Chromogenic v. Digital

[tony_brookes5]

We were having a discussion over Christmeas about the relative detail that current digital cameras can achieve vis. a vis. chromgenic B&W. The best digital camera I have seen offers 2 million pixels per frame. How many equivalnet "dots" or "grains" does a chomogenic film have in the same area ? Can anyone help ? How does this compare with say FP5 ? The digital enthusiast said that electronic cameras were now approaching the same definition as normal film. I said I thought he was way out in his calculations - but maybe I'm wrong. What are the facts ?

[frank_alvaro]

I went to a seminar about 6 months ago that was directly aimed at the

professional market (ie. I was invited by a friend and went along as

a "hanger on". Anyway, your query was was one of the main features

in one of the presentations. I can't find my notes at present, but I

recall that they claimed a 35mm neg has about 18 to 25

million "grains"; a 6x6 neg, somewhere in the area of 128 to 170

million! As a rough rule of thumb, 1 pixel=1 grain. If I find my

notes, I'll post more precise figures. In any event, it seems that

megapixel cameras still have a bit of catching up to do. Whether the

human eye can distinguish.... well, that's another question for

another time...

[alan_gibson]

There are a number of possible measurements.

 

<p>

 

One is grain size. I wrote up an experiment on Delta 3200 in

photo.net, but I can't find the post, and don't seem to have kept a

copy.

 

<p>

 

Another is how much detail can be digitally scrapped from the

negative. A figure of 4000 dpi is often quoted, and this is 157 dots

per mm. For a 24x36mm negative, this is 21 million dots.

 

<p>

 

Another is how much detail is recorded by the lens/film combination.

This could be 50 lp/mm (line PAIRS per mm), or 100 dots per mm. For a

24x36mm neg, this is 8 million dots.

[terry_carraway]

One thing to watch with digital, is that many cameras count EACH

color site as a pixel, and it takes three color sites (Red, Green,

Blue) to display the picture element in full color.

 

<p>

 

So in digital pixels, you need to divide the number of pixels by 3 to

get the actual number of information "spots".

 

<p>

 

This is sort of like counting the number of grains in each of the

three color layers of a piece of color film, and reporting that

as "pixels."

[tony_brookes5]

Many thanks for all your answers. It seems that digital has along way

to go to get anywhere near silver film, and even further for

chromogenic film.