Bronica focusing helicoid (75mm helicoid for zenzanon 100mm?)

[sealionfilm1]

Hello, I just found a cheap Zenzanon 100mm lens but do not have a focusing helicoid. However, I do have a Nikkor P 75mm f2.8 with its focusing helicoid, with "75mm" marked on it. Can I use this helicoid for my Zenzanon 100mm? Will it make the lens interfere with the mirror or anything?

 

[OAPOli]

Yes you can use this helicoid with the 100mm lens. This lens interferes with the mirror when the helicoid is fully retracted (infinity position), but only on the EC-series bodies.

 

[itsdoable]

Yes you can use this helicoid with the 100mm lens. This lens interferes with the mirror when the helicoid is fully retracted (infinity position), but only on the EC-series bodies.

Really? have the EC-TL, and I don't recall the 100mm interfering with the mirror.

There was only one helicoid made for the S series, and the latter ones added the focus scale for the 100mm on it.

 

[OAPOli]

@itsdoable

 

[itsdoable]

@itsdoable
View attachment 423449

Ah yes, I remember that. It's about removing the lens, not shooting.

The mirror clears the lens when shooting (It's a favorite lens for me), I've used it a lot - hence my confusion about interference - I use the S2 more than the EC-TL, so I was wondering if maybe I just never encountered it!

I believe the issue is when you rotate the Helicoid and lens combination, parts of the lens that intrude into the body will rotate and scratch the lower mirror. This does not happen when you just remove the lens block and leave the helicoid on the body. Generally I always leave the helicoid on the body, and just change the lens.

 

[OAPOli]

Yes I think the helicoid needs a longer angular travel to remove, so one of the baffles on the lens can strike the mirror?

I agree, the lens is really good!