Originally Posted by snaggs
the best lenses for the Rollei Dual are the Apogon 2,8/150 and especially the Apogon 2,8/120 (and easier to project your 35mm slides with this lens).
But nevertheless I would keep your Leica P 300 with the excellent Leica Super-Colorplan (the lens is jewel).
Slide projection is one of the best things you can do in film photography. There film really shines and is absolutely unsurpassed in its quality.
Well, as some of you know, Im running a small non-profit optical test lab.
And weve done lots of detailed tests concerning slide film (colour and BW) and slide projection, as well as evaluating the performance of beamers.
Tests from our team:
We have tested all the films with a relative low object contrast of 1:4 (two stops). Lenses were Nikkor AI-S 1,8/50 (long barrel version) and Zeiss ZF 2/50 at f5,6 (and some others as well).
Both lenses have the same performance in the center at f4 and f5,6, but the Zeiss is generally better at the corners and at f2.
Some test results from our resolution tests (Nikon F6, MLU, MC-30, 1/250s, focus bracketing, Zeiss ZF 2/50, f5,6, Nikkor AI-S 1,8/50, object contrast 1:4; Berlebach Report 3032; the first resolution value represents the number of clearly separated lines, the second one the resolution limit where still a contrast difference can be seen):
Fuji Velvia 50: 110 125 Lp/mm
Fuji Sensia 100: 120 135 Lp/mm
Fuji Provia 100F: 120 135 Lp/mm
Fuji Astia 100F: 120 135 Lp/mm
Fuji Velvia 100: 125 140 Lp/mm
Fuji Velvia 100F: 125 140 Lp/mm
Kodak E100G: 120 135 Lp/mm
Kodak Elitechrome 100: 120 135 Lp/mm
Fuji Provia 400X: 105 115 Lp/mm
Agfa Copex Rapid; ISO 64/19°; Agfa Scala reversal process : 165 180 Lp/mm.
Adox CMS 20 / Spur Orthopan UR developed in: Spur Nano Edge, Spur Nanospeed UR, Spur Modular UR, Adotech: 240 - 260 Lp/mm
(that is the physical diffraction limit for white light at f5,6!).
All these values above can be seen under a microscope.
And, with excellent lenses you can transfer the above listed resolution values with only a minimal (not relevant) loss onto the projection screen!
We've tested several projection lenses, e.g. the Leica Super-Colorplan P2, Zeiss P-Sonnar T 2,5/90 and the Doctor-Optics / Kindermann 2,4/90 MC-B.
With all three lenses we could transfer the 120 lp/mm of E100G, Elitechrome 100, Provia 100F, Sensia 100, Astia 100F onto the screen!
Same with 165 lp/mm of Agfa Copex Rapid as BW-Slide (developed in Scala reversal process)!
120 lp/mm: That is an equivalent of 50 Megapixels. You need a 50 MP beamer to get the same detail at this object contrast. The 165 lp/mm of Agfa CoRa are equivalent to 94 MP. But there are no 50 or 94 MP beamers, not even a 10 Mp is existent.
And even better: We projected an Adox CMS 20 negative with 240-260 lp/mm and got 230 lp/mm transferred onto the screen!!
As now the recent tests with CMS 20 as BW slide have been successful, it is planned to do another test with the CMS 20 slide in projection. The resolution then will probably
even higher because of the higher contrast of CMS 20 slide compared to the CMS 20 negative.
If I look at 35mm slide projection with an excellent projection lens, then the quality is even surpassing digital medium format projected with a beamer. Because the imaging chain film+projection is much, much better than the digital imaging chain digital file+beamer. The beamer is the very weak part in this imaging chain and decreases the quality of the file to a big extent. From your 40,50, 60 or 80 MP only 1,2,4 or max 8 MP (most expensive gear) remain as beamer output.
And of course with medium format slide projection, using excellent lenses (camera and projection) like the Rollei Apogon, you can significantly surpass the already outstanding 35mm performance.
For big enlargements slide projection delivers an unsurpassed quality. And at extremely low costs ( a projected slide on a 1m x 1,50m screen cost me less than a buck, a print of the same size cost me more than hundred bucks).