[someasiancameraguy]

Hi all,

My previous experience with the 50mm 1.2 is that the metering is one stop over on some film bodies. Will I need to adjust the ME-Super to shoot at -1 to meter correctly or not?

Thanks

[Vendee]

Hi all,

My previous experience with the 50mm 1.2 is that the metering is one stop over on some film bodies. Will I need to adjust the ME-Super to shoot at -1 to meter correctly or not?

Thanks

Surely its the camera body that is measuring the amount of light coming in and setting the exposure accordingly? Your ME Super won't know what lens you have fitted. It will just measure the light coming through it.

[pres589]

Is it doing that at all stops or just stopped down?

I have a lens that doesn't work properly with my film bodies when stopped down but wide open is fine. But that's a 3rd party lens from very early in k-mount existence. I assume this is a Pentax 50 f1.2?

[Painter]

Im curious how your determining that the metering is off? Are you comparing it to some other metering or another lens? I guess taking a pair of shots one at 1.4 and one at 1.2 and then comparing the negatives. Is it possible that despite the camera giving shutter speeds in full stops that the speeds are actually somewhere in between. Also having an f1.2 problem is a good one to have.

Hi all,

My previous experience with the 50mm 1.2 is that the metering is one stop over on some film bodies. Will I need to adjust the ME-Super to shoot at -1 to meter correctly or not?

Thanks

[someasiancameraguy]

I've asked elsewhere on this forum before that some bodies have their aperture coupler calibrated for 1.4, so shooting with glass such as the Rikenon 50 1.2 or the Pentax 50 1.2 requires using exposure compensation for correct metering. That's why I asked the question.

I guess I'll test it out in the next few days and see whats what.

Thanks for the tips

[pres589]

I would think that they're calibrated for stops down from wide open regardless of max aperture. Otherwise all lenses would need to have a max aperture of 1.4 per your example. Right?

[gofour3]

Hi all,

My previous experience with the 50mm 1.2 is that the metering is one stop over on some film bodies. Will I need to adjust the ME-Super to shoot at -1 to meter correctly or not?

Thanks

If you are shooting your 50/1.2 wide open and using faster film or shooting in sunny weather, your cameras meter range might not be able to handle it.

You're going to have to use a ND filter to reduce the light coming into the meter. Each Pentax film camera had a meter range chart in the back.

Phil.

[mattt]

The manual doesnt specifically remark on max aperture, but seems only to refer to ƒ1.4 as the largest aperture in its examples. Can you confirm the aperture opens all the way when mounted for "open aperture metering" or is it stopped down to 1.4? I have an ME Super but no ƒ1.2 lens to test with.

[UncleVanya]

I've asked elsewhere on this forum before that some bodies have their aperture coupler calibrated for 1.4, so shooting with glass such as the Rikenon 50 1.2 or the Pentax 50 1.2 requires using exposure compensation for correct metering. That's why I asked the question.

I guess I'll test it out in the next few days and see whats what.

Thanks for the tips

My recollection is this:

The problem with metering is typically with f stops that aren’t wide open. The errors in metering linearity may also be less visible with print film than digital.

[someasiancameraguy]

The manual doesnt specifically remark on max aperture, but seems only to refer to ƒ1.4 as the largest aperture in its examples. Can you confirm the aperture opens all the way when mounted for "open aperture metering" or is it stopped down to 1.4? I have an ME Super but no ƒ1.2 lens to test with.

The manual does state that the ME Super comes with a 1.2 lens in certain configurations, and I don't see any specific instructions for it. Testing the Pentax-A 50 in 1.2 and 1.4 Av mode seems to change the exposure settings when in auto so I think its working.

For reference, the MZ-3 guide states:

"When the f/1.2 lens is in use with the lens aperture ring set at a position other than the [A] position, the center-weighted metering mode will be set instead of the multi-segment metering mode. As the exposore will come out 1 stop overexposed, set the lens aperture ring to [A] or adjust the exposure deliberately 1 stop under.

^^^ This was what I was concerned about

[gofour3]

"When the f/1.2 lens is in use with the lens aperture ring set at a position other than the [A] position, the center-weighted metering mode will be set instead of the multi-segment metering mode. As the exposore will come out 1 stop overexposed, set the lens aperture ring to [A] or adjust the exposure deliberately 1 stop under.

^^^ This was what I was concerned about

That's a different issue and the MZ-S is the same. I have used my K501/.2 on all my K Series film bodies with no issues, other than shooting wide open with fast film and keeping the shutter speed below 1/1000. (That's where the Z1-P comes in handy)

Phil.

[Not a Number]

It's only 1/2 stop between f1.2 and f1.4. Even if the camera is only calibrated for f1.4 the exposure should only be off 1/2 a stop.

The 50mm f/1.2 was available with the K series cameras and lenses but an M series was not offered. But it makes no sense to calibrate the M series cameras for only 1.4.

If it were the other way around and no f1.2 lens was made for the K-series I could see the K bodies calibrated for f1.4.

[stevebrot]

I've asked elsewhere on this forum before that some bodies have their aperture coupler calibrated for 1.4

The position of the lens aperture ring position coupler for wide-open is the same for all K-mount lenses. As such, there is no calibration for any particular f-numbers. The meter is biased up/down based on aperture ring offset from wide-open and that alone. Calibration is against a calibrated light source using the offset for wide-open.*


Steve

* Note that wide-open for the coupler is not the same as the same as full travel for the "follower" on the body.

[stevebrot]

Is it doing that at all stops or just stopped down?

I have a lens that doesn't work properly with my film bodies when stopped down but wide open is fine.

Yep...one of the pitfalls of open-aperture metering is that not all iris diaphragms are well-calibrated mechanically. To test, one can do a manual exposure series with constant EV for all apertures using a gray card as reference within the frame.


Steve

[pres589]

I knew something was up when the lens would be set at f2.8 and my XR7 would show an exposure time of 1/125 seconds. Change to f4 and the time was 1/30 seconds. f5.6 was something like 1/2 seconds or some such. The jump in time was not at all what I would have expected.

I have wondered if this is why that lens is extremely rare, that the coupling doesn't stop down in a linear fashion. It's my old Kalt 28mm and the only versions I've seen of this online are m42's. Makes me think the lens did not get a properly engineered k-mount (it's also anodized and not shiny so my K-5 II didn't like it very much either, and it's why I went looking for information and found this forum).