alex7075 Posted February 3, 2008 Share #1 Posted February 3, 2008 Advertisement (gone after registration) Well, just to distract you a little from the M8 upgrade program, how do you explain that I focused on the building in the center of the frame and the two vases in the lower corners are totally sharp? Noctilux stopped down at 4.0 with slight correction on the focus ring against the focus shift. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/44390-can-anybody-explain-me-why/?do=findComment&comment=471574'>More sharing options...
Advertisement Posted February 3, 2008 Posted February 3, 2008 Hi alex7075, Take a look here Can anybody explain me why.... I'm sure you'll find what you were looking for!
tashley Posted February 3, 2008 Share #2 Posted February 3, 2008 Lenses that are prone to focus shift tend not to exhibit it in a uniform manner across the frame. My classically focus shifting 35 luxes (all three of them) all tended to produce (especially at F4 which is where focus shift is often most pronounce) an OOF centre of frame and a better focussed edge. My guess here is that you've hit a weird sweet spot where you've pulled focus forward enough to compensate for centre focus shift, and that there are two differential fields of focus, one in the centre and another at the edges (in fact probably an aspheric continuum) and that both your building and your vases fall within the acceptable depth of these fields at their respective parts of the frame. A useful trick! Tim Link to post Share on other sites More sharing options...
Hookeye Posted February 3, 2008 Share #3 Posted February 3, 2008 A very interesting example of focus shift. I trust your explanation is correct, Tim. I was indeed puzzled by Alex' image before you came up with it. And you are of course sure it is not the vase-recognition built into the 1.201 firmware ? Link to post Share on other sites More sharing options...
jc_braconi Posted February 3, 2008 Share #4 Posted February 3, 2008 Alex, as the 50 in this case is a 65, you must have been far than 6 meter from this vases to take what you wanted to get in the 50 frame so, I think you stayed in between the hyperfocale range, in spite the 4 aperture, to get them sharp. Link to post Share on other sites More sharing options...
Dan States Posted February 3, 2008 Share #5 Posted February 3, 2008 Focus shift only goes outward, not back towards the photographer. With so many pattern shapes in the buildings I'd wager you mis focused. Easy to do with the M when you have a repeating pattern in the rangefinder patch. Of course, if this happens on everything you shoot that's another story. Link to post Share on other sites More sharing options...
tashley Posted February 3, 2008 Share #6 Posted February 3, 2008 Dan, he pulled focus back (I assume) for correct for shift. It's my strong-ish hunch that this brought the centre into correct focus as he intended but also moved the vases into the separate hyperfocal zone that exists at the perimeter of an ASPH lens. Link to post Share on other sites More sharing options...
alex7075 Posted February 3, 2008 Author Share #7 Posted February 3, 2008 Advertisement (gone after registration) And you are of course sure it is not the vase-recognition built into the 1.201 firmware ? :D Of course, if this happens on everything you shoot that's another story. Thanks for your observations, that help me understanding. It actually happens on everything I shoot... I agree with Tim, this lens shows something that can be drawn like this: Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! of course in 3 dimensions (spherical). That should be why, if I put my subject on the borders, it is sharp when I backfocus intentionally (at large apertures and at any distance). You really got to know this lens to use it at its best. Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! of course in 3 dimensions (spherical). That should be why, if I put my subject on the borders, it is sharp when I backfocus intentionally (at large apertures and at any distance). You really got to know this lens to use it at its best. ' data-webShareUrl='https://www.l-camera-forum.com/topic/44390-can-anybody-explain-me-why/?do=findComment&comment=471793'>More sharing options...
MP3 Posted February 3, 2008 Share #8 Posted February 3, 2008 Alex and Tim I cannot agree more with your latest graph on #7. This is exactly what I've been experiencing with many e60 Nocts, old or new. It draws everything like that, no matter at f1 or stop down, though backfocus may further complicated the scenario when stopped down. The Noct's in-focus field simply is not flat, it is spherical in fact. And it is quite steep at extreme side edges. Link to post Share on other sites More sharing options...
luigi bertolotti Posted February 3, 2008 Share #9 Posted February 3, 2008 Dan, he pulled focus back (I assume) for correct for shift. It's my strong-ish hunch that this brought the centre into correct focus as he intended but also moved the vases into the separate hyperfocal zone that exists at the perimeter of an ASPH lens. But Noctilux isn't an Asph... anyway I think your explanation is right... I observed something similar with my old Lux 50... not wide open but (if I remember well) at 2,8-4. Link to post Share on other sites More sharing options...
tashley Posted February 3, 2008 Share #10 Posted February 3, 2008 But Noctilux isn't an Asph... anyway I think your explanation is right... I observed something similar with my old Lux 50... not wide open but (if I remember well) at 2,8-4. Quite correct - as I know, I have one! Doh! Link to post Share on other sites More sharing options...
Shootist Posted February 3, 2008 Share #11 Posted February 3, 2008 Well my question is ARE those 2 vase really IN FOCUS. Could be that they are of a texture that make them appear IN FOCUS but really aren't. I'd like to see the railing and balusters below them becasue those part should also be in focus. I'm not trying to dispute the fact that the Nocti may have a curved focus plane. Link to post Share on other sites More sharing options...
tashley Posted February 3, 2008 Share #12 Posted February 3, 2008 Well my question is ARE those 2 vase really IN FOCUS. Could be that they are of a texture that make them appear IN FOCUS but really aren't.I'd like to see the railing and balusters below them becasue those part should also be in focus. I'm not trying to dispute the fact that the Nocti may have a curved focus plane. Good point - but what's for sure is that the left hand vase is more in focus than the arched window behind it, which is, in terms of distance, somewhere between the vase and the corner of the building that the OP focussed for (if not exactly on!) It was a photo rather like this that I took in Venice a year ago on a 35 lux that started off the whole focus shift debate. It's all very confusing! Link to post Share on other sites More sharing options...
alex7075 Posted February 3, 2008 Author Share #13 Posted February 3, 2008 I'd like to see the railing and balusters below them becasue those part should also be in focus. You're right, here they are: Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Everything is sharp to me at that distance. I made this experiment to check at shorter distance @1.0: full frame, focused on the vase (again!) and recomposed: and the 100% crops, the first is the enlargement of the picture above, the second is with intentional slight backfocus: Pushing the focus backwards gives a sharper image. So, it seems like a general rule for this kind of Noctilux spherical aberration. The curve seems gentle around the center of the image, and much steeper approaching the borders as MP3 says. The funny thing is that if you stop down AND you put your subject on the border, the focus shift compensate with the aberration! Result: subject is sharp (because center of the image shifted away). I tried and it works! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! Everything is sharp to me at that distance. I made this experiment to check at shorter distance @1.0: full frame, focused on the vase (again!) and recomposed: and the 100% crops, the first is the enlargement of the picture above, the second is with intentional slight backfocus: Pushing the focus backwards gives a sharper image. So, it seems like a general rule for this kind of Noctilux spherical aberration. The curve seems gentle around the center of the image, and much steeper approaching the borders as MP3 says. The funny thing is that if you stop down AND you put your subject on the border, the focus shift compensate with the aberration! Result: subject is sharp (because center of the image shifted away). I tried and it works! ' data-webShareUrl='https://www.l-camera-forum.com/topic/44390-can-anybody-explain-me-why/?do=findComment&comment=472277'>More sharing options...
marknorton Posted February 4, 2008 Share #14 Posted February 4, 2008 I actually think your Noctilux is working quite well - I've had images from mine before it was fixed where nothing was in focus, anywhere in the frame, at any distance. Link to post Share on other sites More sharing options...
tashley Posted February 4, 2008 Share #15 Posted February 4, 2008 I actually think your Noctilux is working quite well - I've had images from mine before it was fixed where nothing was in focus, anywhere in the frame, at any distance. Tsk tsk Mark, that's just the famous Noctilux 'look'. The OP here clearly has one that is performing badly and should be sent back until calibrated to the standard of yours! Link to post Share on other sites More sharing options...
marknorton Posted February 4, 2008 Share #16 Posted February 4, 2008 Yes, I accept the field curvature is very marked. Question is, if it's doing this on a crop camera, where would the plane of focus be at the image edges if it was full frame... behind the photographer? Same effect as your 35/1.4 in Venice, no? Link to post Share on other sites More sharing options...
tashley Posted February 4, 2008 Share #17 Posted February 4, 2008 Yes, I accept the field curvature is very marked. Question is, if it's doing this on a crop camera, where would the plane of focus be at the image edges if it was full frame... behind the photographer? Same effect as your 35/1.4 in Venice, no? I'd quiet like that for street work, taking shots behind me in perfect focus. The word Venice still brings me out in a sweat. 1000 frames of guessed focus. You get used to it eventually. :-) Link to post Share on other sites More sharing options...
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