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Bob McCarthy
20-Sep-2011, 09:23
I purchased a new Chanomix during the latest release. In almost every way it is a really nicely done camera, I believe I got an exceptional value for my money.

The one weakness is the ground glass, doesnt come close to my Sinars. Or previous linhofs. It's not a brightness thing, but more a snap into perfect focus issue.

So what is everyone else doing??

Bob

Steve Hamley
20-Sep-2011, 09:40
Bob,

As a general rule I find that brighter, smoother screens and fresnels have less "pop" into focus, while coarser screens and plain GG have that "pop" but are not as bright and easy to compose with f:9 lenses etc.

Not really wanting to start a food fight, but I think a choice of screens/GG is a very personal thing, and you probably need to try something different. For example, can you put a Sinar screen in it? Probably.

Cheers, Steve

Bob McCarthy
20-Sep-2011, 10:21
For me its not as much pop but an exact point of focus, the tiny details get lost in the coarseness and focus is in a small range rather than at a specific point.

Its like all within the DOF, but when I have the bellows a bit twisted up Im not nailing focus on occasion. I get that there are compromises regarding ground glass. I should just order one from the man in the southeast and be done with it.

I think that is a good idea on the Sinar ground glass, I have a spare around here somewhere.

bob

Steve Hamley
20-Sep-2011, 18:34
Bob,

I find the same phenomena applies to fresnels - the brighter and finer they are, the harder they are to precisely focus, including the Maxwell on my 8x10 (came with it).

A nice, bright Maxwell is a joy to compose with, but in the end, it still - for me - doesn't focus as easily or precisely as a ground glass.

Another suggestion, a Steve Hopf ground glass. It will be darker than a fresnel and a pain in low light with f:9 lenses (like all GG versus fresnels), but I've had very good experiences with mine.

Cheers, Steve

ashlee52
20-Sep-2011, 21:15
I have just put a Steve Hopf GG into my Ansco 5x7... and I also have a Chamonix 45n1... the 5x7 is bunches easier to focus even playing the f6.8 Ektar on the 5x7 against an f 5.6 lens on the 4x5. Probably the image size has something to do with it but I believe the screen is brighter.

Bob McCarthy
20-Sep-2011, 21:20
I just remembered the old F in the cabinet has a Steve Hopt GG in it. Wonder if it fits.

Bob

Steve Hamley
21-Sep-2011, 07:22
Bob,

Let us know how things turn out with a ground glass after you've had a chance to assess the results - I for one am interested.

BTW, Don Dudenbostel who posts here has been a commercial and fine art photographer since the 1960s, and told me that he could not recall a professional photographer ever using a fresnel.

Cheers, Steve

Jehu
21-Sep-2011, 08:41
Doesn't the 45N2 have a correction built into it for the fresnel? If that's the case then it seems like a standard GG may be a little off.

Calling Hugo!

Steve Hamley
21-Sep-2011, 17:16
Jehu,

The 45N2 does have a correctly positioned fresnel as I understand it.

The discussion is really about whether a properly positioned fresnel is as easy to critically focus as a ground glass.

I've used both. My inexpert opinion is that I occasionally get mis-focused shots with a fresnel, and less often with a ground glass.

There could be a lot of factors in play since a fresnel is a lens. I suspect that not having your eye aligned with the loupe has more of an effect than if using a GG. Maybe tilting the loupe has a different effect with a fresnel vs GG. Take a pair of drugstore reading glasses and tilt them and look through them especially off center. Just an opinion. I've taken as sharp a picture with fresnels as I have with GG, but a fraction of the time, I don't, and that fraction seems greater than when using a GG.

I have no doubt that the Chamonix 45N2 fresnel is properly installed and don't want to start that discussion all over again. PLEASE, PLEASE don't start that all over again

Cheers, Steve

Brian Ellis
21-Sep-2011, 19:00
For me its not as much pop but an exact point of focus, the tiny details get lost in the coarseness and focus is in a small range rather than at a specific point.

Its like all within the DOF, but when I have the bellows a bit twisted up Im not nailing focus on occasion. I get that there are compromises regarding ground glass. I should just order one from the man in the southeast and be done with it.

I think that is a good idea on the Sinar ground glass, I have a spare around here somewhere.

bob

You're observing one of the major downsides of most Fresnel lenses - difficulty of focusing. The "coarseness" you mention comes from the lines in the Fresnel. The Maxwell screen is the only Fresnel I've used that was about as easy to focus as a plain ground glass and without the light fall-off when using wider lenses that ground glass usually has. I assume Maxwell is the "man in the southeast" you mention. If you can pay the price - about 25% of the cost of your camera - it's well worth it IMHO.

GPS
22-Sep-2011, 01:35
Doesn't the 45N2 have a correction built into it for the fresnel? If that's the case then it seems like a standard GG may be a little off.

Calling Hugo!


Jehu,

The 45N2 does have a correctly positioned fresnel as I understand it.

The discussion is really about whether a properly positioned fresnel is as easy to critically focus as a ground glass.
...
Cheers, Steve

Steve, I think you misunderstand Jehu's point. Jehu doesn't doubt the fact that Chamonix 45N2 has properly positioned its fresnel. He asks if the GG is properly positioned after the fresnell is taken away. That is a very valid point.

Bob McCarthy
22-Sep-2011, 05:34
I understand the frosted side is positioned closest to the lens, unlike previous Chamonix's, so there is no longer any focus shift issue if one removes the fresnel.

I had to work late the last couple of nights, haven't had time or energy to change out GG as offered.

Bob

Jehu
22-Sep-2011, 08:39
Steve, I think you misunderstand Jehu's point. Jehu doesn't doubt the fact that Chamonix 45N2 has properly positioned its fresnel. He asks if the GG is properly positioned after the fresnell is taken away. That is a very valid point.

Yup. That's my point. Thanks GPS.

This thread caught my interest because I'm also a proud (and happy) new owner of the 45N2. I've had some focus trouble recently. I considered removing the fresnel and using the ground glass only. I hesitated because I read something about a minor design change between N1 and N2 that allows for using the fresnel. Does this design change mean that the problem is inversed? Has the camera been designed to use the fresnel so removing it would cause a plane shift that affects focus? If I'm able to remove the fresnel without introducing error I'd like to know about it.

Steve Hamley
22-Sep-2011, 08:58
Jehu,

How is the glass/fresnel installed in the 45N2 back, starting with the lens side?

Cheers, Steve

GPS
22-Sep-2011, 09:51
Yup. That's my point. Thanks GPS.

This thread caught my interest because I'm also a proud (and happy) new owner of the 45N2. I've had some focus trouble recently. I considered removing the fresnel and using the ground glass only. I hesitated because I read something about a minor design change between N1 and N2 that allows for using the fresnel. Does this design change mean that the problem is inversed? Has the camera been designed to use the fresnel so removing it would cause a plane shift that affects focus? If I'm able to remove the fresnel without introducing error I'd like to know about it.

Jehu, the answer depends on the way the fresnel is installed in the back standard. Not only if the fresnel is closer to the lens (behind or in front of the gg) but also if the gg +fresnel assembly is put to the standard leaning against the fresnel or the gg. You yourself can check it.

Jehu
22-Sep-2011, 11:48
Without taking it apart, it looks like the gg is first (nearer the lens), the frenel behind that and then a plastic sheet for retaining. As I understand it, that means that the fresnel can be removed without affecting the focus plane of the ground glass.

GPS
22-Sep-2011, 12:00
Without taking it apart, it looks like the gg is first (nearer the lens), the frenel behind that and then a plastic sheet for retaining. As I understand it, that means that the fresnel can be removed without affecting the focus plane of the ground glass.

Only if the gg is the part that sits agains the back standard frame. If it is the opposite taking the fresnel out would change the position of the gg too.

Steve Hamley
22-Sep-2011, 16:37
Correct, if the fresnel is behind the GG (nearer you) and the GG position does not change when you remove the fresnel, you're good to go.

Cheers, Steve

ashlee52
22-Sep-2011, 18:42
Arghhh.

I have an older Chamonix 45n1 which I used recently with great pleasure.

And just today I took my "improved" 45n2 out for its maiden run... and I can't focus the damned thing. In the newer camera the fresnel is now behind the ground glass and obscures it badly. My Ansco 5x7 which I was also using has just a new Steve Hopf gg and focuses like a charm. I would simply remove the fresnel from the Chamonix, but it looks to be designed in such a way as to require the fresnel to hold the GG in position. I've written Hugo seeking a solution.

GPS
23-Sep-2011, 03:36
Arghhh.

...
I would simply remove the fresnel from the Chamonix, but it looks to be designed in such a way as to require the fresnel to hold the GG in position. I've written Hugo seeking a solution.

What's there to write about? A simple plastic or wooden shim replacing the fresnel's thickness should do. :)

Jehu
23-Sep-2011, 07:58
I was wondering if that would be an issue. I haven't taken mine apart yet.

Steve Hamley
23-Sep-2011, 08:06
Ron Wisner used to have posted on his site that the fresnel shifted the plane of focus by about 1/3 the thickness of the fresnel (it is a lens and not just a spacer). If the fresnel is in front of the GG, I'd want Hugo's advice or to have someone like Precision Camera or Richard Ritter do the work if you don't feel comfortable doing it yourself.

Measuring the "T" distance isn't that much of a problem but any adjustment, if needed, does need to be done precisely.

Just for information, my 4x5 Ebony uses a fresnel that's frosted on the lens side plus a cover glass, and so can be replaced by a GG with no adjustment. My 5x7 ebony has a plain GG facing the lens, a non-frosted fresnel, then a cover glass as a factory install. So you can just remove the fresnel and cover glass if you like. But they are made differently.

Cheers, Steve

Bob McCarthy
28-Sep-2011, 06:04
I have looked everywhere I can. I know I have stored an extra Sinar branded GG. I can not find it. I keep thinking a "bulb" will go off, but in 4 days of looking -nothing. I must have chucked it by accident.

Back to square one.

Bob

36cm2
30-Sep-2011, 20:27
Arghhh.

I have an older Chamonix 45n1 which I used recently with great pleasure.

And just today I took my "improved" 45n2 out for its maiden run... and I can't focus the damned thing. In the newer camera the fresnel is now behind the ground glass and obscures it badly. My Ansco 5x7 which I was also using has just a new Steve Hopf gg and focuses like a charm. I would simply remove the fresnel from the Chamonix, but it looks to be designed in such a way as to require the fresnel to hold the GG in position. I've written Hugo seeking a solution.

Any answer from Hugo on this?