Newsgroups: rec.photo
From: acs@csri.toronto.edu (Alvin Chia-Hua Shih)
Subject: Re: Canon 10s Vs Nikon N90, Which one?
Date: 28 Dec 92 08:11:52 GMT

In <BzyIHq.KoC@jrd.dec.com> diamond@jit533.jit.dec.com (Norman Diamond) writes:

>In article <1992Dec25.032603.25071@jarvis.csri.toronto.edu> acs@csri.toronto.edu (Alvin Chia-Hua Shih) writes:
>>In <BzszB1.ICv@jrd.dec.com> diamond@jit533.jit.dec.com (Norman Diamond) writes:
>>>In article <1992Dec24.205338.11007@jarvis.csri.toronto.edu> acs@csri.toronto.edu (Alvin Chia-Hua Shih) writes:

>>With those "Monitor Preflashes" it should be possible to calculate all
>>of the exposure information at that time and set the flash's power
>>output accordingly.

>To repeat, do you want to quench the flash when only part of the film has
>been exposed?  A better quenching time can be computed using preflashes than
>by ordinary TTL, but it's irrelevant when the slit exposes only part of the
>film at any time.

From my understanding, the F90 lifts its mirror and the preflashes
*with the shutter closed*.  The shutter supposedly has the tone of film
emulsion.  So, with the preflashes, one could calculate how bright the
actual flash has to be, pick the power output in advance, and *then*
fire the flash.

>>(Canon had "Flash Exposure Lock" with the T-90 that did something like this
>>for spotmetering.

>For shutter speeds faster than the fully-open speed?

The 300TL did not support FP sync.  The SB-25 accomplishes FP-sync (I
believe), by simply keeping the flash tube illuminated for the full
duration of the shutter being open.  The trick is to change the
brightness of the flash, rather than the duration.

The point was that it could calculate the flash exposure before any
film was exposed.

>>However, my point still stands that manual FP sync is hardly a generally
>>useful feature.

>If you want fill flash in the first place, sure it's useful.

But calculating exposures for fill flash is kind of a pain.  I'd rather
have all that gee-whiz computing power do it for me.

>                                          [...]  There are other custom
>functions that can also be accessed using the Wizard, but I don't intend
>to buy a Wizard anyway (neither the Japanese nor English speaking versions).

But don't you think it's a pain that you can't get access to custom
functions already built into the camera?

>>I guess Nikon has spared its "professional" users much grief by simply
>>making useful screens unavailable.

>I can't imagine a pro using F90.  I think they'd stick to F4 and do without
>the high speed fill flash.

The F90 is probably a test bed for some stuff to appear in a future pro
body.  But, some pros actually prefer the F-801s over the F4 due to its
smaller size, lighter weight, and faster user interface.  (I think Galen
Rowell is one of them.)

>>>>"Practical Photography" finds the SB-25 performance "disappointing"
>>>>because of "noticable darkening of the image at the edges" [...]

>>>Are they sure that's because of the flash rather than the lens?
>>>(Cynical but at least sometimes true comment here.)

>>The camera pictured (which may not actually be the camera tested) is a
>>Nikon F-90 with an AF 35-70/2.8 (can't see whether it's "D"-series or
>>not, but it shouldn't matter since they're optically the same).
>>I suppose it's possible for a cheap lens like that to have bad
>>vignetting problems...  :-)

>Well, I have a cheap[*] but famous fixed Nikkor lens with vignetting visible
>through my F801s viewfinder, so I wouldn't be surprised if the zooms can
>have it too.

>[* 105 F2.5, cost 24,000 yen from a used camera store, about C$250.  I bought
>it anyway because the vignetting goes away when stopped down, and I didn't
>buy this one for speed :-) ]

I was being facetious about the 35-70/2.8 being a cheap lens.  It
definitely *ain't*!  And with direct flash, I don't imagine they were
shooting wide open.

ACS
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