Poll: Megapixels vs. camera sensitivity
LAS VEGAS--The camera companies keep telling me the megapixel race isn't over, but I'd like to see if you have a different opinion.
I'm one of those people who doesn't believe more megapixels necessarily makes for a better digital camera. Sure, at least theoretically having more megapixels permits larger prints and tighter cropping, but it also can impose penalties such as image noise, lousy low-light performance, smeary noise-reduction artifacts, and other drawbacks. There's a trade-off here.
News.com Poll
So it's time to vote now for what you'd benefit from more in a camera: more megapixels or higher sensitivity. Click the button to register your opinion and explain yourself below in the TalkBack section if you want to make your case in more detail.
Camera makers seem unable to resist the temptation of higher megapixels in compact cameras right now, marching on past 10 megapixels to 12. But in the SLR domain, where buyers are more sophisticated and larger image sensors provide more leeway, there are some interesting trade-offs going on.
Most interesting to me right now is Canon's approach. Its entry-level EOS Rebel XSi is a 12-megapixel model, but one step up the ladder is the 10-megapixel 40D. The Rebel's XSi top sensitivity is ISO 1,600, but the 40D offers 3,200.
Canon and Nikon provide another contrast with their top-end models. Canon's $8,000 1Ds Mark III offers 21 megapixels, while Nikon's $5,000 D3 has 12 megapixels. The 1Ds Mark III reaches ISO 6,400, but the D3 can go to 25,600 in a pinch. (Although these are top-end models, Canon's $4,500 1D Mark III, with 10.7 megapixels and maximum ISO of 6,400 but a smaller image sensor than the D3, is probably a more direct comparison with the D3.)
Now that we're beyond the 2-megapixel era, I'd prefer better sensitivity over a couple extra megapixels. I find myself much more constrained by dim conditions or fast-moving subjects such as children and wildlife than by insufficient pixel quantity. I've blown up my 8-megapixel camera's images to 20x30-inch prints without trouble.
Take a pixel peep at the cropped photo I took with the Nikon D3 of a BMW racing by on a Las Vegas track at about 80 miles per hour. The picture won't be gracing the pages of Sports Illustrated, but using ISO 6,400 let me freeze the action with a 1/8000 shutter speed, and the full image looks fine.
I recognize it's not a simple case that sensitivity is better than megapixels, and clearly some people may have different priorities. If you're in controlled studio conditions and shooting stock photos, a market that sometimes pays by the pixel, more pixels is probably helpful. And lacking a mammoth telephoto lens, I do sometimes wish I had more pixels left over after I crop heavily to better show a bird.
This is a 100 percent crop of a photo I shot with a 12-megapixel Nikon D3 at a shutter speed of 1/8000 sec., f/7.1, at ISO 6,400, with Nikon's new 24-70mm lens. Sure, there's lots of noise and the colors aren't as vivid as they could be, but ISO 6,400 will let you freeze the action of a BMW racing past at about 80 miles per hour (which means the top edge of the wheel is going about 160mph). This crop is from the in-camera JPEG.
(Credit: Stephen Shankland/CNET Networks)Optical resolution is another issue. Lower-end and sometimes even expensive lenses can lack sufficient sharpness to really take advantage of all the pixels on the sensor.
Gratuitous megapixels have other drawbacks besides noise. Image processors that convert sensor data into a JPEG have to do more work--especially with the double whammy that they often must use more sophisticated but power-hungry noise-reduction work.
Perhaps most obviously, more megapixels means memory cards and hard drives fill up faster. Sure, storage is cheap, but what if what you're storing is bulkier but no better?
There are signs that the industry is moving beyond its megapixels-uber-alles worldview. When Panasonic unveiled a number of compact cameras at a press conference Tuesday at the Photo Marketing Association trade show here, the company took pains to emphasize all the attributes besides megapixels it hopes to use to sell cameras.
You know where I stand on the issue. Let's hear your voice.
Update 8:30 a.m. PST: Here's my response to the issue of sensor size raised in some TalkBack comments.
Increasing the sensor size while holding megapixels constant can let manufacturers improve sensitivity, too. However, that's another trade-off because larger sensors cost a lot more to manufacture. I chose the 12 megapixel/ISO 1,600 vs. 10 megapixel/ISO 3,200 comparison because it's a real reflection of choices Canon had in its Rebel XSi vs. 40D.
It's not practical for Canon to fix the sensitivity problem simply by dumping smaller APS-C sensors and moving to full-frame. The cheapest full-frame camera today, Canon's 5D, costs at least $2,100 with no lens, which is hardly competitive in the entry-level SLR market.
It's easier to vary sensor size in compact cameras where the built-in lens can be matched to the sensor. (Indeed, Canon increased the sensor size slightly from the PowerShot G7 generation to the G9.) But the same cost trade-off applies there too, and compact camera buyers are even more price-sensitive.
Stephen Shankland writes about a wide range of technology and products, but has a particular focus on browsers and digital photography. He joined CNET News in 1998 and since then also has covered Google, Yahoo, servers, supercomputing, Linux and open-source software, and science. E-mail Stephen, or follow him on Twitter at http://www.twitter.com/stshank. 
and shoot digital camera. I have a Canon Rebel XT, and an older
Olympus 4MP digital, but I wanted something to pop in my
pocket on trips.
Anyway... the camera we selected was a Canon. It's 10MPs and a
nice little camera. However, I've now found that the camera is
horrible at low light shots. Very grainy, blurry (at times) and poor
sensitivity. My older Olympus camera does a way better job with
the flash off (I don't like the flash most of the time because it
flattens the image).
In hindsight, I'd go back to the drawing board and find one with
better low light capabilities. I miss the sensitivity of the Olympus
and for my artistic shots I'll still use it or the Rebel depending
on the situation.
Your two elememts in an oversimplified equation don't make the whole story of picture quality.
Also, tires usually don't get mpg;-) (See your photo caption)
You can get better pixel size and therefore sensitivity if you go to a full-frame sensor, but that's *way* more expensive to manufacture. That's an entirely different tradeoff, and I was trying to compare apples to apples. In the compact camera area, manufacturers have more choice (Canon increased the sensor size on the G9 slightly from the PowerShot G7 to the G9), but there, too there's a big price penalty to using a larger sensor.
And thanks for the mpg/mph catch!
Before I went to digital, I did a lot of reading etc..., and my
general feeling is that is big fatter pixels are better. The more
they cram into a small area just increase noise and other issues.
No consumer really needs more than 6 anyway. IMHO
MP are a good marketing tool for the mass population that really
don't understand photography, printing and just use the auto
and scene setting on the cameras any way.
However, make the break to backside illuminated CMOS and you can get a jump of a factor of 4 or more in sensitivity at the same pixel density. Thus a 16 Mpixel backside illuminated CMOS camera can have the same sensitivity as a 4 Mpixel frontside illuminated CCD camera.
If it is an interline transfer CCD to which we are comparing as a baseline the difference in sensitivity can be a factor of eight or more.
This article should mention that users, especially the cutting edge users, should push the camera vendors to the newer, better technology.
Just goes to show how much marketing affects camera buying decisions - never mind actual, real-world performance (not talking about closeups of test charts, either). I'm so glad you mentioned getting great 20x30 prints out of your 8mp camera, because that's not what the kid at Best Buy will tell you.
That ISO 6400 crop of the D3 is simply astounding, by the way. Looks like an ISO 1600 crop from my Digital Rebel.
photography needs and can have decent sensitivity up to 6400
ISO. As the author noted, the the Nikon D3 with it's 35mm size
sensor and 12 mp has even greater sensitivity. What's lacking in
these discussions is the characteristic that hasn't carried over
from film, wide dynamic range. Other than Fujifilm no
manufacturer has addressed this issue and
social/wedding/portrait photographers like me it's critical. It's
the difference between shooting a wedding with high contrast
consumer Fuji Superia and using a low contrast film like NPS. In
the former the bride's dress is blown out white with no detail
and the groom's back tux is just one shade of black. In the
latter the full tonal range is available. I want/need this choice in
my digital cameras, too. And....I don't want to constantly screw
around with each image in RAW.
Another aspect that's mostly ignored is the required image processing off the sensor. I'd like to see more direct RGB sensors (like the Foveon used in the Sigma SD14). Several patents have been filed so hopefully the big boys in SLRs will be following suit with such cameras soon. I'd take direct RGB per pixel sensors over one capable of super wide lighting conditions. Image quality first!
little or no noise, just remarkable.
Canon 1D Mark III, all before the infamous focus issues
Do you know how many people across the world have shot poor quality pictures because of dim lighting?
The number of people who shoot poor quality just because of lower MP count is very very low.
Many compact cameras claim they can do ISO 1600, but there is no compact camera out there that does even ISO 400 acceptably (apart from Fuji's now discontinued F31fd). Similarly, even DSLRs made by Sony, Olympus and Panasonic advertise ISO 1600 but don't deliver the goods.
Sometimes manufacturers try to cover up a sub-par sensor with heavy-handed noise reduction that gives the impression of low noise, but by wiping out all fine detail, effectively decreasing resolution.
High ISO ratings would only be meaningful if the manufacturer would quote the signal to noise ratio at the max ISO, but there is no accepted standard for measuring it, and don't expect sleazy camera marketers to stop playing deceptive games anytime soon.
Also, the comparison between the XSi's 1600 and the 40D's 3200 is also a little misleading. If there is any sensitivity difference between these cameras (which I assume there is, I have not read enough about the XSi yet,) it is not a full stop. I'd guess closer to 1/3 stop. The 40D has a higher iso setting mostly because it is a higher-end camera and Canon needs differentiators to get people to spend double the money on it.
Just consider how horribly grainy a real ISO 6400 silver halide film would be.
Some of the cameras also apply some pretty heavy-handed and potentially funky looking NR to achieve high ISO without appearing noisy. I'm not sure this is a satisfying tradeoff, either.
My XTi goes up to 1600 and I never use it there. The images are a mess. In fact, 800 is pretty awful, too.
If I had my druthers, cameras would advertise the size of their active collection sites along with MPix, or better yet, real SnR values. Not gonna happen, though.
-- dave j
- Men usually lack the sensitivity, but lately I'm hating all cameras!
- by irperez January 31, 2008 8:55 AM PST
- Its about time that sensitivity is being brought up!!! I can't take pictures inside or in my church. Its too dark. My camera just doesn't cut it. I'm a perfectionist and I hate it when my pictures come out blurry or dark with tons of noise. The camera industry has to get off this megapixel high and start creating cameras that offer better quality pics even in dark situations. I want to buy an SLR but with the steep prices for the quality I just can't do it. SO I'm waiting until the industry changes their attitude and makes better quality cameras.
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