Focusing idea Chamonix 45N-1

[Jfnphotography]

Have a fall colors trip next week. This will be the first big test of my new camera. Want to use my 90mm lens for the trip. Don’t want to remove the fresnel lens that’s one of the reasons I purchased the camera. I have read some of the other suggestions. Here is my idea.

Seen another e-mail that said

But did note the false focal point at about 25 feet (fresnel in place between gg & lens). This then focused about 30% closer with the fresnel removed (about 17 feet).

So I measured out 25ft from the camera and focused on something. I then put an object 17 feet away and focused on that. I found that the rail moved 2mm back wards to focus at 17ft. (fresnel in place between gg & lens)

I than made a line on the focusing knob and found that the different from 25ft to 17ft is ¼ turn counter clock wise.

If I’m taking a photograph with no camera movement and focus on something like a fence at 25ft then move the focus knob ¼ turn counter clock wise would I be in focus?

Could I use some movement if things were at a distance from the camera? I think any thing close would be out of focus from moving the rail.

It would be a pain to do this for every photograph. I would still need to remove the fresnel to test my idea out. I think I’m going to see if I can order a back with just ground glass, so I can switch them out when I use my 90mm.

[BarryS]

I suggest you test your camera before go on your trip. My 45N-1 focuses correctly. I can tell because I shoot a lot with fast Petzval lenses wide open and the negatives are sharp at my focus point.

[Lachlan 717]

You could drill a hole in the centre of the Freznel (10-12mm should suffice). That way, you can use a loupe to check the brightest part of the GG to corroborate the Freznel focus.

This, of course, will not be of much use if you're swinging/tilting/shifting as it will only show the middle of the shot to be in focus...

Lachlan.

[Robert A. Zeichner]

Jacob, the designers of any camera that was meant to be used with a Fresnel between the GG and the lens should have taken that fact into account when arriving at the plane for the frosted side of that GG. From all that I have read on this forum, this is not the case with the Chamonix unless this has changed very recently. That said, I would test the camera very carefully. I would do this with and without the Fresnel installed at distance of less than 6 feet and with a lens fully open at f 5.6 and compare your results. I'm guessing that you will see a very noticeable difference. Be aware that with shorter lenses, ground glass/film plane coincidence is even more critical. I'll email my article on this topic to you as it may be of help.

[jb7]

That seems like a big problem with that camera-
I'm quite surprised that people seem to be willing to work around it-

If the correct plane of focus is on the gg without a fresnel, then surely removing the fresnel is the only way to work?
That, or replacing the gg on the outside of the camera...

[GPS]

Absolutely amazing! Chamonix is probably the only modern camera manufacturer producing some cameras that cannot be focused properly! Now, when it is known in amateur circles, I wonder how long it will take for them to correct the problem or if they will persevere with their explication (published in a different post) that it doesn't matter as pictures are usually taken at smaller apertures than they are being focused at! Amazingly brazen stupidity!

[eddie]

mine works fine......hhhhmmmm

[Larry Gebhardt]

Mine works fine as well. I tested it at close distances wide open with some old Polaroid film. Focus seemed dead on.

This is the first I have heard of this issue. Do you have any more info on this issue?

[Darin Boville]

Mine is fine as well. I posted my Polaroid in the other thread.

--Darin

[Darin Boville]

Just another thought...

Why don't the people who bought the bad ones list when they bought the unit and which dealer they bought it from--it may turn out to be a bad batch vs an ongoing quality control issue.

--Darin