steve_kofol Posted October 19, 2003 Share Posted October 19, 2003 Does anyone know how sharpness of the Ronar 300mm lens compares with the sharpness of the Schneider G-Claron 305 AT INFINITY for a 4x5? How about color correction of these two lenses at infinity? Any significant difference? Link to comment Share on other sites More sharing options...
bruce_barlow Posted October 20, 2003 Share Posted October 20, 2003 Don't know the Ronar, but eyes I trust compared the G-Claron with the 300mm Symmar and liked the G-Claron better... The G-Claron is a fabulous lens for any use. Link to comment Share on other sites More sharing options...
greg_prior Posted October 20, 2003 Share Posted October 20, 2003 The manufacturer's data sheets give a clue. I haven't been able to find a data sheet for the Ronar 300, but I have found one for the 240. Schneider's page has data for the 270 and 305 which show very similar MTF results. Schneider's data is at infinity, and the Ronar is at 1:20 so you'll have to figure if this is close enough to infinity to draw a conclusion. FWIW, the MTF is much better at 1:20 than 1:1 (it's going the right direction). The G-Claron 305 at f/22, infinity focus, and 12 lp/mm spatial frequency managed 80% MTF on-axis, 55/50% out 75mm (4x5 no shifts) and 52/32% at 190mm (8x10 + some shifts). The APO-Ronar 240 at f/22, 1:20 focus, and 10 lp/mm was 85% on-axis, 75/75% out 75mm, and 60/0% out 110mm (OK, so don't use this one for 8x10). In case you think the Ronar's 10 lp/mm is wimpy compared to the Claron's 12, the APO-Ronar 240 at f/22, 1:20 focus, AND 20 LP/MM was 67% on-axis, 52/58% out 75mm, and 30/0% out 110mm. So DOUBLE THE RESOLUTION at 4x5, no shift. Neither give color data, and I haven't tested them. -Greg Link to comment Share on other sites More sharing options...
armin_seeholzer Posted October 21, 2003 Share Posted October 21, 2003 Hi Steve There is also something else wich counts for me. The Ronar you can get in the MC version the G-Glaron only single coated so you get more contrast on the Ronar and it is less a problem with flare! Link to comment Share on other sites More sharing options...
greg_prior Posted October 22, 2003 Share Posted October 22, 2003 I was curious what a 1:20 focus was, so I did a quick design on the simulator. For a 240mm lens, the object was at 4.2 meters to get 1:20. For a 305mm lens, the distance was 5.3m. So maybe the that doesn't make for an exact comparison to infinity. But if you look at the G-Claron data sheet, it shows data at two shorter focuses. Their numbers don't work out in the simulator, so I don't understand what magnification they are. Conflicting data puts them somewhere between 1:1 and 1:6. So it looks like the 1:20 data for the Ronar won't change that much as you approach infinity. I've been trying to get patent data on these lenses so I can get accurate models into the simulator. Then I could really compare at infinity, get color data etc. Maybe someday... I did get the patents on the new Schneider XL lenses. But they left out the aspherical coefficients. One of these days I'll see if I can do an optimization and get results similar to Schneiders... Of course all of this only applies to a theoritcal lens. Yours will be different - just hopefully not too much. :-) Hope that helps. -Greg Link to comment Share on other sites More sharing options...
steve_kofol Posted November 8, 2003 Author Share Posted November 8, 2003 Greg and Armin, Thank you for your thoughts. Steve Link to comment Share on other sites More sharing options...
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