Gunmen
A7 + Heliar 40/2.8
Pieter, are they fitting that old Cannon tele out with a new E mount adapter, I guess it has radioactive glass, hence the suits
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First of all a very big thanks to all the guys over at FM for all the great information regarding adding a front end filter to the ZM 35mm Distagon to help cure corner smearing caused by the sensor cover glass plate....Brilliant combined work on everybody's behalf
My Opto Sigma correction glass (SLB-50-5000PM) eventually turned up the other day for my ZM 35mm Distagon...I tried a bunch of step up and step down filter rings to find what worked the best to house the glass, whilst checking continuously for any signs of vignetting.
A 49mm step up to 55mm > then a 55mm step down to 52mm > then the Opto Sigma glass held in place with a 52mm retention ring taken from a cheap 52mm UV filter > then a 52mm step up to 58mm filter ring which acts as a shallow hood and also allows a lens cap now to be easily attached ...This worked the best for me....I used a rubber O ring to centre the OS glass within the filter itself, this was awkward to fit and took me several hours! I opted for the convex side of the Opto Sigma glass to be facing in towards the camera rather than outwards.
I tested this with and without the filter above attached at various apertures...The difference was like night and day....The filter is DEFINITELY the way to go if you want improved corners with the ZM.
The downside is that with the OS glass attached it wouldn't allow the lens to focus all the way to infinity
- I tested this with my 4 Leica M to E mount adapters (Novoflex, Yeenon close-up, Voigtlander close-up and a cheap knock off pseudo Hawkes close-up adapter) none of these allowed the lens to focus to infinity.
I therefore had to unscrew the 4 screws on the Leica M mount to get at the shims (This might possibly void the Zeiss warranty as screws are loctited in place).
With the rear M mount now removed I had 4 shims just behind the M mount ZM lens.
2 x thick gold shims
1 x medium silver shim
1 x thin bronze shim
(Note I had different shims inside my lens as opposed to what Bastian K had inside his ZM 35mm Distagon).
I tried various combinations by removing different shims one at a time and reassembling the lens and retesting @ F1.4 for infinity over and over again...on the 4th attempt success!
I found that just removing 1 gold shim with my version of this lens, it now focused as near to infinity as you could possibly hope for.
I then retested for vignetting and DoF tests at various apertures and all works great
...The Zeiss hood will not fit this particular set up BTW...(Note to Teera...Sadly I couldn't find anybody here in Cornwall prepared to grind this 50mm diameter OS glass to fit a 49mm filter ring).
IMO the Zeiss ZM 35mm Distagon is now equal and may possibly be a tad better IQ wise than my Sony 35mm FE Distagon...before the conversion was carried out I thought that my Sony had better IQ for stopped down landscape work...
The Zeiss ZM has better cooler more neutral colours than the warmer Sony FE lens.
I feel the ZM is a true 35mm FL lens (Before conversion) and the Sony is very slightly wider angled.
The ZM 35mm Distagon (including OS glass filter rings and front and rear caps shown) Vs. Sony 35mm Distagon (including B+W thin clear filter, hood and front and rear caps shown) I measured to be 174g lighter in favour of the ZM.
The ZM is much smaller and has a lovely solid feel to it...Manual focusing is buttery smooth and a joy to use.
Both lenses have a superb wide open OoF rendering.
The Sony has less vignetting and provides exif data information unlike the ZM lens does.
Bottom line in terms of IQ - If you don't want to go through all the hassle of the conversion above (i.e. making up a filter and shim removal) then go with the Sony AF and save yourself a load of money and aggro.
If you can be bothered carrying out the conversion above then I think you won't regret going via the ZM route, especially if you prefer manual focus lenses.
I hope that helps anybody interested in getting either of these two great lenses.
Cheers Barry
