Thanks. This is about what I expected would happen in the first place.
The only problem is that I can't explain why.
Chuck Norcutt
Walt Wayman wrote:
> Okay. All you had to do was ask. :-)
>
> The cameras: OM-4Ti with 2-13 screen, Mamiya RB-67 with regular
> split-image WL viewfinder The lenses: 50/3.5 Zuiko Macro, 127/3.8
> Mamiya Sekor C (Don't have a 3.5 lens for the Mamiya, but I figured
> this was close enough.) The light source: 13x17 in. slide viewer at 1
> ft. The measuring device: Sekonic Digi Master L-718 meter using the
> ground glass probe The difference: OM-4Ti 2/10 stop brighter, or just
> about what you might expect to be the difference between f/3.5 and
> f/3.8. As the mythbuster guys would say: BUSTED.
>
> Walt
>
> -- "Anything more than 500 yards from the car just isn't photogenic."
> -- Edward Weston
>
> -------------- Original message ---------------------- From: Chuck
> Norcutt <chucknorcutt@xxxxxxxxxxx>
>
>> What you and Moose have said now seems to make perfect sense but
>> I'm still curious about the reality. According to your arguments
>> an f/4 lens on a 6x6 camera should have approximately the same
>> screen focusing brightness as an f/2 lens on 35mm. In fact, it
>> should be brighter since the eyepiece doesn't have to magnify the
>> image as much.
>>
>> Can someone with a 6x6 and 35mm verify this?
>>
>> Chuck Norcutt
>>
>> Dan Mitchell wrote:
>>
>>> So there's 4 times as much light available on the mirror to be
>>> bounced into the eyepiece, and so if the image I'm seeing is the
>>> same size to my eye, it'll be 4 times as bright in the 120mm
>>> camera. (or it could be twice as large in each direction and the
>>> same brightness).
>>>
>>> It doesn't really matter how large the focussing screen is, or
>>> how much magnification happens between the focussing screen and
>>> my eye; there's Z amount of light available bouncing off the
>>> mirror in the 35mm camera, then there'll be 4Z that amount of
>>> light bouncing off the mirror in the 120mm camera.
>>>
>>> What happens between mirror and eye is then the usual tradeoff
>>> between image size and image brightness -- but the 120mm body has
>>> four times the light available when making that tradeoff.
>>
> ============================================== List usage info:
> http://www.zuikoholic.com List nannies:
> olympusadmin@xxxxxxxxxx
> ==============================================
>
>
==============================================
List usage info: http://www.zuikoholic.com
List nannies: olympusadmin@xxxxxxxxxx
==============================================
|