Coin Imaging At 2x: Lens Comparisons

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Author	Replies: 3 / Views: 4,190
rmpsrpms Pillar of the Community United States 4037 Posts	Posted 09/24/2011 03:13 am There is a thread over on Photomacrography.net with some discussion about the Rodenstock apochromatic duplicating lenses. Some of you may know that Rodenstock offers a "Duplicating" lens that is optimized for 1X magnification, the 75mm f4 Apo Rodagon D 1:1. I've been abbreviating this lens as 75ARD, but now with the talk about their 2X optimized version of this lens, the 75mm f4.5 Apo Rodagon D 2X, I will need to call them 75ARD1 and 75ARD2 respectively. Anyway, I purchased one of the 75ARD2's and just compared it with the 75ARD1 and a 63mm f2.8N EL-Nikkor. Since I used a coin as the comparison vehicle, I thought this might be of interest to folks here so I will paste the entire thread below. Bottom line is that even at 2X, the 75ARD1 significantly outperforms both the 75ARD2 and the 63ELN..Ray ----------------------------- I just tested my new 75ARD2 lens against my 75ARD1 at 2X. I reversed the 75ARD2. Subject was a 1957-D Lincoln Cent and I centered the image around the mintmark. Here are shots of the full 2X frame (4928x3264px reduced to 616x408px) and 100% center crops of the mintmark (580x450px). I am seeing the same thing with this new 75ARD2 as I did with previous. The 100% crops show the 75ARD1 is clearly sharper than the 75ARD2. And this is at 2:1, where the 75ARD2 is optimized and the 75ARD1 is away from its optimum 1:1. Edited to add similar pics using 63mm f2.8N EL-Nikkor. I can hardly tell the difference between the 63ELN and the 75ARD2. Note that all these were taken at f7.1 (setting, not effective). 75ARD2 full 2X frame 75ARD1 full 2X frame 63ELN full 2X frame 75ARD2 center crop 75ARD1 center crop 63ELN center crop Contact me for photographic equipment or visit my home page at: http://macrocoins.com Report this Post to the Staff

SsuperDdave Moderator United States 23522 Posts	Posted 09/24/2011 08:26 am All other things being equal, I think I like the ARD2's color rendition best, but it's no match for the ARD1 in terms of sharpness. Report this Post to the Staff
Frank Cubic New Member Canada 1 Posts	Posted 09/20/2015 12:17 am Thank you very much for this post! I'm just wondering if the results,would be same with full frame sensor.I don't take pictures of coins,but I'm trying to preserve my old collection of film and photo prints.Some of my film is tiny Kodak disc film,and some of my prints are very small and in poor shape. I ordered yesterday brand new(old stock) Rodenstock APO rodagon-D 2X 75mm f/4.5,for my 2X,or 2.5X enlargements.Rest of my equipment is:Nikon D610,Sigma 70mm f/2.8 Macro(for 1:1),Sigma 105mm f/2.8 Macro,Olympus Zuiko 50mm f/3.5 Macro,and Kaiser Reprostand RS1. I would like to know,what length of extension tubes I need to use with this lens for 2X,and 2.5X close up? Yes,and I have old Pentax helicoid extension tube 16mm-32mm (M42). The best and most usefull site for macro lens review is "coin imaging.com",but sadly nothing about this particular lens. Please,help me if you can! Report this Post to the Staff
rmpsrpms Pillar of the Community United States 4037 Posts	Posted 09/20/2015 10:45 am FC...the 75ARD2 has lower resolution at the center, but flatter field, than the 75ARD1 at 2x. This is apparent for APS-C and more so for FF sensors. At the edges of APS-C, the 75ARD1 has degraded to be about equal to the 75ARD2, but I expect the 75ARD2 would be better at the edges of FF, though I have never tested this. Remember, this is for the 75ARD2 in REVERSE configuration. It is optimized for 2x enlargement, ie the object/print is 2x bigger than the feature on the sensor/film. If you are configuring it for 2x magnification, it must be reversed. This is fairly common when using lenses for repro/duplication. An approximate formula for magnification is: M = (Total Extension - Focal Length) / Focal Length or M=(TE-FL)/FL The TE includes the camera register distance, 44mm for Canon. Arranging the formula for TE, you get: TE=FL(M+1) So added extension needed is FL(M+1)-44. If you want 2x, you need 75(2+1)-44 = 181mm of added extension. 2.5x requires 219mm. Note these are approximate since the mounting method will affect the extension required. The numbers above are probably pretty close for normal mounting, but reverse mounting will add some extension due to the lens body dimensions. The total extension should be measured to the center of the lens, which is probably pretty close to the physical aperture. I too am a fan of Mark Goodman's site. Several of the lenses he has measured were consigned by me (both 75ARD1's, the 105mm Printing Nikkor, the Zeiss 74mm S-Planar, the 65mm Nikon Macro-Nikkor, and Nikon 5x MM objective) and I'm extremely happy he was able to take such accurate and useful measurements of these lenses. You may be interested in a "shootout" I did over on photomacrography forum of a wide range of lenses at around 2.4x, which seems appropriate for your purposes. Here is the link: http://www.photomacrography.net/for....php?t=20173 Ray Contact me for photographic equipment or visit my home page at: http://macrocoins.com Report this Post to the Staff
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