Pentamirror vs Pentaprism

Discussion in 'Photography Equipment & Products' started by Sydkid, Aug 23, 2008.

  1. Sydkid
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    Sydkid New Member

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    What's the difference between the two? How would they ultimately effect the outcome of my image? Most dSLRs below the $900 range use mirrors, while most above $900 use prisms. If I found a camera of comparable specs, but one had a mirror, the other a prism, would it be worth it to get the prism?

    Thanks.
  2. prodigy2k7
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    prodigy2k7 New Member

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    Same thing, one is a solid chuck of glass, the other are pieces of glass stuck together to form the same thing.
    Prism = solid chunk
    Advantage/Disadvantages:
    pentamirror = cheap to produce...slightly darker...better for auto focus...
    pentaprism = bulky heavy and more expensive...brighter..easier to manual focus
  3. usayit
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    usayit Well-Known Member

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    Sounds like your are considering Pentax which has pentaprisms in their higher end camera bodies. If you are planning to shoot with manual focus lenses, you will want the pentaprism.

    Personally, I like the bright viewfinders using pentaprisms but thats mostly because of the manual film cameras of the past.
  4. Garbz
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    Garbz New Member

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    Are you confusing your mirrors here? Autofocus has absolutely nothing to do with the pentamirror in the viewfinder. The autofocus runs through the reflex mirror (the one in the lens mount), and it will behave identically regardless if you have a pentamirror or a pentaprism in the viewfinder.
  5. prodigy2k7
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    prodigy2k7 New Member

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    Erm, my bad I meant better for manual focus (cuz its brighter)
    Let me re-state

    Advantage/Disadvantages:
    pentamirror = cheap to produce...slightly darker...better for auto focus...(instead of manual focus/harder to manual focus)
    pentaprism = bulky heavy and more expensive...brighter..easier to manual focus (cuz its brighter)
  6. Hobbes
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    Hobbes New Member

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    uh I thought Canon got pentaprisms in their higher end camera as well :greenpbl: I just love the viewfinder on my EOS 40D :) and I have heard its viewfinder is a lot better than any of the pentax cameras that was one of the reasons why I bought it instead of Pentax :D

    EDIT: not even going to argue with you on that one -.- but he never mentioned Pentax or any other brands. I read the thing about EOS 40Ds viewfinder in some forum and the fact that 40Ds viewfinder is a bit better than 30D/20D. whatever
    Last edited: Aug 24, 2008
  7. Bifurcator
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    Bifurcator New Member

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    Sydkid Wrote:
    What's the difference between the two?


    One bends light into your eye and the other reflects it. The materials used for the mirroring make a big difference. And the materials add some properties to the overall image you view through your camera's VF. These properties are usually a bit of darkness and contrast but in some systems can also include hue or tinting. Pentaprisms last longer too and pentamirrors will fade and speck and pit over the years. A pentaprism generally speaking, is superior to a pentamirror.


    How would they ultimately effect the outcome of my image?

    They don't. It's only for your eye. You might be able to focus a little more precisely with a prism than a mirror - maybe. ;)


    Most dSLRs below the $900 range use mirrors, while most above $900 use prisms.

    Yeah, they're generally considered much better. Although when comparing two high quality parts of the different types "much" is a stretch.


    If I found a camera of comparable specs, but one had a mirror, the other a prism, would it be worth it to get the prism?

    Same price but one had a prism? Get the prism.

    Different prices? It depends on how much weight you place on your OFV (optical viewfinder). If you need or love nice bright and rich views as you look through your camera then it might be worth it. If you're shooting allot of astrophotography or other images with light points the prism will be much more desirable!

    For me I don't care. Sure it's more fun to look through a pentaprism but it's a CCD/NMOS/MOS electronic sensor that's recording the image not your eye. For this reason I actually like EVF (electronic viewfinders) much MUCH better! They can amplify the light in low light conditions, all menu settings can be performed without moving your eye, and if the imager is being used to generate the image you're seeing more exactly what the CCD/NMOS/MOS chip is seeing.
    Last edited: Aug 24, 2008
  8. usayit
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    usayit Well-Known Member

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    Thats not what I said. "Sounds like your are considering Pentax..." My post didn't even have the word "Canon" in it... I was taking a guess. Reason being is that Pentax has a larger than normal consumer base who wish to use manual K-mount lenses. If that is in fact the reasoning behind the OP, then I highly recommend getting the pentaprism. IMO, Canon EOS cameras are good but they feel like they were intended for Autofocus with Manual focus implemented as a side thought.... none of the lenses are damped correctly and the viewfinders not really geared towards it.

    I've seen viewfinders of DSLRs from various brands, most pale in comparison to film cameras of days past. The K10D (assuming K20D) had an ok viewfinder. I've worked with Canon's previous to yours and most were not that great.

    Canonites and Nikonians always trying to justify their purchase against other lesser popular brands... lol
  9. Bifurcator
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    Bifurcator New Member

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    I agree on all points with usayit's post above. :thumbup:
  10. sburatorul
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    sburatorul New Member

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    dunno what to say about the ofv of the d40, it appears to have noise (odd huh?) but that is not much of a disadvantage. as for the efv- i totally hate them. used one on the fuji i own and i hated every bit of it. the only advantage is that you can see view the pictures taken without the sun reflecting in the lcd.
  11. reg
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    reg New Member

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    No there is not "noise" in a viewfinder.

    That would likely be dust.
  12. sburatorul
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    sburatorul New Member

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    maybe its just the one i worked with but if you focus your eyes on the focusing squares instead of the image you can see grain in the viewfinder and it is not dust, i can assure you of that - dust doesn't set in patterns.
  13. Bifurcator
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    Bifurcator New Member

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    Fuji's are the worst EVF's ever... Which is weird cuz their professional grade video camera EVFs are great. Anyway if all you've used is the Fuji ones I can understand why you hate them. ;)
  14. sburatorul
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    sburatorul New Member

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    your post really turns my world around. one of the reasons i went dslr is for the ofv and i am loving it. now all my friends that are into photography love ofvs. you are the first one i hear that loves evf. i guess you make a valid point as there is a histogram, all data and you can see where highlights and shadows will be. I don't use the histogram (yet and dunno if i will any time soon), my ovf gives me all the data i need (would have been nice to have iso in there too) and as for the highlights and shadow... the ofv makes me think more about it, i have to figure it out for my self and its good for me.

    l.e : sorry to pollute the thread. maybe we should continue this somewhere else if it interests anybody else.
  15. Bifurcator
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    Bifurcator New Member

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    I don't think it's thread pollution. It seems directly related to me. Anyway, I know you're right and that OVF's are thee popular way to go. And for a film camera that makes total sense to me. If digital SLR makers would ever get their sh!t together we could all choose which one's we wanted. With the new HDMI connectivity it may not be long although they are WAY WAY late. 15 years ago when I purchased my second pro grade video camera I had my choice of different VFs - I opted for a $3,500 EVF and sold it 6 years later for $3,000. (That's the EVF being sold separately.) Film cameras had waist level VFs, eye level VFs, and various secondary attachments, focusing screens, etc. etc. It seems that when these companies went digital they all forgot how to design a camera and didn't pay any attention at all to the designs they had already came up with for their video products.

    LiveView is totally awesome but LCDs TOTALLY suck without an optical enclosure and an adjustable diopter. If they can run a ribbon cable to the back like that (for the LCD) then they can run one to the prism area and place an LCD there.

    I suppose part of my partiality towards EVFs comes from my extensive career in videography/CG. Video cameras were/are based on CCDs (digital) and while the initial move from film camera OVFs caused me some slight trepidation I soon came to understand why and now wouldn't have it any other way - had I the choice. ;) With the current dSLR LiveView technology where you can
    • zoom up to 10x (and still be at a scaled down resolution from what the MOS/CCD is seeing) in order to focus,
    • see the direct results of shutter-aperture-ISO,
    • see clipping displayed in solid colors for both ends of the luminous range,
    • navigate all the menus without removing your eye and refocusing on an LCD (if you can even see it in daylight),
    • automatically and optionally display the last image(s) taken (in my case for 2 sec, 10 sec, and/or until I give the shutter another half-press)
    • automatically view an amplified brightness level for low-light focusing,
    • see ALL of your settings, histogram, etc. etc. as you shoot,
    • and select any overlay screens you like,
    it just makes more sense to me than an OVF.

    Examples can be seen here:
    [ame]http://uk.youtube.com/watch?v=9IvsMlcuZ1Y[/ame] from 5:45 in the video.
    [ame]http://uk.youtube.com/watch?v=YEcJsksxsOo[/ame] from 5:25 in the video.
    [ame]http://uk.youtube.com/watch?v=xWHjZWvdtHw[/ame] from 3:15 in the video.
    [ame]http://uk.youtube.com/watch?v=1vjBb-mHH-w[/ame] from 4:35 in the video.
    etc.

    Part of the reason dSLR users desire OVFs so much and so often I think is two fold. One is that it's a carry-over from film SLRs where an EVF wouldn't make sense and where oldsters don't wanna learn something new (for focus and etc.). And the other thing is that so many EVFs like the Fuji you looked through, are too small, too contrasty, and don't use proper high grade diopters between the LCD and your eye making them feel distorted and fish-bowl like. Still just because OVFs are more popular doesn't make them better. They are better in general terms of optical quality but they don't relate as directly to digital photography as EVFs. If fact if they would get it together and offer an EVF option we wouldn't even need an LCD stuck on the backs of our cameras! Humpf!

    :soapbox:
    Last edited: Aug 24, 2008

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