Micro Four Thirds Focal Reducer Shootout

Started Feb 20, 2014 | Discussions thread
OP brian Senior Member • Posts: 1,206
Re: Micro Four Thirds Focal Reducer Shootout

MichailK wrote:

I believe no one with a right mind can argue that the results posted by Mr. Brian Caldwell about the best of these 4 special adapters fail to show which is the best performing part of the bunch, by far.-

However, a guy like me who struggled to acquire a modest E-PL5 and shoots for the fun of it on loaned old Nikon glass can take a second best in sharpness part as this is what my wallet dictates at the time and again, just barely... (Of course if I could afford the best adapter I would go for it - why degrade a fine Ai-S '80s lens besides cost reasons?)

So, I want to ask everyone using these adapters if in real life use the results of the second test (Hotspotting) are a deal breaker - we are talking about solid white back illuminating frame and solid black center rectangle which is an extreme case - isn't it? In a "normal" lit scene it should be no real fuss unless nitpicking I suppose but what do you guys using such adapters say?

I also want to ask Mr. Brian Caldwell what exposure settings were set up in the Hotspotting test and verify that they were kept exactly the same between shots (I am sure that a serious guy would never make such a mistake as leaving the camera in auto exposure but I would prefer to ask just in case - hope I am not insulting!). Looking at the jpeg it seems that the white part around the black square is exposed to 100% so less exposure could push the hotspot well into the shadows to be any problem in real life shooting for the parts exhibiting such a fantom image.

By the way, I want to ask for forgiveness from Mr.Caldwell for drooling over pictures of his beautiful brainchild


All of the hotspot test shots were taken with a Panasonic G6 camera set to ISO 200 with the shutter speed held constant at 1/13 sec..  The lens aperture was set to its minimum value.  IIRC, this gave an exposure 3 stops above the "auto" value, which would have rendered the outer white portion as a middle grey value.

Its true that its something of a torture test, but its easy for anybody to understand and reproduce, and thus removes the mystery and apparent unpredictability of the hotspot phenomenon.

Regarding real-world problems with hotspots, anytime you're shooting outdoors at a small aperture you should be aware of how your lenses behave, especially if there is a large area of bright sky.  Outdoor shooting can be particularly troublesome because there is much more deep violet and near UV light.  This is a problem because the lens coating efficiency tends to fade rapidly in the violet/near-uv portion of the spectrum.

Another situation to watch out for is indoor studio shooting against a white background.  Often the illumination and exposure is adjusted to make the background 100% white in such situations, and you wind up basically reproducing my torture test:

A third scenario to watch for is shooting in the IR, where again the lens coatings lose their efficiency and any hotspotting inherent in the optics will become much more visible:

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Brian Caldwell

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