Trap-needle metering - which cameras?

Theo Sulphate · Apr 19, 2019

It's surprising to me that trap-needle metering even works: I would think the forces applied to the needle (both in trapping it and in aperture selection) would eventually lead to failure of the needle movement after a relatively short period of use. Well, I'm not a mechanical engineer, so I'll plead ignorance.

Has this system proven to be reliable over time? Considering some of the cameras listed below, it seems so.

Which cameras used this system? So far, I've found, in order:

Konica C35
Minolta Hi-Matic 7
Olympus Trip 35
Zeiss Contaflex Super B

Pentode · Apr 19, 2019

According to the internets the Kodak Super Six-20 used that system and was, IIRC, the first camera to use autoexposure of any kind.

wiltw · Apr 19, 2019

The Topcon Auto 100 also used (optional) trap needle metering automation

Andrew O'Neill · Apr 20, 2019

Rondo Colormatic 35.

benjiboy · Apr 20, 2019

Theo Sulphate said:
It's surprising to me that trap-needle metering even works: I would think the forces applied to the needle (both in trapping it and in aperture selection) would eventually lead to failure of the needle movement after a relatively short period of use. Well, I'm not a mechanical engineer, so I'll plead ignorance.

Has this system proven to be reliable over time? Considering some of the cameras listed below, it seems so.

Which cameras used this system? So far, I've found, in order:

Konica C35
Minolta Hi-Matic 7
Olympus Trip 35
Zeiss Contaflex Super B

If you press the chrome button to the left of the prism Theo in your EF that traps the needle and holds exposure.

AgX · Apr 20, 2019

Trapped-Needle metering was so universal that I guess one cannot even make a list... The first program autoexposure camera worked that way.

One can design such system in a staggered way, so that the needly only will have to bear a little load. Furthermore the neddle mechanism itself can be designed that way that even a tiny needle can bear great loads.
It only must be able to move freely in idle state without any friction to the counter lock and should have a rather low mass as with a readable needle.

4season · Apr 20, 2019

This:

AgX said:
Trapped-Needle metering was so universal that I guess one cannot even make a list

But in general, if the camera has a long-stroke shutter release, shutter-priority automation, and the design dates back to before the mid-late 1970s, it likely uses such a system. Newer designs like the Olympus XA (and Lomo LC-A!) incorporated integrated circuits.

Theo Sulphate · Apr 20, 2019

benjiboy said:
If you press the chrome button to the left of the prism Theo in your EF that traps the needle and holds exposure.

I was starting to suspect that my EF used such a system. I'm constantly making photos with this camera - it is so nice to use.

AgX said:
Trapped-Needle metering was so universal...

One can design such system in a staggered way, so that the needly only will have to bear a little load. Furthermore the neddle mechanism itself can be designed that way that even a tiny needle can bear great loads.
It only must be able to move freely in idle state without any friction to the counter lock and should have a rather low mass as with a readable needle.

4season said:
This:

But in general, if the camera has a long-stroke shutter release, shutter-priority automation, and the design dates back to before the mid-late 1970s, it likely uses such a system. Newer designs like the Olympus XA (and Lomo LC-A!) incorporated integrated circuits.

I'm starting to realize just how ubiquitous the technique was. At first I thought it was used only for small 35mm non-SLR's, but now I believe the Konica Autoreflex T and Mamiya Sekor Auto XTL may have even advertised it in their more detailed brochures (or perhaps a magazine mentioned it).

awty · Apr 20, 2019

They be the work of the devil!
There is no other logical explanation. How can my little trip 35 know what shutter speed and aperture in a blink of an eye, takes me at leat a few moments. No batteries, no nuclear reactor, no hydrogen fuel cell or wind up mechanism, just a magic stone, amazing.

benjiboy · Apr 21, 2019

Theo Sulphate said:
I was starting to suspect that my EF used such a system. I'm constantly making photos with thiscanon
camera camera - it is so nice to use.

We forget Theo the EF in the days when it came out in 1973 was more advanced with a silicon cell meter and shutter priority AE metering than any other Canon camera of the time. including the F1, and many pros. used to buy them for their meters low light capabilities, and shutter priority AE to supplement their F1 outfits.

Chan Tran · Apr 21, 2019

Theo Sulphate said:
I was starting to suspect that my EF used such a system. I'm constantly making photos with this camera - it is so nice to use.

I'm starting to realize just how ubiquitous the technique was. At first I thought it was used only for small 35mm non-SLR's, but now I believe the Konica Autoreflex T and Mamiya Sekor Auto XTL may have even advertised it in their more detailed brochures (or perhaps a magazine mentioned it).

I have 2 Olympus RC, 2 Canon EF and one Canonet QL 17 and I think all of them use such a system. I tested the cameras without film and they all seem to be OK but I never use any one of them. What kind of system does the Canon AE-1 use? I meant the original AE-1 not the AE-1p.

ciniframe · Apr 21, 2019

The long, often high pressure, shutter release action is the main negative, handling wise, of such a system. On my Olympus RC however I've been able to reliably take up the tension, stopping just short of releasing the shutter. Then a 1mm movement at the right moment to complete the release. I much prefer my M4-2 shutter release action but....the RC is so compact and handy.

AgX · Apr 22, 2019

Chan Tran said:
What kind of system does the Canon AE-1 use? I meant the original AE-1 not the AE-1p.

The trapped-needle saystem was a electromechanic system, though the the Selenium cell as semiconductor made the electronics part to it.

The AE-1 of course employed semiconductors and electromechanics too. But in addition it introduced digital data processing into the world of cameras.

The AE-1P was not different on this respect.

Chan Tran · Apr 22, 2019

AgX said:
The trapped-needle saystem was a electromechanic system, though the the Selenium cell as semiconductor made the electronics part to it.

The AE-1 of course employed semiconductors and electromechanics too. But in addition it introduced digital data processing into the world of cameras.

The AE-1P was not different on this respect.

I do not think the AE-1 has a digital system. It may use the trap needle system that is using the movement of the needle to set the aperture.How to move the meter needle is another matter. Some camera uses the power generated by the selenium cell directly some use Cds cell (as in the case of the Olympus RC or the Canonet QL17 and battery power to move the needle). If the AE-1 does it this way it can't be done in the AE-1p because there is no meter needle in the AE-1p (or the A-1 for that matter).

AgX · Apr 22, 2019

-) the AE-1 was the first camera to use a digital control
-) the trapped-needle system was long obsolete before the AE-1

You got a completely wrong understanding.
-) a trapped-needle system does not neccesarily mean that one sees a needle within the finder.
-) a needle visible within the finder does not necessarily mean that a trapped-needle system is employed

AgX · Apr 22, 2019

ciniframe said:
The long, often high pressure, shutter release action is the main negative, handling wise, of such a system.

One can design a system at which the necessary mechanical work is stored within a spring at cocking and only a tiny force at the release will be sufficient for the needle to be trapped and the following shebang of aperture control and shutter release.

Trap-needle metering - which cameras?

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