Please help me understand megapixels...

[gafftape]

So I'm picking out my camera and I'm struggling with how many megapixels I really need. My old camera is a 4 mp Minolta and it does ok on an 8X10 print but it is just a bit grainy. So I'm expecting with a 5 mp camera to be able to print a pretty good 8X10 shot. But what happens if i crop at all? Is 5 mp just barely enough information to print a good 8X10? If I want a high quality print and I want to be able to crop 20% or so, do I need a 6 mp or higher camera? Is there some sort of magic formula or chart out there to help me understand the megapixel mystery?

Thanks

[ReF]

So I'm picking out my camera and I'm struggling with how many megapixels I really need. My old camera is a 4 mp Minolta and it does ok on an 8X10 print but it is just a bit grainy. So I'm expecting with a 5 mp camera to be able to print a pretty good 8X10 shot. But what happens if i crop at all? Is 5 mp just barely enough information to print a good 8X10? If I want a high quality print and I want to be able to crop 20% or so, do I need a 6 mp or higher camera? Is there some sort of magic formula or chart out there to help me understand the megapixel mystery?

Thanks

i think the graininess that you refer to might have more to do with noise than not having enough resolution. can you link us to the original sized image that you printed the 8x10 from or provide a small section cropped from that image? i made about a dozen 8x10 from a 4mp camera and did not find any lack of resolution or grain/noise problems. btw all but one were shot at ISO 50 on the a80. if you plan to crop then going with the higher MP is the safer route

[Norm in Fujino]

So I'm picking out my camera and I'm struggling with how many megapixels I really need. My old camera is a 4 mp Minolta and it does ok on an 8X10 print but it is just a bit grainy. So I'm expecting with a 5 mp camera to be able to print a pretty good 8X10 shot. But what happens if i crop at all? Is 5 mp just barely enough information to print a good 8X10? If I want a high quality print and I want to be able to crop 20% or so, do I need a 6 mp or higher camera? Is there some sort of magic formula or chart out there to help me understand the megapixel mystery?


There are megapixels, and then there are megapixels. Which is to say, not all megapixels are created equal. 4MP is plenty to print beautiful 8x10 prints, assuming the sensor produces a good original file, and that generally requires shooting at low ISO (50-100) and other factors. I have an Olympus C-755 that I've used to print 8x10 portrait crops of shots originally shot in landscape orientation, and the prints were beautiful (IMO). So I think you need to consider other factors involved. A 6MP Nikon D70 or 5MP Olympus E1 will print fabulous prints up to larger than you're likely going to want to print.
As Ref suggested, if your 4MP camera produced grainy 8x10s, it's likely either got a very poor sensor, or you were shooting at too high an ISO.

[cwphoto]

Ask any D2H owner if 4MP is enough.:)

Norm said it all - the size of the pixels and the quality of the processing are important too.

[AlexMonro]

There is a rule I've heard which relates the camera resolution to the print size, which states that you need between about 150 to 300 pixels per inch for a good quality print, depending on viewing distance. So for example, a 6MP camera (3000 x 2000) could produce high quality prints up to 10 x 6.7" for close up viewing, or 20 x 13" when hung on a wall.

If you crop at all, you're throwing away information, so if you crop 20% from the above example, you'd then only be able to print to 8 x 5.3" for a close up viewing.

Like most photography rules, it's just a guide, don't follow it too slavishly.

[FLiPMaRC]

My old Olympus 1.3mp camera printed beautiful 8x10 pictures. I always set it to take pics at the highest resolution.