Print size and digital resolution advice query

[SriMesh]

I have found conflicting charts about what digital size is best for print processing. And according to the first chart, very few Sony alpha cameras have the capacity for a good 8x12 print or larger. Has anyone any advice for a Sony alpha camera users concerning the ratio of pixel resolution to finished photo development print size at a photo processing centre for example.
(not using a 200 or 300dpi printer as those use different resolution charts)

Recommended resolution is
1440 X 2160 = 3.1 MP for a 4 x 6 inch print
1260 X 1800 =.2.27 MP for a 3 x 5 inch print
1440 X 2520 =3.6 MP for a 4 x 7 inch print
1440 X 3600 =5.1 MP for a 4 x 10 inch print
1800 X 2520 =4.5 MP for a 5 x 7 inch print
2160 X 2880 =6.2 MP for a 6 x 8 inch print
2880 X 3600 =10.4 MP for an 8 x 10 inch print
2880 X 4320 =12.4 MP for an 8 x 12 inch print
3960 X 5040 =19.9 MP for an 11 x 14 inch print
4320 X 6480 =28 MP for a 12 x 18 inch print
4320 X 12960 56 MP for a 12 x 36 inch print

Or from a different chart....
Size Good Better Best Print size
1 MP 5" x 7" 4" x 6" Wallet
2 MP 8" x 10" 5" x 7" 4" x 6"
3 MP 8" x 10" 8" x 10" 5" x 7"
4 MP 11" x 14" 8" x 10" 5" x 7"
5 MP 11" x 14" 11" x 14" 5" x 7"
6-7 MP 16" x 20" 11" x 14" 8" x 10"
8 MP 17" x 22" 16" x 20" 8" x 10"
10 MP 20" x 30" 17" x 22" 11" x 14"

and yet from a different chart which is much lower
For a 4" x 6" print, the image resolution should be 640 x 480 pixels minimum =0.3 MP
For a 5" x 7" print, the image resolution should be 1024 x 768 pixels minimum =0.78 MP .
For an 8" x 10" print, the image resolution should be 1536 x 1024 pixels minimum = 1.57 MP .
For a 16" x 20" print, the image resolution should be 1600 x 1200 pixels minimum =1.92 MP.
For a 20" x 30" print, the image resolution should be 1600 x 1200 pixels minimum =1.92 MP.
For a Wallet-size print, the image resolution should be 320 x 240 pixels minimum =0.08 MP

The Sony Alpha 100 is a ten megapixel (CCD) digital SLR.
The Sony Alpha 200 is a 10.2-megapixel (effective) APS CCD image sensor
Then there is the 14.2-megapixel a (alpha) DSLR-A350 camera and the 10.2-megapixel α (alpha) DSLR A300 model
The Sony DSLR-A380 is a 14.2 Megapixel digital SLR
The 14.2 MP A550 is a bit larger than the 12.3 MP A500
The Sony comes equipped with a 12MP CMOS sensor

[kuvahmagh]

That second chart is closer to what you should expect, the first looks like it is taking the mathematical limits of a file printed at 300ppi. I have a 10 mp E-410 and routinely print 16x20 prints which are just as technically perfect in regards to resolution as people who use a 15mp 50D.

Also it is important to remember that the larger the print the further away it is supposed to be viewed, I believe the rule is the diagonal length should be how far you are away at minimum but I'm not sure. Even with that being said however I have yet to show anyone a 16x20 from my 10mp and had them be able to see any problems even up close.

[teaking]

I dont want to sound rude so please dont feel I am.... if you search this forum "post processing" there are numerous threads on print resolution which tackle this very subject on resolutions for printing. There full of really useful information and lots of peoples opinions and experience.

The bottom line comes down to that print is a different technology than digital screens so output is not the same as what you see on the screen.

[SriMesh]

Thank you for taking the time to answer my query. I hadn't thought of it that a large photo may be like a large artwork painting, and may look better from a distance. I will try a few more prints to see how they turn out