[lakeshore]

I have recently had my K-50 aperture block problem repaired and I am concerned about damaging or stressing my camera by using my M series lenses with the green button stop down method.

Does using the green button stop down metering with M series lenses actually strain the camera's mechanisms or is the camera built to handle this type of use without damage?

If the answer to the first part is yes, then I can see myself using DA lenses almost exclusively in order to protect my camera from damage.

[Not a Number]

I don't see why using the green button would "strain" any of the mechanisms more than say taking exposures with any auto aperture lens at a slow shutter speed. Or shooting in continuous (motor drive) mode. Or using the optical DOF preview.

It has been pointed out before that if you are expecting heavy usage on you camera body you are better off upgrading to a "flagship" model

[pathdoc]

Shouldn't repair of that unit render it as good as new and possibly better?

[lakeshore]

Shouldn't repair of that unit render it as good as new and possibly better?

Using DA lenses doesn't, I believe, require the camera to use the aperture ring mechanism. When using the M series lenses, I can hear the camera mechanism "working" the lens as it stops down the aperture. Is the camera designed to work safely with this load?

Please excuse my ignorance if I am mistaken.

[dakight]

The DA lenses are stopped down to the selected aperture by the same method as the green button stop-down metering. The camera operates the stop down lever on the back of the lens prior to opening the shutter. There should be no additional stress on the camera mechanism. It's true that DA Lenses lack the manual aperture control ring but they are still operated by the same aperture control lever as earlier lenses. and I don't believe that operation of the lever is implicated in aperture block failures.

[paulh]

I've been using my old *ist D almost entirely with M or K lenses (and other completely manual lenses) for the last 6 years. Thousands of shots and still going strong.

[victormeldrew]

As far as the aperture control mechanism is concerned there is no difference between stopping down to take an exposure and stopping down to meter.

So, if you use stop down metering before every exposure, then the aperture control mechanism will be used twice as often as if you use a don't.

[Not a Number]

From the survey and other posts it seems the aperture block failure is not related to shutter count. It also appears that once repaired there have not been repeated failures. However since no statistical analysis was done on the survey data whether or not there is an actual (statistically significant) relationship cannot not be safely concluded. In other words failure due to shutter count cannot entirely be ruled out.

[lakeshore]

Thanks for the feedback guys.

Only two of my M series lenses have slightly sticky aperture blades (based on the "snap" test). The rest seem to operate properly with a nice "snap."

Based on a purely subjective assessment, I'd say the DA lenses have a slightly lighter tension on the aperture lever which may partly account for the auditory difference I'm sensing when using the two types of lenses. Also the plastic construction no doubt contributes to this too as all the M series lenses are metal!.

Anyway, thanks for the info. I'll continue using my M series lenses with more confidence that I'm not damaging my camera.

Now I just have to deal, or not deal, with the sticky blades on my 20 and 35 mm primes. It's too bad, as my 20mm may be my favourite M prime!

[reh321]

As far as the aperture control mechanism is concerned there is no difference between stopping down to take an exposure and stopping down to meter.

So, if you use stop down metering before every exposure, then the aperture control mechanism will be used twice as often as if you use a don't.

We have very little dependable information on what is causing the aperture block issues; we don't know which folk solutions actually work, and what problem they actually fix. Some users have suggested the problem is under-use {problem occurred after period of not using the camera} rather than over-use.

[victormeldrew]

We have very little dependable information on what is causing the aperture block issues; we don't know which folk solutions actually work, and what problem they actually fix. Some users have suggested the problem is under-use {problem occurred after period of not using the camera} rather than over-use.

Absolutely, it may either be usage related or not or something else entirely, without access to the secret Pentax world us mere mortals can only guess at what's going wrong with our own cameras with that particular issue.

But that known fault is not the only way that cameras can break. It is also possible for them to wear out in the conventional way. Using the mechanism twice per exposure will inevitably wear it out quicker than once per exposure.