Sony Alpha

Sony Alpha

How do I change picture settings on Sony Alpha 100?

When I download my pictures from my sony alpha 100. I notice they are only at 72 dpi. Is there a way to change the settings on the camera on the way my pictures are saved on the Memory Card to 300dpi?

You can not control the pixels per inch in your camera, as this is a function of the sensor. I have found the following ppi for SOME cameras by the following manufacturers. I wonder if this specification is available anywhere. I have four camera manuals in front of me and I can't find it in any of them.

NIKON - 300 ppi
CANON - 180 ppi
PENTAX - 72 ppi

We "discussed" this by way of question and answers a while back and decided that the ppi file produced by the camera really did not have any effect on the capability to produce a good print. If I take a photo with my wife's 6 MP Nikon and view the image on the screen, it will start out as 300 ppi. If it's a Full Frame image of 3008 pixels x 2000 pixels, the SCREEN image would be pretty big if I viewed it full sized, but it would print 10.0" x 6.6". If you crop a 5x7 out of this, keeping it as full-frame as possible, it becomes 400 dpi.

With my brother's 6 MP Pentax, the image is 2816 px x 2112 px, but it's at 72 ppi. If you print this without cropping, it would be 39" x 29"!!! If you crop a 5x7 out of this, though, it becomes 402 dpi resolution, which is virtually identical for the Nikon 6 MP camera.

With my son's 6 MP Canon Powershot A620, the image is 3072 px x 2304 px, but it's at 180 ppi. If you could possibly print this without cropping, it would be 17.1" x 12.8". If you crop a 5x7 out of this, though, it becomes 439 dpi resolution, which is a bit better than either of the other 6 MP cameras.

In other words, regardless of the sensor's pixel-per-inch output, 6 MP cameras produced the same resolution when it came time to print comparable images. How about a camera with more pixels?

If I take a photo with my 10 MP Nikon D200 and view the image on the screen, it will start out as 300 ppi. If it's a full frame image of 3872 pixels x 2592 pixels, the SCREEN image would be pretty big if I viewed it full sized, but it would print 12.9" x 8.6", if I had the right paper. If you crop a 5x7 out of this, keeping it as full-frame as possible, it becomes 516 dpi, or higher resolution than the 6 MP cameras. We knew that is would work out like this, though, didn't we?

The REAL question is, what difference does this make in the real world? If we agree that 300 dpi is an excellent resolution for prints, as long as you end up with at least 300 ppi after you are done cropping on the screen, you will get an excellent print as far as resolution goes. All four cameras exceed that amount. I usually resize "down" to 300 dpi before printing, because you can't tell the difference above that resolution anyway. Most people would be quite happy with a 200 dpi print, so go ahead and crop a bit. If you get a print resolution too much below 200 dpi, you will start to see digital artifact in the print and it will be objectionable.

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So, if your goal is an excellent print with dots that are small enough that they are no longer distinguishable as individual dots without magnification, you need to print at 300 dpi. You can go down in resolution to 200 dpi and still have satisfcatory results. The resolution of 200 or 300 dpi is NOT a function of the camera beyond the degree that I have discussed above. It is determined by the software you are editting your pictures with and you usually have enough size to work with using any camera at or above 6 MP to get decent pictures.

Working this out is easy once you understand the concept of print resolution. If you want 300 dpi, just do the math.

4" x 6"
4 inches x 300 dots per inch = 1,200 dots
6 inches x 300 dots per inch = 1,800 dots
1,200 dots x 1,800 dots = 2,160,000 dots or 2.2 MP

5" x 7"
5 inches x 300 dots per inch = 1,500 dots
7 inches x 300 dots per inch = 2,100 dots
1,500 dots x 2,100 dots = 3,150,000 dots or 3.2 MP

8" x 10"
8 inches x 300 dots per inch = 2,400 dots
10 inches x 300 dots per inch = 3,000 dots
2,400 dots x 3,000 dots = 7,200,000 dots or 7.2 MP

I will let you substitute 200 for 300 and do the math on these charts to see what the minimum acceptable resolutions for the various sizes would be.

4" x 6" - 960,000
5" x 7" - 1,400,000
8" x 10" - 3,200,00

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