[rollei_list] Re: Bright Screens
- From: Kirk Thompson <thompsonkirk@xxxxxxxxxxx>
- To: Rollei List <rollei_list@xxxxxxxxxxxxx>
- Date: Tue, 3 Jan 2012 15:03:52 -0800
Not a further thought, but a previous one that didn't make it into your summary:
Bill Maxwell makes two types of focusing screens: plain ones with grids, and
others with split-image focusing aids. User reports in this thread and
elsewhere have spoken more favorably of the former.
'Additional data': Maxwell himself recommends the plain grid screen. When
you're ordering by phone, he can go on at some length about this.
Maxwell seems to offer the split image screens just because people keep asking
for them. Just a guess: prior to autofocus, the majority of DSLRs had a
split-image focusing aid. In the absence of experience, people have perhaps
tended to ask for what looked familiar. That was my own mistake, until I tried
the plain-grid one.
KirkTo: rollei_list@xxxxxxxxxxxxx
From: cuffe@xxxxxxx
Subject: [rollei_list] Re: Bright Screens
Date: Tue, 3 Jan 2012 22:13:17 +0000
This is a wonderful summary in a complex area where opinions are divided. As a
group I would expect our powers of observation to be particularly good, hence
the diversity of opinion indicates to me that there may be something deeper
going on here than just a subjective diversity of opinion. I'm trying to think
of some optical reason why one type of screen could suit some users better than
others.The factors I'm coming up with are in order of significance:Ability to
close focusMaximum pupil diameter, as it affects the depth of field available
for the eye to accommodate.After these two I find myself considering usage
patterns which might affect users perceptions of utility.Here again I list
these in my perceived order of importance:Preferred viewing distance i.e with
magnifying lens up to the eye or truly at waist level.The relative importance
of center and peripheral image areas,A users knowledge of and customary use of
auxiliary features such as micro prisms, or grid lines for aligning the image.
Has any one any further thoughts on this or data to add?
All the best
Laurence Cuffe
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