[rad291]

THoog, Autoiso is on. But looking through the complete menu, could not find how to turn off. And, you're right, AV shows up in upper left hand corner of screen, not M. Can you provide any insight as to how to turn autoiso off on K30? Appears to be unique from prior models; but, more likely just ignorance on my part.

[THoog]

THoog, Autoiso is on. But looking through the complete menu, could not find how to turn off. And, you're right, AV shows up in upper left hand corner of screen, not M. Can you provide any insight as to how to turn autoiso off on K30? Appears to be unique from prior models; but, more likely just ignorance on my part.

Hit the ISO button on the four-way control. AutoISO is the upper line with a range of ISOs; manual ISO is the lower line with just one number. If it's on AutoISO, hit the "down" button to select a manual ISO, then left-right buttons to select the ISO you want, then OK button.

[rad291]

Hit the ISO button on the four-way control. AutoISO is the upper line with a range of ISOs; manual ISO is the lower line with just one number. If it's on AutoISO, hit the "down" button to select a manual ISO, then left-right buttons to select the ISO you want, then OK button.

Thanks. I'll try that when I get home.

[Lowell Goudge]

Yup, seems that way. The Helios seems to be the only one of my M42 lenses with enough bare metal to get accurate metering in Av mode. Will have to fix the Sicor-XL and ZM-5SA so I won't have to fiddle with foil, would you recommend filing off some paint with sandpaper? Or maybe I'll just get a some aluminium duct tape and do a less permanent fix? XD

I still think it's silly, why would the lack of electric contact make it underexpose by almost exactly 2 EV stops in Av mode but not in M mode? The amount of light that comes in through the lens is still the same. Doesn't make any sense to me. (I don't really expect anyone outside of Pentax to know the answer to that, it's more of a rhetorical question)

I am not totally sure why this happens except that perhaps there are some assumptions made.

Note, however that the camera performance as a function of lens is not as consistent as you might think. the K10/20 specifically had terrible trouble metering with manual lenses because the light meter and focusing screen seemed to have a very non linear response to the light, as a function of the F stop selected. it seemed to be optimized for the range F4-5.6 I suspect because that is the native aperture of the consumer grade lenses.

[enemix]

I am not totally sure why this happens except that perhaps there are some assumptions made.

Note, however that the camera performance as a function of lens is not as consistent as you might think. the K10/20 specifically had terrible trouble metering with manual lenses because the light meter and focusing screen seemed to have a very non linear response to the light, as a function of the F stop selected. it seemed to be optimized for the range F4-5.6 I suspect because that is the native aperture of the consumer grade lenses.

I haven't had much trouble with that. I have found metering to be pretty consistent, sometimes I have to make minor adjustments but nothing serious.
Read somewhere that Matrix mode could be the culprit and as Matrix mode is automatically disabled when mounting a manual lens on newer bodies it doesn't cause that much trouble anymore. Since I haven't experienced those issues firsthand I don't really know.

[rad291]

Thanks. I'll try that when I get home.

THoog, That did work. I now understand what manual iso is. And when that choice was made, the standby display does show "M" in the upper left hand corner, instead of "AV." However, after making that change, I still am unable to use the aperture ring. If I change the ISO setting up or down that does change the picture that is taken, of course; but the picture taken does not approach what I can take by using the aperture. So, the use of the lens is still limited to only the focus ring. But, if I unlock the lens, and back it off counteclockwise while looking at the aperture through the lens to the point of the smallest (F22) aperture, then, Oh My! the lens functions like a fully manual lens, with control of both aperture and focus, and takes wonderful pictures (but with the disadvantage that the lens is not locked on to the camera - no other apparent problems though). Doesn't make sense that I can "kludge" a working solution that is not built into the camera. Also, I'm not sure why this actually works. Any thoughts?

[rad291]

rad291...
Have you overlooked the auto/manual switch at the rear of the lens barrel? In 'Auto' the diaphragm remains wide open. In 'Manual' it opens/closes as you turn the aperture ring. You can switch between the two provided the lens is screwed home fully and the tiny pin at the rear is depressed against the flange of the camera body or adapter. Off-camera the switch locks in the Auto position and you can't stop down except via the much fatter diaphragm pin (but there is no actuator/pusher plate within digital bodies so you must forget that). You can test the tiny pin by depressing it with a fingernail to release the switch. Assuming this mechanism is OK, screw the lens into the body firmly and move the Auto/Manual switch to manual and you should be able to stop down using the aperture ring.

I find the 5-to-12 position of the switch awkward given the overhanging top plate of digital SLRs. Much better if it was 20-to-12 so you could flick it with your thumb from wide open (Auto) to your preset aperture (Manual) just before you shoot. For this reason I tend to leave it on Manual and open up to focus and compose, then turn the ring a few clicks - four clicks to f4, six clicks to f5.6 - no need to take your eye from the viewfinder - and take the picture. Leave the mode dial on Av and it meters automatically. Of course, there'll be situations where you need to meter manually and use the 'green button', or AEL button, in which case set the dial to M. I can't speak for what happens on a K30 - I use an istDS and a K-7.

Unfocused, As was pointed out, this does not work for a k mount lens, which is what this one is. Backing the lens counterclockwise while looking through the lens at the diaphragm allows me to just back it off to the point where I can get the full range of stops all the way down to F22, and the lens functions wonderfully. But there is the disadvantage of not being locked on to the camera; so it could be turned off with nothing to stop it coming off completely (except friction - it is not loose, so probably not a problem). However, I also have a couple of M42 mounts - just waiting for the adapter rings to come. So I'm hoping that as you describe they will fully work as intended in a locked in position. Not sure why the k mount works when not fully in locked position. I'll let you know how things go with the M42 lenses when I am able to mount them. Any further thoughts on the k mount issue, though?

[rad291]

Hi there and welcome

It has been brought up earlier in this thread, K mount lenses actually don't stop down until you either press the button to preview/meter or press shutter release to take the shot. The rest of the time it stays fully open. Just mount it fully and try that first.

enemix, Doesn't work on the K-30 for some reason. Only time I have control over the aperture is if the lens is backed off counterclockwise a little from the locked position. Still tightly held on to the camera body, but not locked (I don't like that, but, the results are night and day different from anything the camera can do programmatically. Any more thoughts?

[enemix]

Oh My! the lens functions like a fully manual lens, with control of both aperture and focus, and takes wonderful pictures (but with the disadvantage that the lens is not locked on to the camera - no other apparent problems though). Doesn't make sense that I can "kludge" a working solution that is not built into the camera. Also, I'm not sure why this actually works. Any thoughts?

The function is built into the camera, but something could be malfunctioning. There is a small lever near the back element that the camera uses to open and close the aperture, when the lens is fully mounted that lever is kept in the wide open position at all times except when you press the green button to meter or press shutter release, then the camera should release that lever and the aperture will close. Afterwards it's pulled back to wide open again. If that mechanism is not working then there is either something wrong with your camera or there's something wrong with the lever making it get stuck.
Easiest way to test if it's working is to turn the aperture ring all the way to the smallest aperture, look through the viewfinder and press and hold the green button. If it works it should get quite dark, release it and it should get back to bright again.

[rad291]

The function is built into the camera, but something could be malfunctioning. There is a small lever near the back element that the camera uses to open and close the aperture, when the lens is fully mounted that lever is kept in the wide open position at all times except when you press the green button to meter or press shutter release, then the camera should release that lever and the aperture will close. Afterwards it's pulled back to wide open again. If that mechanism is not working then there is either something wrong with your camera or there's something wrong with the lever making it get stuck.
Easiest way to test if it's working is to turn the aperture ring all the way to the smallest aperture, look through the viewfinder and press and hold the green button. If it works it should get quite dark, release it and it should get back to bright again.

enemix, After a little more careful checking - I see that the aperture diaphragm is actually working. I set the iso way down and a very slow shutter speed and looked into the lens, and I could see the aperture stopped down. So, I'll have to learn a little about the manual iso and speed settings for the situation I'm in, but it does work. Thanks for your help!

[rad291]

Unfocused, As was pointed out, this does not work for a k mount lens, which is what this one is. Backing the lens counterclockwise while looking through the lens at the diaphragm allows me to just back it off to the point where I can get the full range of stops all the way down to F22, and the lens functions wonderfully. But there is the disadvantage of not being locked on to the camera; so it could be turned off with nothing to stop it coming off completely (except friction - it is not loose, so probably not a problem). However, I also have a couple of M42 mounts - just waiting for the adapter rings to come. So I'm hoping that as you describe they will fully work as intended in a locked in position. Not sure why the k mount works when not fully in locked position. I'll let you know how things go with the M42 lenses when I am able to mount them. Any further thoughts on the k mount issue, though?

Unfocused, After a little more careful looking, the aperture is stopped down by the camera if I have selected manual iso. So things work as intended. Thanks for your input.

[rad291]

THoog, That did work. I now understand what manual iso is. And when that choice was made, the standby display does show "M" in the upper left hand corner, instead of "AV." However, after making that change, I still am unable to use the aperture ring. If I change the ISO setting up or down that does change the picture that is taken, of course; but the picture taken does not approach what I can take by using the aperture. So, the use of the lens is still limited to only the focus ring. But, if I unlock the lens, and back it off counteclockwise while looking at the aperture through the lens to the point of the smallest (F22) aperture, then, Oh My! the lens functions like a fully manual lens, with control of both aperture and focus, and takes wonderful pictures (but with the disadvantage that the lens is not locked on to the camera - no other apparent problems though). Doesn't make sense that I can "kludge" a working solution that is not built into the camera. Also, I'm not sure why this actually works. Any thoughts?

THoog, Works as you said - double checked by setting the iso to very low and the shutter speed to very slow while stopping down to 22 by using the ring. And, looking through the lens I saw the diaphragm stop down to the F22 position while the picture was being taken. (I kind of like the other way though, because that way the camera choses the iso and the speed for me in a way that best suits the circumstance of the photo. Try it if you have a manual lens. Thanks again.

[enemix]

enemix, After a little more careful checking - I see that the aperture diaphragm is actually working. I set the iso way down and a very slow shutter speed and looked into the lens, and I could see the aperture stopped down. So, I'll have to learn a little about the manual iso and speed settings for the situation I'm in, but it does work. Thanks for your help!

Glad to help I too am still pretty new so I know it's easy to miss those little things.

[unfocused]

unfocused:
What you are saying would be true for an M42 lens but since his is K mount it doesn't work the same way.

As there's no such thing as a "K-mount Takumar 55mm 1.8" (the Takumar versions of this lens were all screw mount) I assumed rad291 must be using the usual screw lens with K-adapter.

[rad291]

As there's no such thing as a "K-mount Takumar 55mm 1.8" (the Takumar versions of this lens were all screw mount) I assumed rad291 must be using the usual screw lens with K-adapter.

SMC Pentax 55mm f1.8 unit I purchased thru ebay and it is most definitely a bayonet mount lens. It is a later manual lens than the screw mount lens series . No adapter is required, unlike screw mount unit I also own.