Archived posting to the Leica Users Group, 2010/03/21
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]The size of the photosite must have something to do with it too. For example, the BIGGER 6 micron photosite on the S2, M9 etc. needs more photons than, for example, the teeeeeeny smaller than a gnat 4/3 sensor at 4.3 microns (we know hyperbole makes good points). Any case, it stands to reasons (even if not physic :-)), that you would need more photons to fill those wells. Bigger is always better - except when it is not. For MF, aperture of F2.5 would produce fairly narrow DoF for any reasonable normal focal length. So not much point of going faster. On Sun, Mar 21, 2010 at 3:08 AM, philippe.amard <philippe.amard at sfr.fr>wrote: > > Le 21 mars 10 ? 01:08, John Nebel a ?crit : > > > >> Philippe, >> >> Rabs put it this way: "it's a medium format camera in a 35mm package. >> Delight in its deceptiveness." >> >> S2 has an f/2.5 lens vs the M's f/1.4 (or f/1.0 or even f/.95) and is >> slower due to the larger image circle. The S2 sensor is 45x30mm and the >> M's >> is 36x24mm. >> >> Maybe it is not correct, but I was thinking of a projector as an analog, >> move it farther from the screen and the image is bigger, but darker. Twice >> the diagonal size, 1/4 the brightness as the lamp has to illuminate the >> equivalent of four of the original images. Makes me think of the Meno. >> >> > 80/2,8 = 40/1,4 = 28.5714 > > you get different aperture (f) values, but the amount of light is the same > as the 'hole' is the same, or am I completely mistaken in the aperture > calculation formula? > > http://fr.wikipedia.org/wiki/Ouverture_(photographie)<http://fr.wikipedia.org/wiki/Ouverture_%28photographie%29> > > I would bet that the absence of faster f value on a MF/LF sensitive media > lenses results from other considerations such as angle and light fall out > in > the outer parts of the sheet/film/sensor. > > > At the other end of the size spectrum, if we take the Pana 4/3 pancake > you'd get 20/1.7 = 11.7647 a smaller hole, hence slower speeds? unless > compensated by the electronics ? with less fall-out issues? > I really don't know. > > > Thanks > Philippe > > > John >> >> philippe.amard wrote: >> >>> Le 20 mars 10 ? 22:25, John Nebel a ?crit : >>> >>>> Taken literally that doesn't make much sense; I should have said >>>> something like it is lot hungrier for light than a 35mm. >>>> >>>> Expected, given a slower lens spreading the rays out over a bigger area, >>>> but initially surprising with a camera that looks like an R8. Looks >>>> aren't >>>> everything. >>>> >>>> Could you be more explicit if you have time to, curious minds want to >>> understand. >>> TIA >>> Philippe >>> >>>> John >>>> >>> NO ARCHIVE >>> _______________________________________________ >>> Leica Users Group. >>> See http://leica-users.org/mailman/listinfo/lug for more information >>> >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information >> >> NO ARCHIVE > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information > -- // richard <http://www.imagecraft.com/> blog: < http://imagecraft.wordpress.com> // portfolio: <http://www.imagecraft.com/pub/PICS/AnotherCalifornia2> // mailing lists: <http://www.imagecraft.com/contact.html> [ For technical support on ImageCraft products, please include all previous replies in your msgs. ]