6 or 8 MPIX?

On Fri, 04 Mar 2005 01:16:00 -0500, Stacey wrote:

But if the optics can deal with it, 10-15% isn't anything to sneeze at.

The O.P. wants to make drugstore prints and an occasional 8x10.
I'm not saying he shouldn't get an 8MP camera, I'm just saying
that the 6MP DSLRs are up to the task.

This isn't some kind of anti-8MP bias. I'm trying to unload a used
Olympus C-8080, so if I were going to be dishonest, I'd say everyone
needs an 8MP camera. :-) But look, from 6 megapixels you can print
8"x10" at a very respectable 270 dpi. For 4x6s or 5x7s 6MP is
higher resolution than the print.

--
Ben Rosengart (212) 741-4400 x215
Sometimes it only makes sense to focus our attention on those
questions that are equal parts trivial and intriguing.
--Josh Micah Marshall

Stacey wrote:
[]
Didn't say that but maybe you can explain why it would be only a 10%
increase is resolution? Seriously I'm not being a smart ass, just
wondering why it wouldn't be closer to the same as the increase in
pixel count, especially at low ISO's.

But if the optics can deal with it, 10-15% isn't anything to sneeze
at.

6Mp or 8Mp is a count within the sensor area, so the linear density in
each axis only goes up by the square root in the area density, 15.4% in
this case.

From what I've read, however, the better signal-to-noise ratio in a
digital SLR makes their 6Mp pixels look better than the pixels from an 8Mp
point-and-shoot, so that to the eye the extra resolution may (or may not)
be outweighed by the worse signal-to-noise.

It's one of those subjective comparisons, and why some people may prefer
film, which also has a higher resolution and higher noise (grain), to
digital.

Cheers,
David

David J Taylor wrote:

Stacey wrote:
[]
Didn't say that but maybe you can explain why it would be only a 10%
increase is resolution? Seriously I'm not being a smart ass, just
wondering why it wouldn't be closer to the same as the increase in
pixel count, especially at low ISO's.

But if the optics can deal with it, 10-15% isn't anything to sneeze
at.

6Mp or 8Mp is a count within the sensor area, so the linear density in
each axis only goes up by the square root in the area density,

So this "15%" is based on about linear improvement? I thought someone was
saying that the 2D image quality would only improve by 1/2 the increase in
pixels, that didn't make sense. I can see what you mean that the linear
increase (Lpmm) wouldn't increase 33%.


From what I've read, however, the better signal-to-noise ratio in a
digital SLR makes their 6Mp pixels look better than the pixels from an 8Mp
point-and-shoot,

I'm sure that's true. I'm not sure on the larger APS size sensors that the
noise increase would be too much.
--

Stacey

Stacey wrote:
[]
6Mp or 8Mp is a count within the sensor area, so the linear density
in each axis only goes up by the square root in the area density,

So this "15%" is based on about linear improvement? I thought someone
was saying that the 2D image quality would only improve by 1/2 the
increase in pixels, that didn't make sense. I can see what you mean
that the linear increase (Lpmm) wouldn't increase 33%.


From what I've read, however, the better signal-to-noise ratio in a
digital SLR makes their 6Mp pixels look better than the pixels from
an 8Mp point-and-shoot,

I'm sure that's true. I'm not sure on the larger APS size sensors
that the noise increase would be too much.

For a given sensor size, the trade-off in number of pixels isn't obvious.

- If you, say, quadruple the number of pixels, the area of each is
quatered, and the noise goes up proportionately. How does the eye react
to having more pixels but with each pixel being noiser?

- If you halve the pixel-to-pixel centre spacing (to double the number of
pixels in both X and Y dimensions), then there may be a certain fixed are
required per pixel for readout electronics etc., so the smaller pixels may
do worse than you expect, as the readout area is a greater fraction of the
pixel area.

- If you produce a new sensor with these smaller pixels, likely something
else in the process or design has improved, so you may recover some of
that loss due to smaller area!

The way things are measured right now, you end up needing a final subject
judgement about whether you prefer A or B.

Cheers,
David

In article , says...
No, it really won't.

33% more pixels does not equal a 33% increase in resolution. More like
10-12%. Not to say that 10-12% is insignificant, but it isn't so large
as to make one superior and the other useless.


Didn't say that but maybe you can explain why it would be only a 10%
increase is resolution? Seriously I'm not being a smart ass, just wondering
why it wouldn't be closer to the same as the increase in pixel count,
especially at low ISO's.

But if the optics can deal with it, 10-15% isn't anything to sneeze at.

You're equating a factor measurement with a linear one.

The number of pixels increases at a rate higher than the linear
dimensions of the file produced. Since resolution is a feature of
spatial frequency it relies on the number of rows and columns.

To make the example simple, let's imagine a square 3x3 sensor. It
produces 9 pixels (3 x 3) and can't resolve much. Now, compare that to
a 4x4 sensor, which has 16 pixels (an increase of 78%) but only one
additional row and column of pixels for a slight increase in resolution.

It gets a little more complicated when you're dealing with rectangular
sensors of differing aspect ratios, but the basic concept is the same.
In order to record more data over the entire plane, you have to record
more data at each row/column. That adds up fast while the total amount
of resolving power of the sensor is increased only slightly.

"Stacey" wrote in message
...
Ben Rosengart wrote:

On Thu, 03 Mar 2005 20:06:22 -0500, Chuck Deitz
wrote:

Is 8 Mpix really that much better than just 6?

No.



Let me guess, you own a 6MP camera? :-)

Yea your right, 33% again the amount of pixels isn't going to help the
resolution is it?

the number of pixels isn't the whole answer. I can take an 8 megapixel Canon
Pro 1 and the 6.3 megapixel image from a Digital Rebel (300D) will be
better. I hear it every day in the store, well that's 8 MP so it's better.
Sensor size and quality has to be considered.

get the 350D. You already have a lens for it and it will be an ecxellent
camera.

"10-12% is insignificant, but it isn't so large
as to make one superior and the other useless.


Didn't say that but maybe you can explain why it would be only a 10%
increase is resolution? Seriously I'm not being a smart ass,

yeah you area a smart ass...

Chuck Deitz wrote:

Hi,

I'm looking at something like a Minolta A1 or A2, or Panansonic Lumix FZ5.

I also see cameras like the Canons 300D, 20D, 350, Nikon D70, Pentax
*istDS and Minolta 7 on some websites.

Is 8 Mpix really that much better than just 6? I want to make prints up
to a sheet of paper on my inkjet, but mostly smaller, like from the
drugstore.

For "mostly smaller", 6 Mpix is more than enough; for 8x10 or 8.5 x 11,
Mpix is sufficient. If the dollar difference makes no difference to you
then simply go for the 8 Mpix.


Are Nikon and the others going to have 8 Mpix SLR cameras soon? (They
all seem to have 8 Mpix in the other cameras like the Minolta A2, the
Nikon 8400 and so on, so why not on the SLR's? (I know the sensors are
different but if Canon are doing it where's Nikon and the others?).

Canon have their own sensor design capability and are close to the
fabricator (if indeed they don't fabricate themselves). Nikon, Pentax
and Minolta get their sensor from Sony, so they're slaves to Sony's
desires and pace.

I have a film rebel, but I don't use it much.

Pity.


What lens should I get? I just need something to take on a vacation
with the familly and stuff like that. I'll probably use it at work too.
Some of them come with lenses so I'll probably just do that. One of
the Canon 300 kits has a 18-55 lens. Is this okay? Can I use my Rebel
lens instead? 28-80.

Sure. On a 300D it will crop out to seem like a 44-127mm.


I also have a Canon flash, but I don't know the model, it's about 5
years old. can I use it if I get a 300 or the new 350D.

I don't believe the older flashes work properly on the digital cameras,
although in manual mode it might... then you have to set the flash power
per an incident flash meter reading or via a chart.

Cheers,
Alan

--
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-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: there's no such thing as a FreeLunch.

One advantage of 8MP over 6MP is your cropability.... I know I'm always
taking a simpler, better image out of the taken one. By having a 20D I can
go deeper, and still print at 20cm x 30cm.

I agree that you don't even need 6MP for making 10x20's, and If I were
offered a choice between a quick 6MP and a slow 8MP I'd go for the quicker
working camera.... Fortunately it's not a decision if you go with the two
Canon 8MP right now... The write time is very quick on the 20D (and I assume
it will be on the 350XT as well).

As far as the 18-55 kit lens from Canon. My first copy was not great, but
I'm very happy with the replacement. I don't use it that much, but it does
take decent images... especially for the price I paid to have it.

Al...


"Chuck Deitz" wrote in message
...

Is 8 Mpix really that much better than just 6? I want to make prints up
to a sheet of paper on my inkjet, but mostly smaller, like from the
drugstore.