Saturday, June 22, 2024

ZM 25/2.8 Biogon T*

ZM 25/2.8 Biogon T*

ZM 25/2.8 Biogon T*

2.8/25 25mm f2.8



It took me quite a while to decide between the ZM 28/2.8 Biogon or the ZM 25/2.8 Biogon. Finally I got the 28/2.8 Biogon and is very happy with it. So quite a while later I bought this ZM 25/2.8 Biogon, after almost a year wait placing order for the lens during the nuclear reactors disaster in Japan, one of the likely reason causing a short of stock of these made in Japan Zeiss lenses.






I really do not believe there will be observable differences between the two, although everybody seems to comment that the ZM 25/2.8 is superior, as indicated by the MTF curves provided by Zeiss. So am I, very impressed by the 25/2.8 MTFs.



MTF curves for the ZM 25/2.8 Bigon T*



MTF curves for the ZM 28/2.8 Biogon T*




Size wise the 28mm Biogon is much compact than the 25mm Biogon. Also the 28mm is quite attractive as it can be used on most range finders without external finders, which can be a plus point in many shooting situation. The 25mm, however, will find Voigtlander R4M or R4A a very good body to work with. The ZM 25/2.8 can be used with two original Zeiss round hood and square hood. The view finder blockage on a R4* can be found here.



From left to right:  ZM 21/2.8, ZM 25/2.8 and the most compact ZM 28/2.8







Manufacturing quality wise this very recent production of 25/2.8 that I bought improves drastically from my early production badges of ZM made in Japan lenses. Now the focusing ring as smooth and well damp as the made in Germany ZM 15/2.8 Distagon and Zm 85/2 Sonnar. Well done Cosina!

I really do not do lens tests but just buy lenses and use them. But for this 25/2.8 I tried to do a comparison with the ZM 28/2.8 Biogon. The set up was fairly simple and by no means  scientific or very accurate. I set up using a Voigtlander R4M on a Manfrotto 190B tripod with 054Mg Manfrotto ball head. The camera was mounted on a Metz 60CT4, shooting with the flash almost directly bounced on the while ceiling of one of my room. The test negative was Kodak Portra 400. I decided to compare the two lenses based on same image coverage, so when shooting with the ZM 25 the set up was nearer to the test subjects. I placed a Contax RTS III at the centre of the composition, a Rollei 35RF at the left centre, and a Contax Aria on the top right corner. The photographs were shown below:



ZM 28/2.8, f5.6, focus on the RTS III at the centre of the photo.


ZM 25/2.8, f5.6, focus on the RTS III at the centre of the photo.


I had taken shots with both lenses set at f2.8 and f5.6. I decided to focus on the f5.6 pictures as I believed the f2.8 ones could not make conclusion due to high chance of focusing inconsistency between the two lenses for my set up. I got the negative developed and scanned at 16base JPG and could not see any differences. So I went back to the shop to re-scan as 63 MB tiff files and crops on computer screen at the centre, left and top right are shown below.




ZM 28/2.8                                                             ZM 25/2.8




ZM 28/2.8                                                               ZM 25/2.8




ZM 28/2.8                                                               ZM 25/2.8


Frankly I cannot really tell any significant differences between the two lenses. It could be both lenses out resolved the ASA 400 negative. But as what I have believed earlier, the two lenses should be equally good for most practical shooting purposes for amateur like me. Probably the ZM 25/2.8 is a good compromise if you so decide not to bring along a 21mm and a 28mm. 



Voigtlander R4M, f4/5.6 1/250, Manfrotto 190B/410gear, 22 Jun 2013.


Voigtlander R4M, f4 1/60,  22 Jun 2013.



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