At 10:19 pm +0000 18/2/98, Kennedy wrote:
>In article , Clive Warren <Clive.Warren@xxxxxxxxxxxxx> writes
>>At 11:59 pm +0000 17/2/98, Kennedy wrote:
>>
>>>
>>>In article , PCACala@xxxxxxx writes
>>>>
>>>>Hum, a 3 0ncrease in transmittance. Reminds me of the marginal
>>>>performance
>>>>increase from a 200 to 233 MHz Pentium.
>>>>
>>>Its not the 3 0ncrease in transmission that makes the difference, but
>>>the more than 75% relative reduction in reflection.
>>
>>
>>If you like taking shots with the sun or a bright light source in your
>>photos. Where did the 75 0.000000igure come from anyway?
>
>>From your own figures, actually, Clive! :-)
>
>You quoted 95% Tx for single coating and 98% Tx for multicoating.
>Assuming that the optical glass absorbs 1% (a conservative estimate),
>this means that the single coating reflects 4%, and the multicoating
>reflects 1%, giving a 75% *relative* reduction in reflection over the
>single coated part. If the glass absorbs more than 1%, then the
>relative reduction is even greater.
>
>You don't actually need a bright light source in your image to see the
>difference - veiling glare is the bane of all 'contra-jour' or backlit
>work.
Yo Kennedy I own up - you know that 750f almost nothing is still almost
nothing though ;-) See that's the trouble with statistics and how they
sold Super MC to the general public.......
Take your point about 'contra-jour' or backlit work - have had some really
crazy spaceship like flare from a Zuiko 35-135 and equally scary from a
50mm f1.8 MC from fire sculpture work. Ironically it was some of the
excessive flare photos that people really liked :-)
All the best,
Clive http://clive.bel-epa.com
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