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  1. #11

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    Quote Originally Posted by E. von Hoegh View Post
    It's the reverse of a telephoto exender, with all the attendant problems and even more aberrations. "Improves MTF"? Please.
    Nope, untrue. A telephoto extender goes between the rear element of the lens and the image sensor and tries to do its magic while remaining in the same system. That is where most of the stress comes from. To repeat, this technology is different because it utilizes the difference in the flange focal distances of an SLR system and a mirrorless.

    If introducing a lens between (1) source of light, and (2) the image sensor necessarily introduces attendant problems and aberrations, then why even bother taking a photograph in the first place? I mean, all your Summicron is doing is introducing problems and aberrations, no?

    Here's the deal.

    You have light rays emitting from the rear of your lens. It's going to hit the sensor plane after ~45mm and create an image circle that will cover FF.

    It is theoretically very sound and possible to introduce a set of optics within those ~45mm that will converge & concentrate those light rays so that after those ~45mm, the image circle will be smaller and just cover APS-C without significantly reducing the image quality.

    Like it's been said, this concept has been used before most notably in astrophotography (of the best kind, I may add). If it's such a degrading "snake-oil" concept/technology, why would some of the most expensive astrophotographic imaging equipment use it?


    Now, wether or not the actual execution of the concept here is entirely satisfactory remains to be seen. But seeing that one of the most talented lens designers living today is involved in the development of the product, my bet would be on him than people who apprently don't understand some basic principles of physics.

  2. #12

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    With regards to improvement in IQ: this, while being (admittedly) a rather dubious claim, again is not necessarily impossible. Assume a set of optimally designed optics that will do what I described above without reducing IQ by simple introduction of more glass & air.

    Then, what would happen is that when compared to using that lens with a glass-less adapter on the smaller (APS-C) format (this is the important point), all the aberrations etc. of that lens will ALSO be compressed, so that when the image is printed at the same paper size (IMPORTANT: NOT AT THE SAME MAGNIFICATION), then theoretically, you will see much less of those aberrations.

    Again, this isn't anything magical. Think of the purple fringing you see around, say, tree branches against a cloudy sky background. The purple fringing is going to be less significant when you compare an image taken with that lens on FF (it's native magnification) than an image taken with that lens on APS-C (with 1.5x apparent focal length, which magnifies everything including purple fringing).

    If, on the other hand, you bring the two images to the same magnification, then, you should have the same amount of aberrations, etc. You would expect exactly this, because we assumed in the beginning that the optics introduces no IQ degradation. In reality, it probably will, so when the images are shown at the same magnification, then there's probably going to be more aberrations with this product.

    So you see, to repeat, there's really nothing magical or unbelievable or snake-oil-like thing being proposed here at all. Indeed the concept is simple enough that even I came up with it independently a few years ago while chatting with my brother.

  3. #13

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    Just going from first principles, it seems like a focal reducer could improve the MTF precisely because it reduces the size of the image---the same reason small enlargements look sharper than big enlargements. The extra element necessarily introduces some aberrations, but if the improvement due to the smaller image scale exceeds those aberrations, it could be a net win.

    But I don't know how the performance of these things shakes out in the real world. Should we be fitting focal reducers to large-format lenses and mounting them on our 35mm cameras?

    -NT
    Nathan Tenny
    San Diego, CA, USA

    The lady of the house has to be a pretty swell sort of person to put up with the annoyance of a photographer.
    -The Little Technical Library, _Developing, Printing, And Enlarging_

  4. #14

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    Here's an early review and some sample images & video. Too early to make a final judgement, sure, but there's nothing here that supports the "snake-oil" hypothesis, either:

    http://philipbloom.net/2013/01/13/speedbooster/

  5. #15
    Steve Smith's Avatar
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    Am I correct in assuming it takes the 'normal' view a lens would have on 35mm format and focuses the whole of that image onto a smaller sensor?

    If so, it seems logical. It's something I thought about a few years ago when I was temporarily a digital photographer - not as a business idea, just one of the idle thoughts I have occasionally!

    Some people might be querying the faster claim. It's because the lens now actually has a shorter focal length but the aperture diameter range stays the same. Simply, aperture (f No.) = focal length / aperture diameter).

    Quote Originally Posted by ntenny View Post
    Should we be fitting focal reducers to large-format lenses and mounting them on our 35mm cameras?
    That's a thought I had a few minutes ago. It's easy to test the theory. If you have a large format camera and you can find a positive Dioptre (close up lens) which will fit either on the front or back cell, you will find that the bellows extension is shorter for infinity focus than without the positive lens. If you had a big enough ground glass, you could see if the image area increased too but this is not relevant to the system being discussed here as it is for smaller than normal sensors.


    Steve.
    Last edited by Steve Smith; 01-15-2013 at 01:23 PM. Click to view previous post history.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  6. #16

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    Quote Originally Posted by ntenny View Post
    Just going from first principles, it seems like a focal reducer could improve the MTF precisely because it reduces the size of the image---the same reason small enlargements look sharper than big enlargements. The extra element necessarily introduces some aberrations, but if the improvement due to the smaller image scale exceeds those aberrations, it could be a net win.

    But I don't know how the performance of these things shakes out in the real world. Should we be fitting focal reducers to large-format lenses and mounting them on our 35mm cameras?
    -NT
    For the price, $600, I'd say not.

  7. #17

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    Quote Originally Posted by Steve Smith View Post
    Am I correct in assuming it takes the 'normal' view a lens would have on 35mm format and focuses the whole of that image onto a smaller sensor?

    If so, it seems logical. It's something I thought about a few years ago when I was temporarily a digital photographer - not as a business idea, just one of the idle thoughts I have occasionally!

    Some people might be querying the faster claim. It's because the lens now actually has a shorter focal length but the aperture diameter range stays the same. Simply, aperture (f No.) = focal length / aperture diameter).


    Steve.
    That's the only claim which holds water.

  8. #18

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    Quote Originally Posted by Steve Smith View Post
    Am I correct in assuming it takes the 'normal' view a lens would have on 35mm format and focuses the whole of that image onto a smaller sensor?
    Yes you are correct. The only thing that this product purports to achieve is to take the "normal" view a lens would have on a 135 format and give you the exact same view (FOV, DOF, etc) on the smaller APS-C sensor.

    If so, it seems logical. It's something I thought about a few years ago when I was temporarily a digital photographer - not as a business idea, just one of the idle thoughts I have occasionally!
    It is very logical, and simple, theoretically. Simple enough that you and I could come up with it completely independently.

    Some people might be querying the faster claim. It's because the lens now actually has a shorter focal length but the aperture diameter range stays the same. Simply, aperture (f No.) = focal length / aperture diameter).
    Exactly. And, it's really NOT going to make the lens "faster" per se. Because we're dealing with a smaller sensor which, all else being equal, gives you more noise per square inch of the same size print, having a faster F value doesn't really give you an advantage over shooting with that lens on FF with 1-stop extra ISO.

    That is, with everything else in the sensor technology (and processing technology) being equal, taking a 50mm F1.4 lens (on FF) and:'

    (a) shooting it on an APS-C camera with this adapater as a 33mm F1.0 lens at ISO 100, 1/125s, and
    (b) shooting it on an FF camera straight-up as a 50mm F1.4 lens at ISO 200, 1/125

    should optimally give you identical results. Identical in terms of FOV, DOF, AND Noise levels.

  9. #19
    Steve Smith's Avatar
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    Quote Originally Posted by rawhead View Post
    And, it's really NOT going to make the lens "faster" per se. Because we're dealing with a smaller sensor.
    In theory it should because it is gathering the light from a wider area than the sensor would normally see and putting it onto the same sensor area so the light density (if such a term is correct) will increase. This doesn't take into account any light loss through the additional lens though.

    I remember when my father owned an Olympus E20. It came with wide angle and tele convertors which fitted to the front of the lens. I remember him telling me that with a front mounted wide convertor there was no increase in aperture like you get with a tele convertor. There was however, no claim that it made the lens faster though!


    Steve.
    Last edited by Steve Smith; 01-15-2013 at 01:40 PM. Click to view previous post history.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  10. #20

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    Quote Originally Posted by ntenny View Post
    But I don't know how the performance of these things shakes out in the real world. Should we be fitting focal reducers to large-format lenses and mounting them on our 35mm cameras?

    -NT

    This is an interesting question. Let's assume that we can utilize this concept & technology without limits, for the time being (e.g., with the product in question, it's limited to F1.2 lenses that will act on APS-C as an F0.9 lens).

    There are certain lenses in the large format world for which we have no equivalent in smaller formats, and so people go out of the way to shoot them on LF & film in this day & age. The Kodak Aero-Ektar on 4x5 (or 5x7) comes to mind (my fave, by the way: http://www.flickr.com/search/?q=aero...64%40N00&s=int).

    178mm F2.5 lens on 4x5 translates to something like a 53mm f0.8 lens on full frame (ref: http://www.pointsinfocus.com/tools/d...ns-calculator/). We do not have such a lens at our disposal on FF.

    IF there can be a reducer like this that can attach to this large format lens and concentrate the light so that it will act like a 53mm f0.8 lens on my Canon 5Dmk2, then EFF YES, I would purchase such an adapter for $600, in a friggin' nanosecond.

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