An observation on the wartime Biogon 35/2.8 lens
An observation on the wartime Biogon 35/2.8 lens
Today my Biogon 35/2.8 lens arrived in the mail. I was happy (it looks great!) but it came without caps and that got me a bit jumpy, given the fact that the rear end is one huge glass element 😱
After consulting Tom, I cut down a Kodak film canister to fix me a rear cap (works like a charm, thanks Tom!) but how to protect the front of the lens? Some fitting of push-on plastic lens caps resulted in a lot of caps too small or too big, but none that actually fitted nicely... I decided to turn to a 40.5mm filter for the time being.
As you may be aware, the aperture ring of the Biogon (and Jupiter-clone) is receeded in the front of the lens. It has a filter thread there, but when focused at infinity, this thread is covered by the optical block assembly and it takes no filter anymore.
BUT: when first setting the aperture and then setting the preferred distance of 4 meters or closer, enough of the filter thread remains uncovered to fit a filter.
This fact allows it to function as a point-and-shoot lens quite nicely: first set the aperture to desired value, then set the lens to the desired distance, screw the filter on, turn the focus a bit further away (millimeters on the barrel), tighten the filter a bit more and then return to the desired distance on the lens. The filter will then grip both the aperture ring and the filter threads and both aperture and focus are fixed.
You can have the lens set at 3 meters and f8.0 and it will be a perfect pount-and-shoot that is well-protected by the filter and will not shift that easily. It will be hyper-focal from almost infinity down to 2 meters.