Re: Q: Why do DSLRs need mirrors and prisms?


"cjcampbell" <christophercampbell@xxxxxxxxxxx> wrote in message
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John Falstaff wrote:
"cjcampbell" <christophercampbell@xxxxxxxxxxx> wrote in message
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Alexander Arnakis wrote:
Maybe this question has been discussed here before, but I'll ask
again:

Other than being a holdover from the film SLR design, what is the
reason that DSLRs still have mirror boxes and pentaprisms? It seems
that the main thing a mirror (on a DSLR) does is block the sensor so
that the LCD screen can't be used for composing.


If it did not have a pentaprism, it would not be a reflex camera, would
it? You would have to call it something else.

Well, not exactly. The "reflex" implies a mirror, but not necessarily a
pentaprism. There were single- and twin-lens reflexes for many years
before
the first pentaprism came along.


Okay. Even I know what a reflex camera is. But the point is, it would
not be a reflex camera any more if you took out the mirror.

That's what I'm saying: a reflex camera has to have a mirror, but it doesn't
have to have a pentaprism and a great many of them did not.




Not so. The main reason for the DSLR is speed. Interchangeable lenses
are secondary.

The *main reason* for any SLR, historically, is absence of parallax --
seeing the image in the viewfinder (or focusing screen) as formed by the
lens, so just as the film (or sensor) will see it.

HIstorically, that is true. It is why I started using SLRs as soon as I
could afford them back in the '60s. But speaking for today, parallax is
no longer a problem with sensor driven LCDs.

Right. I think that's probably everyone's reaction the very first time he
uses a digital camera -- the LCD monitor makes it just like an SLR. Almost.
Sort of. ;-)


The main reason for not
using the LCD is speed, with focusing a close second. Third is battery
life.

Agreed.



Since the LCD monitor of
almost any non-SLR digital camera does that reasonably well (if
relatively
coarsely, and as you say with some slight delay), the dSLR's advantage in
this characteristic is much diminished, and the advantages of lens
interchangeability, speed, and lower noise become more important.

Any of these things may be "the main reason" for any particular user, and
only he can define it. I don't buy a dSLR primarily for speed, so that's
not
"the main reason" for me. Lens interchangeability is much more important
to
me.



.

Relevant Pages

  • Re: Q: Why do DSLRs need mirrors and prisms?
    ... Other than being a holdover from the film SLR design, ... reason that DSLRs still have mirror boxes and pentaprisms? ... It would seem that the main reason to have a DSLR is to enable the use ...
    (rec.photo.digital.slr-systems)
  • Re: Q: Why do DSLRs need mirrors and prisms?
    ... Other than being a holdover from the film SLR design, ... reason that DSLRs still have mirror boxes and pentaprisms? ... It would seem that the main reason to have a DSLR is to enable the use ...
    (rec.photo.digital.slr-systems)
  • Q: Why do DSLRs need mirrors and prisms?
    ... Other than being a holdover from the film SLR design, ... reason that DSLRs still have mirror boxes and pentaprisms? ... It would seem that the main reason to have a DSLR is to enable the use ...
    (rec.photo.digital.slr-systems)
  • Re: Q: Why do DSLRs need mirrors and prisms?
    ... reason that DSLRs still have mirror boxes and pentaprisms? ... If it did not have a pentaprism, it would not be a reflex camera, would ... The main reason for the DSLR is speed. ...
    (rec.photo.digital.slr-systems)
  • Re: Q: Why do DSLRs need mirrors and prisms?
    ... that the LCD screen can't be used for composing. ... If it did not have a pentaprism, it would not be a reflex camera, would ... whole point of the DSLR is speed and flexibility. ... The main reason for the DSLR is speed. ...
    (rec.photo.digital.slr-systems)
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