Not that difficult, just sort of fiddly...Originally Posted by iogdka
Steve
Not that difficult, just sort of fiddly...
Steve
From Chamonix' website:
In my experience and from what I have learned from test results, it seems that lenses of different structure and lenses of different focal lengths will have different focus shift when used with Fresnel lenses. Certain lenses, for example, will produce slight focus shift when stopping down due to their unique structure of the lens. Based on this, I do not recommend that users of 45N-1 camera to change the position of the Fresnel lens as all cameras are tested for the accuracy of the Fresnel position before leaving our factory. By changing the position of Fresnel lens, one can’t solve the focus shift problem for all the lenses, only some of the lenses.
My recommendation for those of you who have this focus shift problem is the following:
1. Take off the Fresnel lens and use your camera as usual.
2. Return your focus screen to your dealer and our factory will modify it by drilling a hole of 16mm diameter in the middle of the Fresnel lens. This small hole can prevent or fix focus shift that may or has occurred. We have done repeated tests with this method and the result is very satisfactory. The small hole will not interfere with your composition on the ground glass and will easily prevent possible focus shift.
For all 45N-1 camera users, I sincerely apologize for this design error caused by my improper judgment. This warns us to be more careful in future and we will fix this error. For future 45n models, this 16mm hole on the Fresnel lens will be standard.
I just noticed the age of this original post. But, someone searching may find this statement from Chamonix useful.
Just curious how a 16mm hole will fix the focus drift?? Am I missing something?
I was wondering the same thing as well. Maybe someone can explain the principle.
I would second Michael's comments. I have used the Chamonix for several years and I find it very, very easy and have not had any focus issues. I really like the camera.
The website is inaccurate. They did not end up doing the hole. Instead, they did the right thing and moved the fresnel to the outside, and placed a protective glass atop that.
The hole in the fresnel was intended to give you a 16mm fresnel free area in the middle of the ground glass for focusing. Sounded like a real hack to me, since I focus all over the glass. I assume this is why they abandoned that idea.
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