Indeed it does. I've been eye balling one for a week or two now. The whole 2/3's of a stop exposure error is kind of annoying, but if it's truly consistent it'd be ok I suppose.
There are some really beautiful boke examples in this thread:
The boke is really what's drawing me to the lens, it's not perfect, but it is very nice. I almost like the way the 40 f/2 draws a little more, but I think I'd rather have f/1.4 and a little better boke.
There's much less bright ring effect in OOF highlights than the Nikon or Zeiss equivalents from what I've seen and it's pretty rare to see an area that looks particularly nissen, or busy and icky.
Edited by Jammy Straub on Jan 26, 2008 at 04:52 PM GMT
Yes, the +2/3 stop overexposure is consistent. I noticed it as soon as I took the first series of shots. It's a tiny bit annoying but I can live with it.
I don't understand why Klaus is presenting the 2/3 stop overexposure as such a negative. For the small effort of setting the camera to -2/3 EV, you get the metering equivalent of an ~f/1.1 lens. That could save a few shots that would otherwise fall short on shutter speed.
This could be a nice lens for the D40, because it's chipped. I'd sure like to see it reviewed head-to-head with the Nikon 55/1.2. They cost about the same.
Well, it's not the first time I've seen a lens overexpose. I have a manual-focus Tokina 90/2.5 macro, one of my favorite and most used lenses. I noticed it was overexposing the natural light shots, so I tried setting the non-CPU lens data to 2.0. It still overexposed. At 1.8, it exposes perfectly at all apertures. So here I gained a full stop. I have two others that gain 1/3 stop and several that lose 1/3-2/3.
I have a couple of AF lenses that underexpose. With those, I just set the exposure compensation up 1/3 stop. I have one that exposes properly in natural light, but needs a full +1 flash compensation. It's kind of a pain not to forget to change the setting before and after using the lens. Especially after.
The reason for all of this is simple. The lens gathers more or less light than it's rated for. If you're looking for a pattern, my lenses that overexpose all have larger than usual front (and rear) elements, and those that underexpose smaller. If you look at the front element of the Voigtlander, it's about 50mm in size (glass, not filter size). That's about the same as the Nikon 55/1.2 and much larger than the Nikon or Canon 50/1.4. I can't say for sure that this is the reason, but it fits the pattern.
Thanks for the front element size comparison Elan II, that helps clear things up a bit.
I'd bet in all reality the lens is closer to a ~f/1.3 lens, but they just rounded rather than use a less common partial f-stop labeling. They should have known better, people would pay more for a f/1.298 lens.
After extensive testing I have found that my Voigtlander 58mm F1.4 SL11 is also off by 2/3 of a stop. This was suppose to be the corrected lens, late model. I sent it back. The second one arrived and was exactly the same as the first. The problem is the setting of the lens diaphram in relation the the diaphram lever. or if you were to set the lens stop at say F16 the lens diaphram is not at F16 but slightly off by 2/3 of a stop. This is consistant and can be corrected by setting you meter at -.07.
papageno wrote:
Over exposing by 2/3 of a stop is a major, fundamental error and calls into question everything the builder has done with this lens.
I agree.
Does the lens over-expose by the same amount wide open? If not, it could be slow aperture blades. That would be a major defect.
I doubt seriously that the issue is the amount of aperture opening being off. It's like saying the engineers at Cosina don't even have a calculator. In fact, if they were to miscalculate, the CAD would have corrected it right up front anyway. I still think that the glass is capturing more light than expected for some reason. I'm not sure though and could be wrong. Regardless of the reason, it's inexcusable by today's standards.
geniousc wrote:
I'm not sure if that's correct. The diaphram opening size which is a simple ratio between focal length and opening controls the light hitting the film or sensor. Lenses with equal openings (F stop) should let in the same amount of light if calibrated properly. In other words F8 on one lens should be the same as F8 on another lens. This is the founding principle of external light meters, they would never work if it wasn't this way. When film was used before digital, the roll would always come with an exposure guide. If lenses let in different amounts of light when set a specific F stop, the whole system would have been useless. So, I say the lenses that over/under expose have improperly calibrated diaphrams. Larger diameter glass in a lens will get you less vignetting though. In a link above from cameraquest, the owner mentions that if you bought a Voightlander from him that doesn't expose properly, send it in for adjustment. They are adjusting the chip or diaphram. ...Show more →
I too am not sure it's correct, but nothing you wrote truly contradicts it either. The light entering the lens contracts and then expends again in an hourglass shape. A wider front element probably expends both ends of the hourglass. The added light will fall outside of the frame into the light-absorbing coating inside the lens and body, but it's still more light and might have some effect.
After the fact, the only repair possible (other than black paint) is to contract the aperture a corresponding amount to the excess light. A cheat of sorts. But you have to believe that the ratio was right on the dot from day one. It's too simple and too basic for anyone to miscalculate. Btw, the chip doesn't control the aperture opening, the body linkage does that. So if they are adjusting the chip, they're not even changing the aperture, only the setting reported to the body. That's a quick and dirty fix. It also raises the possibility that the chip is somehow inconsistent in the way it reports the aperture opening to the body and thereby causing these exposure errors. So there are other possibilities and I'm open to those.
Both of the lenses I have received have been from Camera Quest. Last one received Sept. 15, 2008. The CPU problem has been corrected but not the over exposure problem. I sent one lens back and the next one I received is exactly the same as the other one. It is consistantly off by 2/3 of a stop at all apertures. The problem is with the position of the diaphram lug. Example F16 if not F16 but off by 2/3 of a stop. If I set the exposure comp. at -07 the lens works fine.
selma-1 wrote:
Both of the lenses I have received have been from Camera Quest. Last one received Sept. 15, 2008. The CPU problem has been corrected but not the over exposure problem. I sent one lens back and the next one I received is exactly the same as the other one. It is consistantly off by 2/3 of a stop at all apertures. The problem is with the position of the diaphram lug. Example F16 if not F16 but off by 2/3 of a stop. If I set the exposure comp. at -07 the lens works fine.
The wide-open overexposure (meaning the iris is fully retracted) eliminates the following:
Slow moving aperture: It's not moving.
Chip sending the wrong info: The aperture is wide-open and reported to be wide-open.
Misaligned aperture linkage (is that what you mean by lug?): Again, it's wide-open. The linkage cannot open it further to cause the overexposure.
Really, if you think about it, with the iris fully retracted, the aperture serves no function at all. The presence of the same problem in this state eliminates the potential for any mechanical or electronic malfunction to be the cause and leaves only the physical properties of the lens as the culprit.
i got mine yesterday and made a test shot wide open. The lens is atleast 10 times sharper at 1.4 and 1.8 than the 50mm/1.8D. I found no problems with the exposure, but I own D80 so it perhaps compensates.
The diaphram opening size which is a simple ratio between focal length and opening controls the light hitting the film or sensor. Lenses with equal openings (F stop) should let in the same amount of light if calibrated properly. In other words F8 on one lens should be the same as F8 on another lens. This is the founding principle of external light meters, they would never work if it wasn't this way. When film was used before digital, the roll would always come with an exposure guide. If lenses let in different