been able to look through
either finder, but only go by written specifications* I can't say which
finder is better, at the cost differential, if I needed the resolution,
I'd have to buy the Nikon. Especially as I'm starting from zero with
both systems.
Based on this it's evident that Pentax must upgrade the 645D to stay
competitive, but that said the same is true of any maker of medium
format backs for existing systems. The only advantage Pentax has here
is that the whole 645D camera body usually costs less than a back for
another system. Pentax's other disadvantages are it's lack of lenses,
only two currently in production, and the fact that it was designed to
medium format requirements, where as the Nikon is a general purpose
camera, designed to near sports photography requirements, that delivers
medium format image quality.
*Based on those specifications of 100% coverage with 70% magnification
for the Nikon and 95% coverage and 65% magnification for the Pentax, I'd
say it's a wash anyway, once again given that I've never actually been
able to look through either.
On 12/14/2012 9:51 AM, George Sinos wrote:
I guess if all you look at is the megapixel count, the two cameras
aren't all that different. And for a lot of applications the d800 is
going to be sufficient. The tests certainly show that technical
differences are small.
But as Bill points out, there will be differences that go beyond counting bits.
The sensor on the 645 is 33x44mm. This is larger than the 35mm full
frame sensors in many DSLRs. That changes a few things. The size of
the viewfinder image, the relationships among lens focal length, depth
of field, angle of view, etc.
Different sizes of media format usually bring a difference in
experience other than numbers of pixels and information quality.
Whether these differences are important to you, or worth the
difference in price become personal decisions.
gs
George Sinos
--------------------
[email protected]
www.georgesphotos.net
plus.georgesinos.com
On Fri, Dec 14, 2012 at 8:38 AM, William Robb
<[email protected]> wrote:
On 13/12/2012 11:25 PM, Tom C wrote:
From: William Robb <[email protected]>
On 13/12/2012 11:57 AM, J.C. O'Connell wrote:
And presto, you have a $10K obsolete piece o crap original 645D.
How is it obsolete? I don't think they stop working when another camera
comes out, and when the 645D was introduced, it was rather a game
changer.
I have spent some time with the 645D. It will take more than a 36mp
small format camera to make the 645D obsolete.
But, one would have to use both to know this.
I have.
Have you?
Not intending to butt heads with you Bill. It's obviously not
obsolete, but it loses a degree of relevance. If one can arguably get
a camera that's quite close in resolution and other performance
factors, with a huge lens catalog to choose from. for about 1/3 the
price...
I looked yesterday and cannot remember the figures, but the DxO
scores were fairly close between the aforementioned bodies (one troll
to another).
Tom C,
I guess viewfinders don't matter any more. The 645 is a joy to look through,
the D800 has, by comparison, a dinky little viewfinder with dancing lights
flashing seemingly at random. I realize this is a small thing that probably
won't matter to many people, but the 645 is a much nicer camera to work
with.
That used to mean something. It seems these days, all that matters is the
number of megapixels.
--
William Robb
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Don't lose heart, they might want to cut it out, and they'll want to avoid a
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