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Can I replace Hasselblad 250 CF front bayonet?


pavelkupcik

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I have a 250mm Superachromat whose front bayonet metal ring is is scratched up and I’m wondering how difficult it would be to replace it myself. The previous owner must have attached to it something with outter screws that tightened against the outer portion of the bayonet and leaving scratches on the smooth part of the bayonet. It’s purely cosmetical so I can always just live with it, but if it’s easy then may try to replace it. I was thinking about trying to be on the lookout for a broken regular 250mm lens for parts, remove the bayonet from it and replace it.

 

Is this possible to do myself? how?

 

Is the bayonet from regular 250mm CF the same as the one for Superachromat? Looking at pictures the exterior mechanical construction of both lenses looks exactly the same.

 

is it possible to just buy the part I want to replace? Where?

 

Thank you.

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The rings on lens hoods and filters are metal. The filter ring on lenses will become scratched in short order. If it bothers you, touch up the metal with a black permanent marker, or better yet, a black paint pen sold at most hobby shops. The filter ring appears to be an integral part of the body of the lens, and probably can't be replaced without extensive disassembly.
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As Ed_Ingold said, the scrapes and wear on the lens bayonet were caused by the metal locking springs of Hasselblad's lens hood (for decades, this extremely common wear was referred to by 'blad enthusiasts as "hood rash"). The problem was so widespread and annoying that Zeiss finally came up with a "cure" during the transition from CF to CB, CFi and CFe: these final lens barrel revisions have replaceable carbon fiber (i.e. plastic) lens bayonets that are highly resistant to hood spring damage.

 

You are correct that the 250mm SA and 250mm standard lenses are both housed in essentially the same CF barrel, and the CF lenses do in fact have replaceable front bayonet rings. The replaceable aluminum CF bayonet rings were Hasselblads first attempt at solving the "hood rash" issue (previous C lenses had bayonets integral with the front lens barrel: these could be replaced but the cost was astronomical).

 

Unfortunately Hasselblad no longer officially services or stocks replacement parts for the V film camera system, so you are extremely unlikely to find a brand new CF bayonet ring easily or inexpensively. If you really want to replace the ring, you would need to harvest it from another mint condition CF lens. The least expensive CF lens you can buy in mint condition would be the standard non-SA 250mm, at around $350-$400 (USD). Swap the nicer bayonet ring to your SA, put the worn ring from the SA on the lens you bought, and immediately resell that lens. You'd likely lose about $150 on the deal, but when Hasselblad was actually still selling spare bayonet rings that was the price they charged anyway.

 

You could also ask a good Hasselblad repair technician to remove the ring from your 250mm SA, and re-finish it in flat black paint. Removed from the lens, it could be completely repainted with no risk of spillover on the rest of the lens barrel. If you wanted to DIY, the bayonet ring is released after you first remove the name ring from the front of a CF lens using a spanner wrench to unscrew it. This must be done VERY carefully, as the name ring is made of soft plastic and very easily damaged. Given the 250mm SA is worth 6x the value of a standard 250mm, it is worth paying a professional to do the work with the correct tools: if you scratch the engravings or break the wrench slots in an SA name ring, there is zero chance of getting a pristine replacement.

Edited by orsetto
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Thank you for the feedback. Good to know it’s possible, if I find a good deal one day on the regular 250mm I may try do this myself. I would likely use one of those rubber cones to unscrew the front as to not damage the name ring.

 

Attached is a photo of the scratch I’m talking about, it’s on three sides of the lens, left, right, top.

 

7A199AED-F019-452B-A31E-A07E30A8AB58.thumb.jpeg.468b918768c66207447f8768439f9005.jpeg

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That's relatively minor "hood rash" for a CF lens.

 

If it is limited to just three little circular scrapes like the one side pictured, I would probably be inclined to just touch it up with a medium Sharpie and forget about it: you'd be able to tell it was slightly touched up if looking closely, but it still would be nicer than the silver scrape circles.. Wear on the bayonet lugs is uglier and more difficult to touch up: if there was was wear all over the ring it would make more sense to risk a swap. In this case, a little flat black camera paint or a Sharpie should be sufficient.

 

I understand the emotional irritation in owning a 99% mint, rare, premium lens that is only just knocked off 100% by such small defects: the temptation is great to do anything possible to restore 100% appearance. Leaving cost aside, there is another consideration: proper fitting of the replacement ring is difficult to DIY. In many cases, a DIY bayonet ring swap results in an imperfect fit, in that the "new" ring wiggles when touched or a filter/hood is mounted/removed. This is mildly annoying on $400 CF lens, on a $2500 SA lens it might be more irksome than touched-up hood rash. Hasselblad and its trained independent technicians had access to bespoke tools that can safely tighten the assembly after fitting a replacement ring, eliminating any looseness or wiggle. But this is difficult or impossible to achieve with the usual DIY rubber stopper or spanner tools: there's often a little "play" after a swap.

 

Try touching it up first and live with it for awhile: you could always change your mind if not satisfied (Sharpie ink removes with alcohol, and you could look for another ring or donor lens at your leisure).

Edited by orsetto
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