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06-03-2017, 09:24 AM   #1
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ME Super Stop-down Metering?

Hello,

I recently purchased a mount-converted lens that only allows stop-down metering on ME Super. And during testing it seems that the meter is reporting strange values. When set to f8 and ISO 100, the meter reports 1/125s under broad daylight. However no strange values were observed on open-aperture metering lenses. Does ME Super suffer from similar metering issues like digital Pentax SLRs when using stop-down metering?

Sincerely

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06-03-2017, 01:25 PM - 1 Like   #2
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QuoteOriginally posted by butangmucat Quote
Hello,

I recently purchased a mount-converted lens that only allows stop-down metering on ME Super. And during testing it seems that the meter is reporting strange values. When set to f8 and ISO 100, the meter reports 1/125s under broad daylight. However no strange values were observed on open-aperture metering lenses. Does ME Super suffer from similar metering issues like digital Pentax SLRs when using stop-down metering?

Sincerely

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No, there are no quirks to stop-down metering on M-series bodies. It should be fine. Are you sure that the aperture ring calibration is correct on the lens?


Steve
06-03-2017, 06:41 PM   #3
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QuoteOriginally posted by stevebrot Quote
No, there are no quirks to stop-down metering on M-series bodies. It should be fine. Are you sure that the aperture ring calibration is correct on the lens?


Steve
I think the aperture is calibrated correctly. On my NEX-6, the modded lens generated similar readings at the same aperture as my FA43.

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06-04-2017, 02:03 PM - 1 Like   #4
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QuoteOriginally posted by butangmucat Quote
I think the aperture is calibrated correctly. On my NEX-6, the modded lens generated similar readings at the same aperture as my FA43.

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Out of curiosity, what mount-converted lens are we talking about?

How does your FA 43 compare to the mod'ed lens on your ME Super? Use a uniformly lit blank wall as the target. Likewise, how does the FA 43 on your NEX compare to the FA 43 on the ME Super (use the same blank wall).

FWIW...f/8 and 1/125s at ISO 100 on a sunlit day is not too far out of line. The Sunny 16 rule is not a hard rule. Much depends on latitude, day of year, and amount of atmospheric haze/pollution. It is also not good to use it in comparison to a reflected light reading such as the TTL meter in your camera. Sunny 16 is an incident-light system and does not take subject into account. For example:
  • It is a sunny day at my house, ~46 N latitude
  • It is June 4, 13:45 PDT
  • With my DA 50/1.8 mounted to my K-3, I just metered the neighbor's house across the street to the south at f/8 and 1/125s @ ISO 100 using matrix metering
  • The exposure reading from my K-3 does not alarm me.
In my region, a true "sunny 16" is rare, even in mid-summer. "Sunny 11" is the usual in Summer with "sunny 8" or lower being the norm the rest of the year.


Steve

06-04-2017, 07:19 PM   #5
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QuoteOriginally posted by stevebrot Quote
Out of curiosity, what mount-converted lens are we talking about?
It's a Rollei HFT Planar 50mm f1.8 (probably a later version made in Singapore), originally in QBM mount. There is one shop in China that I know does the conversion (into K, M42, EF, and F, and A mounts and also convert a converted QBM lens to another mount if needed). They also seem to have a bunch of NOS lenses so I bought one from them, and they did the conversion before shipping it out. The rear element housing seems have been machined to give enough clearance on full-frame Pentax. There is also no aperture coupling for M42, K, F, and A mounts. Fore EF and F, a chip can be added to enable metering.

---------- Post added 06-04-17 at 07:21 PM ----------

QuoteOriginally posted by stevebrot Quote
How does your FA 43 compare to the mod'ed lens on your ME Super? Use a uniformly lit blank wall as the target. Likewise, how does the FA 43 on your NEX compare to the FA 43 on the ME Super (use the same blank wall).
Haven't tried this yet. But yesterday was a gloomy day and the meter was pretty much in-line with Sunny 16. I.e. 1/500s, f4 when using ISO 400 film.
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