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Old May 18, 2007, 10:56 AM   #1
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I'm still using film, but have a big field botany project that will take me the next couple of hundred years, and it's time for a digital body, probably the K10D, if only to minimize scanning slides (Nikon slide scanner). I'll keep shooting slides on my Pentax KX.

Has anyone advice or a pointer to discussion of the available lenses for the K10D? I'll probably buy just the body and one lens -- tempted by their current rebate list.

I realize the lens is the real investment here, not the camera body. But it appears Pentax will soon add weather-resistant lenses, tho' there's nothing on the website yet but the heading for them and they're not on the rebate list.

So I figure now buy a pancake or small lens, if possible a macro, and wait for the weather-resistant lenses. What to get, since I've got my old manual lenses also?

I will keep the KX and some of the old lenses, Pentax's compatibility chart
doesn't go past the *ist model right now.

I think I can use most of the K-mount lenses picked up over the years. I'll keep using the KX while film's available, and sometimes want both cameras to have about "the same" effective lens, to take a digital and a film image of the same scene for longterm record purposes.

I realize the effective focal length on the digital is, what, half again the film number?
Does the f-stop also increase proportionately?

What would these numbers be, used on a K10D? I realize I lose at the macro/wide end, so am guessing I'll want a macro as the new lens if I buy the K10D

-- Pentax-M Macro f1.4 50mm
-- Pentax-F f1.4/5.6 35-80mm
-- Pentax-F f3.5/4.5 28-80mm macro
-- Sigma-XQ f3.2 18mm
-- Sigma 'Mini-Wide' f2.8/28mm
-- Miranda f3.5/4.8 35-70mm macro

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Old May 18, 2007, 11:23 AM   #2
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You could ask in the Pentax DSLR or Pentax lens forums (this will probably be moved to one):

The Pentax DSLR has a 1.5x effective focal length multiplier (or "crop factor"). This doesn't affect f-stop as far as light gathering ability (or exposure). But you can apply this also to the f-stop to get the equivalent for depth of field.

So 50 f1.4 would look about the same as 75mm f2.1 on full frame (assuming you also adjusted ISO or shutter speed to get the same exposure).

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Old May 18, 2007, 11:40 AM   #3
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Oops, yes, management please feel free to move this; I came back realizing there was a better place for it. Haven't bought the camera yet but I'm assuming Pentax and the questions belong in teh Pentax lens area. Sorry.
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