Why 50 mm and not 30 or 35 with primes ?

i think sigma do a 30mm f/1.4...?

http://www.dyxum.com/lenses/detail.asp?IDLens=267

Edited by Turerkan - 29 August 2007 at 13:25

OK , a Sony 35 mm. Never seen it before, strange. Expensive indeed, out of my reach. Much more expensive than the 50 1.4.

And I didn't know it was 42 instead of 50 mm. Intresting. The Sony 28 2.8 isn't expensive. About the same as the 50 1.4. Intresting.

I understand that 50-58mm lenses became "standard" because they were close to the true normal of 43mm (the diagonal measurement of 35mm film) and the focal length was long enough the the "standard" lens design cleared the mirror. Anything wider needed special designs to make the lens physically clear the camera innards.

Now with digital the "true normal" is 28mm. 30-31mm would be closer to what 35mm film shooters are used to, and even 35mm isn't too far off (being about 58mm equiv, which was the standard for a while if you go back far enough in history).

There are many 28mm lenses, a few 30mm, and many 35mm. The 28/2.8 is the "new normal", though the mirror box design prevents it from being the uncompromised goodness that 50mm lenses used to be.

I think you guys are missing the point. Most of you anyways. ;-)

As alluded to, the physics dictates what the "standard" lens is...the cheapest lens manufactureable with a big aperture. This is a function of registration distance and sensor size, with the former being based off the latter.

With APS-C, the registration distance didn't change, therefore the standard lens size can't change much. Hence the 30mm 1.4 lenses are still built like wide angle lenses and cost $$$.

Sure, a 30mm lens would be the "standard" lens...if it could be built from scratch and moved closer to the sensor (by 33%?).

Greg

I'd suggest to play with a suitable zoom in the 28-35mm range and you'll quickly notice that this produces a VERY natural perspective. Despite all arguments for the 28 (42-43) 'normal' focal length on APS-C, I find this perspective, subjectively, tending a little to the 'wider view' (but still very natural for the eye). For me, 30-35mm pics produce the most natural look.

I guess for the subjective part of viewing photos, you have to factor in your individual usual viewing distance to a pic as this changes the field of view, and of course I would define the 'normal' perspective as that perspective in which viewing angles to points in an image are equal to viewing angles to the corresponding points in 'reality' from a 'real' eye position in the scene.

There are terrific 'normal' primes around for APS-C, from the 28/2 over the Sigma 30/1.4 to the 35/2 and 35/1.4...

regards, maurus

Edited by Maurus - 21 August 2007 at 20:48

Honestly, the difference between a 28mm and a 35mm is about one or two steps forward or backwards in most "people" shots... Why all the fussing about which is a "true" normal.

What I find interesting is that with the 28mm Minolta lens, the f/2 is predictably expensive and hard to find but the f/2.8 version are a dime a dozen. As for the 35mm, the f/1.4 is really expensive and the f/2 is also really hard to find and commands a good price.

I have often wondered whether there are just fewer 35s out there or whether the demand is that much higher for the 35mm.