Archived posting to the Leica Users Group, 2012/06/10
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]the cron 50 doesn't even offer the same field of view as the nikon 1.4 G or a canon 1.4 FD, probably not the same focal length either Ph Le 10 juin 12 ? 23:33, Jim Nichols a ?crit : > Aram, > > I got to wondering if the mechanical details of the lens design > enter into this. Some lenses have aperture leaves near the rear of > the lens, while others have them between primary groups of > elements. With zooms, I feel that there have to be compromises > involved. I was surprised that the Summacron 50mm was so far off > the primary curve in both your data and mine. > > Jim Nichols > Tullahoma, TN USA > ----- Original Message ----- From: "Aram Langhans" <leica_r8 at > hotmail.com > > > To: "Leica Users Group" <lug at leica-users.org> > Sent: Sunday, June 10, 2012 4:25 PM > Subject: Re: [Leica] Using M (and R) glass on a Sony NEX-7 Now DATA > > >> I have more questions than answers as to why this is even so. I >> need to adapt more lenses to see what is happening. My 100 APO is >> adapted, but I did not use it. I want to try an f2, f2.8, f4, f5.6 >> (I don't have) primes or zooms wide open and see how the match up >> with a Nikon at those f-stops. >>> From my field experience, all three of my lenses when used wide >>> open give >> what I would consider perfect exposure, even though the data from >> my test seems to suggest the zoom is underexposing up to 1 stop. >> Ignoring that, one question is, why does an f/4 lens wide open >> meter the same as an f/2 lens wide open (correct exposure that >> is)? And then, why does the f/2 lens when stopped down to f/4 not >> behave like an f/4 lens wide open? How the heck does the meter >> know that you have stopped a lens down vs a lens with the same >> aperture wide open? F4 should be F/4 on any manual lens, letting >> the same intensity of light through. Is it something to do with >> the angle of light rays? Maybe wide open they all have about the >> same angle of light from a given point in the field, but as you >> stop down the angle changes? I am just thinking out loud. >> >> Aram >> >> -------------------------------------------------- >> From: "Jim Nichols" <jhnichols at lighttube.net> >> Sent: Sunday, June 10, 2012 12:45 PM >> To: "Leica Users Group" <lug at leica-users.org> >> Subject: Re: [Leica] Using M (and R) glass on a Sony NEX-7 Now DATA >> >>> Aram, >>> >>> I will add to the confusion. >>> >>> After plotting your data on the NEX-7, I became curious about my >>> Olympus E-1, which is an early professional model. I compared the >>> companion lens, which was the Olympus 14-54 zoom, to my Summicron- >>> R and my Elmarit-R 60mm Macro. By some stroke of luck, I was able >>> to use a log scale for this one, which helps with the comparison. >>> I have tried to do the same for my first chart of your data, but >>> can't find that option again. >>> >>> If the 14-54 lens, which communicates with the camera, is taken as >>> the "standard", then my Elmarit-60 is not too far off this line. >>> However, my sample of the Summacron-R 50mm shows that it departs >>> from the norm, particularly above f/8. In your data, this >>> departure starts at about f/5.6. After seeing this, I would not >>> choose the Summicron-R as a measure of performance for a Leica >>> prime lens. My Elmarit-R 60 looks much better. >>> >>> In looking at your data for the Leica zoom, I begin to wonder if >>> there are too many compromises in zoom lens design. I did not >>> pursue recording the 14-54 data at other focal lengths. >>> >>> Jim Nichols >>> Tullahoma, TN USA >>> ----- Original Message ----- From: "Aram Langhans" <leica_r8 at >>> hotmail.com >>> > >>> To: "Leica Users Group" <lug at leica-users.org> >>> Sent: Sunday, June 10, 2012 11:00 AM >>> Subject: Re: [Leica] Using M (and R) glass on a Sony NEX-7 Now DATA >>> >>> >>>> That's what I mean, too, except the Nikon D7000 and D300 does not >>>> behave the same as Howard's D700. >>>> >>>> Can anyone make sense of these data? >>>> >>>> Lens 1 is Nikon 50/1.2 >>>> Lens 2 is Leica-R 50/2 Summicron >>>> Lens 3a is Leica-r 35-70/4 shot at 35mm >>>> Lens 3b is same lens shot at 50mm >>>> Lens 3c is same lens shot at 70mm >>>> >>>> Subject, an evenly lit patch of grass in my front lawn. Went >>>> through the f-stops twice for each lens to check consistency. >>>> Same reading each time. >>>> >>>> >>>> f-stop Lens 1 Lens 2 Lens 3a >>>> Lens 3b Lens 3c >>>> 2 1600 1600 >>>> 2.8 800 1000 >>>> 4 400 400 640 500 640 >>>> 5.6 200 100 160 200 320 >>>> 8 100 40 50 60 >>>> 100 >>>> 11 50 25 30 30 50 >>>> 16 25 15 20 20 20 >>>> >>>> As you can see, the Nikon behaves as it should be and meters >>>> correctly through the f-stop range, halving the shutter speed for >>>> each smaller f-stop. >>>> The Leica lenses do not and progressively overexpose as you stop >>>> the lens down. I am surprised that the zoom did not meter >>>> correctly wide open. In my field experience, wide open is not a >>>> problem, and the overexposure only starts to show up as you stop >>>> down. >>>> >>>> I am also surprised that the overexposure is limited to about one >>>> stop. In my field experience I sometimes have to compensate about >>>> 2 stops. >>>> >>>> That said, there is about a one stop overexposure in this test >>>> while my Canon, when I had it, would overexpose about 4 stops if >>>> you stopped down enough. >>>> >>>> >>>> >>>> >>>> -------------------------------------------------- >>>> From: "H&E Cummer" <cummer at netvigator.com> >>>> Sent: Sunday, June 10, 2012 6:04 AM >>>> To: <lug at leica-users.org> >>>> Subject: [Leica] Using M (and R) glass on a Sony NEX-7 >>>> >>>>> >>>>> Date: Sat, 9 Jun 2012 16:13:38 -0600 >>>>> From: Bill Nelsch <photobynelsch at gmail.com> >>>>> Subject: Re: [Leica] Using M (and R) glass on a Sony NEX-7 >>>>> To: Leica Users Group <lug at leica-users.org> >>>>> >>>>> I have a stupid question: When you say the D7000 is "linear" - >>>>> what does >>>>> that mean actually? How does that affect the exposure? >>>>> >>>>> Bill in Denver >>>>> >>>>> Hi Bill, >>>>> By linear I mean that as you close down the lens aperture the >>>>> shutter speed drops by an equal amount in terms of light >>>>> transmission >>>>> If you are at f5.6 and 1/500 and then close down to f8.0 the >>>>> shutter speed adjusts to 1/250 - to f11.0 the shutter speed >>>>> drops to 1/125 >>>>> keeping the light transmission the same. That's what happens on >>>>> the Nikon. On the Canon without Canon lenses that "talk" to the >>>>> body >>>>> as you close down a Leica R lens mounted with an adapter that >>>>> isn't chipped the shutter speeds drift away from the above >>>>> response and you get more and more exposure variation. >>>>> Hope this clarifies my point for you. >>>>> Cheers >>>>> Howard >>>>> >>>>> >>>>> >>>> >>>> _______________________________________________ >>>> 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 >> > > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information