OS Planar outer bayonet

[Anscojohn]

Can someone tell me the size of the outer bayonet on the Hassy old-style chrome 80 mm Planar?

 

[Q.G.]

The diameter is 60 mm.
On top of that are three bayonet 'ridges' 1 mm high, about 24 mm long (including slopes on either end).

 

[Anscojohn]

The diameter is 60 mm.
On top of that are three bayonet 'ridges' 1 mm high, about 24 mm long (including slopes on either end).

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Thanks for your response. That is what I thought, come to find that the 60 mm is too big. I guess the old style chrome planar is smaller.

 

[Q.G.]

Those are the dimensions of Hasselblad's Bayonet 50 mount. The one that is on the "old style chrome planar", and many other lenses too.

 

[Anscojohn]

Ahhhh, so I need a Bayonet 50 hood, not a 60. Rather confusing, methinks.

 

[Q.G.]

You do, yes.

These mount names are indeed rather confusing. That is because Hasselblad has chosen to name their mount sizes after the (approximate) size of the glass bit in the filters they each take.
Zeiss took the outer diameter of the filter (they made Proxars and Softars for the same mounts) as a guide, and initially called the thingies that fit Hasselblad's Bayonet 50 mount "B 57".
(Later Zeiss too adopted the Hasselblad mount name for thingies that should fit Hasselblad lenses. Made sense.)

It also leads to confusion when people are looking for adapters to fit their screw mount filters on Hasselblad lenses.
There are step up rings in the market that, going by these numbers, would work, yet take thread mount filters that are too small.
Hasselblad Bayonet 60 filters - the next step up - are the same size as regular 67 mm threaded filters. So despite what the numbers suggest, a Bayonet 60 to 62 mm thread mount filter adapter is not something you would want to spend money on.