Making landscape photographs
Do I need "Full Frame"
 

 Many people (including marketing departments) seem to be looking at cameras almost purely in terms of megapixels. Is this a valid approach? The sensor is efectively the "film" in a digital camera and the number of megapixels is equivelent to the grain in film and who wants grainy pictures? But how "grainy" is a low megapixel image and would you notice in the way you use images?
Certainly if you make very large prints you will choose a high megapixel count, but do you do that? 
I decided to take test images with my three camera bodies and show you the results. 

First time I used a Sigma 24-70 lens, relied on the AF system for focusing and hand held the camera, the results were influenced more by focus and camera shake than pixels, the results are here.

This time I will use a prime 70mm lens (Sigma) and a tripod, I will process all the images in the same way, having shot in raw mode at the same settings and converted to JPEG for the web images, using the same sharpening. Lets see what will happen:-

Pentax Ist 6 megapixels

Pentax K10 10 megapixels

Pentax K20 14.6 megapixels

Well, that showed the three cameras getting different results, but for other reasons than the sensor I think, (I will have to do this under  more controlled conditions next time).
 

(Now of course the three cameras do of course have other differences, the K10 and K20 for instance, can shoot in an automatic mode where the user sets shutter and aperture and the camera adjusts ISO speed to get a correct exposure. If buying a compact camera the lens offered may vary widely between models with a similar pixel count). 

But anyway, now lets try cropping and really enlarging the images...........................
Pentax Ist 6 megapixels

Pentax K10 10 megapixels

Pentax K20 14.6 megapixels