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pelicle problems

Discussion in 'Sony Chat' started by bechisbest, Oct 9, 2010.

  1. bechisbest

    bechisbest Well-Known Member

    Both Canon, and to a lesser extent,Nikon used this technology,and then because of the well known problems,dropped it.What has Sony done to resolve (1) Fragility of mirror (2)deposits, and debris on mirror, therefore extreme difficulty of cleaning mirror.
     
  2. Zou

    Zou Well-Known Member

    It isn't exactly a pellicle, for a start.
     
  3. bechisbest

    bechisbest Well-Known Member

    What is it then? Is it a glass construction ?That would be better,but you are still left with light loss, and cleaning dirt off the thing.Have you seen/used one, if so what do you think ?
     
  4. Malcolm_Stewart

    Malcolm_Stewart Well-Known Member

    I know nothing about the Sony, but I have seen the recent claims for the benefits of fluorine coatings on lenses with respect to shedding dirt, so perhaps this or something similar has been used. It will still leave the light loss, but perhaps this may not be noticed by their target market.

    I do hate the term "translucent" which to me implies a somewhat misty view, or even something like a piece of opalised glass for providing uniform illumination in a slide viewer or similar. (Bad translation, perhaps? The early Japanese camera instruction books were frequently hilarious.)
     
  5. Roger_Provins

    Roger_Provins Well-Known Member

    From the various pictures and diagrams I've seen (a Google search gets many) it appears that the mirror would be easier and less necessary to clean than the normal sensor filter glass. Debris on the mirror would probably not affect the picture so much as the same debris on the sensor as it is well out of focus, not directly blocking a sensor site, and would only be causing a minute light loss.

    The 30% light diverted to the viewfinder is apparently still available for autofocus. I suppose slightly increasing ISO from your usual will cancel the loss to the sensor.

    The term translucent is rather unfortunate and has been picked up by many people as being wrong. Obviously they mean semi-transparent and probably the fault is in translation.

    Well it's certainly different anyway :)
     
  6. P_Stoddart

    P_Stoddart Well-Known Member

    I am not so sure. It the debris is on the mirror it will probably cause a softing of detail over quite a bit of the image. When you have debris on a sensor it can be easier to remove in say Photoshop because it affects small area. Unless it is a general layer of dirt.

    Once detail is softened it is lost. Cannot be put back. Also the mirror is more exposed than the sensor which is deep in the camera body and protected in some cases by a focal plane shutter.
     
  7. Roger_Provins

    Roger_Provins Well-Known Member

    Detail softened by a bit of dust?

    Seen this? :eek: :D
     
  8. P_Stoddart

    P_Stoddart Well-Known Member

    Matbe it is different for SLR or SLT? I had a bridge camera couple of years ago. Panasonic FZ30. It would take fine image as long as the aperture was wide open. Soon as you stopped down to say f8 then marks would appear. The technican who I asked about fixing it said you have dirt on internal optics. Not the sensor. Otherwise the marks would be there all the time.

    So I wonder if you have say dirt or debris on the mirror and you use a wide/ultra wide angle lens stopped down it will start to show.

    The question is why did Nikon and Canon stop using the technology? One suggestion was the mirror being prone to dust and dirt. Which as you know is not a problem on a SLR as the mirror being dirty does not affect image quality.
     
  9. Myrdhinn

    Myrdhinn Member

    Nikon and Canon abandoned the pellicle due to the viewfinder was so dim it was unusable. OVF cannot be used with pellicles. Sony uses a EVF so that is not a problem.
     
  10. Benchista

    Benchista Which Tyler

    There speaks someone clearly without a shred of experience of using a pellicle mirrored SLR. I have never, ever read anything on here less true than that ridiculous statement. Canon abandoned pellicle mirrors because there was no need for the cost and complexity any more once normal SLRs could reach 10 fps with reduced lag. In actual fact, the viewfinder is less than a stop darker than on a non-pellicle equipped camera.
     
  11. Benchista

    Benchista Which Tyler

    It's certainly true that front element damage is almost always inconsequential; the closer to the film/sensor that there's any obstruction, the more obvious it will be. So rear element damage can cause problems, hairs or a thick layer of dust on a pellicle mirror will do, and the same on a sensor are going to be worst of all. My experience of a pelicle-mirrored SLR is that a little dust makes no difference whatsoever to picture quality, and I would expect the same to be true for these Sonys. Hairs etc might be more problematic, but normally a rocket blower should clear such things.
     
  12. Myrdhinn

    Myrdhinn Member

    We had a bunch RT's when I worked for the Toronto Star. The sports photogs loved them but I was in Art/Entertainment and they were god awful in dim light, you could barely see a stage in theatres or shows with the light loss in the OVF. My old Pentax LX was far better in that regard. Even Canon I believe said there was a 2/3 stop loss on film with them. But whatever since I've not a shred of experience with them even though I have used them. *shrugs* I care not.
     
  13. Benchista

    Benchista Which Tyler

    Well 2/3 stop is 1/3 stop less than one stop...

    I would agree that the LX is better in such conditions, but actually, I found the RT ideal in relatively low light because of the continuous viewing. But your initial statements were utterly ridiculous - even you accept that the sports togs "loved them", which makes it fairly clear they weren't unusable.
     
  14. Roger_Provins

    Roger_Provins Well-Known Member

    That's what I also would expect and blasting the mirror with a blower should be very easy. To my mind dust or whatever on the mirror would be a trivial problem to deal with - probably easier than the same on a sensor filter glass.

    As far as 2/3rds of a stop of light loss is concerned I find little difference between viewing at (say) f/1.4 and f/1.8 or between f/2.8 and f/3.5 etc.
     
  15. Benchista

    Benchista Which Tyler

    Now there I'm less sure - mirrors are always fairly delicate, and I wouldn't want to use a contact cleaning method, whereas I've no issue with cleaning the sensor filter. But the frequency should be low.

    Indeed. I used to use the EOS RT alongside the 600 - basically the same camera with a normal mirror. With the same lens, there's no obvious difference in viewfinder brightness, but neither are as good as the best manual focus SLRs of the same era, or as better DSLRs. Where there's a real brightness gain with Sony's EVF solution is when stopped down, of course, or with a lens with a slow maximum aperture. Should be really useful with macro, for example.
     
  16. bechisbest

    bechisbest Well-Known Member

    This reminds me of the astronomer who stuck a postage stamp on a lens/mirror to prove that small imperfections have no ill effect on image quality.
     
  17. P_Stoddart

    P_Stoddart Well-Known Member

    Saw another review which has shown a problem (including images). Ghosting. It is cause by light bouncing around between the lens and mirror.
     

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