Hasselblad 80mm 2.8 CF T* Bokeh

Discussion in 'Medium Format' started by martinangus, Nov 20, 2011.

  1. As I am still getting to know my new (old) hasselblad 500cm I just discovered a real difference between normal lenses. I was doing a shoot-out against my Nikon D2X with a AF-S Nikkor 35mm 1:1.8G DX ( a lens that I have much respect for). Same speed and aperture...same tripod, same everything except the Nikon chose the white balance in auto mode. ISO160 for both and Portra NC film scanned on a Epson V500.
    I printed this out onto a 19X13 sheet and the hassy is sharper (not a shock)....but check out that bokeh!!
    00ZdIf-417371684.jpg
     
  2. Ok, first the depth of field is so different between the two photos, it can't be compared. Second, Zeiss lenses are famous for having a harsh bokeh and your example shows it.
     
  3. I think that you are seeing and commenting on depth of field, (more limited with the medium format's longer normal lens),
    not bokeh.
     
  4. Ok, first the depth of field is so different between the two photos, it can't be compared. Second, Zeiss lenses are famous for having a harsh bokeh and your example shows it.​
    Sure, you can compare them! Martin just did! I think that while Zeiss bokeh may not be everyone's cup of tea, bokeh is nevertheless subjective. A favorable thing we can say about the Hasselblad shot is that it gives 3D "pop" to the foreground details. In the Nikon shot, those same details are (literally) lost in the woods!
     
  5. (Hmmmm, I guess another medium vs small format DoF debate... )
    In my experience, the sharpest the lens the worst bokeh, and good bokeh belong to softer lenses. This specially applies to current or modern ones.
    I`d say your Hasselblad pic show a very similar bokeh to fast "standard" Nikkors.
     
  6. You can get roughly the same background blurring if you open up the APS-C lens two stops compared to what you shot the 'blad at. You may want to get the Sigma 30/1.4, though, if you shoot the 'blad wide open. Comparing at the same f stop is problematic, because when you went to a shorter focal length to keep the FoV the same on the smaller format camera, your DoF increased by the square of the ratio of the focal lengths.
    Which is to say, that this is a problematic comparison, since it doesn't reflect what a technically knowledgable photographer would get with the smaller format camera. Larger formats can have advantages for this sort of shallow-DoF work, but it's nowhere near as enormous as this comparison implies.
     
  7. If you did another test, with the Nikon 35mm at f1.8 and the Hasselblad 80mm at f4, you would have the same linear aperture diameter (~20mm in both cases: 35 divided by 1.8 and 80 divided by 4), and so the same focus falloff with distance. Then you would be in a position to compare the quality of the bokeh from each lens. Unfortunately, the non-circular iris of the stopped-down 80mm lens would then become a factor as well.
     
  8. For a true final effect comparison, the 80mm Hasselblad lens should be compared with the same focal length in medium-format, or a 50mm lens in 35mm format, with both/all at the same aperture, eg f2.8, and printed to same print / on-screen format. Some of the Zeiss lenses do have harsh Bokeh, and some Mamiya lenses are absolutely awful, however were you to use a Zeiss 120mm S-Planar / Macro-Panar, at full aperture, or indeed the 250mm Sonnar the Bokeh can be beautifully soft. Focal length, aperture, distance between subject in focus and the background all have a bearing on the softness of background. There are some lenses with superb out-of-focus regions, at all apertures, such as certain Leica 35mm Summicron, the Summaron, (to name just a few of the Leitz line up) .. in large format, the Schneider Tele Xenar, and Arton, and the Cooke Portrait PS945 Lens are excellent. Most of the best have many more iris blades than the 5 of the 80mm Planar, and the bulk of the run-of-the-mill lenses for 35mm cameras. I don't like to see those pentagon shaped highlights, so I try to avoid them.
     
  9. The above photos confirm what I dislike about digital color: the presence of too much yellow, which makes greenery look fake. Even worse with grass.
    What ever happened to the color green?
     
  10. Rob, you can compare APS to medium format, but it is completely meaningless. You might as well compare a car stereo to turkey sandwiches, for all the enlightenment that it provides. Second, "bokeh" doesn't refer to the amount of out-of-focus rendering, but the quality of the out-of-focus rendering. Of course a 35mm lens and 80mm lens are going to have different depths of field, especially if you're comparing them to different formats with widely different circle of confusion. The OP needs to use a DOF calculator like this:
    http://www.dofmaster.com/dofjs.html
    To preserve the same depth of field for it to be at least the tiniest bit valid.
    Scott, there is no such thing as "digital color;" the OP got the white balance wrong. Besides having color temperature and tint settings for white balance, there's hue, saturation, luminance, selective saturation, etc. I could just as easily mess up an analog print by using the incorrect film, or as the OP scanned the film into his computer before uploading, he could have just as easily adjusted the color (he in fact did do this, it's just that he let the computer do it automatically instead of realizing that he had any control over it). I put it in photoshop, and within 15 seconds used the Curves tool to get the color in the neighborhood. Not perfect, but worlds better than what someone who posts a "35mm vs 80mm bokeh test, both at the same aperture and on completely different formats" has done.
    00ZdcO-417691584.jpg
     
  11. "...as the OP scanned the film into his computer before uploading, he could have just as easily adjusted the color (he in fact did do this, it's just that he let the computer do it automatically instead of realizing that he had any control over it). I put it in photoshop, and within 15 seconds used the Curves tool to get the color in the neighborhood. Not perfect, but worlds better than what someone who posts a "35mm vs 80mm bokeh test, both at the same aperture and on completely different formats" has done."

    Ariel, I take offense to your words and tone. "instead of realizing he had any control over it" - how arrogant!
    35mm on DX and 80mm on MF are a comparsion of "normals".
    The point was to compare the "pictures" produced by normal lenses from the two different formats. The original post was simply an observation regarding the difference in bokeh.
    Anyone who says something cannot be compared has perhaps forgotten why we press the shutter button... to make a picture.
     
  12. Martin: You'd do better to listen to what people are saying (which is that you haven't made a valid comparison) and learn something than to take offense.
     
  13. David, you are wrong....but thanks for the fatherly advice.
     
  14. Martin, while 35mm on DX and 80mm on MF are both normal, you didn't take DOF changes into consideration. While both lenses at the same aperture will give the same exposure, they will give wildly different depths of field. APS needs to be opened up about 2.5-3 stops more than the 6x6 lens to give comparable depth of field. Look at your photos! Look at the obviously completely different depth of field! How do you figure that it's a valid test at all, comparing a 35mm lens and an 80mm lens at the SAME aperture? Do you realize little enough about photography that you don't know that a longer focal length will have a shallower depth of field, given two lenses that are otherwise set identically? Use a depth of field calculator as an example, and let's say that you focused 5 feet away a f/4, both lenses:
    http://www.dofmaster.com/dofjs.html
    The Hasselblad has a depth of field of 0.4 feet, while the Nikon has over double that, at 1 foot. Now, set the focus to 10 feet away, and the Hasselblad now has a DOF of 1.7 ft., compared to the Nikon's 4.1 ft. Smaller formats inherently have a deeper depth of field for the same angle of view, due to two things:
    -You are using wider angle lenses to capture the same scene, and wider lenses have a deeper depth of field
    -the circle of confusion is smaller for smaller format film/sensors. APS has a CoC about 3 times smaller than 6x6
    And again: bokeh does NOT AT ALL refer to the AMOUNT of out of focus rendition. It refers to the QUALITY of out of focus rendition. There is no such thing as "more" or "less" bokeh. Bokeh is how the out-of-focus specular highlights are rendered, the quality and description of them. Since you have such wildly different depths of field in your shots, you cannot draw any solid conclusions between the two photographs with any sort of certainty. In fact, you seem to be confusing "shallow depth of field" with "bokeh." In addition, regarding the color, by choosing Porta NC film, you effectively consciously selected a white balance for the Hasselblad, since Porta is a daylight-balanced film. However, you failed to set a white balance for your D2x, leading to a yellow cast.
    I stand by my previous statement. While you do have a comparison, it isn't a sensical or a valid comparison. I might just as well compare my dining room table to a pair of running shorts: the the running shorts are better than my table, because when I'm working out, my table doesn't help keep me cooler and dryer than without it. Or, I could claim that I am faster than my girlfriend, because I just went and ran around the block, and beat her, even though she is laying in bed and reading, not racing me. David Littleboy, Ray Butler, and Kevin Parratt understand what is being compared here; go read their posts carefully, and take them to heart. Think about what's being said, because what you have "compared" is meaningless. If you have any confusion about any of the terms that I mentioned, a few creative search terms in this forum's search, along with google, should clear everything up.
     
  15. Medium format is about 4x larger than 35mm. Therefore you need to stop down at least 2 stops more(smaller) than 35mm, for similar depth of field. Personally the Hasselblad with film blows the Nikon away in color and "look"".
    I am not a fan of Hasselblad, having had too much trouble focusing. Used Pentax 6x7, Mamiya in TLR and SLR. I kept the Rollie 'cause of the many aperture blades in the simple Tessar.
    The Zeiss Lenses are unmatched by any other medium system.
     
  16. And again: bokeh does NOT AT ALL refer to the AMOUNT of out of focus rendition. It refers to the QUALITY of out of focus rendition. There is no such thing as "more" or "less" bokeh. Bokeh is how the out-of-focus specular highlights are rendered, the quality and description of them.​
    Ariel...are you saying that a perfectly clear image with huge DOF (f64?) can have wonderful bokeh? I don't think the general photography enthusiast would agree that "quantity" (or the lens' ability to differentiate in/out of focus regions) is not a factor in favoring one lens over another when trying to achieve a creamy background blend!
    I prefer the following definition of bokeh (to yours that states quantity or degree of out-of-focus is not a factor in bokeh): Bokeh, the quality of the out-of-focus image, is determined by the circles of confusion characteristic of the lens, its aperture and how far out-of-focus it is.
    In practical terms, the image comparison I provided unquestionably illustrates the ultimate bogie of using bokeh in an image: to emphasize the intended subject in an artistic and subjective manner.
    I still disagree that this comparison lacks merit. If I wanted to factor the different depths of field as an artistic element of "bokeh", this image provides me direction as to which lens/camera I might choose.
    One closing comment - I have no issue with using this forum to learn. This is why I made the original post. I do object to snot-nosed superior-than-thou comments that attack as a means of self gratification. Keep it clinical and lose the personal judgements and we will all keep focused on the sharing and learning rather than the crap.
     
  17. IMHO, if you include the "how far OOF" in your bokeh definition, similar (if not equal) conditions should be considered.
    If not, the comparison is unfair; you are not comparing the very same thing. In this case; you are only showing that the ammount of background blur is greater on the picture at left. DoF is shallower here. Then any larger format lens, even the very worst ones will have "better" bokeh.
    We can compare a 50/1.5 Contax Sonnar to a 50/1.4 Nikkor. Or even your 80 Planar to the 100 Planar. If we compare my 125cc scooter to my 1200cc BMW motorbike, we can say the scooter engine is better, it has almost half fuel compsumption. But is has less than one-tenth horsepower; the BMW is way more efficient.
    Once the equivalent settings have been achieved, you can do a comparison with the parameters you mention: the ammount of blur, the shape of the spots, etc.
     
  18. And in the opposite, if you`re refering to pictures, -and not comparing lenses-, you can use then the term bokeh in whatever conditions, in its most subjective interpretation. That`s the way I understand it.
     
  19. No, a perfectly clear image with huge DOF doesn't have ANY bokeh, because it doesn't have ANY out-of-focus rendition or specular highlights. Read your own definition of bokeh. Your definition states that bokeh is "quality of the out-of-focus image." While how far out of focus a photo is CAUSES bokeh, being far out of focus is not CONSIDERED bokeh. Moreover, you COMPLETELY failed to take the circles of confusion characteristic of the lens into account, because you stopped a 6x6 lens and a DX lens down to the same aperture, despite them both giving the same field of view on their respective formats, and you then trumpeted the superiority of medium format for a shallower depth of field (which you called superior bokeh, even though again, even by your definition, you don't have MORE or LESS bokeh, just BETTER or WORSE bokeh). You can't even compare quality between the two images because you've blurred the background to different amounts, and since, again by your definition, not mine, bokeh is "quality of the out-of-focus image," you can't compare quality if you have one image that's further out of focus AND has a 3 times larger circle of confusion. With both of those criteria for comparing bokeh missing from your test, I hope you'll concede that your test is flawed.
    Although, as the Hasselblad stands on it's own, it has horrible bokeh, completely busy and distracting. Look at the twig shapes still visible in the bottom center of the image, just under the darker vine! First, do you understand that a longer lens has a shallower depth of field? Because if you really think about that, you'll understand why your test doesn't show you anything meaningful. All your test showed is that using a shallow depth of field isolates a subject. It doesn't show anything meaningful whatsoever as to the comparative abilities of the different formats or the different lenses. Realize that the comparative lenses for 35mm photography open up much wider than the medium format lenses. Compare your 80mm f/2.8 to a proper large aperture lens like the 35mm f/1.4, both shot wide open, and see who comes out ahead when you have both image with the backgrounds thrown out of focus to the same amount. Why are you comparing two lenses when you're stopping one down more than the other, how do you view that as fair? Nikon also has a 50mm f/1.2, 85mm f/1.4, 135mm f/2, and 200mm f/2. Compare any of those lenses wide open to account for the circles of confusion, and you'll find no difference in depth of field against the medium format lenses that give the same angle of view.
    I could do a test converse to yours, stop both a 135 lens and a MF lens of equal angle of view down to f/8 for a landscape shot, and then trumpet around that the 135 lens is better for landscape photography. I really really hope that you see why this is a completely flawed argument; I hope you don't believe that 35mm is better than medium format for landscape.
     
  20. The Zeiss Lenses are unmatched by any other medium system.
    My Mamiya 6 lenses are just as sharp and have less distortion (as in 0).
    Ariel,
    My observation of poor color accuracy with greenery is from simply looking at thousands of posted photos. Most photographers, then, would seem to be using incorrect white balance. My Pentax k20d showed a strong bias towards yellow, and I had to remove about 30 units in PS. It just seems to me that the issue is so prevalent that florescent green become accepted. Let's face it--the modern photographer is not interested in the accuracy of Portra films. Even Velvia looks more accurate to me.
    Scott
     
  21. Ariel correctly states:
    ... bokeh does NOT AT ALL refer to the AMOUNT of out of focus rendition. It refers to the QUALITY of out of focus rendition. There is no such thing as "more" or "less" bokeh. Bokeh is how the out-of-focus specular highlights are rendered, the quality and description of them. Since you have such wildly different depths of field in your shots, you cannot draw any solid conclusions between the two photographs with any sort of certainty. In fact, you seem to be confusing "shallow depth of field" with "bokeh."​
    That's it in a nut shell.
    again ,,,
    It refers to the QUALITY of out of focus rendition. There is no such thing as "more" or "less" bokeh.​
    It refers to the quality of the out of focus regions in a real photograph, as rendered by the lens. Discussions, magazine articles, reviews, an appreciation of this subject was already highly developed in Japan several decades ago, whilst the amateur photography band waggons of America were completely obsessed with sharpness. In 1997 a Leica photographer friend sent me a copy of Photo Techniques containing an article, a very informative article, with the introduction of the term Bokeh, and what it was about in the context of that Japanese awareness. Not only did it enhance my own appreciation of lens designs, I bought a subscription to the magazine.
    And now we have all the "photo editing" programs, faking one quality after another, hijacking terminology and defecating everywhere. It's no wonder there is confusion and obscurity of the real.
    Some of this may help.
     
  22. Even the Wikipedia article I link to above goes off the track, taking the word "Bokeh" out of context of the Japanese discussion, an aesthetic appreciation of camera optics, with specific reference to all of the regions of an image, before and behind the plane of focus. It is not about how much blur is obtained by opening up the aperture, let alone what effects are simulated in graphics software.
    As for pronunciation, there is no need for argument. It is a Japanese word, so listen to how a native Japanese person says it.
    Wikipedia is of course 'open source', so is subject to the democracy of errors. As for Youtube, with no verification of source required at all, a new trendy term is picked up, misused, spreads like a disease and becomes implanted in the market place. To illustrate the disease effect, read down here to find a graphics feature named "Bokeh Depth of Field". At least the author does seem to know something of the origins.
    Have fun ... good bye
    00Ze0s-418301684.jpg
     
  23. [/flame war] Martin: What is it about the Hasselblad bokeh that you didn't like? Is it that the major outlines, such as that one tree trunk, have retained their edges too much?
     
  24. [/flame war] Martin: What is it about the Hasselblad bokeh that you didn't like? Is it that the major outlines, such as that one tree trunk, have retained their edges too much?
     
  25. Not to rekindle the flame war, but it has to be understood that the quality of the blur indeed depends a lot on whether the blur is blur to begin with, i.e. on the amount of blur as well as how blur is rendered by the lens. The more there is, the more clear it can display it's full character.<br>As such, the Hasselblad image shows ample opportunity to judge its Bokeh, while the Nikon image barely gives us a chance to guess at its Bokeh.<br>It's like rain. A little rain (a drop or two) is wet. But not as wet as a monsoon shower. Yet wetness of water is a quality that doesn't come in more or less varieties.<br><Br>Having said that, Rob's question is the far more interesting one: what is it about the Bokeh that you like or dislike?
     
  26. No flames here, nor fear of burning. I not only studied the articles, in fact there were three on the subject published in Photo Techniques, but a year or two later, lunched with a Japanese friend in London who translated a lens review in a Japanese magazine, which in his summary, read almost like a wine tasting critique. As with wines, there is an established vocabulary on the subject of lens Bokeh. "Blur" is, in varying degrees, only one of many characteristics. I have managed to track down one of the three articles. Here is a link to a free download in PDF form. The others are not available online.
    A Technical View of Bokeh by Harald Merklinger - as published in Photo Techniques May/June 1997
     
  27. There is a vocabulary, but that doesn't necessarily mean that people talking the lingo also understand what they are talking about. ;-)
    (Mind you, i'm not necessarily implying that anyone here does not ;-) ).

    Blur is the deciding factor in bokeh. So much so that's it not even a factor.
    Without blur, without an out-of-focus image there is no quality of the out-of-focus image.
    See?

    And it's a matter of degree: the more the image is out of focus, the more we get to see bokeh, being the quality of the out-of-focus image.

    So do understand, anyone who wants to consider and discus bokeh, that blur is definitely not "only one of many characteristics".
    It's the substrate, the very substance other characteristics that may or not be considered to be part of bokeh are characteristics of.
     
  28. The articles are obviously wasted on you Q.G. de Bakker, so here is something more on your level.
    00ZeN8-418787584.jpg
     
  29. :)<br><br>Yet, seeing your "only one of many" goof, you had better spent your time trying to understand the articles yourself.<br>But it's never too late, so while you do, i'm sure i'll find a good use for your kind present.<br><br>Seriously, what is it with some PNetters that they, when presented with explanations that address the issue at hand, instead of dealing with the relevant bits find it better to play the "i think you are like me, though i don't think i'm like me myself"-card?<br>Can't be that self confessed learned people like you do not grasp the simple concepts they are presented with in a easily understandable fashion. So what else?
     
  30. How sweet! A "hassifyer!" LOL!
    Many thanks to all of you for the 2011 PhotoNet info & entertainment.
     
  31. And it's a matter of degree: the more the image is out of focus, the more we get to see bokeh, being the quality of the out-of-focus image.​
    Actually Q.G., the more the image is out of focus, the more that the niceties of bokeh are lost, and the more that different lenses will all start to look alike in their oof rendering. When you trace rays at larger intrafocal and extrafocal planes, the disk of light becomes more uniform, even if at small degrees of defocus it was very lacking in uniformity and had the characteristics of particularly "good" or "bad" bokeh.
    It is for this reason that when "star-testing" an optic like a telescope or telephoto lens, the star image must only be racked a few waves either side of focus. Defocus by too much, and both the uniformity and symmetry (similarity of appearance on both sides of focus) improve, giving you get the false impression that the lens or mirror is better than it actually is. This is the bible for star-testing: http://www.willbell.com/tm/tm5.htm
    Here is a simulation I did in Aberrator of an optic with a small amount (1/4 wave) of spherical aberration. At 1 wave of defocus, the intra-and extra-focal images are strikingly different:
    [​IMG]
    At 8 waves of defocus, the intra-and extra-focal images are starting to look more alike. The left is what we expect to cause good bokeh (pretty uniform disk, light slightly brighter in the middle than the outside, outermost ring getting fainter and softly rolling off), and the right is what we expect to cause bad bokeh (the outermost ring is brighter than any of the others and the centre, and is relatively hard-edged).
    [​IMG]
    Finally, at 40 waves of defocus - the sort of regime where photographers clearly see background bokeh - they are quite hard to distinguish. Now both left and right would lead to a conclusion of pretty neutral bokeh.
    [​IMG]
    [This is actually a very good optic: as a telescope it meets the minimum definition for diffraction-limited, and as a photographic objective it would be absolutely outstanding in the plane of focus. More typical objectives have higher aberration, which I can simulate, but not to the same relative degree of oof comparison].
    The point being again: too much defocus blur and all lenses start to look alike in their bokeh; all converge towards "neutral". The really, really "bad" bokeh examples may never 'get there' within the range of defocus in a typical photographic subject, but wads of defocus does help them to look their best.
     
  32. Ray,<br><br>What you are saying is that there comes a point when all blur looks alike, where bokeh is equalized.<br>And i can agree with that (to a degree: change the aperture shape, the shape of the diffraction pattern, and the amount of blur will not equalize the end results across all shapes).<br><br>The part that's relevant to photographers, though, is what happens before. That's where the differences are.<br>It's quite a bit like saying that the quality of rain, the differences in character between showers (a mild spring shower vs. a monsoon downpour, for instance), disappears into one Big Uniform Wetness once it rains so hard that here's no air left in between drops<br>It's true enough. But what does it say about those showers?<br><br>So what you have correctly established is that bokeh is found between the (ideally) sharp image (exclusive limit) and the point where one blur becomes indistuiguishable from another (inclusive other limit).<br>One can argue that whether just unsharp, rather unsharp, or very unsharp, there's always a quality of the unsharp image to talk about. And that's true. But that does not mean that - as was argued before by some - the amount of blur, the amount of what the thing is a quality of, does not make a difference. Your simulation demonstrates that just fine.
     
  33. We didn't say that the amount of blur doesn't make a difference. We said that the amount of blur CAUSES bokeh and changes its qualities, because the OP was claiming that having a smaller depth of field was CHARACTERISTIC of good bokeh, and that having defocus in and of itself WAS bokeh, which is not true. He was wildly defocusing the background with the medium format camera, and then claiming that the bokeh was better than a 35mm camera stopped down to increase the depth of field. Go back and re-read; look at the original post and the image posted.
     
  34. It's important to remember that (as you too mention) the amount of blur does not just 'cause' bokeh, it does so in varying degrees. Just as a smell changes the more there is of the stuff that gives off that smell.<br>It's of course not correct that having more or less DoF is a characteristic of good (!) bokeh. But bokeh changes with the amount of blur.<br><br>Saying that the difference between a 'stopped down' image and a 'wide open' image is not also a difference in bokeh would be more wrong than saying that just having less DoF equals good bokeh.<br>The latter could be true, is a matter of judgement. Something that is said about the quality of the out of focus image.<br>The first is never true.<br><br>Since you do indeed acknowledge that bokeh changes with the amount of blur, you cannot but also acknowledge that someone who thinks that bokeh is better in the image with less DoF - though you may not agree with the judgement - is not talking nonsense.
     
  35. Again, we didn't say that there wasn't a difference in bokeh in the two images. We just said that the first post wasn't a valid comparison, and didn't tell us anything meaningful about the capability of the two systems in relation to one another, which is what the OP was trying to test. Also, you can absolutely disagree with someone who thinks the bokeh is better in the first image. First, as many people have mentioned, the bokeh in the first image is fairly poor quality. Second, as many have mentioned, and Ray has painstakingly and exhaustively shown just a few posts above, having more defocus masks the bokeh's poor quality. It's no different than the difference between trying to review a small painting from 20 feet away versus 2 feet away.
     
  36. "[...] having more defocus masks the bokeh's poor quality."

    No. It shows how bokeh changes with the amount of blur.
    From something you call poor (and perhaps rightly so) to something that, since you think it masks the previously poor quality of the out of focus image, must be better bokeh (unless you think that what you mistake for a mask is even worse looking).
     
  37. See you later Q.G! Enjoy your pacifier!
     
  38. Since we are talking about the "quality" of bokeh, wouldn't that have a subjective component?
     
  39. The esthetic quality of the quality of the out of focus image is entirely subjective.
     
  40. You might as well compare a car stereo to turkey sandwiches, for all the enlightenment that it provides.​
    Something about this analogy has been bothering me for days. I needed a little time to think about it. It would, of course, make more sense to compare two car stereos and leave the turkey sandwich out of it. But it needs more than that. The two stereos might be compared under different acoustic conditions; they could be installed in two different cars, for example. Then the brand of stereo would be confounded with the acoustics, rendering the comparison difficult to meaningless.
    But I think what it's really like is comparing two different recordings of the same performance of a Beethoven symphony. The recordings are made with two different microphones, and the idea was to compare the soundstage depth captured by the two microphones. The problem is that the two microphones were placed at different distances from the orchestra, which would confound microphone distance with depth capture. If we like one recoding better, we won't know if that's because one mike was a Neumann and the other an RCA or Telefunken, or because of the different microphone placements.
    The importance of ensuring that the two photos were taken at equivalent DOF seems entirely straightforward to me. It's just the analogy that was bothering me.
     
  41. Suppose someone asks you how you like the sound of his Bose hifi set. And suppose you then do indeed have an opinion about it.<br>Suppose that a day later someone else asks you how you like the sound of the cheap stereo in his car. And then too you have no problem forming an opinion.<br>Why would it be difficult, or even impossible, to say you like one better than the other?<br><br>It's not necessary for two things to be just about equal to be able to compare them. On the contrary, the smaller the difference, the more difficult it is to distinguish between them (remember Ray's limit example?)<br>And it's not necessary either to know what the reason behind the differences is: you could say you like the one Beethoven recording better than the other without knowing anything about microphones, microphone placement, etc.<br><br>There's one thing that would make it difficult to compare the Bose set to the car stereo: if you can't hear one of them well enough to form an opinion. That translates too: if one of two images that are to be compared has no out of focus parts, it would be extremely difficult to say something about the quality of the out of focus parts. But as long as they both have recognizable out of focus bits, the esthetic qualities of those can be compared. DoF does not have to be equal in both images.<br><br>If one lens produces good bokeh in parts that are slightly out of focus, that bokeh may change quite dramatacillay when stopping down changes (for instance) the undercorrection of spherical aberrations into an overcorraction. Another lens can show the opposite, have pleasing bokeh when the degree of blur is considerable, but terrible when there's little blur.<br>Why could you not compare the bokeh when the degree of blur is not the same? Would "good bokeh" mean completely different, incomparable things, because the degree of blur at which each lens shows good bokeh is not the same?<br>You of course can, and provided you don't change the basis on which you base your likes or dislikes, a verdict like "good bokeh" means the same in both cases.
     
  42. Q.G., I see nothing wrong with your argument, which speaks to the subjective nature of bokeh (and sound). You like it, or you don't. For example, I have no real problem with the Hasselblad picture or its bokeh; while others do. I was just striving for a better analogy. I decided to stay within the realm of sound, but to get away from sound reproducing in favor of recording. The recording device is analogous to the photographic device: microphone = lens. The playback gear, whether Bose, Pioneer, or Alpine, is the audio analog of the viewing equipment: my iMac vs. your PC/Macbook, etc. In the present example, no one is worried about what their LCD or CRT screen might be doing to the image. It's about the input end of the process, and not the output end: thus, microphones and not stereo sets. And the difference in microphone position I intended to stand for the difference in aperture/DOF in the two pictures.
    OK?
     
  43. Absolutely, Rob.<br>Just wanted to get rid of the idea that bokeh in both images could not be compared because DoF in one is not the same as in the other.<br><br>By the way, how do you like the overly dramatic new word "dramatacillay"? I must have been "overcorracting" something or other. That, or it's proof that it's just idle to still harbour hopes that one day, i could learn to use a keyboard. Just too late. ;-)
     
  44. My spelling would be worse than that if I didn't have a spell checker. Spell checkers can be humbling for those of us who thought we were good spellers.
     
  45. My spelling would be worse than that if I didn't have a spell checker. Spell checkers can be humbling for those of us who thought we were good spellers.
     
  46. Thanks for the info, Q.G! I think I am following your logic and have to agree, especially about the subjective nature. Ray Butler - excellent stuff! I have been fiddling with some older telescopes and your info is useful! Thanks! Time to head outside to a crispy, cold clear night sky! It's going to be be brisk! Don't forget lunar eclipse on Dec 10.
     
  47. Ray Butler - excellent stuff! I have been fiddling with some older telescopes and your info is useful! Thanks! Time to head outside to a crispy, cold clear night sky! It's going to be be brisk! Don't forget lunar eclipse on Dec 10.​
    You're very welcome, Jeff. Nice to know that there are other people here with a dual-interest in astronomy and medium format photography!
     

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