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Old Jun 7, 2007, 7:20 PM   #1
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I had been a 35mm film photographer for many [25-30] years, but lugging around a bag full of gear while backpacking, canoeing and horsepacking was too much - both for me and the camerqa gear. So I just stopped taking pictures.
In 2004 I dipped back into the camera world, and "discovered" the superzooms - I took a 4mp 10x optical zoom [Olympus C750] to Europe, Africa twice, and all over the US and Canada in the last 3 years. From one Africa trip alone I brought back 6500 digital images - the sort-through problems were awful!! However, the images are acceptable to very good, and now I want to do farther in terms of technique and editing. So...

It's time to step up to a better camera. I have been pouring over Steve's Reviews on many cameras.

My major criterion is sharpness of the printed (often cropped) image. I want a camera which will give me the sharpest and clearest printed image. I do not care what number of MP my camera chip contains; if a 6mp camera's image actually gives me a sharper image than a 9mp camera's: fine.

One of the "tests" I devised was to download the same picture [the red brick building with some traffic and street name signs] posted in the Samples section of each of Steve's Reviews; then I open it in Photoshop Elements and crop the image to show the same dimensions of the building [approximately 14% of the original image]; and then print this same-view image at 8x10 on the same paper with the same printer. Each of the prints reveals that the image is right on the edge of pixelization (by that I mean, individual pixels are just becomming visible in some of the prints.)

My question for the more experienced and technologically savvy is: is this a valid test? Have I failed to take something into account?

P.S. My comparisons are now focussed on the Fuji S6000fd and the Fuji S9100. These two are close, with the 9100 slightly edging out the 6000. Both Fujis are sharper than the Canon S2IS, which is sharper than the Canon S3IS. The Canon Rebel XTi beats the four above, but its price and use of interchangeable lenses lowers it in my ranking.

Any suggestions, criticisms, shortcomings will be appreciated!!!
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Old Jun 7, 2007, 7:57 PM   #2
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IMO, no, unless you plan on printing all of your photos that way with smaller crops printed to 8x10" ("on the edge of pixelation" as you put it). ;-)

At the print sizes I typically use, even 3MP would be fine, and I tend to rank things like Dynamic Range, color accuracy, and and Metering accuracy over perceived sharpness of a crop at a larger print size.

You're basically spreading the pixels thinner (not as much pixel density) when you try and crop and enlarge that way. So, if you start out with more megapixels, you'll have a higer pixel density for printing (pixels per inch). Even an excellent camera can produce crummy prints if you don't have enough pixel density for the desired print size.

As a general rule of thumb, you'll want a mininum of about 150 pixels per inch for an 8x10" print for acceptable quality. More than that is usually better on most printers.

So, you'd need an image size of around 1500 x 1200 pixels to achieve that minimal acceptable pixel density (or about 1.8 Megapixels after cropping). I've made a number of 8x10" prints from 2 Megapixel cameras. But, 3MP is noticeably better.

If you only have around 14% of the original image before printing to an 8x10 size from the cameras being discussed, you don't even have 2MP if you're trying to print at 8x10". That's not enough pixel density, even if you're not viewing the images from very close (because you tend to view 8x10" prints from further away, you can get by with around 2MP in a pinch).

Subject type can play a role, and you can interpolate with software (add pixels based on values of adjacent pixels) to help prevent pixelation and improve quality. But, it sounds like you're trying to go well beyond what would be considered an acceptable starting point before printing your test images.

If you need more optical zoom, buy a camera with more optical zoom and use the desired framing to begin with. Don't rely on cropping any more than absolutely necessary, because you can degrade print quality rapidly if you crop too much.

Then, if you want to compare print quality from cameras, do it with the full resolution images, at the print sizes you'd normally print at, using images with the types of subjects you normally shoot, in the conditions you normally shoot them in.

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Old Jun 7, 2007, 8:47 PM   #3
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I wasn't comfortable with your methodology, but I wasn't sure why, so I took a look at the images you're using from 3 different cameras. I used the Canon PowerShot A630, the Fuji FinePix E900, and the Nikon CoolPix P4.

There are a number of variables that can affect the quality of an image from a digicam, and an ideal test would have all the variables controlled such that when comparing the quality of the images, the differences would be entirely the result of the inherent quality of the camera's image sensor and lens.

The EXIF data I found are as follows:

Model = Canon PowerShot A630
Exposure Time = 1/800"
F Number = F4
Focal Length = 9.56mm
Calculated 35mm Eq Focal Length45.83561644mm

Model = FinePix E900
Exposure Time = 1/320"
F Number = F5
ISO Speed Ratings = 80
Focal Length = 10.5mm
Calculated 35mm Eq Focal Length46.66666667mm

Model = COOLPIX P4
Exposure Time = 1/431"
F Number = F6.1
ISO Speed Ratings = 50
Focal Length = 10.1mm
Focal Length In 35mm Film = 48mm
Calculated 35mm Eq Focal Length48.48mm

Unfortunately, the EXIF data for the Canon PowerShot A630 does not include the ISO setting, so I can't compare it to the others. But the FinePix E900 was set at 80 while the CoolPix P4 was set at 50. ISO has an affect on image quality, but usually only near the upper limits. Still, I would have liked to have seen them with identical settings. And I would definitely like to know the ISO setting for the Canon.

The exposure time should not be a consideration, as it should be allowed to vary in order to obtain a proper exposure. In fact, in a test like this,it should be the only variable that is allowed to vary. And it should not affect the image quality as long as it is fast enough to prevent camera shake in the event that Steve didn't use a tripod. I believe that all shutter speeds were fast enough not to affect image quality.

I would like to see the same aperture used for all the images, and, for the best possible image, I'd like to see it stopped down a bit, possibly to f/8. Aperture, all by itself does not have an affect on image quality, but the lens does, and lenses are generally sharpest in the middle of their aperture range, getting softer as they approach their limits. While the image from the Nikon was made at f/6.1 (close to the center of its range) the image from the Canon was made at f/4 (close to the limit of it's range.)

The focal length (or the amount of magnification provided by the lens) also can affect image quality, and Steve managed to control the focal length enough to suit me.

So I think Steve was able to sufficiently control most of the variables that affect image quality, with the notable exception of aperture. While the f-numbers for these 3 images from these 3 cameras are not wildly different, they are different enough to keep me from using these images as the only criterion by which I would select one from among these three fine cameras.
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Old Jun 7, 2007, 8:50 PM   #4
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When it comes to digital, bigger is better. I mean sensor size, not necessarily pixel count.

Unfortunately, unless you want to get into a DSLR, your choices are VERY limited. There is the Sony R1 and the upcoming Sigma DP1, beyond that, all other cameras have teensy sensors, most smaller than a fingernail. And the image quality of some of them simply sucks.
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Old Jun 8, 2007, 6:30 AM   #5
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I did a lot of research when I decided to make the jump from film to digital. I know right where you're coming from, having carted a Canon FTb I've had since 1972with several lenses and other accessories on backpacking trips. It amounted to several pounds, mostly glass with the normal 55 mm and a 135 mm, 28 mmand 2X teleconverter.

I started with resolution being the primary criterion. I compared several cameras through the resolution tests of theEIA1956 target at Imaging Resource. I was mainly interested in "prosumer" and low-end DSLRs, and looked at Panasonic, Canon, Nikon, Fujifilm and Sony, with at least 8 Mpixels. The Fuji S9000 came out on top in the comparison.

After considering other necessary/desirable options such as RAW capability, battery type, zoom range, ISO-dependent noise, image stabilization, memory card format, capability of manual controls, external flash, placement of tripod socket, and ability to use shutter release cable, I chose the S9000. It allows RAW format, takes AA batteries (cheap, universal, and rechargable), pretty good zoom (10X, 28-300 mm), acceptable noise, especially at ISO 80 or 100 where I shoot most of my pics), xD or CF memory cards, full manual control of exposure/zoom/focus, external hot shoe for flash (you'll want to get one because the built-in flash sucks), tripod mounting socket is located on the lens axis,and screw threads on shutter release button for standard release cable.

I've been very happy with it, but did encounter the "broken command dial" problem after less than a year. They fixed it under warranty, but I had to send it back again because somehow they got dust on the sensor during the first repair. I think they beefed up the faulty parts on the command dial, and I haven't seen any complaints about it on the S9100.

It is a bit slow in writing the RAW data, but that's about the only thing I've got to complain about. It takes wonderful pictures, with excellent detail when printed at 8 x 10. Coupled with an Epson C86 printer, I've got nothing but praise for this camera.
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Old Jun 9, 2007, 8:14 PM   #6
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Thanks to all four of you who replied.

JimC- I take your basic point to be that I have simply spread the available pixels way too thin to judge sharpness by printing only about 14% of the image. Indeed, all the images, even that from the 10mp Canon rebel XTi, are on the edge or over of pixilization. I understand!

TCav- I certainly understand that aperature and ISO setting will affect the image; I was looking for a "quick and dirty" way to get some objective data in front of my eyes, even if everything was not perfectly controlled. It's very hard to do!

Right now, I am leaning toward the Fuji S6000fd, though the S9000 does have a higher resolution EVF and CF media. We'll see... But many thanks for getting me off of an erroneous track!!
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Old Jun 9, 2007, 9:24 PM   #7
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johnr42 wrote:
I certainly understand that aperature and ISO setting will affect the image; I was looking for a "quick and dirty" way to get some objective data in front of my eyes, even if everything was not perfectly controlled. It's very hard to do!
Perhaps now that you've narrowed your choices down to a more manageable number, you can take a close look at other sample images. My only real issue with your methodology is that you're basing your selection on a single image.

And, of course, your methodolgy doesn't even include what I consider to be the most important criterion: How does it feel? Do the common controls naturally fall under your thumb and index finger? Do you find that the camera's menu structure makes sense to you? Can you find what you're looking for in the manual?
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