Digital Camera Question - How many pixels does a digital camera need to be equivalent to a good 35mm film camera?

I want to make big prints from the images. With roll film in a 35mm camera I am happy going to 30"x40". Assuming lenses etc are the same on the digital camera and the roll film one, how many pixels will give the same definition?

Best Answer: I think it is worth coming at this another way. If you want to print a 30"x40" poster at 300dpi, you will need a resolution of 108Mp. This is calculated as (30x300) x (40x300) = 108x10^6.
If you are prepared to reduce the printing resolution to 200dpi, you will need 48MP. For a print this size, it is probably reasonable to use this lower printing resolution as viewers will need to be some distance away.
Scanned at 9600 dpi, a 35mm film will give you 123MP. The film is an analogue storage mechanism, so whether this is realistic is an entirely different matter. However, there seems to be little point in making 9600dpi scanners if there weren't real quality gains to be made in scanning film at this higher resolution.
That said, I agree with the comment that this is quite a large enlargement from 35mm. For most consumer grade film you will not be getting anything like the equivalent of 48MP, and the suggestion that around 25MP is possible might even be a stretch. At this resolution, you would be effectively only printing at about 150dpi if you enlarged to 30" x 40". (Note that I haven't done this last calculation exactly).

- how long is a piece of string.!!!!!!!!!!
pixels are not the only thing that effect quality,
there so many other factors,
if you look at a three mega pixel camera will give you better image than a 5+ mega pixel mobile camera,
you need good quality glass firstly,
good cmos sensor etc,
10+ mega pixel would be good but with a good piece of glass(lens quality)....

- 20meg is widley excepted as the film/digital equiv.saying that i use a fuji pro 3 12.3meg which gives me good enlargment capacity.using a poster facility i use i also can get to thatsize.hope this helps.

- From a strictly mathematical perspective, 24 megapixels...

- go to howstuffworks.com
to find your answer

- You will hear anything from 8 and up, but to really be able to match the quality of good 32mm film, you really need about 11 megapixels.

- If you're happy with 30"x40" prints from 35mm negatives, I would guess that you'd probably be more than happy with a 10mp dSLR.
30"x40" is awfully big to print from anything short of medium format film, though.