John, the original poster of the question, asked me privately about the caps for Contax hoods.Here is my detailed answer in case anyone has such question him/herself.
Dear John,
I have gotten myself into something here. I think this should be preserved in RFF or ContaxG ...
Anyway:
There are snap-in caps with two springs to hold/set a hood cap inside the hood.
There are snap-on caps which go over the outside of the hood's front.
The three Contax G hoods all have an inside diameter of 55mm, an outside diameter of 57mm.
Contax made a snap-in cap (GK-51) specifically for the 21mm Biogon lens that fits all three available hoods uniformly.
They also made a snap-on hood (GK-54) that fits over all their hoods.
On the market (ebay) there are now remade Contax G hoods (virtual-village, China, .. ?) that are slightly smaller in front diameter. These outfits also make cloned GK-54 caps that do not fit well, not even their own hoods. Beware.
(The caps, both Contax and cloned, are metal, with a thin felt ring inside of them to jam the cap onto the hood. The chinese felt is too thick and too loose to even let the lens cover slide all the way on. The Contax felt is firmer and thinner and slips on ok, but also easily off. Slippery felt ..)
For what follows I assume you have original Contax made hoods. The clones are not worth any money in my book.
Snap-in:
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All snap-ins sometimes do not hold well on first being put back on; they need to be pushed and jiggled into the inner hood groves or they might just jump off at the slightest touch. Sometimes the ears (to connect to the spring mechanics) protrude and get caught in tight places in my bag.
Details:
Contax GK-51: nice, but not ideal; does not catch too well inside the hood.
Hama 55mm: Nice since the ears do not protrude and none of its edge does either, but the springs are a bit weak and the diameter too small for a tight fit, so the cap comes off too easily when the lens is handled
Generic 55mm (B+H): ok; it is the only inside snap cover that fits the smaller diameter Chinese hoods.The ears and its rim stick out a lot.
(Note: Contax GK-51 or Hama 55mm will not fit inside the Chinese hoods)
Snap on caps:
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Their problem is that small outside forces will loosen them in the field, or when pulled out of the bag.
Contax GK-54: jumps off easily when touched ligthly on the outside. I have lost one inadvertantly going through some light bush. Some plant leaves (or my shirt, arm swing, ... ?) must have tickled it off my camera that was hanging behind my body over the shoulder on my first outing with it. A true bummer, unless you only photograph in spacious uncrowded saloons and vast castle chambers with no contact from the "outside" touching your lens.
Generic black 57mm cover (B+H): fits tightly and well, but still suffers (a bit less) from the touch = pull off weakness of the Contax one.
My choice: (From my experiences) I use one of each of the snap-in hoods on my 21, 28, 45, 90 mm lenses and the generic 57mm snap-on on the 16mm. Besides, I have a spare snap-on 57mm in the bag in case I lose another darn hood cover.
All these hood caps have jumped off onto the floor inadvertantly at one time or another. Why?
This had never happened to me before - the inadvertant loss, slip-off of lens hood covers before with Nikons, OMs, ..., Practicas, ...
The Contax is so special they say -and I agree; my G2 is marvellous, but with tongue in cheek here.
So, Here you have my knowledge gained since I switched to the G2.
My bag is a Lowepro RES 50AW that holdsall the lenses (face down with hoods attached, on the left and right sides), camera (face down in the center), flash etc; with extra Lowepro hip belt, and lined with a set of extra small velcroed dividers from Maury Cohen (search phnet) at Lowepro.
