Adjusting shutter speeds on AF SLRs?

[Andreas Thaler]

I can't find any information about adjusting the shutter speed in the technical documentation for the Minolta (Maxxum, Alpha) 7000 AF.

Can it be that this is no longer possible with this generation of computer-controlled SLRs?

As far as the speed of the shutter rollers is concerned, if there is a deviation, the instruction is to replace the entire vertical focal plane shutter as a unit.

 

[Nicholas Lindan]

Electronically controlled shutters aren't adjustable. If the shutter is running at the wrong speed in spite of the electronics best efforts then there is something munged up in the mechanics. Dried out lubricant and mechanical failures can't be 'adjusted out.' It is the same with mechanical shutters - adjusting roller tension to combat lubrication issues is, obviously, the wrong approach. Mechanical shutters have adjustments because they need them. If there was a mechanical analog to a quartz crystal (leaving aside that quartz crystals are mechanical...) then mechanical shutters (if they could be made cleverly enough) wouldn't have adjustments either.

 

[Andreas Thaler]

Electronically controlled shutters aren't adjustable. If the shutter is running at the wrong speed in spite of the electronics best efforts then there is something munged up in the mechanics. Dried out lubricant and mechanical failures can't be 'adjusted out.' It is the same with mechanical shutters - adjusting roller tension to combat lubrication issues is, obviously, the wrong approach. Mechanical shutters have adjustments because they need them. If there was a mechanical analog to a quartz crystal (leaving aside that quartz crystals are mechanical...) then mechanical shutters (if they could be made cleverly enough) wouldn't have adjustments either.

Thanks

With the Minolta XG-M (horizontal electronically controlled shutter), there are two potentiometers for the shortest 1/1000 s and 1/30 s, I believe. This allowed me to improve the shutter speeds.

Obviously, the computer control in later SLRs is infallible, one less worry

 

[Nicholas Lindan]

Obviously, the computer control in later SLRs is infallible, one less worry.

Oh, I didn't say that. There is a saying: "To err is human, to really screw things up requires a computer." A saying AI fan-boys are about to prove big-time.

Older electronic shutters with analog timing circuits will usually have trim pots - high accuracy components are not cost-effective and so it is better to have someone in the factory do the adjustment. Once adjusted they shouldn't need twiddling again as high stability components aren't all that expensive (assuming it has been designed correctly).

 

[Andreas Thaler]

It is also interesting that the Copal shutters in the Minolta 7000 and 9000 are replacement parts, meaning that they should neither be adjusted nor repaired according to the service manual. Even handling them incorrectly can affect the accuracy.

This makes things easy: put the shutter in and take it out - if you have a replacement.

 

[ic-racer]

The adjustment process might be described in a service manual from a similar model. Some Nikon service manuals follow that convention.

 

[Andreas Thaler]

The adjustment process might be described in a service manual from a similar model. Some Nikon service manuals follow that convention.

Thanks will check the service manual for the Minolta 9000.

 

[Chan Tran]

The timing of an electronically controlled shutter is very accurate. The error mostly because of shutter curtain travel time which is determined by spring tension.

 

[koraks]

It is also interesting that the Copal shutters in the Minolta 7000 and 9000 are replacement parts, meaning that they should neither be adjusted nor repaired according to the service manual. Even handling them incorrectly can affect the accuracy.

I'm not sure if they're not supposed to be repaired. I interpret this choice as a policy that aims for the lowest cost in repair & servicing of these cameras. It probably was a lot cheaper to just swap out the shutter instead of having a repair tech partially disassembling it, testing it etc. It's a matter of service tech hours vs. module cost. The latter often turns out to be the cheaper commodity - and it's also more predictable (i.e. you know how much time it costs to replace a shutter, but repairing/adjusting one depends...), so more attractive from an operations management viewpoint.
It's still quite conceivable that some repairs are technically feasible - given enough time and dedication.

As to the accuracy issue, that's addressed already in this thread. The whole point of these electronically controlled shutters is that they're pretty consistent, even after decades.

 

[Nimbus62]

The timing of an electronically controlled shutter is very accurate. The error mostly because of shutter curtain travel time which is determined by spring tension.

Yes, What I saw several time on XE / Leica R3 was a lower spring tension due to age. Have to adjust spring tension to obtain the nominal curtain speed ( nominal X sync). Then have to adjust low and high speed.
Curtain speed is some time critical (too low) in this case have to adjust spring and all will be fine.
I think it is the same on digital control of shutter curtain. Need to have the correct curtain speed and all will be fine.

 

[ic-racer]

This has come up before, but the most recently designed Nikon film cameras don't have any trimmer pots, the adjustments are done thorugh software. Since the software does not tend to 'drift' with time, and many of the cameras can check their own shutter speed, need for adjustment would be low. But there is still a provision for adjustment in the software if needed.

 

[Chan Tran]

This has come up before, but the most recently designed Nikon film cameras don't have any trimmer pots, the adjustments are done thorugh software. Since the software does not tend to 'drift' with time, and many of the cameras can check their own shutter speed, need for adjustment would be low. But there is still a provision for adjustment in the software if needed.

The problem is to get the software. Nikon doesn't use those software anymore but let nobody has them.

 

[ic-racer]

The problem is to get the software. Nikon doesn't use those software anymore but let nobody has them.

That is for sure. I have a dream that a these things (floppies and interfaces) show up on ebay...