# Comparing Olympus 4/3lenses to FX "Full Frame" offerings

Started Jan 25, 2014 | Discussions thread
Re: you wouldn't want

Tiger1 wrote:

Sensor size has little to do with enlargement.

I am puzzled (no surprise there) - in film, if I used a regular SLR (135 film), I had to enlarge the captured image certain amount to make the output image say 30cm by 20 cm, but if I used a medium format camera I had to enlarge the captured image much less, so size of the film dictated how much I needed to enlarge the image to make the print of desired size. I don't understand why it would be different for digital - please help me!

The first Canon D30 had an aps sensor of 3MP. The sony digicam has a tiny sensor comparatively but has 20MP. You can enlarge the sony pictures far more than the canons. A sigma merrill camera has an aps-c sized sensor but you can enlarge the images from it far more than a Nikon D3 which has a FF sensor, despite the texta balloon example you gave us.

But I've read that the Sigma Merrill pixel has about 25 electron read noise, and the other modern cameras have just about 2 to 4 electron read noise - it is something to do with no correlated double sampling (or something like that) in the Sigma and having three photodetectors per pixel. And unless I'm badly informed, the Sigmas colour transformation increases noise even more. Have I been misinformed?

Enlargement in the digital era is all about numbers of pixels coupled with cleanliness/sharpness per pixel. It has little to do with sensor size (although I have been arguing that the larger sensors can have larger photosites which trap more photons and you can have more of them to boot!).

I've read that the formula for signal in an image in digital is: p*pixel count where the p = pixel signal level and that the noise in general is sqrt((s^2 + r^2)*pixel count), where s = shot noise = sqrt(p) and r=read noise. I don't understand how what you say and these formulas would agree - I know there must be something wrong in the formulas - I'd appreciate your guidance!

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