Been a while since doing any of this.
Mount the lens to be tested on the Sinar P. There is a reason for this, lenses are checked at full aperture and stopped down. Camera alignment cannot be an issue that affects the performance of the lens. If the camera's front to rear standards are NOT absolute parallel out of focus due to the front to rear standards being out of alignment this applies to full aperture more than stopped down. Lens must be properly mounted to it's lens board. If the lens mounting is outa-whack, this can and will affect lens performance.
Point the lens out a open window on a bright sunny day at some far distance object with fine details like a building, tree cluster or similar. Apply a high quality 5x to 7x loupe on the GG, examine the GG image very carefully for focus, image quality and all that at full aperture, then two stops down then f22, then f45 across the entire area of the GG.
If the lens cannot pass the GG basic test, stop here and reject the lens. Don't bother wasting any film as the lens will be an automatic dud.
Film flatness is an issue, simplest way to aid this is to apply a small piece of double stick tape ( 1/2" x 1/2" or so will do for 4x5) to the center of the film holder before the film is loaded (bit tricky as the film sheet might want to hang up on the small piece of tape while loading, so do this upside down or curve the film slightly while loading) . Press down gently with a cotton cloth at the center of the film after it is loaded. Yes, it raises the film by a few thousands of an inch, but it is a LOT better than having the film pop out or not stay flat to the film holder affecting the test results.
If the lens looks GOOD on the GG, make two color transparencies at full aperture then at f22. Exposure will typically be sunny 16, verify with a good light meter. Take the film to the processing lab, get the film processed then examine the results on a 5000K light table with a good microscope or high quality loupe 10x or so. Schneider once made high magnification loupe that were not bad, there is certainly equal to better ones easily available today.
If the lens gets this far. To the color rendition test as noted in post# 20.
https://www.largeformatphotography.i...ght=elinchrome
Rinse-repeat what was done above. If the results are acceptable. Apply the lens to your print image goals, evaluate the results to see if all is acceptable. This is where the personality of the lens begins to be revealed in ways those test above cannot reveal.
For image circle test. lenses for 4x5 is easier than lenses for larger film formats. Set up a 8x10 view camera (easy with a Sinar) mount the 4x5 lens to be tested and do the point the lens out a open window on a sunny day test. This will give some idea of how big the image circle is and how the lens behaves at the edges of it's image circle. Keeping film flatness and camera alignment is a LOT more difficult with 8x10 due to the physically large parts involved.
Bernice
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