Medium format versus digital sharpness

"Robert Montgomery" <info-block.RemoveThis@stargate_tech.net> wrote:
> How many megapixels would a digital camera image file need to equal the
> sharpness of a six-by-seven centimeter or a four-by-five-inch
> transparency?

The short answer is that there are no affordable digital systems that
compete with 6x7 and 4x5.

Your mileage will vary, but my experience is that for practical purposes,
12.7MP (the Canon 5D) acts very much like 645. But 6x7 scanned on a Nikon
8000 is noticeably better than the 5D.

So the new 21MP Canon 1DsIII should give 6x7 a run for its money. (Although
the only Canon wide angle lens up to that is probably the new 14/2.8 II L.
And maybe the new 16-35/2.8 when stopped way down. Maybe.)

I'd guess the 39MP digital backs would be encroaching on 4x5 territory.

David J. Littleboy
Tokyo, Japan
 >> Stay informed about: Medium format versus digital sharpness 

"Robert Montgomery" <info-block RemoveThis @stargate_tech.net> wrote in message
news:NZgNi.145964$bO6.50583@edtnps89...
> How many megapixels would a digital camera image file need to equal the
> sharpness of a six-by-seven centimeter or a four-by-five-inch
> transparency?
>
> Robert

There are a Lot of variables involved: the lens used to make the original
image, the method used to make the print (lens or printer) and the type of
film you are using for comparison.

You could make the assumption that to record equivalent detail, the digital
imager would need to have the same number of pixels as the film has grains.
A high speed film has larger grains and fewer of them per area, a fine grain
film has smaller grains and more of them.

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.

But you asked for file size-- that brings in more variables if that is
really what you want. Some file types compress the image so that it fits in
a smaller size. For example, an outdoor picture may include an area of sky
of a certain solid color. The file storage won't store individual pixels,
but rather an indication that a certain area is to be a certain solid color.
A photograph of a white sand beach (very little detail) may make a smaller
size file than a close-up of an elderly face (wrinkles, hair, etc.).
 >> Stay informed about: Medium format versus digital sharpness 

Robert Montgomery wrote:

> How many megapixels would a digital camera image file need to equal the
> sharpness of a six-by-seven centimeter or a four-by-five-inch
> transparency?

6x7 cm: about 112 MP
4x5": about 352 MP

Please don't believe reports that suggest that 21 MP even comes close to 6x7
quality.
 >> Stay informed about: Medium format versus digital sharpness 

Q.G. de Bakker wrote:
> Robert Montgomery wrote:
>
>> How many megapixels would a digital camera image file need to equal the
>> sharpness of a six-by-seven centimeter or a four-by-five-inch
>> transparency?
>
> 6x7 cm: about 112 MP
> 4x5": about 352 MP
>
> Please don't believe reports that suggest that 21 MP even comes close to 6x7
> quality.

Doesn't it really come down to print size?

Dana
 >> Stay informed about: Medium format versus digital sharpness 

Recently, Dana Myers <dana.myers.RemoveThis@gmail.com> posted:

> Q.G. de Bakker wrote:
>> Robert Montgomery wrote:
>>
>>> How many megapixels would a digital camera image file need to equal
>>> the sharpness of a six-by-seven centimeter or a four-by-five-inch
>>> transparency?
>>
>> 6x7 cm: about 112 MP
>> 4x5": about 352 MP
>>
>> Please don't believe reports that suggest that 21 MP even comes
>> close to 6x7 quality.
>
> Doesn't it really come down to print size?
>
Some people think so, others (including me) don't think that's the whole
picture.

Compare a 4x5" contact print with a 4x5" enlargement from whatever source
you want, and see if they look the same. To me, they do not. The same can
be said for other format comparisons, and the larger the print, the more
obvious the differences.

Neil
 >> Stay informed about: Medium format versus digital sharpness 

Dana Myers wrote:

> Doesn't it really come down to print size?

Not at all.
If about print sizes at all, it is about (not comes down to) the maximum
print size you can get out of each.
 >> Stay informed about: Medium format versus digital sharpness 

Ken Hart wrote:

> "Robert Montgomery" <info-block DeleteThis @stargate_tech.net> wrote in message
> news:NZgNi.145964$bO6.50583@edtnps89...
>> How many megapixels would a digital camera image file [..]
>
> [...]
>
> But you asked for file size-- [...]

No, he didn't.
He asked about how many megapixels there would need to be in that file.

Why keep people confusing matters by bringing in megabytes?
The number of those does not tell us a single thing.
 >> Stay informed about: Medium format versus digital sharpness 

Q.G. de Bakker wrote:
> Robert Montgomery wrote:
>
>> How many megapixels would a digital camera image file need to equal the
>> sharpness of a six-by-seven centimeter or a four-by-five-inch
>> transparency?
>
> 6x7 cm: about 112 MP
> 4x5": about 352 MP
>
> Please don't believe reports that suggest that 21 MP even comes close to 6x7
> quality.
>
>

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

Scott
 >> Stay informed about: Medium format versus digital sharpness 

"Scott W" <biphoto.DeleteThis@hotmail.com> wrote in message
news:47080163$0$11056$4c368faf@roadrunner.com...
> Q.G. de Bakker wrote:
>> Robert Montgomery wrote:
>>
>>> How many megapixels would a digital camera image file need to equal the
>>> sharpness of a six-by-seven centimeter or a four-by-five-inch
>>> transparency?
>>
>> 6x7 cm: about 112 MP
>> 4x5": about 352 MP
>>
>> Please don't believe reports that suggest that 21 MP even comes close to
>> 6x7 quality.
>>
>>
>
> Hmmm, 112MP from 6x7, that is pretty impressive and far past anything I
> have seen, you go a scan that shows that?
>
> Scott

I'm not sure how Q.G. came up with the 112 MP figure but it's not
implausible.
You figure desktop film scanners such as those from Nikon and Minolta can do
4000 DPI.
Taking a 6x7CM transparancy and converting to inches 2 1/4x4000=9000

2 3/4x4000=11000

9000x11000=99MP
Now when you get into drum scan terrority the resolutions get much higher.
 >> Stay informed about: 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?
 >> Stay informed about: Medium format versus digital sharpness 

On Fri, 5 Oct 2007 13:21:14 -0500, "Ken Hart" <kwhart RemoveThis @aec.nu> 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"]
 >> Stay informed about: Medium format versus digital sharpness 

"Q.G. de Bakker" <qnu DeleteThis @tiscali.nl> 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
 >> Stay informed about: Medium format versus digital sharpness 

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...
 >> Stay informed about: Medium format versus digital sharpness