I have a simple plastic reflective attachment and tried to use it on Minolta Flashmeter III. It gives consistent error +2.5 stops (pictures will be overexposed). The lightmeter is accurate with incident dome attachment.
I wonder, what may cause this error - is this attachment not for this model?
Will any of 5 or 10 degrees attachments work better here?

Certain attachments like this require a standard correction with different Minolta meters. I don't have the one you're describing, but with the Flashmeter III and 5-degree attachment, for instance, you need to reduce exposure by 1-1/3 stop from the reading. It's on the instruction sheet. I just adjust the ASA setting when I use this attachment. I think some of the later meters have settings to compensate automatically for different attachments. Once you know the correction factor, though, you can just apply it.

I had a III and now have a IVF. On the IVF, there is a spring loaded pin underneath the attachments, and, IIRC, there is one on the III also. When you install the reflective attachment there is a tab on that attachment that depresses the pin to correct the reading. Take a reading with the attachments off and depress the pin while doing so. There should be about a 2.5 stop difference.

I may have these two attachments backwards with regard to pin actuation but most likely the pin contact is dirty and can be revived by exercising (depressing) it until it comes back to life unless it is terminally damaged, then there will be a trip to the meter doctor. If you have never used the reflective attachment on the meter before then there is a high liklihood that the contact is tarnished and will recover with exercise.

-Fred

The Flashmeter III doesn't have those auto-correcting features.

You're right, David, I was addressing the Autometer III.

-Fred

The reflective attachment for my III does not look like what your picture shows at all. It has a much larger opening. Perhaps you have the wrong attachment, and the smaller opening is causing the meter to read darker, thus causing you to overexpose.
Caveat: I never use my attachment, so can't really verify its accuracy.

Thank you for your replies. Indeed, for correct measurement the hole in attachment needs to be larger. However this will increase the angle of light acceptance too much.

There is no way for a tab on attachment to depress the pin. Its construction does not allow for it. But the switch connected to the pin is working - when the pin is depressed by the tip of the pocket knife, the reading differs by 3 stops.

I am neither going to drill a bigger hole, nor to mess with the pin. I also do not like the idea to recalculate the exposure every time different attachment is installed. So, this lightmeter will serve only indoors when working with flashes. For outdoors I will stay with my old trusty Sverdlovsk 4.

That attachment looks identical to the one I used on my Autometer IVF for 40 deg. acceptance angle.

-Fred

I rarely change attachments during any single shoot, so it's easy just to add the correction to the ASA setting on the meter. I do the same for filter factors.

You have the wrong attachment. The one you have doesn't have white plastic ring to activate the pin. You can make the ring yourself or buy the correct one. The one without the ring are for the older meter without the pin then you have to make the reading at the REF position.

Papageno

I have the same attachment, but I use the AutoMeter IIIF. I have no problem.

See the attached jpg scan I've attached, it appears to be the correct one and according to the instruction sheet, no exposure compensation is required.

Hope this helps
Ira

You have to look at the underside of the attachment to see the different. From version III and up (flashmeter III and Autometer III/IIIf) you need a ring in the groove to work correctly.

You have to look at the underside of the attachment to see the different. From version III and up (flashmeter III and Autometer III/IIIf) you need a ring in the groove to work correctly.

Looking at mine now, I see the ring, no wonder I don't have a problem.

Guess mine is not the same after all. Stand corrected.