I think someone needs to tell you that you cant calculate resolution of a sensor required to match "120" film because there is not a single 120 film format. there is a whole bunch: 645, 6x6 6x7 6x9 6x12 and 6x17 formats all in wide usage by 120 film users. I hate to say it but that oversight gives you away as not really knowing very much about medium format at all... That's OK you wont need to know as its dying away along with 35mm soon. But "120", that's really not a format....and you cant calculate unless you specify which specific format on the 120 film you are trying to match on digital. JCO -----Original Message----- From: Adam Maas [mailto:[EMAIL PROTECTED] Sent: Monday, September 19, 2005 11:07 PM To: [email protected] Subject: Re: Pentax K 2.5/200mm
Note you're assuming that resolution scales linearly with sensor size. It doesn't, although it's not that far off. Note that I also did not say that the 17MP can exceed 120, and your own math shows that it can match it under the same 'average' conditions that I quoted for 6MP. So your math doesn't prove your point. Since it suggests that 27-43MP will exceed 120 and 17-26MP will match it. And the latter was exactly what I asserted. Since the resolution scales slightly slower than the sensor size (And this is primarily a lens limitation, not a film one) it's fairly easy to consider 17MP a match for 120 in general. -Adam Mishka wrote: >120 film has at least 2.8 times (645) or 4.3 (67) the area of 35mm film >per shot. > >10MP * 2.8 == 27MP != 17MP. >10MP * 4.3 == 43MP != 17MP. > >6MP * 2.8 == 16.7MP ~ 17MP >6MP * 4.3 == 26MP != 17MP > >the simple kind. >and, yes, MF lenses are every bit as good as 35mm (comparing >best to the best and mediocre to mediocre) > >so according to your own numbers, 17MP is the lower bound on 120 >format(s) -- the smallest one (645) under average conditions. this is >again, according to your own post. > >in other words, "17MP" is bullshit. > >mishka > >On 9/19/05, Adam Maas <[EMAIL PROTECTED]> wrote: > > >>I suspect you are misunderstanding me. >> >>Here it is again. Under average conditions, 6MP about equals the best >>35mm films, 8MP will do a little better. Under ideal conditions ~10MP >>equals 35mm. The conditions affect the resolution of the film more >>than it does the resolution of digital, which doesn't tail off as >>quickly as film resolution does under poor conditions (Grain size >>varies, sensor site size is fixed, combine with the linear response of >>digital sensors and digital has advantage under poor conditions that >>disappears under ideal conditions). Note that this is for APS and FF >>Bayer sensors of traditional design (I'm not getting into the Foveon >>and Fuji sensors), the little sensors in most Prosumer P&S's do not >>fare as well (6MP DSLR's generally outperform 8MP Prosumer cameras for >>resolution) >> >>A 17MP camera can match the resolution of 120 film in most cases, as >>proven by teh Canon 1Ds mk II. >> >> >> >> >>Mishka wrote: >> >> >> >>>do the math (the simple kind: multiplication and division) >>> >>>mishka >>> >>>On 9/19/05, Adam Maas <[EMAIL PROTECTED]> wrote: >>> >>> >>> >>> >>>>They do not contradict at all. When used under ideal conditions, >>>>35mm film is still exceeded by a 10+MP sensor (All other things >>>>being equal and using glass of sufficient quality). 17MP can match >>>>120 film. >>>> >>>>-Adam >>>> >>>> >>>> >>>>Mishka wrote: >>>> >>>> >>>> >>>> >>>> >>>>>Those are mutually contradictory statements. Both cannot be true at >>>>>the same time. >>>>> >>>>>mishka >>>>> >>>>>On 9/18/05, Adam Maas <[EMAIL PROTECTED]> wrote: >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>>>It takes 10+MP to exceed 35mm film under idea; conditions, and as >>>>>>the 1Ds mkII has shown you can match 120 film with 17MP. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>> >>>> >> >>
