claytume said:
Early Riser
I appreciate the extensive testing you have done and the point of view you have, having seen the outcome with your own eyes. I too would be expecting to see sharp negs with 15x loupe.
My question is why would Sinar with the reputation they have sell a shutter system that can't use all the shutter speeds?
Doesn't make sense to me.
Clayton
Clayton, I don't know why Sinar does what it does, all i can do is see if whatever tools they make do what I need them to do. Here's an example though of Sinar thinking. I bought a Sinar expolux shutter and monitor system. It was listed in their catalog as being capable of giving 1/10th of a stop adjustments. Something you might consider reasonable for a shutter system costing $10,000. After buying the expolux I discovered that the f stops are at best adjustable by 1/3 stop as it's smallest increment, not the 1/10 that was stated in their catalog.
It was photo expo time and I knew Sinar people would be there. So I went to photo expo and explained the situation to the sinar engineers that were there. They explained to me that moving the aperture with motors only had so much precision and small f stops on lenses were such tiny apertures that they could only guarantee increment accuracy to 1/3rd of a stop. Ok I could see their point, f 45 is a tiny aperture and setting such an aperture with motors could be tricky. However what he said next really floored me, he then told me that it was moot because no one can tell the difference between anything smaller than 1/3 of a stop anyway, and that's why film companies increment their film in thirds. Now by this point in my life i had been a photographer for quite a while, and the standard for brackets for every single studio I knew of was a 1/4 stop. My own push/pull brackets at the lab were done in 1/8th stop increments and to me, and my clients, the differences were always apparent. But anyway, an engineer from Sinar said that no one could tell the difference and that's that.
So sinar made a $10,000 shutter that did not actually work consistently to the standards of professional photographers, that standard being 1/4 stop bracketing. Most people who buy Sinar Auto aperture shutters are studio photographers. During the 1970's to 1990's probably 95 percent of those photographers primarily used strobe. In the studio using strobes the auto ap shutter is superb, out of doors with a long lens and slow shutter speed, the huge shutter blades vibrate too much.
When you do a slow shutter speed exposure with a 35mm camera, do you lock up the mirror? All that vibration from a tiny mirror slapping. Compare the size of that mirror to the size of the shutterblades and other moving parts inside an Auto Ap shutter.
BTW my testing was with an 8x loupe, not a 15x. Nothing looks sharp through a 15x loupe.