Sometimes the magnifying glass in the hood gets thrown of adjustment.
The metal holding the glass diopter bends easily and can affect one's
perception of what is in focus or not.
Slobodan Dimitrov Studio G-8, Angels Gate Cultural Center http://sdimitrovphoto.com
On Jun 5, 2006, at 6:35 AM, chatanooga@xxxxxxxxx wrote:
Listers
I've pretty much convinced myself that my 2.8FX tends to focus about 3cm in front when nominally foucussed at 1m. I've verified this after noticing quite a few f2.8/ f4 type closeups didnt seem to be optimally sharp. I did a few angled-ruler type tests and shot several frames in quick succesion at the same focus to average out any film flatness issues. I see small shifts but the focus error is consistently in the front.
Assuming the error is due to some fixed mechanical offset between the taking and viewing lense I'm wondering is this going to have a pro-rata effect at larger distances (for the same wide aperture)? My suspicion is it won't but would be interested to hear from someone less optically-challenged..! And suppose I put a Rolleinar on..........
I would guess the 3cm I mentioned is equivalent to a very small film-plane offset - is such a small tweak possible (for the service centre, etc)?
rgds
Chat
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