From: "Willem-Jan Markerink" To: eos@avocado.pc.Helsinki.fi Date sent: Mon, 10 Jan 2000 02:30:05 +0100 Subject: Re: EOS: Re: EOS 1N RS Priority: normal Send reply to: eos@avocado.pc.Helsinki.fi On 20 Dec 99 at 12:03, Antony Boshier wrote: > >The RS is a one-of-a-kind unique camera, and I can't imagine > >ever selling mine -- I love it! > > > >BTW -- the loss is around 1/3 stop > > I just wanted to say that I called Canon and they said that the loss is > about 2/3 of a stop. But who knows maybe the person from Canon had > incorrect information. Both numbers play a role....on the film plane, it's 1/3rd (or 33%) loss, which makes 2/3rd stop (50% would have been 1.0 stop)....hence the confusion....:-)) In the viewfinder things are a bit more subtle: the 1/3rd of light that is reflected upwards is not 2/3 less than normal (which would be 1.5 stop loss)....normal cameras don't reflect 100% upwards either, about 1/3rd is used for AF and spotmetering (1(n))....so this is 1/3rd (RS/RT) vs 2/3 (other), IOW, only one stop. And that one stop is almost completely compensated by the brighter viewscreen on the RS (the RT doesn't have one AFAIK)....which fits the normal 1(n) too btw (at the expense of less easy manual focus). -- Bye, Willem-Jan Markerink The desire to understand is sometimes far less intelligent than the inability to understand [note: 'a-one' & 'en-el'!] From: "Willem-Jan Markerink" To: eos@avocado.pc.Helsinki.fi Date sent: Mon, 10 Jan 2000 03:19:49 +0100 Subject: Re: Subject: Re: EOS: Re: EOS 1N RS Priority: normal Send reply to: eos@avocado.pc.Helsinki.fi On 21 Dec 99 at 17:09, dherzstein@juno.com wrote: > > > Watch where you loose light! You loose 1/3 on film and 2/3 of light > > > in the viewfinder. > > > > This sounds quite confusing. You lose 1/3rd of the light (which is > > NOT 1/3rd of an f-stop) at the film plane. This is a 35% loss (a full > > f-stop loss is 50%). In the viewfinder you lose 65% of the light (two > > f-stops is about 75% and it is quite near). > > Since the mirror stays "down" when the shutter is open, the 65% > transmission rate (35% loss) translates into a 2/3-stop loss of light at > the film plane. > > Since only 35% of the light relects onto the viewfinder (instead of the > normal 100%), that's about 1½-stops lost at the focusing screen (remember 25% > would be a 2-stops less). The brighter viewing screen reduces that to about a > ½-stop darker viewfinder. A normal camera doesn't reflect 100% light to the viewfinder....it needs 1/3rd for AF (and (fine)spotmetering in case of 1(n)). Older non-AF models might attain 100%.... -- Bye, Willem-Jan Markerink The desire to understand is sometimes far less intelligent than the inability to understand [note: 'a-one' & 'en-el'!] From: "Willem-Jan Markerink" To: eos@a1.nl Date sent: Fri, 3 May 2002 15:54:55 +0100 Subject: 1n-RS & Manual lenses & lightmeter deviances (was: EOS Fisheyes Send reply to: eos@a1.nl On 30 Apr 02 at 22:32, Willem-Jan Markerink wrote: > On 30 Apr 02 at 13:48, gerard.maas@alcatel.be wrote: > > "Neil K." wrote: > > > > > Actually, Julian Loke and Gerard Maas have written an interesting > > > and detailed article for the EOSDoc Web site about this, not me. > > > > > > http://www.eosdoc.com/manuals.asp?q=E7EMFlens > > > > > > They say that their tests lead them to believe that the Elan 7/EOS > > > 30/33 consistently meters out by 3 stops and that (I think) this is a > > > linear error. However, I've been contacted by at least one other person > > > who claims that the error is non-linear. > > > > Neil, > > > > Do you know which lens this person was using? Does it works on other EOS > > bodies? > > > > I did many test with different manual lenses. > > - The "mystic" EOS-FD adaptor and a 135f/3.5 FD > > - The 135/3.5 and 50f/1.8FD on a FL bellows and an a hand-made FD-EOS > > Macro adapter (no glass) > > - The Macrophoto 35f/2.8 with the previously described bellows & adaptor - > > Undocked EF100f/2.8 (you just don't click the lens on the mount, so there's > > no electronic communication) - ... and the Zenitar 16mm fisheye. > > > > All of them showed a linear difference of 3 stops tested by photographing a > > kodak gray card and comparing with a slide of the same card photographed > > with the 100f/2.8 USM and the EOS 30. > > Try a 1000mm/f10.5 mirror, and you'll end up with 7 stops....:)) > My rule is and >. > Additional problem with 7 stops is that you run out of compensation > with 50 ASA film....3 stops per ordinary +/- correction, 2 stops per > ASA-correction (12 ASA is minimum, on itself a lousy spec; with > infrared film and very strong filters you end up with fractions of > ASA; if not for auto-exposure, at least in manual mode (with exposure > information in the viewfinder)). Please note that this experience is based on the (fine)spotmeter in the EOS 1(n (RS)), but seeing the same values for the 30/33/7 I assume it is the same structural problem. Which leads me to another question, related to the 1n-RS: In a recent thread on de.rec.fotografie someone asked how the non-RS viewfinder-screens should be compensated, as they are 1 stop less bright than the special RS-screen. This seems an easy question (dial in 1 stop overexposure), but it's definately not, since the same finespotmeter in the bottom of the mirror-box spoils things....it sees the same amount of light, regardless of screen. Add matrix-mode, which includes the finespot sensor, and things get even more confused.... I vaguely even recall a (S?)CF option which would compensate for non-RS screens, but other than that, shouldn't Canon Service be capable of recalibrating this camera? -- Bye, Willem-Jan Markerink The desire to understand is sometimes far less intelligent than the inability to understand [note: 'a-one' & 'en-el'!] FROM: Helmut Faugel SUBJECT: Re: Belichtungskorrektur EOS 1 N RS DATE: Tue, 07 May 2002 11:09:03 +0200 NEWSGROUPS: de.rec.fotografie Helmut Faugel wrote: > [..] > Wenn ich nicht falsch liege dann hat Canon eine Moeglichkeit vorge- > sehen bei der EOS 1n RS eine Anpassung an andere Mattscheiben vor- > zunehmen, ich schau da gerne mal im Prospekt nach. Oje! Da steht nur drinn das man mit Belichtungskorrekturen arbeiten muss, und was in der Anleitung der Mattscheiben drin steht erspar ich mir lieber, bin ich froh das die EOS 3 sowas einfach durch setzen der C.Fn. 0 erledigt. -- Helmut Faugel