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Nikon: System camera prices to fall

Discussion in 'News - Discussion' started by CSBC, Feb 6, 2013.

  1. BikerMike

    BikerMike Well-Known Member

    Er, no, sorry, just the opposite - Panny GF1 - almost always with me.:)

    I worded it very carelessly, I'm afraid. Yes, Canikon do make pancake lenses, but because of the need to have extra elements to enable a short focal length to reach through to the sensor (retro-focus), they are not as flat as mirrorless pancakes.

    I'm getting sloppy, aren't I?

    Regards, Mike
     
  2. dangie

    dangie Senior Knobhead

    Slightly off topic, but I have a friend who works in the furniture retail business. He says that despite the recession expensive top of the range quality furniture has shown little change in sales. It's still selling. It's the middle to lower ranges that aren't selling so well. Maybe it's similar in the photographic industry.
     
  3. Benchista

    Benchista Which Tyler

    Well yes you are, because that's just not true either. As I pointed out earlier, Canon's DSLR 40mm pancake is flatter than their 22mm mirrorless pancake - and also flatter than the Olympus 17mm f2.8 MFT pancake, for that matter.
     
  4. BikerMike

    BikerMike Well-Known Member

    Oh dear, not just sloppy then - completely wrong. My apologies, never happened before. :)

    Regards, Mike
     
  5. Roy5051

    Roy5051 Well-Known Member

    Is that because of the opposite reason - that the mirrorless bodies are so thin, the pancake lenses have to be made fatter? Or what?
     
  6. Benchista

    Benchista Which Tyler


    I would guess that you're right, Roy. For DSLRs, the sort of focal lengths we're talking about only have to be mildly retrofocus to clear the mirror, whereas for CSCs, they have to be more strongly retrofocus to bring light to focus in relatively parallel beams so as to avoid huge vignetting - the telecentricity issue. Thinking about it, it's possibly one of the (few) valid reasons for CSCs being comparatively dearer than DSLRs - the design of microlenses above the sensor must be more complex to allow for this difficulty in edge illumination. Perhaps...
     
  7. BikerMike

    BikerMike Well-Known Member

    Does this help to explain?

    http://en.wikipedia.org/wiki/Pancake_lens

    It appears to say that DSLR pancakes need more retrofocus than CSCs as the natural focal point would otherwise fall short of the sensor which is further back due to the mirror box.

    But then that makes the Canon EF 40mm STM the exception.(?).

    Interesting to see a pic of a Pentax pancake too.

    Regards, Mike
     
  8. Benchista

    Benchista Which Tyler

    I can't see where you get that from - below is the whole article, and it doesn't say that anywhere as far as I can see - I guess you're interpreting the "pocketable" bit to be talking about lens construction, whereas I think they're just talking about the practicality of putting an SLR with a normal lens in a pocket:

    "Pancake lensFrom Wikipedia, the free encyclopedia


    [​IMG]
    [​IMG]
    Canon EF 40mm f/2.8 STM pancake lens​


    [​IMG]
    [​IMG]
    A digital SLR camera with a pancake lens.​

    A pancake lens is colloquial term for a flat, thin lens (short barrel), generally a normal or slightly wide prime lens for a camera.
    [TABLE="class: toc"]
    [TR]
    [TD]
    [h=2]Contents[/h] [hide] ​

    [/TD]
    [/TR]
    [/TABLE]
    [h=2][edit]Motivation[/h]Pancake lenses are primarily valued for providing quality optics in a compact package. The resulting camera and lens assembly may even be small enough to be pocketable, a design feature which is usually impractical with conventional SLR bodies and lens assembiles.
    [h=2][edit]History[/h]An early example is the (Zeiss) Tessar of 1902.
    In the 1960s and 1970s the Nikon GN lens was a notable example, while in the 1970s and 1980s pancake lenses were used in compact single lens reflex (SLR) cameras.[SUP][1][/SUP]
    The design has seen a resurgence due to the growth of the mirrorless interchangeable-lens digital camera market, notably the Micro Four Thirds system.

    • [​IMG]
      SMC Pentax-M 40 mm


    • [​IMG]
      Pentax DA 1:3.2 21 mm

    [h=2][edit]See also[/h]
    [h=2][edit]References[/h]


     
  9. BikerMike

    BikerMike Well-Known Member

    This is where I get it from - the bit you left out.

    Pancake lenses can be very short and flat because they do not need large amounts of optical correction, i.e. extra lens elements. The problem arises when such lenses have too short a focal length to fit in front of the retractable mirrors used in reflex cameras. In such a situation a pancake lens focuses in front of, rather than on, the focal plane (film or light sensor) of the camera. This has necessitated the design of retrofocus lenses that refocus the image further back, which is why such lenses are longer and bulkier that their "pancake" equivalents.

    In other words, short focal length pancakes for (D) SLRs need optical correction (retrofocus), which adds to their length and bulk. Whereas pancakes for mirrorless don't need retrofocus.

    That makes perfect sense to me. I can visualise a cross-section of a DSLR and m4/3 and see where they get that from.

    I must admit I don't like the way it calls retro and non-retro lenses pancakes, but then refers to "pancake" equivalents. It's just badly worded.

    Interpreting "pocketable" as "lens construction" ???

    I wouldn't get very far as an English teacher if I did that :)

    Regards, Mike
     
  10. Benchista

    Benchista Which Tyler

    But I haven't left anything out - what I quoted is the only bit that shows from your link. However, the bit you've got there seems to me to be totally wrong anyway.
     
  11. ianwaite

    ianwaite Well-Known Member

    Sorry Mike this doesn't sound correct to me either, if anything I think it's the wrong way round.

    Ian
     
  12. Benchista

    Benchista Which Tyler

    Odd, the bit you're quoting is in the "current revision" in the history tab, but not in the actual page. However, I can't imagine such a badly-worded bit of info will last long.

    Regardless, it doesn't really apply to normal focal length pancakes for DSLRs, but for the reasons I've mentioned, CSC pancakes will actually need to be MORE retrofocus to give even illumination.
     
  13. BikerMike

    BikerMike Well-Known Member

    Are you saying that you can't see the whole paragraph? Because what you posted me was only the first two sentences of it. How strange that the link should take you to an incomplete article - it works fine my end.

    All I can say is that the paragraph I posted to you makes good sense to me. I'll do a bit more browsing later and see what I can find.

    What then is your explanation of the need for retrofocus? Perhaps I should also ask what you understand by retrofocus?

    Regards, Mike
     
  14. BikerMike

    BikerMike Well-Known Member

    Check this out. It shows why retrofocus lenses are needed on (D)SLRs, but not on mirrorless, and why they are bigger, and apparently, have poorer image quality (?).

    Regards, Mike



    [​IMG]
     
  15. Benchista

    Benchista Which Tyler

    That's true for film, yes; however, look at the angle of incidence of light in the non-reflex view - with that, you would have horrific vignetting on digital sensors, which really need light coming into each pixel perpendicular to the sensor. To achieve that - telecentricity - you pretty much need a retrofocus construction (or very complex microlenses above the sensor, as Leica do). So your example is out of date, I'm afraid.
     
  16. BikerMike

    BikerMike Well-Known Member

    That would explain a lot, but then how do legacy lenses work perfectly well on digital cameras if the angle of strike needs to be more perpendicular? As far as I know, the same lenses work on both, or have I still missed something here?

    Regards, Mike
     
  17. Benchista

    Benchista Which Tyler

    Because they're designed for longer back focus systems, and are extended by the converters so that they work, so the angles are a little more gentle than they might be otherwise. Not sure I've explained that all that well!
     
  18. SqueamishOssifrage

    SqueamishOssifrage Well-Known Member

    While we're on the subject, can anyone tell me when Shrove Tuesday is this year?

    Ooops - sorry - I'm leaving now. :eek:
     
  19. Roy5051

    Roy5051 Well-Known Member

    The day before Ash Wednesday (I'm leaving, too!)
     
  20. thornrider

    thornrider In the Stop Bath


    Tuesday 12th February - but only for CSC pancakes :)
     

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