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03-03-2016, 04:58 AM   #16
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QuoteOriginally posted by Johnny Rod Quote
Adjustment is possible with the pots under the top cover. If you;re unhappy with that then just set the ISO to double the box (rated) speed. Depending on your film and preference, some people set ISO to double box speed on any camera. Overexposure is mostly preferable to underexposure. Two of my old 1960s 35mm rangefinders overexpose by 1-2 stops, more in bright light (hello selenium meters), but are also prone to some stray light on the meter anyway so it's as broad as it's long.
Thanks for answering.
I'm not unhappy with stripping it down, as I did in fact tinker with my spare (the one metering right, but doing plenty of other things wrong) just to see if I could do it without breaking anything... so far so good.
In the mean time I came across a page which illustrates the disassembly, as well as the metering adjustement, except... it's in Japanese. A machine-translation can be roughly followed right up to that point (third to last image), but then I'm all lost. What am I supposed to do there? Also, wouldn't it be simpler to just turn the corresponding ISO thingy (in red in that "guide") by one stop and put the dial back in its original position (making it a sort of permanent double box speed setting, which in fact turns out to be the actual one)?
Sorry if this makes no sense, I tried to explain it as best as I could

03-07-2016, 08:03 AM   #17
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Hi Sabine
Check out the augmented diagram by the awesome Ray:
https://www.pentaxforums.com/forums/8-pentax-film-slr-discussion/311985-locat...ml#post3497156
There is a coarse and fine adjustment, shouldn't matter which you use if you arrive at the right answer. The diagram in the link looks to be viewing the camera from the front, whereas the photos (including yours) are from teh back, so be careful about identifying the potentiometers.

I would use a surface that will be good for metering (18% grey card or just a matt wall with little direct reflection, you know the sort of thing), measure with a meter (e.g. Pocket Light Meter app, or another camera you are happy with). Adjust your MX to match - this will be close enough for the real world, without having to resort to standard light sources and all that stuff. Obviously, be careful with ISO and F-stop settings to match them. I think the ISO dial can't be adjusted? I seem to remember the bits will only go back on in the correct position. Otherwise yes, you could do it that way (let me know if you can) - it just combines with the shutter speed position to act on a single pot.
02-25-2020, 05:51 PM   #18
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QuoteOriginally posted by wombat2go Quote
Hit3k
There is one condition where the MX will do do as you describe in normal operation.
If you set iso 800 or 1600, the metering will be disabled below 1/4 and 1/8 sec respectively, and in this case the "under" red led comes on.
So when you shift from 1/8 to 1/15, the leds can change from "under" to 'over" without transition through the yellow and green leds.

But as you mention it is skipping yellow and green at iso 400 and 1/500, then I agree it must be faulty.
Hello, I'm David from Argentina, I have a pentax mx. I see the some issue with the light meter that happens when I use 1/15 or slow, the red led goes down and, for example, I change in the same scene to 1/30, the green led appear.
You mention this is a normal condition right? so why this happen? I think I'm using a 400 film pushed to 1600.

Thanks!!
02-25-2020, 06:18 PM   #19
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This happens because with 1600 speed film, that is the limit for the camera meter.
The camera will still continue to fire properly, but the meter does not work at light levels that low.
When using slower films, the light level that corresponds to 1/15 is higher, and within the range of the meter.

-Eric

02-25-2020, 06:57 PM   #20
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QuoteOriginally posted by Nofugnosis Quote
You mention this is a normal condition right? so why this happen? I think I'm using a 400 film pushed to 1600.
QuoteOriginally posted by TwoUptons Quote
This happens because with 1600 speed film, that is the limit for the camera meter.
This ^ ^ ^

A similar situation exists for my K-3 and when the combination of shutter, aperture, and ISO calculates to an EV100 less or greater than the meter's linear range the camera responds with lots of blinking lights. The meter range on your MX is 1 -- 19 EV100 and not that much different than many modern cameras with GPD cells. There is a chart on page 22 of the English version MX manual that shows the permissible combinations of shutter speeds and ISO that work on that camera.


Steve
02-25-2020, 08:42 PM   #21
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Yes, thank you very much. I've downloaded the manual and found my response.
That's something I didn't know before I bought it, I still love this camera but If I like to push my films to 1600 or 3200 (this is not possible with this MX) I'll have to look for another camera with this posibility.


Regards.
02-25-2020, 10:44 PM   #22
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QuoteOriginally posted by Nofugnosis Quote
Yes, thank you very much. I've downloaded the manual and found my response.
That's something I didn't know before I bought it, I still love this camera but If I like to push my films to 1600 or 3200 (this is not possible with this MX) I'll have to look for another camera with this posibility.


Regards.
I have several bodies with meters going to ISO/ASA 3200, but the meters still bottom out at a similar point to the MX. While not as compact as the MX, you might be interested in the KX, its immediate forerunner. The KX supports up to ISO/ASA 6400 with a fully mechanical shutter and a meter sensitivity range the same as the MX. The shutter speed dial will not "bottom out" in the same manner as the MX and will allow you to choose any speed on the dial.

FWIW, a lower limit for in-camera meter sensitivity of between 0 and 2 EV100 is not unusual for premium cameras of the day, and for most current market consumer dSLRs today as well. That doesn't mean the cameras would advertise the fact*, only that one should be aware that 1/15s at ISO 3200, even with an f/1.4 lens is the bottom limit and that following the meter further down will result in underexposure.

If you need a camera capable of supporting arbitrarily long metered exposures at high ISO, the Pentax LX or similar OOF metering models from Olympus might be a good option.

Addendum: I usually carry a reference card for exposure settings in common low-light situations to use in lieu of a meter. Works like a charm.


Steve

* Pentax was one of the few makers that published the so-called meter coupling range (aka range of light measurement).


Last edited by stevebrot; 02-25-2020 at 10:50 PM.
02-25-2020, 11:54 PM   #23
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Don't forget it's only the meter. You can use a hand held meter and set the exposure accordingly. Probably more accurate for difficult low light situations anyway and as, I presume, you are using a tripod, not much additional fiddling about.
02-26-2020, 08:29 AM   #24
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QuoteOriginally posted by stevebrot Quote
The KX supports up to ISO/ASA 6400 with a fully mechanical shutter
Yeah that was always a big plus with the KX, having an ASA range (8-6400) the same as the more expensive K2.

Phil.
02-26-2020, 04:31 PM   #25
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QuoteOriginally posted by Nofugnosis Quote
Yes, thank you very much. I've downloaded the manual and found my response.
That's something I didn't know before I bought it, I still love this camera but If I like to push my films to 1600 or 3200 (this is not possible with this MX) I'll have to look for another camera with this posibility.


Regards.
You can also meter wide open with one film speed and then count stops to the aperture and film speed you want to use.
If you meter at 1/15 at f2.0 with 1600 asa but want to shoot f5.6 at 3200 asa, you’ll need to slow your shutter speed two stops to 1/4:
Three stops slower to account for the difference between f2.0 and f5.6 plus one stop faster to account for the faster film.

That doesn’t actually gain you any meter sensitivity, but you can use that to account for lenses that don’t connect to he meter, pushed film, and other weird scenarios.

Or use a flash

-Eric
02-27-2020, 03:12 PM   #26
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QuoteOriginally posted by TwoUptons Quote
You can also meter wide open with one film speed and then count stops to the aperture and film speed you want to use.
If you meter at 1/15 at f2.0 with 1600 asa but want to shoot f5.6 at 3200 asa, you’ll need to slow your shutter speed two stops to 1/4:
Three stops slower to account for the difference between f2.0 and f5.6 plus one stop faster to account for the faster film.

That doesn’t actually gain you any meter sensitivity, but you can use that to account for lenses that don’t connect to he meter, pushed film, and other weird scenarios.

Or use a flash

-Eric
Hey! yes, that's exactly what I will do next time. I just didn't know this condition of the light meter with high ISO so now that I do I can manage to meter using the stops up and down depending of the scene I want to shoot.

Thank you all for the replies . Something very important I learned here definitely is that we all should read the manual before we use the camera and I'm sure a lot of people don't do it :P
02-27-2020, 03:18 PM   #27
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QuoteOriginally posted by stevebrot Quote
I have several bodies with meters going to ISO/ASA 3200, but the meters still bottom out at a similar point to the MX. While not as compact as the MX, you might be interested in the KX, its immediate forerunner. The KX supports up to ISO/ASA 6400 with a fully mechanical shutter and a meter sensitivity range the same as the MX. The shutter speed dial will not "bottom out" in the same manner as the MX and will allow you to choose any speed on the dial.

FWIW, a lower limit for in-camera meter sensitivity of between 0 and 2 EV100 is not unusual for premium cameras of the day, and for most current market consumer dSLRs today as well. That doesn't mean the cameras would advertise the fact*, only that one should be aware that 1/15s at ISO 3200, even with an f/1.4 lens is the bottom limit and that following the meter further down will result in underexposure.

If you need a camera capable of supporting arbitrarily long metered exposures at high ISO, the Pentax LX or similar OOF metering models from Olympus might be a good option.

Addendum: I usually carry a reference card for exposure settings in common low-light situations to use in lieu of a meter. Works like a charm.


Steve

* Pentax was one of the few makers that published the so-called meter coupling range (aka range of light measurement).
The thing here is that I don't want to buy the KX when I have the MX. I like having more ISO like in the KX have but I bought this MX less than one year ago and I want still to use before buying another new gear. Maybe I will try to jump up to the LX, I love it and I like how it looks but here in Argentina there is only one for sale and it's very expensive for the kind of camara it is. It's almost 570 dollars at today change.


Thanks!!
02-27-2020, 04:40 PM - 1 Like   #28
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QuoteOriginally posted by Nofugnosis Quote
The thing here is that I don't want to buy the KX when I have the MX.
I understand and even the KX will not meter accurately below EV100 1. If you are open to a hand-held meter, a Gossen Luna Pro SBC in very good to excellent condition may be had for $50-$75 USD. It is a bit bulky, but is sensitive to -4 EV100. That failing, the EV chart and exposure chart relationship chart on the Ultimate Light Meter page may be all you need.

Ultimate Exposure Computer | Exposure Value Chart

Ultimate Exposure Computer | Exposure Factor Relationship Chart B


Steve
02-27-2020, 07:02 PM - 1 Like   #29
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QuoteOriginally posted by Nofugnosis Quote
The thing here is that I don't want to buy the KX when I have the MX. I like having more ISO like in the KX have but I bought this MX less than one year ago and I want still to use before buying another new gear. Maybe I will try to jump up to the LX, I love it and I like how it looks but here in Argentina there is only one for sale and it's very expensive for the kind of camara it is. It's almost 570 dollars at today change.


Thanks!!
If you don't want to spend the money on a LX, do not, under any circumstances, read up about its metering system...

... the one that if you leave the camera in "A" mode will leave the shutter open as long as it takes to get enough light... whatever that may be...

-Eric
02-28-2020, 10:42 AM   #30
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QuoteOriginally posted by TwoUptons Quote
If you don't want to spend the money on a LX, do not, under any circumstances, read up about its metering system...

... the one that if you leave the camera in "A" mode will leave the shutter open as long as it takes to get enough light... whatever that may be...

-Eric
I've just read about the metering and the only thing I understood is that I have to learn more about the metering the cameras use lol
It seems in Automatic mode, the LX, choose the shutter speed depending the scene you shoot the photo, this is high technology for the time the LX was building.

Am I right? or what did you mean when you mention the metering of the LX?


Regards,

David.

---------- Post added 02-28-20 at 10:43 AM ----------

QuoteOriginally posted by stevebrot Quote
I understand and even the KX will not meter accurately below EV100 1. If you are open to a hand-held meter, a Gossen Luna Pro SBC in very good to excellent condition may be had for $50-$75 USD. It is a bit bulky, but is sensitive to -4 EV100. That failing, the EV chart and exposure chart relationship chart on the Ultimate Light Meter page may be all you need.

Ultimate Exposure Computer | Exposure Value Chart

Ultimate Exposure Computer | Exposure Factor Relationship Chart B


Steve
Nice link buddy, I will read it carefully later!!


David.
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