maxxum 100/2.8 macro AF hunts

[pete.purvis]

I bought a MM 100/2.8 Macro recently. It's attached to my M 7. Dynamite lens. Great camera.

Lens in non-macro use, however, hunts furiously (to me) even when I activate the limit

switch. Is this normal? Manual focus works fine, although I need to hunt a split image

focusing screen to make sure.

[michael_hohner]

Two things to make sure:

<p>

<ol>

<li>Hold your camera as steady as you can. If the AF sensors can't concentrate on one object, the camera will have a hard time focusing.

<li>Check if the aperture is fully open when the lens is mounted. You should not see any part of the aperture when you look into the front of the lens (use a flashlight to see better). If the aperture is not fully open, the lens or the camera may be broken.

</ol>

[pete.purvis]

Michael...

 

Thanks. I'll check those items. I had the latter problem with a 600si I owned. The problem

manifested itself in a completely unexposed roll. Worked fine after overhaul.

 

The slides from the 100/2.8 M were brilliant! Impressive lens.

[brettdeacon]

Hi Michael. I too have this lens and absolutely love the results. However, the hunting you described is normal (even with the limit switch) and happens to me too. It's at its worst when you move from focusing on near objects to far objects. When everything I'm pointing the lens at is far away I rarely have focus hunting. I guess this is the price we pay for such great optics.

[jamesdak]

I've got a 100/2.8 macro D and it's mainly used for macro work with manual focus. But the few times I used it in AF it did seem to hunt around more than I was used to with my other lenses.

[bill_thorlin]

Maybe yours is a faulty lens ( will be interesting to hear the test results in line with Michael's advice ). Have to confess that I have never really noticed much of a "hunting" problem but will check it out when I next use it. However considering the results one gets I would think it is a small price to pay.

[weatherman]

I have 100 macro as well and yes it is the only prime that hunts (in macro mode only).

Michael makes sense to me. Using a tripod might solve the problem and one needs tripod while macro work anyway..

[pete.purvis]

Haven't yet used the 100/2.8 M for macro, and in that case I will use a tripod. My workaround

(interim or permanent) is to use the non-macro function with manual focus. Not a big

problem as long as my eyes don't go south. The manually focused slides taken to this point

have been dead on.

 

I'll give you all a rundown on the checks that Michael suggested early next week when

camera/lens and I are reunited at my place of business.

[pete.purvis]

Do Maxxum 7 focusing screens (M or ML) have a split image focusing display? KM info on

web not forthcoming on that question.

 

Thanks,

[michael_hohner]

There are no split image focusing screens for the 7.

[pete.purvis]

OK...my M7 and 100/2.8 m has recombined. It's operator error. One must, one, select

limit, and two must carefully select the focus point (forget scintillating flowers or anything

else scintillating) with a steady hand, go to half-action (first detent), check the focus and

photo and shoot. If in manual, go to half-action, play with the focus until you get a steady

green moon, and shoot. Point-and-shoot mode is dicey here -- for anyone into that.

 

Thank you Michael for the lens/camera checkout advice...and your answer concerning the

lack of split-image focus on KM focusing screens. Had I thought about it, I'd have realized

that I have a superb, virtual split-image focusing screen built in -- the green moon

combined with

the focusing ring in half-action. Steady moon = in-focus.

 

Cheers,

[weatherman]

As far as I know selected Af point needs to "see" a contrast change n the subject. If you are trying to focus on a uniformly coloured subject with no stripes, patterns etc., and under low light situations, Af hunts. Have you considered this? Point and shoot surely does not work in every situation. It might be as simple as that..