From: Clay (wcharmon@wt.net)
Date: 11/27/02-12:17:15 PM Z
Here's another possibly stupid idea: Face the probe toward some
reflecting surface such as a piece of mat board that will reflect the
light toward the probe, instead of reading the light directly. The
amount of light reflected from a gray card or something similar should
be much reduced, but should still be proportional to the total light
emitted by your source. It would be cheap and quick to try this.
Clay
On Wednesday, November 27, 2002, at 11:11 AM, jeffbuck@swcp.com wrote:
> Yes, there's the equivalent of "waterhouse stops," but even at the most
> restrictive "stop," I'm still getting something like ten times more
> light than
> the probe wants to deal with, that is, the longest measurement the
> machine can
> calibrate for is about a minute and a half (at the smallest stop, the
> read-out
> runs all the way from 00.0 back to 00.0 in about a minute and a half).
> The
> instructions speak of a little damping disk one can place over the
> sensor cell
> cavity inside the probe to adjust for very bright light sources, but I
> don't
> appear to have this item (inside the probe housing -- the probe's
> about the
> size of a wrist-watch -- you see the little sensor apparatus, topped
> w/ an
> off-white plastic disk a few centimeters across; you're supposed to
> place the
> damper over this). I wonder how it would be to cut a little disk of
> rubylith
> and place it over the sensor disk? This would mask the spectrum very
> unevenly
> (the lamp is rated at 5200K), but do you agree with me that that
> should not
> matter as long as the uneven-ness is consistent? I mean, pt/pd does
> not
> respond to red light, but presumably the sensor cell of this
> integrator does.
> I'm gonna try this unless you or someone figures it's an essentially
> stupid
> idea.... Happy Thanksgiving to the List! -JB
>
>
> Clay <wcharmon@wt.net> said:
>
>>
>> Jeff:
>>
>> My Nuarc unit has a little aperture device above the integrator cell,
>> sort of like waterhouse stops on old lenses. The idea is to rotate
>> around to holes of differing diameters - smaller diameters admitting
>> less light of course. It sounds like you need to restrict the amount
>> of
>> light reaching the photocell in some manner. Does your device have
>> something similar, or could you rig up something like that if it
>> doesn't?
>>
>> Clay
>>
>> On Wednesday, November 27, 2002, at 09:42 AM, Jeff Buck wrote:
>>
>>> To Those Who Weighed In On Integrator Issues Recently: I got hold of
>>> an Olec "Olix AI 950." Having trouble calibrating it for my HID
>>> lamp,
>>> which is a 1000W metal halide lamp and is positioned 34" above the
>>> printing surface (from bottom tip of the massive lamp bulb). I
>>> positioned the probe on the printing surface looking up at the lamp.
>>> I then commenced the attempt to calibrate the integrator for this
>>> light source. No good. No matter where I set the probe dial (you
>>> rotate it back and forth to let more or less light reach the photo
>>> cell itself), the read-out numbers raced by like Seabiscuit. The
>>> numbers ran from 00.0 to 99.9 (or 000 to 999) in about a minute and a
>>> half. The manual says nothing about the capacity of the integrator
>>> to
>>> handle any particular maximum of light. Comments? -jeff buckels
>>>
>>>
>>
>>
>
>
>
> --
>
>
>
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