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This discussion is way, way over my head but I can't resist the question:
I assume these "tests" are meant to confirm focusing error correction with wide angle lenses as a result of Chamonix's recommended placement of the fresnel.
Once the results have been confirmed, is this information then made available to Hugo for discussion with the factory, and shouldn't the factory be conducting similar tests either independently or based on Jeremy's findings?
This test has absolutely nothing to do with the Chamonix factory or Hugo.Quote:
Originally Posted by lilmsmaggie
I am making this test for myself as a Chamonix user and for the benefit of the users of the LFForum and Apug.org (I linked over to this thread on a thread there about Chamonix focusing issues).
Well, since you asked for suggestions...
It occurs to em that it would be nice to have a control...if you have access to another brand of field camera you might want to include that. That would give us insight into the "compared to what?" question...
See what you are getting yourself into :)
--Darin
See what happens when you offer to help, Jeremy? :D Many good points though.
There is no need for such a control in this instance. I'm comparing focusing with a fresnel between GG and lens on a Chamonix camera to no fresnel. Adding another 4x5 camera won't make any difference and just confuse the issue. Showing a sharp scan from a Cambo 4x5 in the same location adds nothing to the final results or the validity of the test.Quote:
Originally Posted by Darin Boville
Actually, this is one of the easier things to test because there will only be 1 variable in play as I can lock down every other practical variable in the lab. That variable is whether the fresnel is installed in the camera.
I will focus on a fixed point with the fresnel installed and make a scan--if the scan is sharp then the fresnel is not causing a focus shift under these conditions.
If this scan is not sharp then I can remove the fresnel, refocus using the same technique and focusing point and make another scan. If this scan is sharp, assuming everything else stays constant, then the difference in sharpness is due to the fresnel.
Obviously, the veracity of the test does rest on my ability to focus a camera and use my equipment, but part of my job is art reproduction which is head-and-shoulders above the difficulty level we're talking here and I have graduate scientific experience designing experimental models and tests. Regardless of all of this, someone will still cry "foul!", but then again studies have shown that people will believe something even when shown overwhelming facts denoting the opposite.
I think you need to buy a 47XL and an 80XL, plus 5 of the most expensive view cameras available, put all of it on the Space Shuttle, and conduct this under weightless conditions. :).
As a Chamonix owner (who has had no issues with this, nor have the other owners I have checked with, whose response has been basically, "say what?"), I am really touched by the fervor of those who neither own or have used the camera :). If only we could channel some of that into feeding the poor or sheltering the homeless etc-type issues.
Appreciate what YOU are putting into this.
Donations accepted :DQuote:
Originally Posted by SW Rick
I'm tired of people spouting off opinions supported by hypotheticals without any practical, real-world testing. The fact these opinions come from those who don't even own the camera makes it even worse. So I figured it time to do those tests myself and lay the issue, at least for myself, to rest.Quote:
Originally Posted by SW Rick
No problem. I've benefited so much from the practical testing of photographic issues by Sandy King and Clay Harmon and Kerik Kouklis and the like that, since I have the skills and equipment to test this, it was time to give back.Quote:
Originally Posted by SW Rick
Thanks for doing this Jeremy.
>>Showing a sharp scan from a Cambo 4x5 in the same location adds nothing to the final results or the validity of the test.<<
Well, that depends on what question you are trig to answer!
:)
The other brand issue can wait for the results of this test...
--Darin
As it is, the proposed test will only answer one question for Exactly one camera - Jeremy's....and is therefore, of little real use to anybody else. We have no idea, for example, what the variation in this critical dimension is from the factory. It would be interesting to select a random sample of production...and measure. In the real world it would just be nice if the sample size were greater than one - forget about the random sample just test more than one item!
I also agree it would be interesting to know how one brand compares to another...but again, it is meaningless to test a sample size of one.
Classic. :rolleyes: