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Thread: Sean Reid's observations on M mount lenses on the G1

  1. #51
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    Re: Sean Reid's observations on M mount lenses on the G1

    OK now I understand this is not a scientific test, etc, etc.
    But it really shows quite well the effect that I'm trying to understand.

    First is the D 25 Lux 100% A little to the left of the frame there's a leave I focussed on.
    Second is the M 28 Cron. Same focuspoint.
    Third is the D 25 Lux upper right corner.
    Fourth is the M 28 Cron upper right corner.
    Fifth there's the complete shot.

    As you can see the Lux is sharper on the focuspoint.
    Now the Lux' base aperture is at f1,4 and the Cron's is at f2.0, so as allways it's apples to oranges, in a way.
    That said, the Lux is still sharper than the Cron @ f4,0.
    The lens-camera communication and the firmware will probably help the Lux here.

    It's the cornershot that I'm interested in.
    This is the distortion I'd like to find out where it's coming from and what is causing it.
    This is the distortion I talked about in my other examples.

    We know about the following issues

    - Maze Pattern in some raw converters
    - CA when no post correction applied
    - What else?

    My question:
    What causes the distortion we see in the corner of the upper right corner cron shot?

    Thanks, Peter

  2. #52
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    Re: Sean Reid's observations on M mount lenses on the G1

    Quote Originally Posted by peterv View Post
    We know about the following issues

    - Maze Pattern in some raw converters
    - CA when no post correction applied
    - What else?

    My question:
    What causes the distortion we see in the corner of the upper right corner cron shot?
    I'm just guessing -- but again, that's all anyone can do, since the full Four Thirds spec is proprietary.

    But based on the article I linked in a previous post, I'd say that:

    -- Four Thirds lenses are designed to be "telecentric," i.e, designed so that rays from the lens strike the sensor at a fairly perpendicular angle. The angle at which rays strike the sensor is called the "chief ray angle."

    -- The microlens array used in the Four Thirds sensor is optimized for the chief ray angle dictated by the lens spec.

    -- Camera lenses that produce a significantly different chief ray angle will interact with the microlens array in a non-optimal way. Intuitively, I suspect that effects of this non-optimal interaction might include reduced sharpness, distortion, and color fringing.

    Those are the sorts of effects you're seeing, right?

    This is kind of a new world for everybody. Until Four Thirds, digital-camera systems with interchangeable lenses were designed to work with legacy lens systems from the film era. That meant that microlenses etc. had to be compromises.

    The effects of these compromises were hard to isolate, and often tended to be blamed on the lens -- e.g. the digicam website "lens tests" that would say "lens X has chromatic aberration" because they'd see color fringing... even when lens X had never shown any sign of chromatic aberration in years of use on film cameras. (Color fringing and chromatic aberration are NOT one and the same thing -- chromatic aberration is actually a specific lens design fault of which color fringing is only one possible symptom.)

    With Four Thirds, for the first time, we started seeing cameras, lenses, and sensors that had been designed without any concessions to the film-camera world. It wasn't a big deal because relatively few people were using legacy lenses on Four Thirds cameras. Now Micro Four Thirds comes along, with its thinner body depth that makes it possible to adapt all kinds of crazy lenses, and we have to expect to see more dramatic effects from lens-design philosophies that conflict with the assumptions under which Micro Four Thirds sensors were designed.

    Cripes, that sounds pedantic! But it seems clear that "your mileage may vary" is going to be more true than ever as we experiment with various lenses on Micro Four Thirds.

  3. #53
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    Re: Sean Reid's observations on M mount lenses on the G1

    Thanks! That's all very interesting and your explanation sounds logical to me.
    And thanks for the link too. I read the article and thought it was very helpfull.

    Maybe the rather naive assumption I (we) made was that we focussed too much on the mechanical aspects of this relatively new µFT phenomenon. Thinking that if we could fit a 20th century lens with an image circle that is wide enough (through an adapter) on a 21st century camera, everything would be just fine...

    As I said above, we'll have to come up with a list of lenses (lens designs) that work well on the G1 and other µFT cameras

    Kind Regards, Peter

  4. #54
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    Re: Sean Reid's observations on M mount lenses on the G1

    I just conducted my own, totally unscientific test of the edge phenomena using a "film" lens on the G1 that is currently being discussed.

    The lenses used were a 21 mm Leica ASPH, Olympus 25 mm pancake, and the 14-45 mm kit lens. I used a tripod, and self timer.

    I used f 2,8, 4, and 8 on the Leica, f 2.8, 4 and 8 on the Olympus, and f 4.5, and 8 on the kit lens.

    There was a small, but distinct zone of smearing, and light drop off in all 4 corners of the Leica images at f 2.8, a smaller zone at f 4, and no smearing at f8. All of the corners seemed to be equally involved.

    The Olympus showed a much smaller zone of smearing, and light drop off at f 2.8, and none at all at f 4,and f 8. I guess this telecentric stuff works.

    The kit lens, as expected, showed the least smearing, and light drop off in the corners at f 4.5, and none at f 8.

    Again, I invite comments on this totally unscientific test.

    Martin

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    Re: Sean Reid's observations on M mount lenses on the G1

    Quote Originally Posted by Ranger 9 View Post
    reduced sharpness, distortion, and color fringing.[/indent]

    Those are the sorts of effects you're seeing, right?
    Yes, that's what I'm seeing. And a sort of 'glow', diffused highlights effect too.

    Again, thanks!

  6. #56
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    Re: Sean Reid's observations on M mount lenses on the G1

    Hi Martin,
    could you please post some examples?

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    Re: Sean Reid's observations on M mount lenses on the G1

    Quote Originally Posted by Brian Mosley View Post
    I haven't checked the samples you're quoting here - I only have my own experience which shows the 9-18 being extremely sharp right into the corners. Unfortunately I'm not a professional tester so will be happy to wait for dpreview to prove me right

    Could be sample variation - or amateurish testing.
    Well, looking at the images it is hard to understand how the corners can be smeared due to an user error. But wth, maybe it is. Then *I* surely should stay away. You know I need a foolproof lens.


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    Re: Sean Reid's observations on M mount lenses on the G1

    Here are some boring and quick wallpaper shots using the 18, 25, 35, and 50 mm Zeiss lenses. All shot with M8 and G1 at ISO 160 and 100 respectively. All at f/5.6 and about 4 feet from the wall. Center and upper left corner samples at 100%. Images imported into LR 2.2 and only levels adjusted, no sharpening applied and no corner corrections applied to the un-coded 18mm Distagon. All lenses had B+W 486 UV/IR filters on for both the M8 and G1 shots.
    Bottom line, some corner distortion on all G1 shots except the 50mm. Keep in mind that these are flat field shots so unless you are doing flat copy work you may or may not notice the corner and side distortion, depending on subject matter, aperture, etc.

    Images start here

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    Re: Sean Reid's observations on M mount lenses on the G1

    I have read this whole thread and no one has pointed out that any M lens test is being done with a third party adapter, many of them of questionable precision. All it would take would be the slightest bit of tilt in the adapter to whack out the corners at 1.4.

  10. #60
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    Re: Sean Reid's observations on M mount lenses on the G1

    Quote Originally Posted by Kachadurian View Post
    I have read this whole thread and no one has pointed out that any M lens test is being done with a third party adapter, many of them of questionable precision. All it would take would be the slightest bit of tilt in the adapter to whack out the corners at 1.4.
    Agreed, but since there's no way to mount a third-party lens except via an adapter, it may be a moot point.

    Thickness measurements of my CQ adapter vary by no more than 0.01mm around its periphery. If that's not good enough to get good corner performance, I don't think any third-party solution is going to give good corner performance.

  11. #61
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    Re: Sean Reid's observations on M mount lenses on the G1

    The issues with the adapters haven't been with regard to coplanarity, rather, they've set the lens either too close or too far from the sensor. I suppose it's possible they could add a bit of tilt, but they'd have to work hard to err in that regard.

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    Re: Sean Reid's observations on M mount lenses on the G1

    Quote Originally Posted by scho View Post
    Here are some boring and quick wallpaper shots using the 18, 25, 35, and 50 mm Zeiss lenses. (...)
    Thank you, speak volumes, at least if we are talking f/5.6 only.

    I don't mind boring targets. They can tell us a lot.

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    Re: Sean Reid's observations on M mount lenses on the G1

    Oh, where is Roland Barthes when we need him? In the end it's the studium and the punctum, which truly make the photograph not the sensor or the lens.

    "The market wants a Leica to be a Leica: the inheritor of tradition, the subject of lore, and indisputably a mark of status to own."
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    Re: Sean Reid's observations on M mount lenses on the G1

    Quote Originally Posted by Jonas View Post
    Thank you, speak volumes, at least if we are talking f/5.6 only.

    I don't mind boring targets. They can tell us a lot.
    You are welcome Jonas. I also shot wide open (lens dependent f/2, f/2.8, f/4) and all at f/4. Same conclusion.

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    G1 and CV28/2 Ultron results

    I mentioned the f/5.6 comparison because I got another result today. I wonder what you can do out of this:

    Earlier today I received a Cosina Voigtländer M-mount lens, the CV28/2 Ultron. I had high hopes for this lens as I have seen a lot great images taken with it (at flickr that is).

    Pretty early when playing with it I noticed a (quite severe) focus shift problem. Then I aimed the camera towards a book shelf to see what the borders/corners would be like. I shot two series; one without refocusing between the exposures and then another one where I did refocus thinking of the mentioned focusing shift.

    The images below are from the second series - refocusing was, simply put, necessary with this lens.

    First an overview:



    Then, in order, f/2 - f/5.6 100% crops. There is no sharpening applied to the crops:








    I can't believe the lens is supposed to behave this way and the images I have seen (Bessa and M8 images) didn't prepare me for this. There is no difference between the left and right side or any of the corners.

    Now the lens will go back anyway due to the focus shift. I knew about the focus shift but it was worse than anything I had read at the rangefinder forum.

    What do you think about all this? Should I buy Zeiss lenses instead?

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    Re: G1 and CV28/2 Ultron results

    Quote Originally Posted by Jonas View Post
    I mentioned the f/5.6 comparison because I got another result today. I wonder what you can do out of this:

    Earlier today I received a Cosina Voigtländer M-mount lens, the CV28/2 Ultron. I had high hopes for this lens as I have seen a lot great images taken with it (at flickr that is).

    Pretty early when playing with it I noticed a (quite severe) focus shift problem. Then I aimed the camera towards a book shelf to see what the borders/corners would be like. I shot two series; one without refocusing between the exposures and then another one where I did refocus thinking of the mentioned focusing shift.

    The images below are from the second series - refocusing was, simply put, necessary with this lens.

    First an overview:



    Then, in order, f/2 - f/5.6 100% crops. There is no sharpening applied to the crops:








    I can't believe the lens is supposed to behave this way and the images I have seen (Bessa and M8 images) didn't prepare me for this. There is no difference between the left and right side or any of the corners.

    Now the lens will go back anyway due to the focus shift. I knew about the focus shift but it was worse than anything I had read at the rangefinder forum.





    What do you think about all this? Should I buy Zeiss lenses instead?
    I do not understand what this is all about. Focus shift????
    I have / have had lenses with focus shift on my M8. These are fast lenses in my case. The Noctilux was the worst. I had to focus it (when wide open) and then give it a little twist to the right. Stopped down, there was no shift. The problem was that the focus patch indicated that the lens was in perfect focus when it was at f/1, but it wasn't.

    With the G1, focus shift is not a problem. Just focus the lens for the shot and it is always perfect. This is the one of the reasons that I like the G1 so much. When you focus, you can be sure that you are in focus.

    Smearing corners is a different thing, but I haven't seen it in my photos yet. Thanks Carl for doing testing on this. I am interested in taking photos, not testing, so I'll wait to hear what info others gather.

    If I'm missing something here, please enlighten me.

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    Re: Sean Reid's observations on M mount lenses on the G1

    Well if you focus with the lens wide open than stop down after you make the focus , than focus shift can occur. On the G1 you should be really focusing at the working aperture than it should not happen. Alas the G1 has gain with it so it does make it finder friendly to focus at the working aperture .

    The question I have here and maybe the case is if you focused wide open than left that alone and just stopped down and shot WITHOUT refocusing at the working aperture than the focus shift could occur. In this case you really need to refocus each time with the G1 at the working aperture
    Photography is all about experimentation and without it you will never learn art.

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    Re: G1 and CV28/2 Ultron results

    Quote Originally Posted by Jonas View Post
    I mentioned the f/5.6 comparison because I got another result today. I wonder what you can do out of this:

    Earlier today I received a Cosina Voigtländer M-mount lens, the CV28/2 Ultron. I had high hopes for this lens as I have seen a lot great images taken with it (at flickr that is).

    Pretty early when playing with it I noticed a (quite severe) focus shift problem. Then I aimed the camera towards a book shelf to see what the borders/corners would be like. I shot two series; one without refocusing between the exposures and then another one where I did refocus thinking of the mentioned focusing shift.
    I can't believe the lens is supposed to behave this way and the images I have seen (Bessa and M8 images) didn't prepare me for this. There is no difference between the left and right side or any of the corners.

    Now the lens will go back anyway due to the focus shift. I knew about the focus shift but it was worse than anything I had read at the rangefinder forum.

    What do you think about all this? Should I buy Zeiss lenses instead?
    I have this lens also and yes, it does focus shift. I get around it by either shooting wide open or stopping down to about f/8 for landscapes on the M8. However, focus shift, as Cindy noted, is really a non-issue on the G1. What you are seeing with your series of bookshelf shots is exactly the same as what I found with my wallpaper shots and the Zeiss lenses. This peripheral distortion/smearing seems to be most prominent in the 20 to 35 mm focal lengths that I have tested on the G1 with the M adapter and it is worse at wider apertures. It has nothing to do with focus shift.

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    Re: G1 and CV28/2 Ultron results

    Quote Originally Posted by scho View Post
    I have this lens also and yes, it does focus shift. I get around it by either shooting wide open or stopping down to about f/8 for landscapes on the M8. However, focus shift, as Cindy noted, is really a non-issue on the G1. What you are seeing with your series of bookshelf shots is exactly the same as what I found with my wallpaper shots and the Zeiss lenses. This peripheral distortion/smearing seems to be most prominent in the 20 to 35 mm focal lengths that I have tested on the G1 with the M adapter and it is worse at wider apertures. It has nothing to do with focus shift.
    Carl and Guy, thanks for the input and clarification.

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    Re: G1 and CV28/2 Ultron results

    Quote Originally Posted by Cindy Flood View Post
    I do not understand what this is all about. Focus shift????
    It is known the CV28/2 suffer from some focus shift. I mentioned it most of all to make sure anyone reading the post should know I knew about it, and hence did refocus between the shots.

    Quote Originally Posted by Cindy Flood View Post
    I have / have had lenses with focus shift on my M8. These are fast lenses in my case. The Noctilux was the worst. I had to focus it (when wide open) and then give it a little twist to the right. Stopped down, there was no shift. The problem was that the focus patch indicated that the lens was in perfect focus when it was at f/1, but it wasn't.

    With the G1, focus shift is not a problem. Just focus the lens for the shot and it is always perfect. This is the one of the reasons that I like the G1 so much. When you focus, you can be sure that you are in focus.
    If I focus the CV28/2 with the G1 (with the lens opened up to f/2) and then stop down the focus plane has moved. That is focus shift. With the CV28/2 stopping down to f/8 didn't help; the focus plane has moved away so far that the DOF doesn't cover the are first focused at. That was way more severe than I expected.

    Quote Originally Posted by Cindy Flood View Post
    Smearing corners is a different thing, but I haven't seen it in my photos yet. Thanks Carl for doing testing on this. I am interested in taking photos, not testing, so I'll wait to hear what info others gather.

    If I'm missing something here, please enlighten me.
    My post was about smearing corners and I hope we are talking about the same thing. Maybe i shouldn't have mentioned about the focus shift at all.

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    Re: Sean Reid's observations on M mount lenses on the G1

    i'm confused...isn't the crop from the center, not the corners?

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    Re: G1 and CV28/2 Ultron results

    Quote Originally Posted by scho View Post
    I have this lens also and yes, it does focus shift. I get around it by either shooting wide open or stopping down to about f/8 for landscapes on the M8. However, focus shift, as Cindy noted, is really a non-issue on the G1. What you are seeing with your series of bookshelf shots is exactly the same as what I found with my wallpaper shots and the Zeiss lenses. This peripheral distortion/smearing seems to be most prominent in the 20 to 35 mm focal lengths that I have tested on the G1 with the M adapter and it is worse at wider apertures. It has nothing to do with focus shift.
    To anyone:

    My post was about the smeared borders. I shouldn't have mentioned "focus shift" as there is nothing making people more confused. And I did mention I took two series and the crops are from the second one where I did re-focus between the images (meaning I refocused for every step I moved the aperture ring). OK now?

    ==

    @ Carl:

    Thank you.

    To me it is clear there is something with the G1 and the short focal length lenses that doesn't work very well. The left border crop in my images are approximately 8mm from the center when looking at the sensor. I can't imagine the lens behaves like that on film where it is about 21mm from the center to the corner.

    The problem is probably also lens dependent, some lenses may be more telecentric than other ones.

  23. #73
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    Re: Sean Reid's observations on M mount lenses on the G1

    Quote Originally Posted by Guy Mancuso View Post
    (...)
    The question I have here and maybe the case is if you focused wide open than left that alone and just stopped down and shot WITHOUT refocusing at the working aperture than the focus shift could occur. In this case you really need to refocus each time with the G1 at the working aperture
    Hi,

    As mentioned in my post i refocused between the shots. I started with f/2, focused, triggered the shutter, stopped down to f/2.8, refocused (10x magnification activated), took the shot, stopped down to f/4... and so on.

    I think the only mistake I did was to mention the focus shift problem i noticed with the lens...

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    Re: Sean Reid's observations on M mount lenses on the G1

    Jonas, Thank you for your explanation of your method. Did you use a tripod?

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    Re: Sean Reid's observations on M mount lenses on the G1

    Quote Originally Posted by Cindy Flood View Post
    Jonas, Thank you for your explanation of your method. Did you use a tripod?
    Hi Cindy,
    Yes, I indeed used a tripod. The images are ISO100, f/2 1/8 sec and so on, taken with the camera on a tripod and with the 2 sec timer turned on.

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    Re: Sean Reid's observations on M mount lenses on the G1

    If you looked at Sean's test of the CV28/2 you would see that even on the M8 it is soft in the corners at f2. It is softer focused even in the center at f2 compared to the f1.9 nockton and the 28 cron. It isn't until f5.6 that it is getting close and at f8 it looks pretty good.
    V/r John

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    Re: Sean Reid's observations on M mount lenses on the G1

    Jonas, I think you're just confirming for yourself what we already know from Sean's review.

    Maybe this is why the 20mm f1.7 won't arrive for some months... The 25mm f2.8 pancake for 4/3rds was quite an achievement. And that's for Olympus.

    At this short FL you can have slow or big, pick one

    For street shooting, maybe the lumix 14-45mm kit lens is the optimum choice for now?

    Kind Regards

    Brian

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    Re: Sean Reid's observations on M mount lenses on the G1

    Hi Jonas, sorry to see so many got confused. Of course your test is not about focus shift. What you get from your new CV lens is, from what I've seen from my own tests, not a problem specific for this lens. I've seen it with the 28 Cron, and with the 50 Lux and the 90 Cron, too. I would like to understand what it is that makes the G1 produce so much distortion around the edges of the frames with my (your) M-mount lenses.

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    Re: Sean Reid's observations on M mount lenses on the G1

    Interesting that there's a problem with your 90 Cron... maybe it's the registration distance of the M-mount lenses being too close, hence greater angle of incident light rays at the edges?

    With the Hexanon lenses and the 4/3rds adapter the lens is at normal 4/3rds distance - I'll have to check whether I'm getting the same problem - I can check with a 21mm f4 I have.

    Kind Regards

    Brian

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    pixel peepers delight!

    I've always believed that if you want the scoop on your own lenses, one must test them for themselves. Pixel peepers delight! Heres the test shot, the wall in my studio. Processing in LR, no processing, sharpening or manipulation. I took this shot, wide open on the following lenses. I then cropped the BEST corner at around 100%, results to follow.

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    Re: Sean Reid's observations on M mount lenses on the G1

    1st is the CV 1.7 Ultron cropping.

    Next is the CV 35 Skopar cropping

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    Re: Sean Reid's observations on M mount lenses on the G1

    next is the Leica Sumicron 50 (pre asph)

    then the Leica 75 Sumarrit

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    Re: Sean Reid's observations on M mount lenses on the G1

    now, the Leica 90 Elmerit_M

    then the CV 28 Skopar

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    Re: Sean Reid's observations on M mount lenses on the G1

    and finally the kit lens.

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    Re: Sean Reid's observations on M mount lenses on the G1

    Lovely Pictures. Worst bit of Bricklaying I've seen in a long time, though!

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    Re: Sean Reid's observations on M mount lenses on the G1

    Sorry if i confused the issue with the focus shift. Here is a thought and not sure it applies though. Does the G1 with the Raws in ACR and other programs correcting for distortion and such even if it does not know the lens on it. From these examples there certainly is falloff of sharpness but i wonder if the G1 is making general corrections in the raw on any lens if this could be the issue. Just a thought. Seems the wider the lens the worse the issue
    Photography is all about experimentation and without it you will never learn art.

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    Re: Sean Reid's observations on M mount lenses on the G1

    Quote Originally Posted by Guy Mancuso View Post
    Seems the wider the lens the worse the issue
    Guy, you may be right here - seems from the 50 on up, all is fine...

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    Re: Sean Reid's observations on M mount lenses on the G1

    This is actually making some sense to me because the longer lenses the correction be applying if there is would have very little effect , on wide angles a much bigger effect. Maybe need to take these files into a program that does not make the corrections and see if the results are the same. That would tell us right off the bat . Than we need to get Pana. to be able to turn this OFF in the menu item.
    Photography is all about experimentation and without it you will never learn art.

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    Re: Sean Reid's observations on M mount lenses on the G1

    Guy:

    It is the same problem I mentioned in the MFDB thread. The Leica M8 has angled micro lenses to correct the problems with the wides and the edges of the frame, the G1 doesn't.

    We saw the same thing comparing the RD1 to the M8. Lenses that were crap on the RD-1 actually looked good on the M8.

    Robert

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    Re: Sean Reid's observations on M mount lenses on the G1

    Quote Originally Posted by Brian Mosley View Post
    Interesting that there's a problem with your 90 Cron...
    Hi Brian, I take that back. I'm sorry to cause more confusion here... Took another good look at the test I did with the 90 Cron, and cannot be sure it's not motion blur I'm seeing with the shots I took with the 90mm. Unfortunately I can't perform more tests since my adapter is back to the homeland for the second time.

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    Re: Sean Reid's observations on M mount lenses on the G1

    Quote Originally Posted by robsteve View Post
    We saw the same thing comparing the RD1 to the M8. Lenses that were crap on the RD-1 actually looked good on the M8.

    Robert
    Hi Robert, good to see you here
    I hope you can post some examples of the 'faulty' RD1 photos so we can compare. Thanks in advance, Peter

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    Re: Sean Reid's observations on M mount lenses on the G1

    Quote Originally Posted by robsteve View Post
    Guy:

    It is the same problem I mentioned in the MFDB thread. The Leica M8 has angled micro lenses to correct the problems with the wides and the edges of the frame, the G1 doesn't.

    We saw the same thing comparing the RD1 to the M8. Lenses that were crap on the RD-1 actually looked good on the M8.

    Robert
    Robert micro lenses are only used to gather light in the corners and are not to increase or fix any sharpness issues in the corners. They just angle the light to illuminate the frame. Leica engineers will tell you the same thing. It does not fix any lens issues with regard to sharpness. Leica lenses do not have sharpness issue with a film Leica and will not with a crop M8 either it is to gather light.
    Photography is all about experimentation and without it you will never learn art.

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    Re: Sean Reid's observations on M mount lenses on the G1

    Quote Originally Posted by Guy Mancuso View Post
    micro lenses are only used to gather light in the corners and are not to increase or fix any sharpness issues in the corners.
    Yes, but they're still lenses, which means they're part of the total optical system. While I don't believe they're used to "fix" sharpness issues, it seems to me that they certainly could induce sharpness issues if they're poorly matched to the characteristics of the main camera lens.

    What I suspect we're being shown in this situation is that the M8's sensor array, for all its flaws and compromises, is optimized about as well as is possible for the characteristics of M-mount lenses... while the G1's array is highly optimized for the characteristics of Micro Four Thirds lenses.

    My interpretation is that for people who buy a G1 as a way of experimenting with the "looks" of a lot of different lenses, this difference in optimization simply will be another opportunity for interesting discoveries. For people who buy a G1 thinking it will serve as a budget M8 substitute, though, it's likely to produce some disappointments.

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    Re: Sean Reid's observations on M mount lenses on the G1

    Quote Originally Posted by Ranger 9 View Post

    My interpretation is that for people who buy a G1 as a way of experimenting with the "looks" of a lot of different lenses, this difference in optimization simply will be another opportunity for interesting discoveries. For people who buy a G1 thinking it will serve as a budget M8 substitute, though, it's likely to produce some disappointments.
    I agree, however, knowing that the wider ones will give me much more corner trouble than telephoto ones (with my lenses anyway), will save me from some disappointment down the road. Course' I'm not using a G1 for landscape or architectural work either. Horses for courses....

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    Re: Sean Reid's observations on M mount lenses on the G1

    Guy:

    From the Dpreview review of the M8. It is item 2 that I am referring to. I guess it is called offset microlenses, not angled.

    Robert

    http://www.dpreview.com/reviews/leicam8/

    Solving the corner vignetting problem

    Because a rangefinder camera doesn't have a mirror box doesn't need to use retrofocus lenses, meaning they sit much closer to the film (or in this case the sensor). The problem with this comes with wide angle lenses (which are pretty much the main staple of the rangefinder camera). Towards the corner of the frame the angle of incidence of light coming from the rear of the lens is so severely off-perpendicular that they would not pass equally through the microlenses above the sensor leading to fairly strong vignetting. Even a modest wide angle lens at this kind of distance could produce a difference of a stop or two between the center of the frame and the edges using a standard CCD sensor.

    Leica, obviously keen to solve this problem, took a three pronged approach with the M8:

    1. Don't use a full frame sensor - at this time it would be cost prohibitive and too complex to produce a sensor which can cover the entire 36x24 mm frame and still work with rangefinder lenses. For this reason the M8's sensor measures 27x18 mm (or 1.33x crop).

    2. Use offset microlenses - instead of placing all microlenses directly over the photodiode they are gradually offset as you get closer to the edge of the frame (see below).

    3. Know which lens is being used and apply some software correction - all new M series lenses now carry a six-bit code which allows the M8 to identify which lens is used and (optionally) apply a 'final stage' software based vignetting correction (for RAW images the lens used is simply recorded, no change is made).

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    Re: Sean Reid's observations on M mount lenses on the G1

    Good reading here:

    http://www.olympus-europa.com/consumer/dslr_7045.htm





    I'd like to see some results with SLR wide angles, which may be more telecentric.

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    Re: Sean Reid's observations on M mount lenses on the G1

    Quote Originally Posted by Ranger 9 View Post
    Yes, but they're still lenses, which means they're part of the total optical system. While I don't believe they're used to "fix" sharpness issues, it seems to me that they certainly could induce sharpness issues if they're poorly matched to the characteristics of the main camera lens.
    ....
    While any single lens will give a more unsharp image if the light rays are at an angle with the optical axis, I can“t believe any such shortcoming of the microlenses would show up as unsharpness in the final image.

    The reason is that each microlens serves a single pixel only, and there simply isn“t any way to see resolution within one pixel. Loss of illumination certainly, bleeding into adjacent pixels possibly, but resolution just cannot be affected by the microlenses; one pixel is the minimum detail in the image, period.

    I“ve just returned from a week“s travel with the G1. and FWIW, before I went, I tested several Leica R and M lenses on a bookshelf (carefully checking parallelity, but no focus bracketing) wide open. I found both my Summicrons 35“s (old M one, and R) were quite bad, both Summicron 50“s (again, old M and R) good in the center, the M bad corners while the R was OK. Both my 90“s (Tele Elmarit M and Summicron R) were very good across the field.

    I ended up taking the 50 R along. Sean“s review wasn“t posted by then, and no discussions had started, so I simply noted the results for my own use and threw out the test files... Now, when reading what“s going on, I“m more confused than anyone else...

    While the 50 R may conceivably be more "telecentric" than the 50 M (to make room for the mirror), then why wasn“t the 35 R better? It clears that same mirror...

    I don“t have the gear for measuring the position and size of the exit pupils (probably a relevant parameter), so I just give up...

    I use those lenses that give me good pics in practice (and I use them for people, not bookshelves....). But I“ll follow the discussions from ringside...

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    Re: Sean Reid's observations on M mount lenses on the G1

    Very interesting data, Per. What vintage 35 R?

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    Re: Sean Reid's observations on M mount lenses on the G1

    Quote Originally Posted by jklotz View Post
    I agree, however, knowing that the wider ones will give me much more corner trouble than telephoto ones ......
    Thinks you are right; see here:

    http://forum.getdpi.com/forum/showth...6854#post76854 (post 29 and next)

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    Re: Sean Reid's observations on M mount lenses on the G1

    so...
    on the M8, both long and wide lenses show no sharpness falloff in the corners; wouldn't one then conclude that the M8 microlenses are not affecting corner sharpness?
    Using the same lenses on a smaller G1 sensor is even less demanding, yet there is a falloff in sharpness with the wides, not the longs, compared to the kit lens.
    Makes me suspect some sort of image processing in the G1 instead of microlenses

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