RE: good source for UV tubes?

Judy Seigel wrote:

>
>Sandy, Just between us, don't tell anybody, I don't do speedpoint, in fact
>if you asked me to define it to save my life I'm dead.

How you determine speed point makes little difference from a
practical point of view. In that sense what difference does it make
if exposure time is 100 seconds, or 80 seconds (-20%) or 120 seconds
(+120 seconds). We manage.

But, how you determine speed point makes a big difference if you plan
to compare effective printing speed of light sources. With most of
our processes there is no absolute Dmax, but gradual shading into
Dmax. Same is true in the mid-tones. In other words, results are
constantly sliding and revealing themselves anew depending on initial
assumptions.

>
> I used his tests
>and then some of my own -- this was probably 5 years ago, and I can't
>SWEAR no other anomalies were involved, but frankly the difference had as
>far as I know been widely stated and accepted, which was the reason I
>bought the BL to begin with. I can't remember what the sources of that
>info were, but yours is the first I've ever heard to the contrary.

The literature is full of anecdotal evidence. But, frankly, what I
see is lots of people repeating the same old information from book to
book, and even from generation to generation. But my comparisons are
not based on anecdote, but actual testing in which common standards
of comparison were established.

>
>
>What medium did you make these tests in? All may not be the same.

I have made the comparison with the great majority of processes
discussed on this list, and the results can be seen in the article on
UV printing at Unblinkingeye.com. I have also repeated the tests with
BL and BLB tubes of different manufacture. Although there have been
some anomalies in results the great majority of my comparisons
indicates a difference in printing speed of less than 1/4 step (of
21) between these two types of tubes, which amounts to around 10% in
time.

>
>You are looking at your negatives under UV light? That's another thing I
>was taught -- a no-no.

I wear protective UV glasses when exposing prints. If you don't some
of that UV light is going to reach your eyes by reflection.

Sandy
Received on Tue Jan 13 21:21:34 2004