Discussion in 'Equipment' started by Sim2, Nov 22, 2009.

NEW GENERATION 35MM LENSES AND THE MEDIUM FORMAT LENS

NEW GENERATION 35MM LENSES AND THE MEDIUM FORMAT LENS

  1. Sim2

    Sim2 Member

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    Sim2 submitted a new resource:

    NEW GENERATION 35MM LENSES AND THE MEDIUM FORMAT LENS - NEW GENERATION 35MM LENSES AND THE MEDIUM FORMAT LENS

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  2. Christopher Walrath

    Christopher Walrath Member

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    Well, I managed to read it all ;p . I will try to pose a couple thoughts for arguement's sake.

    'Consumer' products, are generally the lesser of like. By this I mean that the lower dollar figure attached to an item in a similar line could be considered as 'consumer' rather than 'pro'. Examples might be a Leica RF being a pro item where a Zeiss Ikon RF would be considered consumer. Though this may have been the case, the Zeiss is a fantastic camera with which I have made many great photographs. Another example would be the 35mm SLR systems for Nikon and Minolta in the 70's and early 80's. The Nikon could be considered the 'pro' setup where the Minolta could be condsidered 'consumer'. And some of the best glass out there is Rokkor and Vivitar Series 1 glass. In this vein, I would venture that 'Consumer' is not always merely a step sister to the 'Pro' product.

    I differ in opinion to your assessment of medium format glass at wider apertures. As you say, and I DO agree, without side by side testing it may never be known for certain the varying degrees of effectiveness of each tool in varying mediums. However, MF glass, by and large, performs great at wider apertures, IMO, or else they would not offer MF lenses with apertures wider than an arbitrary f/8.

    A very well thought out and well written article. Thank you for sharing your thoughts with us.
     
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  3. polyglot

    polyglot Member

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    Available DOF for a given perspective depends on the physical aperture diameter; e.g. 50mm f/2 is 25mm (I'm assuming a simple lens here with no pupil magnification). This diameter defines the cone of light coming from each point in the plane of focus and therefore how far out-of-focus things are outside the plane of focus.

    You can take the same (FOV, DOF, duration) photo on different formats of course, assuming a lens can be opened up or stopped down far enough. For simplicity of this example, consider a square crop from whatever size film you're using; all of the following are equivalent images:
    35mm = 24x24mm, 50mm f/2, ISO100, 1/1000s
    6x6 = 55x55mm, 114.5mm f/4.6, ISO525, 1/1000s
    4x5" = 100x100mm, 208mm f/8.3, ISO1730, 1/1000s

    Note that they all have the same field of view (37.5 deg diagonal), same DOF in the final print and the same exposure time therefore the same motion visible. Also note that the ISO in each case is proportional to the film area in use, which is to be expected from conservation of energy (photon count): in each case, you have the same physical aperture collecting the same number of photons from the same field of view. If you make an image k times larger in each dimension, you spread the photons k^2 thinner on the film and require a k^2 higher sensitivity to get the same exposure. And that fits with the relative aperture being k times smaller, which is how photographers normally think of exposure.

    If film technology was such that grain size (area of each granule) was proportional to ISO, and I think that this is very very very approximately true with some significant exceptions, then choice of format would be nearly moot. You could do anything with any format you want, within the limits of lens design... and there's the rub. If someone invented a stupidly-fine-grained (10x finer than Tech Pan!) film of ISO0.25 then we could (according to the above theory of equivalence) shoot with a 5mm f/0.2 lens onto 3mm film. The problem is that we can't really build a lens with a relative aperture bigger than f/0.75 and your final camera won't be that much smaller anyway - the film might be only 3x3mm per frame, but you still need that 25mm hole in the front to collect the light. And then it's a bitch to build an enlarging lens!

    The same scaling issues occur when going to larger formats. ISO400 is bearable on 35mm, but there isn't really a viable option of ISO7000 available on 4x5" film though it's very easy to build a 200 f/8 lens. So despite the geometric ability of the formats to be equivalent optically, the technology (lens construction and emulsion too) limits us in each direction. Though you can often pick any two systems and be able to take some equivalent images as per the above definition, the differences in format mean that the two systems have different DOF/speed/resolution envelopes.

    If you ignore the time-vs-ISO thing and stick to films not digital, then the distinction becomes more significant. While the best 35mm lenses are over 100lp/mm, films don't get much better than that and I don't see the emulsion research occurring to improve it. 35mm film isn't really going to get better even if the lenses improve because the lenses are not the limiting factor.

    However, we already have easily-available MF lenses capable of 50-80lp/mm. And even moreso for LF: 40-50lp/mm is quite achievable with more than 4x5" coverage; see the GigaPxl project, which is using 9x18" film at about 30lp/mm, a custom lens and scanning to achieve massive resolution. You're not going to see that sort of resolution from 35mm in my lifetime, unless it's by stitching (I've done 500MP stitches from a 12MP DSLR) and stitching is basically just a longhand way of using the same sensor area repeatedly to effectively form a much larger sensor. A stitch is merely a larger-format photograph, taken piecemeal.

    So if you're using film, your choice of format does, effectively, constrain you because of the limits on emulsion and lens construction technologies. You can use smaller formats, get fast shutter speeds, more DOF and less resolution, or you can use larger formats, get longer shutter speed, less DOF and more resolution.

    If you go digital, the constraints do go away a bit. Because of the way electronic sensors work (CCD and CMOS), they have a specific sensitivity so using them at a higher EI just reduces your signal to noise ratio, which means your noise amplitude in the print increases. It turns out that the noise magnitude in a final print does follow the EI in the same manner as defined above for the optical equivalence of different format sizes. This means that the equivalence rule between format sizes does actually hold for digital if you use the same sensor technology in all sensor sizes.

    IMHO, MF digital exists at the moment only to take advantage of existing MF lenses[1]. Because of the economics of digital sensor manufacture (yield reduces dramatically with larger chips), it makes more sense to build smaller chips and higher resolution lenses with less coverage. For this reason and the huge market share held by 24x16mm and 36x24mm digital sensors, I think most of the development will occur in the 35mm space - in other words, I suspect I partially agree with the OP in that there will be better lenses available and you'll be able to use them on film bodies.

    However, I don't think films will improve to the point where you can make any use of that additional performance. Edge sharpness wide-open will get better on the latest lenses but even if you're using the finest 35mm films available, you're not ever going to match the resolution you get from MF or LF film or 35mm digital. In other words, 35mm film photography has basically reached its peak of quality - if you want better, you need to change format and/or capture technology.

    If MF digital becomes mainstream and some development occurs on lenses that cover the larger MF formats, IMHO that's where the gains for film users will be. We have 6x6 and 6x7 lenses now that can resolve about as much as Pan-F but not necessarily wide-open. That means there are some small improvements to be made to the lenses that will give a quality improvement on existing films, at least with the lenses wide-open. The likelihood of a mainstream 6x7 digital sensor is kind of low though I think, at least for a while but I can hope I'm wrong!


    [1] Ignore the Leica S2. Just because it exists does not mean it's a good place to be in terms of optimal or even sustainable price/performance - that's Leica for you.
     
  4. Sim2

    Sim2 Member

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    At the risk of waffling on perhaps I should clarify – I do not criticise medium format lenses wide open, I actually have no reference point as most medium format I have seen has been said to be f8, 11 etc rather than f2.8,4.0. So my experience of seeing medium format is of being shot with smaller apertures. Knowing my need/liking of shooting wide open I am intrigued with the capability of medium format wide open compared to 35mm wide open, which is where my lack of reference ponts hinders my assesment of potential results.

    Btw, having shot with lenses such as the ef200/1.8L, fd&ef300/2.8L, ef 600/4.0 and seen the results from stellar lenses such as the nikon 300/2.0 I have a reference point for 35mm capabilities though would have loved to have seen the zeiss 1000/5.6 used in anger! If vivitar produced their series 1 90 macro in an ef mount I would be near the front of the queue.

    Thanks for reading the post, apologies for not being a more concise writer - more of a verbal ambler really!
    Sim.
     
  5. Sim2

    Sim2 Member

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    LOL! Was only looking over at the S2 to ask, why? :tongue: honest...

    Thanks for the great reply - much more technical evaluation than I was expecting - welcomed though.
    Interesting that that your assessment of "new" style 35mm lenses will give little quality gains over "old" style lenses, sort of what I had been thinking; gains there may be but not quantum leaps in quality. The technology of film (grain size) being the limiting factor - the new lenses may outperform the technology of film but tightening up of edge sharpness etc may be of benefit to a 35mm shooter.
    Would love to see a direct comparison shot between say a Hass 120 lens and a Canon 85/1.2 for instance (or comparable portait type lenses) on film stock - just for arguements sake!
    Thanks for the input.
    Sim.
     
  6. polyglot

    polyglot Member

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    I don't have an 85/1.2 but I do have a Minolta 85/1.4. It's a beautiful lens in terms of bokeh but certainly not sharp at all wide open. Its equivalent on 6x7 would be 170/2.8; I have a 180/4.5. I also have a Sony 50/1.4 (a bit sharper, not half as buttery) and a near perfect equivalent in the RZ 110/2.8. I could do some comparison shots if you like, but beware my scanner is only 2500dpi (50lp/mm) so you won't necessarily see all of the resolution available from the 35mm shots.
     
  7. Mike1234

    Mike1234 Inactive

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    Where's the science?
     
  8. polyglot

    polyglot Member

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  9. Christopher Walrath

    Christopher Walrath Member

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    Hey, like I said, it is a great read. Provokes thought.

    IMHO an 80mm f/3.5 Sekor C mounted on a Mamiya M645j can do wonderful things. Put a Rokkor-X 50mm f/1.4 on a Minolta sr-T101 and focus close and strange things can happen. The DOF can outweigh the give up in forum.

    And ask anyone around here. If you consider your self a verbal ambler then you are in awesome company.