Interesting find on OOF: 35 lux pre- vs. asph comparison @ f/1.7

Discussion in 'Leica and Rangefinders' started by lutz, Jun 14, 2002.

  1. Hi there,
    Just had a couple of test slides back. I did a side to side comparison at various f-stops of my 35 lux asph with a 35 lux pre-asph which I intend to buy. To my surprise the two lenses show quite a different OOF signature. At identical f-stops the OOF areas of the pre- asph look visibly *sharper* than those of the asph, which appear much more blurred! I'm attaching two samples taken at f/1.7. Have a close look at the poster on the wall, for instance...
    Even if in this case there might be a very slight difference in the subject-to-camera distance from one shot to the other, the phenomenon is identical in a number of shots I've taken with the tripod (of less interesting subjects). And it is consistent from f/1.4 thru 16. Has any of you ever experienced this before? I would have bet, that if at all, it would have been the other way round, as I was looking for a pre-asph 35 lux because of its proverbial "glow".
    Now, what is this? A practical example of better bokeh in the asph...? Comments welcome. Cheers.
    http://www.konermann.net/
    35.lux.comp.29.(pre-asph).jpeg
    above: 35 lux pre-asph @ f/1.7 - below: 35 lux asph @ f/1.7
    [​IMG]
     
  2. Yes the Asph Lux is well known for bokeh which is slightly on the
    harsh side at times. It varies significantly depending on aperture
    and focused distance. However you can also notice how much
    sharper it is even on a 100k jpg!

    The only way you will get mine is to pry it out of my cold dead
    hands...
     
  3. Thanks Lutz,
    Can you or anyone tell me how much a pre 35 lux, boxed, mint goes for?
     
  4. Sorry John C. but (apart from the bokeh) I can not detect any difference in the sharpness between these 2 pictures. IMHO it would have needed a little fill-in flash though.
     
  5. Frank, as I was comparing the lenses for flare resistance in backlit situations flashing was no issue at that time and for that purpose. BTW, I like the shady mood.<P>As for the sharpness issue, I, too, find the two lenses surprisingly close @ f/1.7(!) - no argument to really justify a price difference of $1000 between a new asph and an excellent pre-asph.<P>Expect to pay $750 for a mintish pre-asph, though, John. An original shade easily accounts for another $100, boxes are for collectors.<P>Any comment on the OOF issue?
     
  6. Check out the OOF white spots on the hill. In the case of the Asph, they appear to have a darker centre. Although the overall effect is that of a more blurry background, you can see some of the double image, jaggie artifacts the bokeh causes. Look again, at the transmission tower blur on top of the hill.

    I am willing to concede that I may be talking through my hat, of course !

    :-D
     
  7. Hi, Mani. Even thru your hat I can read you clearly...;o) Nevertheless, the donut effect is there in the pre-asph OOF, too. Only are the donuts smaller in size - which is exactly what I was surprised by. <P>Donut=bonut or badnut, bokehwise? (You can leave your hat on...) LOL
     
  8. Lutz, I can see exactly what you're talking about even on the web.
    The slight difference could be attributed to a slightly different
    focus point... as well as a slight shift in lighting conditions. To
    really test your notion, you should set up a constant situation in
    constant light. Plus, it is possible you have an exceptional non
    ASPH 35. I had one like that once. I had no clue what people
    were talking about when they went on about the "glow". It was as
    sharp and contrasty as my 50/2.
     
  9. Hey Lutz, what a funny comparison. Many years ago I owned a pre ASPH summilux 35 mm but I don't remember its look. Meanwhile I use a 35/1.4 ASPH - very often at f1.4 or f2.8.Until today I never thought about how different the pics of both lenses are. Very interesting. Nevertheless, I prefer the new 'lux and my little gem - a pre ASPH Summicron :)

    Frank Thoma
     
  10. Frank, I owned the pre-asph lux twice before... and should never have sold either of them. There WAS that special glow to it, at least @ 1.4 and 1.7 - but I can't detect it with the sample I'm testing. I was considering getting my third sample (yeah, I'm totally obsessed, I confess...) to regain that special quality for special purposes. Tell me more about your pr-asph cron gem, from addict to addict...;o)
     
  11. Hi Lutz,

    A thought. If all things are equal then is it possible that the 1.7 on the pre-ASPH is not a true 1.7 but more like a 2?

    I have a pre-ASPH 35 lux and at 1.4 to about 2 it is on the soft side. All reports say that the 35/1.4 ASPH is a vast impovement over the old non-ASPH.

    My pre-ASPH 35/1.4 flares like the Fourth of July. I love its glow, however. My 35/2 ASPH is a great little lens--perfect--but does not glow. It is literal and unmerciful.

    I don't know what to say about your two pictures. What you say is true. Why it is true may be quite enlightening.

    Best,

    Alex
     
  12. ... I owned the pre-asph lux twice before...

    Lutz, I know what you are talking about. When I left fotoMAGAZIN seven years ago I made myself a little present: Bought a (used) M6, a 35/2 and a 90/2.8 from the Leica academy in Solms - just to complete my SLR equippment. In 2001 I sold the well used Canadian made 35 mm Summicron just to buy a german made 35 in mint condition some weeks ago. That's crazy, isn't it? I think that's true Leica-Lunism... :)
    Meanwhile I have a bunch of M-lenses and four bodies, but the strangest thing is: I use them all.

    Best regards

    Frank
     
  13. hi lutz, what version 35' slux do you have. the 1st version (ollux
    hood) or the second version (seven series filter). At a guess I'd
    say you had a 2nd version or later, as there is little light fall off in
    the top right and lower corners. cheers,
     
  14. Hmn, I like the pre-asph bokeh better. Seems like a higher performing lens since you have bokeh, but less blurred. Although it seems the cellist looks crisper in the bottom photo. As said before, hard to tell on a jpg. Thanks for the comparison!
     
  15. yeh, i agree wit'cha. the pre has a cleaner more natural look. the
    asph seem to be too contrasty and the blend from sharp to OOF
    seems to be over exaggerated. JMHO <shrug shoulders>
     
  16. Spearhead

    Spearhead Moderator

    This looks like a big difference in DOF. Are you sure the older lens is stopping down completely? That difference would seem to be confirmed by some difference in exposure also.
     
  17. IMHO it would have needed a little fill-in flash though.

    um, no. fill-in flash would have killed the mood.
     
  18. I hate to burst everybody's Bo-Ke bubble, but here is what I see: It appears to me that the point of focus on the Pre-Asph shot is somewhere between the far edge of the body of the Cello(?) and the edge of the table where the TV is sitting. (If you look at the edge of the instrument and the edge of the table under the TV you can see what I am referring to.) On the Asph shot, it appears the point of focus is somewhere near the crook of the musician's arm. (Sharper appearing than either the edge of the instrument of the edge of the TV table.) If I am in fact seeing this correctly on the jpg's, then IMO, this is more than enough of a difference in POF to create a significantly different DOF profile for the images.

    Furthermore, I agree wholeheartedly with John that the Asph shot appears much sharper. But I also think the shot with the Pre-Asph hasd a very pleasant quality.

    Cheers,
     
  19. Lutz, I think the most reasonable explanation is that despite the markings on the lenses, the two are not set at identical f stops.
     
  20. The point of focus is closer with the Asph. Another test is needed.
     
  21. I don't know how anyone could tell anything about the point of focus from those two images, but I agree with John. The ASPH image appears sharper, but the OOF areas appear less smooth. If you can tell increased sharpness on a Jpeg viewed on a computer screen, you can bet it would be more visible on a projected transparency.

    That said, which image is more pleasing to the eye is still very subjective, and I don't find a large difference between the two in this regard.
     
  22. Im looking at the chrome base of the music stand, and the musicians shoulder to determine point of focus.In the 1st pic the stand is more in focus and the shoulder is out. In the 2nd pic the stand is more out and the shoulder is more in focus as well as the watch.This combined with the really blurry bokeh leads me to believe the Asph was focused closer.
     
  23. About exposition, because of the tv screen I can say time exposure was the same, so I guess f/stop too.

    Three questions Lutz, this preasph you used does the glows wide open as other preasph do?, what serial # is it?; and last, do you know of element edge pain work done in order to improve flare in this lense?
     
  24. Maybe another comparison @ f/1.4 which is what the difference is all about?
    [​IMG]
    taken with the 35mm 'lux ASPH
    [​IMG]
    taken with the 35mm 'lux pre-ASPH
    Comments welcome. Greg
     
  25. N-eerrf! I read half the posts before I realized we were talking 'luxes, not 'crons!

    Nice comparison, Lutz. I CAN see the sharpness/edge-contrast difference - most clearly in the highlights on the woman's hair. The ASPH nails them.

    The places where people are seeing the biggest bokeh differences are near the edges/corners (hill towers, poster, etc.). I think the preASPH's really strong coma (as shown in Greg's (?) picture of kid and Xmas lights) is having a lot of influence - the light rays are going all kinds of weird places and 'roughening/sharpening' the image even when out of focus.

    (How can something 'roughen' and 'sharpen' at the same time? By redistributing the light from a point into a long narrow line - which looks sharper than a perfectly circular blur but also interacts/interferes with the other interlocking 'lines' to form a sort of tic-tac-toe cross-hatching.)

    Coma correction is supposed to be the single biggest 'feature' from all Leica's wide-angle ASPH designs.
     
  26. </CENTER>Hi folks,<P>Just back from the darkroom. Interesting speculations here. Just one thing, first: When I do a comparison, be assured I shoot same stops at same shutter speeds... ;o) BTW, I guess it was 1/500th, as about a tenth of the 50Hz TV screen is visible. <P>
    As the slides are equally dense, I assume 1.7 on the pre (yes, it does step down correctly...) equals 1.7 on the asph. As I wrote before I doubt that any difference in camera to object distance (of a maximum of maybe 3 cm) can be held responsible for the effect in question, IMHO. At this point I must add for the record, that a very valid contribution to this topic has been made off-line by Samuel Dilworth, whom I heartily invite to post here!<P>As for the glow I was looking for - I found some of it in the b&w negs that I just developed. I'm posting a scan of one of them in order for all of you to see what the glow-nuts are talking about...;o) BTW, I never experienced a similar koma like in Greg's pic with any of the three pre-asphs used so far... <P>Roberto, I do not know of any correction been made to this lens, the serial # is 2803324, Canada. Cheers.<P><P>
    <CENTER><IMG SRC="http://www.konermann.net/leaves.dusk.jpeg"><P>
    35 lux pre-asph, f/1.7, 1/60th, Delta 400</CENTER>
     
  27. Nice photo Lutz.
     
  28. Here are the relevant parts of the email I sent Lutz. It's rather longwinded; apologies.

    I saw your bokeh comparison of the pre-ASPH 35mm Summilux with the current ASPH version. I've noticed this phenomenon before, most clearly when comparing shots from my Nikkor primes to those from the Leica equivalents. The Summilux ASPH that seems to have poor bokeh in your example actually produces a much more cohesive background than the Nikkor AI 35mm f/1.4 at identical apertures and distances. I'm sure you know that bokeh refers to the quality of the out-of-focus areas rather than simply the extent to which they are out of focus. Personally, I like the lens to render the background and foreground areas in a style that is smoothly out of focus while maintaining clear legibility. The most obvious differences appear in shots where text is in the background (advertising slogans, for example). The Nikkor renders the text unreadable in situations (aperture and distance) where the Summilux ASPH allows the viewer to quite easily make out the lettering. Clearly the pre-ASPH would provide an even greater improvement over the Nikkor in this regard.

    From my experience, it is clear that these differences are not due to a discrepancy between the indicated f/stop (f/1.4) and the actual f/stop. The pre-ASPH is a genuine f/1.4 (at least at low image heights, i.e., on axis), and this lens is no slower than the ASPH, which in turn is no slower than the Nikkor. They all produce genuine f/1.4 image brightness at the centre (with artificial vignetting and natural light falloff evident to varying degrees at greater image heights). Rather, it is the design of the lenses that causes these differences, and perhaps the position of the aperture stop relative to the lens elements is one influencing factor (among many others that certainly affect bokeh). Some designs result in the physical size of the aperture stop being somewhat different to what the f/stop would indicate (e.g., a 35mm lens at f/1.4 may not have a physical aperture size of 25mm).

    Your sample photos do show evidence to support these facts. The JPEGs are a little small for us to read too much into them, but observe the large difference between the rendition of the picture frame on the right (and the upward-running text on the poster which is only readable in the pre-ASPH image). One might expect the difference to be even greater at farther distances, such as infinity, but in fact the difference remains the same or perhaps even decreases slightly. This indicates that the largest factor responsible for the bokeh difference is the degree to which the lenses corrupt lines or point sources of light in the out-of-focus areas, rather than the actual degree to which they render the image out of focus. Clearly the ASPH causes more corruption of the bokeh.

    By the way, depth of field is computed solely from the numerical specifications of a lens. It would be incorrect to deduce from these images that the pre-ASPH has more depth of field than the ASPH at the same f/stop (they have identical depth of field). In fact the depth of field of a lens is quite discrete from its bokeh characteristics.

    It's interesting to note the huge difference in contrast between the two lenses (at f/1.7, of course). Look how much darker the vertical window frame is in the ASPH image! A silhouette against a brighter background is a critical test of flare resistance, and the pre-ASPH is clearly very much more susceptible to veiling flare than the ASPH. This flare spills over into the music sheets also (to a lesser degree), though the differences are almost undetectable at the area around her shoulder. So although the pre-ASPH does flare seriously, it contains it within a relatively localised area. The apparent slight difference in exposure is probably caused by veiling glare. I see practically no difference in focus point that Jack Flesher comments on, and even if it were true, bokeh is not nearly as sensitive to focal distance as is commonly assumed. Besides, you say you see the effect in other shots. I think it's the extra contrast that makes the ASPH image seem sharper; it's hard to believe one could see a sharpness difference at this image size, though the ASPH image certainly appears a good bit sharper to me.
     

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