Pixel Density?????

Started Sep 4, 2008 | Discussions
mike397x Regular Member • Posts: 315
Pixel Density?????

In a nutshell,can anyone briefly tell me how much does Pixel density play in the relation to image quality.I'm currently using a 40D,but,also have an old 300D as a back up.
The density of the 40D is 3.1mp,the 300D is 1.8mp.
Am I correct in assuming that the lower the number,the better the image quality?
Also,I use 2 L lenses ..the 17-40L,and the 70-200L.
I rarely make enlargements bigger than 16X20.

I've gone through some of the threads concerning pixel density,and found myself more confused than ever.
I'm planning to geta FF 5D,and this camera has a pixel density of 1.5mp.
Should this be an issue for me to consider?
If anyone can straighten me out on this ,I'd appreciate it..
Thanks,
Mike
--
Mike397x
http://mike397x.zenfolio.com/

EricDP Regular Member • Posts: 456
Re: Pixel Density?????

There are so many factors that one can't just say "lower density equals better IQ". The 300D is a much older sensor. The micro-lenses provide much less coverage of the pixel, it has less DR, and it has noisier A/D circuitry. You can probably safely say that sensors of the same generation with the same internal technology but lower pixel density will have lower noise and perhaps higher DR, but they'll also less detail than a higher density sensor. You can't compare sensors of different generations or different manufacturers based on anything other than actual tests.

About the 5D, at least wait until the end of the month. Photokina (perhaps the largest photo show in the world?) is this month, and there will be a lot of new cameras introduced. Most think a new model to replace the 5D will be one of the things we see.

Ben_Egbert Forum Pro • Posts: 20,228
Re: Pixel Density?????

Not sure where you got your pixel density values, but pixel density is merely a count of pixels per unit area. Whether this is good or bad depends on other things. The higher the pixel count for any given sensor size, the higher the pixel density. High density equal small pixels, low density equals large pixels.

Some people like large pixels. They claim that small pixels have more noise and cause diffraction. Unless you have degree in optical physics, I suggest that you take such arguments with a grain of salt. Let the results speak for themselves.

For large size prints, you need lots of pixels. A crop sensor with high pixel density, or a FF with less. But even the 21mpix 1DS-mk3 which has moderatly high pixel density (about like a 30D) does not have enough pixels to print 16x24 at 360PPI. It will get you 240 PPI which is the best you can currently get with a DSLR.

Where pixel density pays off is for shooting with telephoto lenses, especially action with uncontrolled targets like birds . It has always been pixel density not crop factor that provided the telephoto advantage. What this means is that after you crop your image, you have more pixels left. Telephoto shots seldom fill the frame, so crops are usually required.

For images where you have control of the subject and placement of your camera, you won't normally be cropping and will be able to use all the pixels. But as I showed in the 1DS-mk3 example, we stil don't have enough pixels for large prints without faking them with uprez.

Take the large pixel argument to its logical conclusion and you end up with a one pixel camera.

Higher pixel density is always good if it does not produce more noise than you want, and does not reduce dynamic range. I tend to think it has no effect on diffraction, but then I am not qualified to answer that question.

-- hide signature --
 Ben_Egbert's gear list:Ben_Egbert's gear list
Canon EOS 5D Mark III Canon TS-E 17mm f/4L Canon EF 70-200mm f/2.8L IS USM Samyang 14mm F2.8 ED AS IF UMC Canon EF 16-35mm F2.8L II USM +1 more
gdanmitchell
gdanmitchell Veteran Member • Posts: 7,734
Re: Pixel Density?????

Ben_Egbert wrote:

Some people like large pixels. They claim that small pixels have more
noise and cause diffraction.

That is a photographic "urban myth" that I continually find astonishing.

Smaller pixels very definitely do not "cause diffraction" nor to they lower IQ due to diffraction blur, as some would have it.

With a given sensor size, and a given lens, focal length, and aperture there is NO DIFFERENCE in the "amount" of diffraction captured by the sensor/film of different cameras. With a given sensor/film size, diffraction is a function of aperture and focal lenght. Period.

The same diffraction-containing image falls on a 12 MP FF sensor and a 24 MP FF sensor. The same "amount" of diffraction is recorded by both. (Those who understand this stuff a bit will point out that the sensor with higher photosite density can form a more accurate image of the diffraction, but that does not increase the amount of diffraction.) A print of a given size will show no more or less diffraction in either case.

In situations where diffraction blur is less the limiting factor (e.g. as you open up a very high quality lens) it is possible that the performance from the sensor with more photosites (again, with the same sensor dimensions) may include the ability to capture a bit more detail.

Dan

-- hide signature --
Ben_Egbert Forum Pro • Posts: 20,228
Re: Pixel Density?????

Hmm, something we agree on? I have read your arguments on this, and my experience tends to conifrm it.

gdanmitchell wrote:

Ben_Egbert wrote:

Some people like large pixels. They claim that small pixels have more
noise and cause diffraction.

That is a photographic "urban myth" that I continually find astonishing.

Smaller pixels very definitely do not "cause diffraction" nor to they
lower IQ due to diffraction blur, as some would have it.

With a given sensor size, and a given lens, focal length, and
aperture there is NO DIFFERENCE in the "amount" of diffraction
captured by the sensor/film of different cameras. With a given
sensor/film size, diffraction is a function of aperture and focal
lenght. Period.

The same diffraction-containing image falls on a 12 MP FF sensor and
a 24 MP FF sensor. The same "amount" of diffraction is recorded by
both. (Those who understand this stuff a bit will point out that the
sensor with higher photosite density can form a more accurate image
of the diffraction, but that does not increase the amount of
diffraction.) A print of a given size will show no more or less
diffraction in either case.

In situations where diffraction blur is less the limiting factor
(e.g. as you open up a very high quality lens) it is possible that
the performance from the sensor with more photosites (again, with the
same sensor dimensions) may include the ability to capture a bit more
detail.

Dan

-- hide signature --
 Ben_Egbert's gear list:Ben_Egbert's gear list
Canon EOS 5D Mark III Canon TS-E 17mm f/4L Canon EF 70-200mm f/2.8L IS USM Samyang 14mm F2.8 ED AS IF UMC Canon EF 16-35mm F2.8L II USM +1 more
beltzclan Senior Member • Posts: 1,511
Best description yet
-- hide signature --

That was perfect!

nokem
nokem Contributing Member • Posts: 729
Pixel Density and AA filter

Comparing two sensors with different pixel density, but same size, I would think that the higher pixel density (on the same size sensor) would lessen the impact of the AA filter if you downsample to the lower density.

-- hide signature --

Shoot.

 nokem's gear list:nokem's gear list
Canon EOS 6D Canon EOS Rebel SL1 Canon EOS-1D X Canon EF 14mm f/2.8L II USM Canon EF 16-35mm F2.8L II USM +30 more
jonlee1 Contributing Member • Posts: 589
Re: Pixel Density?????

Depends on the sensor.

At the FF level, fewer pixels usually requires larger pixel size to provide coverage, meaning it captures more light and thus usually provides slightly better low light performance.

Higher pixel count means more detail in the shots. With today's technology, that does not necessarily mean noise.

If you are buying FF, the 5D is a great value. Sure, it will lose some of its value if Canon produces a replacement, but I dount it will drop that much considering what a new model will cost.

Joel Muniz Regular Member • Posts: 153
Re: Pixel Density?????

Nikon D700 has 1.4 MP/cm² Pixel Density and the camera costs $2799.00
Canon 5D has 1.5 MP/cm² Pixel Density and the camera costs $1899.00

Both full Frame.... lower is better. do a feature search on this site and you will see a trend on high performers have lower pixel density.

jonrobertp Forum Pro • Posts: 12,880
Thanks Dan. Example of no diffraction prob. is Romy's fantastic moon

shots from a 40D, w 400 lens and 2 stacked tc's for 1200 mm lens at f18. The image looks like Nasa made it. Way to much bs on these columns. Like someone said, "money talks (or in this case, the image) --bs walks".
--

Every new day is a gift--use it wisely.
http://www.jonrp.smugmug.com

 jonrobertp's gear list:jonrobertp's gear list
Canon PowerShot G7 X Canon G3 X Panasonic ZS100
olderbob Senior Member • Posts: 1,051
5D for $1900.? where?

I assume thats new..Bob

gdanmitchell
gdanmitchell Veteran Member • Posts: 7,734
Re: Pixel Density?????

Ben_Egbert wrote:

Hmm, something we agree on? I have read your arguments on this, and
my experience tends to conifrm it.

Dan

-- hide signature --
Joel Muniz Regular Member • Posts: 153
Re: 5D for $1900.? where?

dpreview.com under Canon EOS 5D digital camera specifications

Vladimir Ilyich Ulyanov Regular Member • Posts: 125
Higher is better.

In a nutshell,can anyone briefly tell me how much does Pixel density
play in the relation to image quality.

The more pixels you have, the better your image will look. The reason some feel otherwise is that they are examining at the pixel level, rather than the image level.

Now, that is not to say that a higher pixel density on a smaller sensor is better than a lower pixel density on a larger sensor (that gets tricky), but for a given sensor size, the more pixels you have on it, the better off you are in terms of IQ.

To that end, the important considerations in IQ are: sensor size, pixel count, and quality of available lenses. The stipulation of the lenses is important, because if the lenses are not up to the task, then more pixels will not help if the lens cannot resolve the pixels. However, even in that case, more pixels will not hurt, either, so you have nothing to lose by going with more pixels.

Keyboard shortcuts:
FForum MMy threads