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Comment by Jboyde posted on *M lenses shoot wide open on my K100D at 07/12/2008 - 23:42
Sorry I didnt specify. Its the K100d.
It looks like ANY lens mounted on the camera will automatically open up wide. Even my A lens. At least the other lenses will stop down when I shoot but not the M. If there's any defect it may be in the camera body. The mount my be leaving the iris wide open. At least the lenses that can autoexpose can stop down.
It looks like ANY lens mounted on the camera will automatically open up wide. Even my A lens. At least the other lenses will stop down when I shoot but not the M. If there's any defect it may be in the camera body. The mount my be leaving the iris wide open. At least the lenses that can autoexpose can stop down.
Comment by Jboyde posted on *M lenses shoot wide open on my K100D at 06/12/2008 - 22:08
Hello from the States.
I bought this beautiful 40-80 mm Pentax-M lens that goes down to 2.8 so I have something to use for low light. The problem is that for anyone that uses the older lenses- you have to manually turn the f-dial for the aperture, and it doesnt send the f-stop to the camera.
What I've noticed is that no matter what aperture I turn to on the lens its always going to meter and shoot at f2.8 (max aperture). I can set it to f/11 or 22 but itll still meter at 2.8 when I press the AE-L button. Even though its in M mode. And I'm allowing the aperture ring. If you don't, then the cam just flashes Av and does nothing.
All the blades snap open and close very well with the lever. I'm glad to say that its a well-made and kept lens. I was reading up on this situation and I think what's going on is that one of the contacts on the camera is keeping the lens open. This is probably why I can open and close the aperture when the lens is off the camera but opens wide once I mount it. When I put the lens on my older K1000 the meter needle reacts as it should with the change in aperture. I guess it isnt too bad a problem since I use this lens in low-light situations only.
Also, I just tried my A lens with just using the aperture ring and the same thing happens. As soon as you mount the lens- it opens completely wide! Sigh.
Sorry about my introductory post being so lengthy but I'm at my wits end! I hate spending money on something and not be able to use it to the fullest. I may just have to get used to the fact that, technically, its a 40-800 mm 2.8 fixed aperture lens when put on a digital camera.
Thanks.
I bought this beautiful 40-80 mm Pentax-M lens that goes down to 2.8 so I have something to use for low light. The problem is that for anyone that uses the older lenses- you have to manually turn the f-dial for the aperture, and it doesnt send the f-stop to the camera.
What I've noticed is that no matter what aperture I turn to on the lens its always going to meter and shoot at f2.8 (max aperture). I can set it to f/11 or 22 but itll still meter at 2.8 when I press the AE-L button. Even though its in M mode. And I'm allowing the aperture ring. If you don't, then the cam just flashes Av and does nothing.
All the blades snap open and close very well with the lever. I'm glad to say that its a well-made and kept lens. I was reading up on this situation and I think what's going on is that one of the contacts on the camera is keeping the lens open. This is probably why I can open and close the aperture when the lens is off the camera but opens wide once I mount it. When I put the lens on my older K1000 the meter needle reacts as it should with the change in aperture. I guess it isnt too bad a problem since I use this lens in low-light situations only.
Also, I just tried my A lens with just using the aperture ring and the same thing happens. As soon as you mount the lens- it opens completely wide! Sigh.
Sorry about my introductory post being so lengthy but I'm at my wits end! I hate spending money on something and not be able to use it to the fullest. I may just have to get used to the fact that, technically, its a 40-800 mm 2.8 fixed aperture lens when put on a digital camera.
Thanks.
Comment by Jboyde posted on *M lenses shoot wide open on my K100D at 05/12/2008 - 23:41
Sorry I didnt specify. Its the K100d.
It looks like ANY lens mounted on the camera will automatically open up wide. Even my A lens. At least the other lenses will stop down when I shoot but not the M. If there's any defect it may be in the camera body. The mount my be leaving the iris wide open. At least the lenses that can autoexpose can stop down.
Can you cofirm that you are using Manual exposure mode and "Using aperture ring" is permitted?
Have you compared depth of field with different aperture settings? Test with a subject where you can get a shallow DOF with f2.8, then compare with an attempt at f11. That will prove definitely whether the lens is stopping down when the shutter is fired.
If not working, I would suspect the lens before the camera. If the camera can stop down an A lens, it can stop down an M lens. First of all, though, you must be sure that you are using the appropriate camera settings, hence me asking you to confirm.
As for taking a light reading with M and K lenses before firing the shutter: it's well known that this can give unreliable results - worst with the K10D, but can be unreliable with other models as well. With smaller apertures, I never found it much use with my *ist DS as well as my K10D. So you may need to do some trial and error or calculation before achieving the exposure you want.
Yes, I can definitely say that I have "aperture ring permitted" and I have the knob set to M. But as far as the camera's concerned, its still in Av mode. When I set the f-stop on the ring and then press the Ae-L button I can the same shutter speed no matter what aperture I pick. So I can honestly say the lens isn't stopping down at all, and that goes for ANY lens that has an aperture ring, even my more modern A lenses.
It does make that "whoosh" sound when I press the Ae-L button when I meter so it does sound like its stopping down. I don't think my camera will allow me to adjust the aperture at all thru the ring. It'll meter thru any lens at whatever max aperture that lens has.
Sorry, its just frustrating.