Bronica EC help(!)

[fotografista]

Hello everybody.. New to APUG relatively old to MF photography but in love with it for sure!
The reason for posting is the following. I'm totally confused about my Bronica EC camera.
I got my camera through ebay featuring a 75mm Nikkor-P. The camera was performing great! Lens sharp, focus accurate
The problem starts when i got a second lens from ebay, a 50mm Nikkor H/f3.5. Every film i developed and scanned afterwards is misfocused. The focus is far behind my target object of focus. Note that focussing though the wail level finder with the magnifier in place is done absolutely sharp and clear!!! I googled a bit and found some people saying that the helicoid mechanism of the camera has to be swapped for another to suit every lens i get. So my questions are :
a. Do i need to have separate focus rings (helicoids?) for every lens?
b. The focusing ring on my lens has a marking 75mm at the edge. Does this means that its suitable only for 75mm lenses?
c. I dont have any users manual. but a users manual i found for the S2 which is the same system in terms of mounting/lenses etc describes that the focusing ring is suitable for 50/75/135/200mm nikkors. The Bronica EC ring is different?

Anyone that could help will be appreciated cause I have already bid for a 150mm and a 200mm lens for this Bronica. before noticing these issues.. I need to know if i can use them on my system as is or i need to purchase extra part to do so.
Really thanks in advance.
George P. from Crete, Greece

 

[David A. Goldfarb]

The Bronica EC and S series use the same focusing rings, and the basic focusing ring is suitable for most lenses, the exceptions being some telephoto lenses longer than 300mm that require a longer focusing ring.

The problem is likely to be either the common groundglass issue that happens to most classic Bronicas (the foam under the groundglass frame needs to be replaced--a simple and inexpensive repair), or you could have a mirror alignment problem that is more specific to the EC and EC-TL. When you fix it, your shots with the 75mm will probably be sharper as well, even though you may not currently notice a problem, because a small groundglass placement error will cause a more severe focus error with a wider lens.

 

[fotografista]

Thanks David
I managed to talk w/an experienced technician and he assumes (hw want to see the camera/lens first) that its a camera issue/prob and not the lens.
I prefer the problem to be a camera prob than the lens but what seems strange to me is that every photo w/the 75mm NikkorP/2.8 seemed very sharp
Anyway, i'm sending camera + lenses to the technician for a proper check.
By the way.. i think its important to share with all of you my dissapointment with the ebay purchases.. Bought a yashicamat 124g, turned to be faulty.. Bought the Bronica, seems to be faulty, bought some m42 lenses, 2 of the 4 turned to be faulty.. Its a pitty.. Nothing of them was described as faulty... Not to mention the films i used to test all these, the chemicals.. but most of all the dissapointment of a purchase of a faulty item... Never mind.. Just emotions..