There is nothing magical about full frame (as some people in these
forums seem to believe) - it is still subject to the same laws of
physics. All full frame does is give you an extra 1.5 stops in
terms of image noise (for a given number of photosites), which
personally I do not consider a very big deal, especially with
improving sensor technology and image processing firmware.
Any improvements to sensor technology and image processing software
apply to full frame as much as they do to smaller sensors.
Yes, and the converse is true. The point is that in terms of ISO and image noise the advantage of full frame over APS is an
absolute 1.5 stops, however as technology improves the 'usable' ISO range will increase for both full frame and APS in unison, hence the
relative advantage of full frame will decrease. (An extra 1.5 stops in a usable range of, say, 2 stops is very significant, but an extra 1.5 stops in a usable range of, say, 5 stops is less so.)
Full frame also puts you 'higher up on the MTF curve'. DSLR
resolution on the charts peters out at 3 pixels per line pair,
which corresponds to 40 lp/mm on the 5D and 60 lp/mm on the D2x.
It's a lot easier to provide decent contrast at 40 lp/mm than at
60 lp/mm. (Basically, to cough up 5D resolution and contrast,
you'll have to produce all new lenses for the D2x (which Nikon has
started to do with the 12-24 and the fisheye).)
Fair point, but I have not noticed it to be significant for current sensors and as sensor resolution increases it is apparent that many existing lenses will prove to be inadequate in which case new lenses will be required anyway. Personally, I have no concerns about replacing my old 35mm film lenses with new 'designed for digital' lenses (with, if necessary, reduced focal lengths matched to the smaller APS sensor).
Further, assuming users take a rational approrach to resolution (which I admit is a fairly big assumption based on some of the posts I read in these forums) then we should be approaching the 'end game' in terms of the megapixel war anyway. Except for highly specialist applications I cannot conceive of why anyone would want more than, say, 20-25 megapixels. (No doubt there will be someone who comes up with a contrived reason, such as extreme cropping, but if this is the case then he or she would be better off with a cropped camera in the first place!)
On the
downside, full frame also gives you greater expense (it may come
down in price but will always cost more than APS) and greater bulk
and weight of body (need full size pentaprism, shutter, mirror etc)
and of lenses for a given FOV range (most notable with telephotos).
As long as photography remains a game of collecting photons focused
onto a planar photosensitive medium, larger is going to be better.
And just as with medium and large formats, there are going to be
diminishing returns and increased costs.
Yes, I agree. Purely in terms of image quality "larger is going to be better", however if the advantage is, in practical terms, imperceptible then (for at least some users) it may be more than offset by its disadvantages of greater cost, bulk and weight - in these respects 'larger is going to be worse'. This is nothing new, most photographers were willing to forego the image quality advantage of medium/large format film for the extra convenience of 35mm.
Terry.
--
David J. Littleboy
Tokyo, Japan
