Mu-43 Hall of Famer
- Jan 29, 2010
- South Gippsland, Australia
- Real Name
- Ray, not Oz
I would guess that in Fotodiox's case, it was whoever they were contracting out to do the optical work for early versions. They were not paying for the tightest standards. In my opinion, Fotodiox products aren't particularly precise although they have become better over the years.I was thinking about the problems that Fotodiox had with their first focal length reducing adapters.
I remember the Nikon D100 and D1 had one of the thinnest stacks I'd seen... They used to advertise that they were made with Lithium Niobate. I remember taking apart a D1 sensor that was dead and finding that the cover glass wasn't much thicker than your typical microscope cover glass - Maybe a mm or two thick. It was so easy to damage those.Interesting indeed and it would be nice to see what cameras have what thickness of glass in front of their sensors!
Again, confused. Regardless of the aperture the image circle would be the same size, right?So, even if the piezo shaker doesn't shed all of the dust particles, you'd have to work with very tiny apertures to see some of the smaller particles stuck to that filter stack..
It's got nothing to do with that. It's got to do with how the rays of light strike any dirt on the cover glass. That's why you can see dust particles in your photos when they are taken at small apertures. Large apertures let more oblique rays through the lens system effectively bending around the dust particle. When you close the aperture down (with the exception of the rays that bend around the blades (i.e.: diffraction) the light is centralized causing a deeper shadow behind the dust particle.1)
Again, confused. Regardless of the aperture the image circle would be the same size, right?
I think the danger is possible damage to the image stablisation system.1) If there's all this glass in front of our sensors, why are we worried about cleaning them ourselves? NEX and Pentax Q clearly has glass. I thought my PM2 had nothing but the sensor. So, I CAN touch it!
Focal reducers really give a 'whoa' result. Its kinda amazing the first time you are in your image editor looking over results. Actually I could see something wonderful was up through the evf.2) I'm not understanding how this will affect anything. We here have tried hundreds of adapted lenses with very good, predictable results. What the article and you guys are saying makes sense, however, I'm not seeing any lack of quality.
Have a look at the Metabones Speedbooster white paper on page 5 - http://www.metabones.com/assets/a/stories/Speed Booster White Paper.pdf. The first picture quite clearly shows the effect a piece of flat glass has on the light rays. It also suggests to me that the Metabones Speedbooster for the m43 mount takes the ~4mm filter into account. Also remember that some of the long tele lenses with drop in filters recommends to have simple uv/skylight filter in place while not using any other filter, because a filter in that location is part of the optical design.3) Speed booster: the glass simply makes the image circle of the 35mm lens smaller and thus faster and wider. Since you're using a higher percentage of the intended image circle, sure, I can see how this might be better. But I don't see how the sensor stack could be making anything better or worse. I'm confused.
Ignore fortwodriver, it has nothing to do with dirt.Again, confused. Regardless of the aperture the image circle would be the same size, right?
I'm happy because there is choice in the market place for focal reducers. Roxsen is selling a decent one. Metabones is selling their Speedbooster which was designed by Brian Caldwell, the gent in the article. From the pdf linked above and Brian's comments in the article, it seems very likely that the Speedbooster design is taking the sensor stack into account giving very good results. Its not clear if the Roxsen does. When I bought mine I took a chance on Brian's reputation on his previous designs, and feel my purchase decision have been right for me.So, in short, why is finding out the thickness of the sensor stack making those who use speed boosters happier? And, if a flange distance of a certain mount is X, it will be X regardless. You don't even need to know the thickness of the sensor stack, right?
As he says, its troublesome for fast lenses. Perhaps the effect only becomes visible for f2.8 and faster. But it does explain why a great many threads on this subforum is about getting film era fast 50's working well on m43 sensors. Given the comment above, it could be a bit of a fools errant unless you adapt with a focal reducer. I have a Konica 57mm f1.2... I'm kinda looking forward to a hypothetical Metabones Konica adapter... *crosses fingers*.A dirty little secret in digital photography is that the filter pack (low-pass filter + infraredfilter + sensor cover glass) found in virtually all digital cameras can contribute significant aberration to the image when a lens designed for film is used. This problem is particularly troublesome for very fast lenses. The Speed Booster corrects this defect, and automatically corrects for filter pack aberrations regard less of the objective lens used.
Here's an implication: You might actually lose out by straight adapting over a lens with an adapter to correct for flange as the lens optics are not designed for a different filter stack. (Ex: Canon might have a different thickness than Nikon, they both have a different thickness than m43s.) While the properly designed telecompressors will compensate for this so that you get the MTF gain when you adapt a lens from one system to another wherein the filter stacks are significantly different.So, in short, why is finding out the thickness of the sensor stack making those who use speed boosters happier? And, if a flange distance of a certain mount is X, it will be X regardless. You don't even need to know the thickness of the sensor stack, right?