Medium format versus digital sharpness

Scott W wrote

Hmmm, 112MP from 6x7, that is pretty impressive and far past anything I
have seen, you go a scan that shows that?

Yes.

Quite impressive, or disturbing rather, is that you find that impressive.
Why is that?

"Q.G. de Bakker" wrote:
Scott W wrote

Hmmm, 112MP from 6x7, that is pretty impressive and far past anything I
have seen, you go a scan that shows that?

Yes.

Quite impressive, or disturbing rather, is that you find that impressive.
Why is that?

Maybe he's seen how poor film looks when enlarged 14x, and knows how many
dSLR pixels are required to produce that quality of image?

Example: Print 35mm at 13x19 by your favorite method*. You then pretend that
you had scanned so as to print at 300 ppi. Therefore 35mm is 24MP. But an
8MP dSLR produces similar, and a 10MP dSLR produces better looking 13x19s.
So is 35mm 24MP or 8MP?

You say 24, Scott and I say 8.

That's the difference. (People shooting 39MP MF digital report they get
images far better than anything they had ever seen from any MF system.)

David J. Littleboy
Tokyo, Japan

David J. Littleboy wrote:

Quite impressive, or disturbing rather, is that you find that impressive.
Why is that?

Maybe he's seen how poor film looks when enlarged 14x, and knows how many
dSLR pixels are required to produce that quality of image?

Maybe not.
Probably because the hype says direct digital capture is so much better, and
he, like so many, believes that marketing crap?

Example: Print 35mm at 13x19 by your favorite method*. You then pretend
that you had scanned so as to print at 300 ppi. Therefore 35mm is 24MP.
But an 8MP dSLR produces similar, and a 10MP dSLR produces better looking
13x19s. So is 35mm 24MP or 8MP?

You say 24, Scott and I say 8.

You would.
You are also discussing methods of throwing away MF quality. Then rejoice in
the fact that you can reduce MF quality to something your 8 MP digithingy
can also produce.

That's the difference.

Indeed! ;-)

(People shooting 39MP MF digital report they get images far better than
anything they had ever seen from any MF system.)

And you too believe that? I don't.

Direct digital capture images look cleaner (no grain). But that's it.
If that's the only thing you would judge, then yes. Otherwise: they wish!

"Scott W" wrote:

I would put 6x7 MP much closer to 25-30MP of real useful detail

Yep. But QG's not concerned with "real useful detail" or how good prints
actually look. The emperor is completely buck naked, but he hasn't noticed
yet.

David J. Littleboy
Tokyo, Japan

On Fri, 5 Oct 2007 13:21:14 -0500, "Ken Hart" wrote:

A source that I trust (but no longer remember who!) claims that 36Mpixels
equals average consumer 35mm film. A 35mm negative is 24x36mm, so if my math
is right (!), a 6x7 neg would be equal to 175Mpixels.

That's 102 line pairs per millimetre, which is at least double what
I'd expect for average consumer film because the ability to retain
contrast down to the level of individual grains is poor. Some modern
films can manage that resolution but I'd be surprised if a consumer
film could offer significantly more than 10MP of useful detail in
35mm, especially if coupled with a consumer zoom.

If you assume around 60 line pairs per mm, 6 x 7 comes out as about
54MP. But given the dispersion of answers offered and the fact that
resolution of film rolls off gradually depending on the contrast of
the subject, the best reply to the original question is that there is
no right answer because the question itself isn't sufficiently well
defined. Film and digital work in fundamentally different ways, and
there is no One True Conversion Factor.

--
Matthew Winn
[If replying by mail remove the "r" from "urk"]

Scott W wrote:
I have to wonder if you have ever seen one, if not here
is your chance to see just how much real detail a 112MP image can have.

http://www.sewcon.com/largephotos/112_mp_Image.jpg (about 20 MBytes in
size)

Amazing... where can I get that gear? I'll sell my house...

Scott W wrote:

If you re-read what David wrote you will see that he said to make the
print with you favorite method, no throwing away quality there,

'Yes'...
Print sizes have nothing to do with how good a MF scan is compared to a
direct digitalo capture file.
Comparing both using a fixed, small print size is an even worse thing to do.
You don't see that (it's simple though), so i'll explain:

You can produce perfectly good passport photo format prints using a 2MP
camera.
You can do that too using an 8x10" film camera.
You can then calculate that you would need to scan that 8x10" using a
certain resolution to get a good result print of that size.
You can then also mention that the print you make from the 2 MP camera looks
equally good (an assertion - why not calculate that too?) at that size.
And hey presto: there it is: 2 MP is just as good as 8x10".

[...]
In the end if you can't produce a good looking print, then what is the
point?

Do you now see the point?

I'll tell you again, just to be su when you want to compare scanned MF to
direct digital capture, this is the silliest way of trying to do so.
I'll explain why again too: you are not comparing scanned MF to direct
digital capture at all. Just playing foolish games.

Scott W wrote:

Quite impressive, or disturbing rather, is that you find that impressive.
Why is that?



Because an 112MP image that is not all soft and full of noise if pretty
dam impressive.

But was that (you being impressed) the subject? If you read again, you'll
find it's not.

I have to wonder if you have ever seen one, [...]

:-)

Now i'm sure - as if i wasn't when you said that an 11 MP image is "dam
impressive" - that you have never seen what a really good image file looks
like.
Scott, you asked me before if i had (seen) an 112 (!) MP file. I told you i
have.

David J. Littleboy wrote:

I would put 6x7 MP much closer to 25-30MP of real useful detail

Yep. But QG's not concerned with "real useful detail" or how good prints
actually look. The emperor is completely buck naked, but he hasn't noticed
yet.

That's true, David.
You're completely wrong though about who the emperor is... ;-)

There is loads more usefull detail in scanned MF than there is in the
(relatively) small direct capture files.
Pitty that people rather believe their convenient consumeristic instant
gratification bull ****, rather than open their eyes and see for themselves.
Ah wel... I guess there is no way of stopping this nonsense being repeated
and repeated, and repeated again, until even the last sucker believes it
would be gospel truth.

"Q.G. de Bakker" wrote:

There is loads more usefull detail in scanned MF than there is in the
(relatively) small direct capture files.

Sure. There's between 1.5 and 2 times as much useful detail in a high-res
scan of a 6x7 frame as there is in a 12.7MP 5D image. Mamiya 7, TMX100, 65mm
lens vs. 5D with Tamron zoom. The 6x7 scan handles the high contrast detail
in archtecture and signs noticeably better than the 5D. But when the
contrast is lower, there's no advantage. And the slide films people actually
use aren't as good as TMX100.

The idea that a single frame of 6x7 film has almost ten times (112/12.7) as
much information as a single 5D frame is completely ridiculous: you are off
by a factor of four.

Everyone who has tried to do the comparison with any amount of seriousness
comes to basically the same conclusion (i.e. 35mm = 6 to 8MP, 645 = 12 to 16
MP, 6x7 = 24MP). Except QG.

David J. Littleboy
Tokyo, Japan