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[OM] Questions, Re: When is enough enough? ...

Subject: [OM] Questions, Re: When is enough enough? ...
From: Der Eiserne Reiter <ferider@xxxxxxxxx>
Date: Mon, 18 Oct 2004 08:03:34 -0700 (PDT)
Hi AG,

interesting.

Do you know where I could get a copy of the chart that you are using ? I wanted 
to do some
resolution testing myself. Maybe a scanned tiff file that I can print out ? How 
does the
experiment look, i.e. distance from the lens, etc. ?

I have always wondered how the typical lines/mm numbers translate into MPixels.
A good lens has a resolution of anywhere between 30 and 100 lines/mm.
If you translate this to Mpixels, on 35mm Film this gives roughly anywhere 
between
800 kPixels and 8 MPixels.When people compare film to digital they mostly 
compare film
grain to chip resolution.I never understood this as the above numbers show that 
the lens
should be the limiting factor on a digital camera with more than 5 MPixels
(> 100 lns/mm is rare, and easily impacted by attached filters, dust on the 
lens, etc).
I always thought I missed something as I have seen good larger prints of photos 
taken
with lenses with a resolution of less than 50 lines/mm. Forgive me if I just 
misunderstand
the experiment setup used to collect the above resolution information.

I have found charts for various lenses (Russian and Leitz lenses, for instance) 
including
lines/mm. I was always looking for such charts for Zuiko lenses (including PEN 
lenses). Does
anybody on the list know if such information is available ?

Thanks

Roland.


--- AG Schnozz <agschnozz@xxxxxxxxx> wrote:

> I'm doing some additional resolution testing lately. 
> Interesting results.  The more I try, the harder it is to beat
> the old glass.  However, I am highly pleased at how well the
> digicam holds up.
> 
> Using an old fashioned line-pair resolution chart (you know, the
> ones with three vertical and three horizontal bars arranged in
> an ever decreasing size and circling in on itself), I've found
> that when comparing same-size images, the Zuikos outperform the
> digicam by over eight steps.
> 
> Ok, sure, I'm comparing to a 5MP Minolta A1, which isn't known
> for having a perfectly sharp lens. However, when drilling down
> to pixel level, five of those steps are beyond the resolving
> capability of the sensor!  I ran out of pixels.
> 
> So, what does this mean?  A 5mp sensor is beat by film by a fair
> margin.  It also means that several of my ancient Zuikos should
> be sharp enough for mating to a digital body.  I'm sure there is
> a point where they'll puke out, but overall, they do quite well.
> 
> Ok, for the sake of full-disclosure, the Zuiko lens tests were
> performed using Delta 100 B&W film, processed DD-X (which is a
> slightly soft developer) with the test prints blown up to the
> equivelent of 24x36".  Hopefully, later tonight I'll post some
> of these tests on my website.  If not tonight, sometime during
> the week.
> 
> www.image66media.com
> 
> The biggest suprise was how well the A1 actually did. The trick,
> though, is to shoot RAW. I lost an entire step, and sometimes
> more, when shooting JPEG.
> 
> Oh, when scanned, most, if not all, of that resolution gain with
> the film is gone.  As long as I stay optical the increased
> resolution is gained. The moment I digitize, the playing field
> is leveled.  I wonder what a 5400dpi scanner must be like...
> 
> This addresses one of those things that has always caused me to
> scratch my head about resolution differences between film and
> digital.  We're almost always comparing digitized to digital. In
> this particular test, I tested full-analog to full digital.
> 
> How does this parlay into real-life?  I'm getting about a 1/2 mm
> blur in 24x36" B&W enlargements.  Imagine what it could be if I
> used an unsharp mask!
> 
> Course, that's when you use mirror pre-fire, cable-release, yada
> yada yada.
> 
> But, through it all, it also means that a quality 8MP sensor
> will equal the Zuikos maximum resolution.  But the film itself
> (Delta 100 or PanF+) is still another order of magnitude beyond
> anything the lens is capable of doing. I've maximized ISO 400
> films and even ISO 100 slides films, but I've never outdone
> Delta 100, PanF+, Kodachrome 25 or Velvia 50.
> 
> Ag
> AG
> 
> 
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=====
FeRider (R.)


                
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