K3 aperture issue

**othar** · 10-10-2019, 02:43 AM - **1 Like**

Originally posted by Liney

Now, that raised another couple of questions which I shall explain and see if you can confirm this understanding. The primary lens I was using was a Sigma 28-90 zoom. This lens has an aperture ring with an "A" automatic setting. Leaving it set to "A" and selecting AV mode will wash out the images with the EV of +5. Staying in AV mode but selecting any other aperture but "A" works fine (DoF changes with the aperture and the shutter speed is adjusted automatically}.

Selecting any other aperture should still wash out every image with EV +5, the only difference beeing the aperture will always be fully open. Manualy selected aperture only works in M mode, provided you have allowed the camera to release the shutter when no A lens is mounted.

Originally posted by Liney

So let me get this straight, EV compensation will only work if I am in AV mode, on the condition that the lens has an aperture ring with "A" selected? EV compensation may work in other modes but at the moment I am only concerned with AV mode to resolve this issue. I'd need to confirm this with a DA lens which I may do later.

The EV compensation of +5 will in my understanding also mess up other shooting modes. You basically tell your camera to overexpose by +5, the only difference will be how the camera achieves this exposer (in Av via shutter speed and ISO (depending on your settings maybe just shutter speed) ; in Tv via aperture and ISO (or just aperture, there is not so much leeway so the camera might doesn't reach +5 overexposure) ;in Sv via shutter speed and aperture and so on)
Even M mode should be effected, while it doesn't change any settings on it's own (except you use green button metering) your exposure meter will be affected by the +5 EV compensation, setting the 0 on your +5 EV value.

**UncleVanya** · 10-10-2019, 06:03 AM - **1 Like**

Originally posted by stevebrot

Exposure compensation is sort of sneaky in that it is easy to forget it has been set and by default, the camera will remember the setting between (on/off) power cycles. After a couple of episodes like yours, I edited the menu settings so that that feature returns to zero when the camera is turned off.

menu --> Record mode 4 --> Memory --> EV Compensation: uncheck

Steve

I've done the same as Steve - too easy to forget it is on.

Liney · 10-11-2019, 06:48 PM

Well every day is a school day!

pschlute:

Originally posted by pschlute

That is not right. Try a few test shots again. The aperture should stay wide open irrespective of where you place the aperture ring (other than "A") in Av mode. Take a shot at f4 and at f16. what shutter speed and ISO are you getting ?

So a bit of experimenting gave me the following results, all while in AV mode:

Sigma 28 - 90 lens -

ISO selected at 200, Aperture ring on "A"
F5.6 Shutter speed 1000
F16 shutter speed 125

ISO selected at 200, Aperture ring being used
F5.6 shutter speed 1600
F16 shutter speed 1600
Data on each image shows that the 1600 / F4.5 being used for the images which are both exposed normally. Interesting as that would appear to indicate that the selection of the aperture ring in this case is not changing the physical aperture size. In order to use the aperture in AV mode then I need to have the aperture ring set to "A"

Sigma 28 - 90 lens on manual extension tubes (no electrical contacts} -

ISO selected at 200, Aperture ring on "A"
Shutter speed is dependant on the amount of light entering, but at the aperture is on "A" that will depend on where I point it!

ISO selected at 200, Aperture ring not on "A"
Again shutter speed is dependant on amount of light, however changing the aperture size using the aperture ring will change the amount of light but also the depth of field. This is the mode I use most often when doing macro work, perhaps though I need to be in Manual mode rather than incorrectly using AV mode. Either that or set up a user preset for macro mode, I haven't tried that yet.

stevebrot:

Quote:

Exposure compensation is sort of sneaky in that it is easy to forget it has been set and by default, the camera will remember the setting between (on/off) power cycles. After a couple of episodes like yours, I edited the menu settings so that that feature returns to zero when the camera is turned off.
menu --> Record mode 4 --> Memory --> EV Compensation: uncheck

Done that cheers, I had never been in the memory mode menu option before so I might go back and reset a few other things!

Not a Number · 10-11-2019, 09:28 PM - **1 Like**

Originally posted by Liney

Sigma 28 - 90 lens on manual extension tubes (no electrical contacts} -

ISO selected at 200, Aperture ring on "A"
Shutter speed is dependant on the amount of light entering, but at the aperture is on "A" that will depend on where I point it!

ISO selected at 200, Aperture ring not on "A"
Again shutter speed is dependant on amount of light, however changing the aperture size using the aperture ring will change the amount of light but also the depth of field. This is the mode I use most often when doing macro work, perhaps though I need to be in Manual mode rather than incorrectly using AV mode. Either that or set up a user preset for macro mode, I haven't tried that yet.

Sounds like the tubes do not have an auto aperture lever. It is the lever that holds the iris wide open. See for yourself by taking the lens off the "A" setting and moving the aperture ring while looking through the front of the lens. If you can see the iris opening up and closing down. Then remove the tube and repeat the process. The diaphragm should remain wide open. If the tube has a lever the iris should behave the same when mounted with or without the tubes.

Without the tubes in Av mode with the ring off "A" the camera should select a shutter speed with the amount of light coming through the wide open lens regardless what the ring is set to. There is no connection (crippled KA2 mount) to communicate the f-stop setting from the lens to the body and the aperture lever on the camera body should keep the lens wide open.

Originally posted by Liney

ISO selected at 200, Aperture ring being used
F5.6 shutter speed 1600
F16 shutter speed 1600
Data on each image shows that the 1600 / F4.5 being used for the images which are both exposed normally. Interesting as that would appear to indicate that the selection of the aperture ring in this case is not changing the physical aperture size. In order to use the aperture in AV mode then I need to have the aperture ring set to "A"

This should not be happening. When you take the lens of the "A" position the f-stop setting on the camera should show "F --" and be blank in EXIF.

MrB1 · 10-11-2019, 11:36 PM - **1 Like**

Originally posted by stevebrot

Exposure compensation is sort of sneaky in that it is easy to forget it has been set and by default, the camera will remember the setting between (on/off) power cycles. After a couple of episodes like yours, I edited the menu settings so that that feature returns to zero when the camera is turned off.

menu --> Record mode 4 --> Memory --> EV Compensation: uncheck

Steve

That's a good tip - I've always overlooked the memory settings, but have now set them more appropriately.

Thank you, Steve.

Philip

pschlute · 10-12-2019, 02:32 AM - **1 Like**

Originally posted by Liney

Data on each image shows that the 1600 / F4.5 being used for the images which are both exposed normally. Interesting as that would appear to indicate that the selection of the aperture ring in this case is not changing the physical aperture size. In order to use the aperture in AV mode then I need to have the aperture ring set to "A"

Yes every Pentax DSLR works this way with older lenses. They changed the mount so it wont physically read the position of the aperture ring, and in Av mode the aperture lever is not triggered. Keep your lens on the A setting for full compatibility. If you use an old lens without an A setting, then stick to manual mode where the lens will be stopped down during capture.

Liney · 10-12-2019, 04:32 PM

Originally posted by Not a Number

Sounds like the tubes do not have an auto aperture lever. It is the lever that holds the iris wide open. See for yourself by taking the lens off the "A" setting and moving the aperture ring while looking through the front of the lens. If you can see the iris opening up and closing down. Then remove the tube and repeat the process. The diaphragm should remain wide open. If the tube has a lever the iris should behave the same when mounted with or without the tubes.

Without the tubes in Av mode with the ring off "A" the camera should select a shutter speed with the amount of light coming through the wide open lens regardless what the ring is set to. There is no connection (crippled KA2 mount) to communicate the f-stop setting from the lens to the body and the aperture lever on the camera body should keep the lens wide open.

Ok I see that. No the tubes don't have an auto aperture lever so the aperture is free to move as the ring is set. Which explains why I tried an older manual lens with no electrical contacts but an aperture lever on the camera and got the same sort of results as the Sigma lens but with the aperture ring not on"A"

Originally posted by Not a Number

This should not be happening. When you take the lens of the "A" position the f-stop setting on the camera should show "F --" and be blank in EXIF.

Well I agree that the camera top display shows "F--", but once I had taken the image and reviewed it on the LCD display on the back that was what was displayed. I can go back and check again as I didn't look at the EXIF.

10-10-2019, 06:03 AM - 1 Like	#17
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,472	Originally posted by stevebrot Exposure compensation is sort of sneaky in that it is easy to forget it has been set and by default, the camera will remember the setting between (on/off) power cycles. After a couple of episodes like yours, I edited the menu settings so that that feature returns to zero when the camera is turned off. menu --> Record mode 4 --> Memory --> EV Compensation: uncheck Steve I've done the same as Steve - too easy to forget it is on.

10-11-2019, 11:36 PM - 1 Like	#20
MrB1 Pentaxian Join Date: May 2013 Location: Hertfordshire, England Posts: 845	Originally posted by stevebrot Exposure compensation is sort of sneaky in that it is easy to forget it has been set and by default, the camera will remember the setting between (on/off) power cycles. After a couple of episodes like yours, I edited the menu settings so that that feature returns to zero when the camera is turned off. menu --> Record mode 4 --> Memory --> EV Compensation: uncheck Steve That's a good tip - I've always overlooked the memory settings, but have now set them more appropriately. Thank you, Steve. Philip

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10-10-2019, 02:43 AM - 1 Like	#16
othar Site Supporter Join Date: May 2014 Location: Linz Photos: Albums Posts: 3,098	Originally posted by Liney Now, that raised another couple of questions which I shall explain and see if you can confirm this understanding. The primary lens I was using was a Sigma 28-90 zoom. This lens has an aperture ring with an "A" automatic setting. Leaving it set to "A" and selecting AV mode will wash out the images with the EV of +5. Staying in AV mode but selecting any other aperture but "A" works fine (DoF changes with the aperture and the shutter speed is adjusted automatically}. Selecting any other aperture should still wash out every image with EV +5, the only difference beeing the aperture will always be fully open. Manualy selected aperture only works in M mode, provided you have allowed the camera to release the shutter when no A lens is mounted. Originally posted by Liney So let me get this straight, EV compensation will only work if I am in AV mode, on the condition that the lens has an aperture ring with "A" selected? EV compensation may work in other modes but at the moment I am only concerned with AV mode to resolve this issue. I'd need to confirm this with a DA lens which I may do later. The EV compensation of +5 will in my understanding also mess up other shooting modes. You basically tell your camera to overexpose by +5, the only difference will be how the camera achieves this exposer (in Av via shutter speed and ISO (depending on your settings maybe just shutter speed) ; in Tv via aperture and ISO (or just aperture, there is not so much leeway so the camera might doesn't reach +5 overexposure) ;in Sv via shutter speed and aperture and so on) Even M mode should be effected, while it doesn't change any settings on it's own (except you use green button metering) your exposure meter will be affected by the +5 EV compensation, setting the 0 on your +5 EV value.

10-11-2019, 06:48 PM	#18
Liney Veteran Member Join Date: Apr 2013 Posts: 1,237 Original Poster	Well every day is a school day! pschlute: Originally posted by pschlute That is not right. Try a few test shots again. The aperture should stay wide open irrespective of where you place the aperture ring (other than "A") in Av mode. Take a shot at f4 and at f16. what shutter speed and ISO are you getting ? So a bit of experimenting gave me the following results, all while in AV mode: Sigma 28 - 90 lens - ISO selected at 200, Aperture ring on "A" F5.6 Shutter speed 1000 F16 shutter speed 125 ISO selected at 200, Aperture ring being used F5.6 shutter speed 1600 F16 shutter speed 1600 Data on each image shows that the 1600 / F4.5 being used for the images which are both exposed normally. Interesting as that would appear to indicate that the selection of the aperture ring in this case is not changing the physical aperture size. In order to use the aperture in AV mode then I need to have the aperture ring set to "A" Sigma 28 - 90 lens on manual extension tubes (no electrical contacts} - ISO selected at 200, Aperture ring on "A" Shutter speed is dependant on the amount of light entering, but at the aperture is on "A" that will depend on where I point it! ISO selected at 200, Aperture ring not on "A" Again shutter speed is dependant on amount of light, however changing the aperture size using the aperture ring will change the amount of light but also the depth of field. This is the mode I use most often when doing macro work, perhaps though I need to be in Manual mode rather than incorrectly using AV mode. Either that or set up a user preset for macro mode, I haven't tried that yet. stevebrot: Quote: Exposure compensation is sort of sneaky in that it is easy to forget it has been set and by default, the camera will remember the setting between (on/off) power cycles. After a couple of episodes like yours, I edited the menu settings so that that feature returns to zero when the camera is turned off. menu --> Record mode 4 --> Memory --> EV Compensation: uncheck Done that cheers, I had never been in the memory mode menu option before so I might go back and reset a few other things!

10-11-2019, 09:28 PM - 1 Like	#19
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Originally posted by Liney Sigma 28 - 90 lens on manual extension tubes (no electrical contacts} - ISO selected at 200, Aperture ring on "A" Shutter speed is dependant on the amount of light entering, but at the aperture is on "A" that will depend on where I point it! ISO selected at 200, Aperture ring not on "A" Again shutter speed is dependant on amount of light, however changing the aperture size using the aperture ring will change the amount of light but also the depth of field. This is the mode I use most often when doing macro work, perhaps though I need to be in Manual mode rather than incorrectly using AV mode. Either that or set up a user preset for macro mode, I haven't tried that yet. Sounds like the tubes do not have an auto aperture lever. It is the lever that holds the iris wide open. See for yourself by taking the lens off the "A" setting and moving the aperture ring while looking through the front of the lens. If you can see the iris opening up and closing down. Then remove the tube and repeat the process. The diaphragm should remain wide open. If the tube has a lever the iris should behave the same when mounted with or without the tubes. Without the tubes in Av mode with the ring off "A" the camera should select a shutter speed with the amount of light coming through the wide open lens regardless what the ring is set to. There is no connection (crippled KA2 mount) to communicate the f-stop setting from the lens to the body and the aperture lever on the camera body should keep the lens wide open. Originally posted by Liney ISO selected at 200, Aperture ring being used F5.6 shutter speed 1600 F16 shutter speed 1600 Data on each image shows that the 1600 / F4.5 being used for the images which are both exposed normally. Interesting as that would appear to indicate that the selection of the aperture ring in this case is not changing the physical aperture size. In order to use the aperture in AV mode then I need to have the aperture ring set to "A" This should not be happening. When you take the lens of the "A" position the f-stop setting on the camera should show "F --" and be blank in EXIF.

10-12-2019, 02:32 AM - 1 Like	#21
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,219	Originally posted by Liney Data on each image shows that the 1600 / F4.5 being used for the images which are both exposed normally. Interesting as that would appear to indicate that the selection of the aperture ring in this case is not changing the physical aperture size. In order to use the aperture in AV mode then I need to have the aperture ring set to "A" Yes every Pentax DSLR works this way with older lenses. They changed the mount so it wont physically read the position of the aperture ring, and in Av mode the aperture lever is not triggered. Keep your lens on the A setting for full compatibility. If you use an old lens without an A setting, then stick to manual mode where the lens will be stopped down during capture.

10-12-2019, 04:32 PM	#22
Liney Veteran Member Join Date: Apr 2013 Posts: 1,237 Original Poster	Originally posted by Not a Number Sounds like the tubes do not have an auto aperture lever. It is the lever that holds the iris wide open. See for yourself by taking the lens off the "A" setting and moving the aperture ring while looking through the front of the lens. If you can see the iris opening up and closing down. Then remove the tube and repeat the process. The diaphragm should remain wide open. If the tube has a lever the iris should behave the same when mounted with or without the tubes. Without the tubes in Av mode with the ring off "A" the camera should select a shutter speed with the amount of light coming through the wide open lens regardless what the ring is set to. There is no connection (crippled KA2 mount) to communicate the f-stop setting from the lens to the body and the aperture lever on the camera body should keep the lens wide open. Ok I see that. No the tubes don't have an auto aperture lever so the aperture is free to move as the ring is set. Which explains why I tried an older manual lens with no electrical contacts but an aperture lever on the camera and got the same sort of results as the Sigma lens but with the aperture ring not on"A" Originally posted by Not a Number This should not be happening. When you take the lens of the "A" position the f-stop setting on the camera should show "F --" and be blank in EXIF. Well I agree that the camera top display shows "F--", but once I had taken the image and reviewed it on the LCD display on the back that was what was displayed. I can go back and check again as I didn't look at the EXIF.