Saturday, February 23, 2013

Quartz fluorite lens vs 100mm Focotar enlarger lenses for reflected UV photography III

Today again about comparing a quartz fluorite lens with two conventional, but UV capable enlarger lenses. I have done a similar comparison for a 100mm lens here and here and a comparison for 50mm lenses previously here. I'm using a yellow/red Phalaenopsis flower for that and my "work horse" UV filter, the Baader-U filter plus the deeper reaching Jupiter-U filter. Lenses used are a CERCO 94mm quartz fluorite lens as well as two different 100mm Focotar enlarger lenses. Light source was an UV enhanced Xenon flash. All shots were done at f8 and are presented in a side-a-side format for easier comparison. CERCO lens is leftmost.

[click on image to see a larger one]

Visible light images:

UV images using Baader-U filter (approx. 320-395nm, effective peak approx. 375nm):

UV images using Jupiter-U filter (approx. 280-385nm, effective peak approx. 365nm):

It gets pretty obvious that both enlarger lenses reach quite close to the quartz fluorite lens, but neither can't quite beat it in terms of sharpness + contrast. Admittedly both are quite close. Both enlarger lenses have a very small and nearly neglectable focus shift, 0.45% (middle lens) and 0.46% (right lens). I rate them very useful lenses and the best I have found so far!

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site