Mamiya 7 focus knob question

[richard_livitski]

I've recently purchased a used Mamiya 7II w/lenses. When going to

focus on infinity, unlike all other 35mm cameras I've used, the focus

ring on the Mamiya doesn't stop at actual infinity, it still has some

additional play at the end.

Having never encountered this with any other camera I've owned, it

made me wonder if perhaps (because my camera was bought used) my

focus might need calibration. So I called Mamiya and asked if it was

normal with these cameras to have additional play after having

reached infinity, and they said yes it was, as the focus was designed

to allow for expansion and contraction of the camera body. This sure

seemed fishy to me as the camera bodies aren't made of wood!

My question is this....does the focus ring on your Mamiya stop when

infinity is reached? or does it have additional play at the end?

Thanks

[don_karon1]

My three lenses all go past the infinity marking. This is normal and many other users have reported the same finding. Are your negatives sharp? If so, no worries.

[david_henderson]

Neither my 80 or 50mm lenses go past infinity. I guess my question in your position would now be "OK, so how do I focus on infinity? At the infinity mark? At the end of the focus ring's travel?"

[andrew_schank]

If a rangefinder camera does not have the double image line up when the lens is focused on infinity and a very distant object (at least several miles away) is sighted, the finder is definately out of allignment and the focus will be off at ALL DISTANCES. Get it fixed, or you will end up with slightly out of focus images, especially shooting wide open and at closer distances where the depth of field will not cover the error.

[dale_cotton]

<p>FYI: <a href="http://www.luminous-landscape.com/m7_hands-on.htm">Mamiya 7 II Hands-On</a>.

<p>See especially the section titled: The Rangefinder and 150mm Lens.

[lanierb]

The response above is wrong. The M7 lenses are designed to focus slightly past infinity to allow for expansion/contraction due to temperature. The behavior of the lens above sounds normal -- all my M7 lenses act this way.

 

The way you are supposed to focus the M7 is "near to far". That is, you should start with the focus set nearer than your subject, then turn the focus ring until the split image exactly aligns. Do not "hunt" back and forth as any play that exists in the rangefinder cam will lead to slightly inaccurate focus if you do (though you may only notice it with the 150 at close range). The same is technically true at infinity, though depth of field at infinity is great enough that you might not notice.

[andrew_schank]

Seems pretty odd to have a rangefinder lens designed to focus past infinity. Without direct viewing on a ground glass, how is one supposed to know when "atmospheric conditions" would call for an alteration in the focus?

[duncan_ross1]

I had the same problem with mine and Mamiya in the UK diagnosed it as a rangefinder problem (which I verified prior to repair with a test roll. As a previous poster stated, the rangefinder will be off at all distances if it is off at infinity. My camera rangefinder lines up perfectly at infinity on the 3 lenses I have.

 

No other camera I know of has "allowed for expansion/contraction" by focussing past infinity. Applying logic here -

 

1) The amount of temperature variance the camera sees in actual use is very small.

 

2) If the lens heats up and the lens needs to go past infinity to focus, how would the rangefinder know this? It would need a temperature sensor and auto adjustment to be calibrated exctly for the amount of lens expansion factor.

 

3) The reverse is true if there is focus play for body expansion. The lens/rf coupling would need automatic calibration for the temperature.

This sounds really complicated and I doubt the M7 includes these features. In an SLR you could do this because you are looking through the lens. I've never seen an SLR that focussed past infinity unless it needed repair.

 

Then again, maybe the Mamiya USA M7's do have an automatic temperature calibration and that explains the price difference with the rest of the world.

[andrew_schank]

Sounds like Lanier above also has a camera that is out of calibration on the finder, and has also been told some bogus info about it as well. Who the heck at Mamiya is telling people this nonsense? These cameras are known to get out of whack (most all rangefinder camera can)and need a simple adjustment to line things up again. I guess instead of repairing the cameras, they find it easier to make up a bogus story about expansion and contraction and hope the person buys it and doesn't call back. Bizarre. I owned a 7 for a while with the 65 and 150mm, and infinity lined up perfect with both lenses. I guess mine was broke.

[ralf]

Just checked my 7II with the 80mm and 43mm. Both lenses can't go over the infinity mark and when I look at a distant light across the SF bay (it's 11pm now), the rangefinder is completely in focus. You should do the same and see if infinity mark and rangefinder are in sink. As mentioned, your camera might need adjustment. That the focusing ring on the lens goes over infinity doesn�t mean anything. It could be just some production glitch where the threads don�t end at the right mark, nothing to worry about.

 

Just a couple of words regarding temperature expansion. That argument is bogus IMHO. If there were any noticeable expansions/contractions, you would need them for an SLR camera also. It has nothing to do with the rangefinder principle. If the lens would expanse from heat so much that you couldn�t focus on infinity (which it doesn�t), because the ring is at the end, it wouldn�t matter if you could look through the lens or not.

 

Regarding temperature meter in the rangefinder: if the rangefinder had the same expansion coefficient as the lens, it would always be in sink with the lens, no matter what the temperature.

[lomografieur]

My 7 does the same thing. Correct alignment in the finder is slightly short of infinity. My question: Should I rotate the lens all the way to infinity as indicated on the lens or accept the correct alignment as I can see it through the finder?

Thanks in advance,

Jim