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Thread: CV wide on m4/3?

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    Senior Member aleksanderpolo's Avatar
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    CV wide on m4/3?

    Hi, anyone have experience using CV's wide (12mm - 28mm) on m4/3? Do you see any corner smearing problem with any of the lens that is absent in film? I sort of asked a similar question in a different forum but not that many m4/3 user there. Thanks.

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    Re: CV wide on m4/3?

    The 15mm works pretty well. Some smearing, but nothing too extreme. It's a great lens on film, too.

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    Re: CV wide on m4/3?

    Hi all, Ive used a 25 mm Skopar but it smears sides and corners unless you go to f11, then it is nice all over the image, on film it is OK at 5.6/8

    Best

    Jose

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    Senior Member aleksanderpolo's Avatar
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    Re: CV wide on m4/3?

    Thanks, so even 25mm have problem? How about 28mm f2 or 1.9? Anyone using those?

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    Re: CV wide on m4/3?

    The only lens CV WA lens I see a point in using is the 12mm. The 15mm can work, also if some smearing problems has been mentioned here, I have seen nice images taken with it.

    But, what do you gain with the longer than 12mm compared to use the kit zoom? Tactical feeling, prefocusing? IQ, no I doubt that.

    I have seen wonderful images taken with the 12mm and 4/3 cameras.

    /Jonas

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    Re: CV wide on m4/3?

    Quote Originally Posted by aleksanderpolo View Post
    Thanks, so even 25mm have problem? How about 28mm f2 or 1.9? Anyone using those?
    The CV 28/2 Ultron has a border/corner smearing problem. The CV28/1.9 is reported to work much better also if not totally flawless.

    /Jonas

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    Super Moderator Cindy Flood's Avatar
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    Re: CV wide on m4/3?

    Quote Originally Posted by Jonas View Post
    The CV 28/2 Ultron has a border/corner smearing problem. The CV28/1.9 is reported to work much better also if not totally flawless.

    /Jonas
    I use the CV 28 f/1.9 and am happy with the results.

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    Senior Member aleksanderpolo's Avatar
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    Re: CV wide on m4/3?

    Jonas, did you experience the CV 28/2 problem or do you remember the source that state the problem? I am interested in 28/2 but not sure why 28/1.9 is better? Do they have different rear element->sensor distance?

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    Re: CV wide on m4/3?

    aleksanderpolo,

    The CV28/2 is an oddball. There is something in the way it draws that is very pleasing to my eyes; the OOF areas and the transitions (or how it should be described) are great. I wasn't very impressed with absolute resolution, or "sharpness wide open". There may be sample variations though as some describe it as very sharp. Anyway, that isn't the most important feature of a lens in my opinion.

    The build quality is excellent, the handling good and the size is fine for our small cameras. The corner/border smearing is pronounced at f/2 and f/2.8, clears somewhat at f/4 and is fine for most work at f/5.6. That may or may not be of importance for you. To me it was a bummer. I hoped the lens should work as a sort of trusty work horse, suitable for snaps and demanding works, just as a traditional 50mm normal lens also if somewhat on the long side.

    There is a focus shift problem with the lens. That doesn't matter a lot provided you adjust the focus after having set the aperture. For use with a rangefinder camera that is a bigger problem.

    After having seen several excellent images from this lens I bought it new. That was good as the store accepted a return.

    I haven't used the CV28/1.9, there I just trust reports saying it is good.

    There are obvious construction differences between these lenses and I think the smear problem is due to the exit pupil distances.

    Here are two samples from a test series with the CV28/2:

    and


    Try to get hold of a copy you can try for yourself. It may well be worth it depending on your needs.

    regards,

    /Jonas

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    Senior Member aleksanderpolo's Avatar
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    Re: CV wide on m4/3?

    Hi Jonas,

    Thank you so much for your detailed explanation. I am surprised that the edge smearing is so pronounced. Wonder if this is a bad copy as I've heard that 28/2 is sharper than 28/1.9, which might/might not be relevant to the smearing.

    Anyway, it's quite a bummer. I supposed if Sony comes out with a APSC mirrorless, the corner smearing problem with other M lens might be even more serious...

    By the way, I wonder if the LTM vs M mount have something to do with rear element->sensor distance difference? I cannot find that info on cameraquest though, wonder if anyone measured it?

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    Super Moderator Cindy Flood's Avatar
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    Re: CV wide on m4/3?

    Carl (scho) and I both have good copies of the 28 f/1.9. My copy is sharp on my M8 and on my G1's. I also can do IR on the M8 with it because there is no hot-spot.
    I think it is a sleeper bargain. You can find them for much less than the f/2 version. YMMV!

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    Senior Member aleksanderpolo's Avatar
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    Re: CV wide on m4/3?

    Thank you Cindy for your recommendation.

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    Re: CV wide on m4/3?

    I concur, that 28/1.9 has better corner performance on m4/3 than 28/2. (but slightly larger/heavier and has a bit less contrast, which could be a plus, for those who like more details)

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    Senior Member biglouis's Avatar
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    Re: CV wide on m4/3?

    My first test shots with the CV15 on the GF1 showed 'smearing' and until I read this thread I assumed that this was me not the camera. Some were a lot sharper and I assume these are shots where I stopped down to f8.

    The CV15 works best on film and my M8 up to f5.6 - seems odd to me that it requires higher stopping down on a GF1 but I'd be delighted if someone can explain why.

    I've also used my Leica 28/2.8 and 50/2.8 and the results are spectacular.

    So, is the smearing a function of the lens design (e.g. CV vs Leica) or the aperture, e.g. the wider you go the more chance of smearing?

    LouisB

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    Re: CV wide on m4/3?

    Quote Originally Posted by biglouis View Post
    So, is the smearing a function of the lens design (e.g. CV vs Leica) or the aperture, e.g. the wider you go the more chance of smearing?
    I think it's a combination of lens design and the aperture. I tried a Zeiss ZM Biogon 25/2.8 which showed lots of smearing at the wider apertures while the Biogon 35/2 was a lot better even at f2. Not perfect, but usable even wide open.

    -Thomas

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    Senior Member aleksanderpolo's Avatar
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    Re: CV wide on m4/3?

    From my reading of the issue it seem to be related to the angle of light striking the sensor (or the filter in front of it), which is affected by the following factors:

    1. The distance between the rear element and the sensor.
    2. The diameter of the rear element.
    3. The aperture.

    It is quite curious to see a reported difference between CV 28/1.9 LTM vs CV 28/2 M, I suspected that the 28/2 has the rear element closer to the sensor, but I don't have them so I cannot take any actual measurement... The photo on cameraquest seems to be in agreement with this...

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    Re: CV wide on m4/3?

    Quote Originally Posted by biglouis View Post
    So, is the smearing a function of the lens design (e.g. CV vs Leica) or the aperture, e.g. the wider you go the more chance of smearing?

    LouisB

    The smearing and vignetting can be blamed on sensor and lens design.
    Smearing appears when Angle of Incidence is too high, which happens when Exit Pupil is located too close to the sensor.
    The solution: You can stop down aperture, thus making the light fall under a lees steep angle. And/or you can try taking more pictures at closer focusing distances which will move the Exit pupil away from sensor.

    But in long run, we should expect the manufacturers to improve the sensors, so they can take the light under extreme angles (more less like film, Leica M9 has it, the others will follow once the cost is down) That is the reason we don't see really fast primes from Oly and Pana today, because the sensor is not there yet.

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