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06-22-2022, 02:16 PM   #1
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Apeture closes and opens when lens is off the camera, but not when it is on

i have a pentax KM and (i admit) havent been using the apeture.

ive wanted to try it out, but twisting the ring to see what happpens, i find that nothing does...
however, when i take the lens off the camera, the apeture opens and closes like normal, its just when it is on that it doesnt, and the needle doesnt move.

have any solutions?

06-22-2022, 03:26 PM - 3 Likes   #2
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QuoteOriginally posted by Anrk_i Quote
i have a pentax KM and (i admit) havent been using the apeture.

ive wanted to try it out, but twisting the ring to see what happpens, i find that nothing does...
however, when i take the lens off the camera, the apeture opens and closes like normal, its just when it is on that it doesnt, and the needle doesnt move.

have any solutions?
You are describing normal behavior.
When the lens is on a camera body, the body holds a K-mount lens wide open, so you have lots of light to frame your photo and focus, then the body closes the lens to the requested aperture just as you take a photo.
06-22-2022, 03:28 PM - 1 Like   #3
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Point the camera at yourself. Set an high aperture number. Set a long exposure. Fire. You’re going to see the aperture close down.
06-22-2022, 04:38 PM   #4
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QuoteOriginally posted by reh321 Quote
You are describing normal behavior.
When the lens is on a camera body, the body holds a K-mount lens wide open, so you have lots of light to frame your photo and focus, then the body closes the lens to the requested aperture just as you take a photo.
Thank you so much! im glad theres nothing wrong!

06-22-2022, 06:52 PM   #5
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Press the depth of field preview button (round button above the self timer) and the lens should close down.
06-23-2022, 12:04 AM   #6
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QuoteOriginally posted by pentaxus Quote
Press the depth of field preview button (round button above the self timer) and the lens should close down.
Depends if it is the Pentax KM film-camera or the digital K-m (K-2000 in USA)
His is the K-m/K-2000 DSLR as you can tell from his profile (at least no KM film version is mentioned)

But the way he wrote his first message hints towards the early Pentax KM film version.

@Arnk_i: Always good to be precise, particular with KM vs. K-m (or KX vs. K-x). But also about which lens you use.
This usually helps a good deal, doesn't lead to unnecessary confusion.

Have fun with the K-m, which is the last Pentax with a 10MP CCD sensor. Also a very simple AF with just 5 AFsensors, something Pentax did only with the K-m, it is a simple but very nice camera and worth to be used with good lenses.
Not to use high ISO, one could say everything that is recommended for the K200D goes for the K-m, same sensor and chip, they
took the chip changes applied from the K10D towards the K200D into the K-m. So it makes very good natural photos and has a good
JPEG engine. And with the K-x it is the smallest DSLR Pentax made with SR (shake reduction). The K-x has the new 12.4 MP CMOS sensor, similar to the one in the K-r, both of those very nice for vintage lenses, because their sensor doesn't show up limitations that strongly.
I use the K200D (and at times the K10D) again and again, the K200D is always in my car.

Get yourself either a good set of Eneloop Pro AA's and a really good charger.
Best value-money is the Technoline BC700:
https://www.tme.com/us/en-us/details/bc-700/chargers/technoline/+


Or use just Energizer Lithium Ultimate AA's.
They last very long and if not used, can be stored without danger for 20 years, they don't leak!

Last edited by photogem; 06-23-2022 at 11:43 PM.
06-23-2022, 12:57 PM   #7
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QuoteOriginally posted by Anrk_i Quote

however, when i take the lens off the camera, the apeture opens and closes like normal, its just when it is on that it doesnt, and the needle doesnt move.
The needle should move if you point the camera towards a source of light and play around with the aperture (and time) settings. If it doesn't, then it means that either the battery is flat, or there is something wrong with the light meter.

5 Days Ago   #8
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QuoteOriginally posted by Wojciech Quote
The needle should move if you point the camera towards a source of light and play around with the aperture (and time) settings. If it doesn't, then it means that either the battery is flat, or there is something wrong with the light meter.
probably i need a new battery, im not surprised...
thanks!

---------- Post added 06-25-22 at 08:34 AM ----------

QuoteOriginally posted by photogem Quote
Depends if it is the Pentax KM film-camera or the digital K-m (K-2000 in USA)
His is the K-m/K-2000 DSLR as you can tell from his profile (at least no KM film version is mentioned)

But the way he wrote his first message hints towards the early Pentax KM film version.

@Arnk_i: Always good to be precise, particular with KM vs. K-m (or KX vs. K-x). But also about which lens you use.
This usually helps a good deal, doesn't lead to unnecessary confusion.

Have fun with the K-m, which is the last Pentax with a 10MP CCD sensor. Also a very simple AF with just 5 AFsensors, something Pentax did only with the K-m, it is a simple but very nice camera and worth to be used with good lenses.
Not to use high ISO, one could say everything that is recommended for the K200D goes for the K-m, same sensor and chip, they
took the chip changes applied from the K10D towards the K200D into the K-m. So it makes very good natural photos and has a good
JPEG engine. And with the K-x it is the smallest DSLR Pentax made with SR (shake reduction). The K-x has the new 12.4 MP CMOS sensor, similar to the one in the K-r, both of those very nice for vintage lenses, because their sensor doesn't show up limitations that strongly.
I use the K200D (and at times the K10D) again and again, the K200D is always in my car.

Get yourself either a good set of Eneloop Pro AA's and a really good charger.
Best value-money is the Technoline BC700:
https://www.tme.com/us/en-us/details/bc-700/chargers/technoline/+


Or use just Energizer Lithium Ultimate AA's.
They last very long and if not used, can be stored without danger for 20 years, they don't leak!
mine is the KM film camera, whether or not your reply if for that or the electrical, im not sure, but thank you anyway for taking the time out of your day to reply so extensively to my question!
5 Days Ago   #9
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QuoteOriginally posted by Anrk_i Quote
.... mine is the KM film camera, whether or not your reply if for that or the electrical, im not sure, but thank you anyway for taking the time out of your day to reply so extensively to my question!
so precision is what helps
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