Contax G21 performance w/o baffles

[Nelson Tan]

I considering a G21mm that had its rear baffles/flange removed (to be used on a Sony Nex). Can any owners with a G21 missing its rear baffles confirm if it affects the performance on a Contax G1/G2?

Thanks in advance!

 

[Bill Jones]

Nelson,

No experience there, but the legs were originally put on the Contax G wide angle lenses to protect the rear elements when the lens cap was removed, expecially if one stood the lens on its rear face without a lens cap. So they are not necessary for lens performance. The area where the legs were cut or removed, of course, must be well covered with a black non-reflecting paint.

As I side note, I never cut mine and now I've seen an un-cut Biogon 2.8/21mm successfully mounted on a Sony A7.

 

[Nelson Tan]

Bill,

Thank you for the short and succinct answer - it answered my query perfectly. I had imagined the legs to be some sort of baffle against stray optical flare for the Biogon design. If they are for protecting the rear elements, it makes me feel a lot more assured that the optical performance of the lens won't be compromised even if they are missing.

 

[YYV_146]

Bill,

Thank you for the short and succinct answer - it answered my query perfectly. I had imagined the legs to be some sort of baffle against stray optical flare for the Biogon design. If they are for protecting the rear elements, it makes me feel a lot more assured that the optical performance of the lens won't be compromised even if they are missing.

The issue is that While the G21 may be able to mount and clear the sensor, the original design does not take into account the position of the NEX cameras' shutter, which is further away from the sensor than the G cameras. The 16mm Hologon mounts to the A7 without any modifications, but if you take a picture with an unmodified lens you are more than likely to dent the shutter and cause internal damage to the camera.

I would proceed with caution; even the metal protection is removed, I'd check adapter tolerances and clearance to the sensor via the sensor plane indication line. Make sure you have a good few mm's between the rear element and the sensor before taking pictures with the combination.

 

[Nelson Tan]

Hi Viktor,

Thanks for the heads-up on the Sony. I'll be using the G21 on the Contax G1/G2 instead, which is why I'm checking if the missing baffles will affect its optical performance.