[DeanG]

Hi, I'm wondering if anyone might explain why I need a -2 stop exposure comp if I use my takumar 35mm f/3.5 screwmount on my K-S2, BUT no exp comp is needed if I use Live View. If I use my auto Chinon 28mm f/2.8 K mount, there isn't any problem. I have used Manual mode with green button, as well as Av with the Tak, same result. I am ok with using exp comp but I just don't get it. Is this normal? btw I do stop the takumar down before pressing for metering and it is in manual .

[UncleVanya]

My understanding is the green button manual is used on K mount non-A series lenses. I thought with screwmount the correct method was to use M or to use Av and simply use the aperture ring in manual (stop down) mode.

[Adam]

Hi, I'm wondering if anyone might explain why I need a -2 stop exposure comp if I use my takumar 35mm f/3.5 screwmount on my K-S2, BUT no exp comp is needed if I use Live View. If I use my auto Chinon 28mm f/2.8 K mount, there isn't any problem. I have used Manual mode with green button, as well as Av with the Tak, same result. I am ok with using exp comp but I just don't get it. Is this normal? btw I do stop the takumar down before pressing for metering and it is in manual .

Matrix metering is unavailable through the viewfinder when using manual lenses, so that could partially explain the difference in exposure. Generally speaking, live view will be more accurate with manual lenses.

[pschlute]

Hi, I'm wondering if anyone might explain why I need a -2 stop exposure comp if I use my takumar 35mm f/3.5 screwmount on my K-S2, BUT no exp comp is needed if I use Live View. If I use my auto Chinon 28mm f/2.8 K mount, there isn't any problem. I have used Manual mode with green button, as well as Av with the Tak, same result. I am ok with using exp comp but I just don't get it. Is this normal? btw I do stop the takumar down before pressing for metering and it is in manual .

Have a look here How to use/meter Manual & M42 Lenses on all Pentax DSLRs (K-1, K-3, K-5, K-30, etc) - PentaxForums.com

1. "Enable Aperture ring" setting in the camera should be on

2. M mode green button action should be set to Tv shift

3. Your lens has a M/A setting on it. Place it in M.

When you look through the viewfinder and turn the aperture ring the scene should darken/lighten. So focus, then set aperture, then in M mode press the green button and you should get a correct shutter speed set by the camera. But with M42 lenses it is easier to use Av mode. Because the aperture actually stops down as you turn the ring Av mode will give you correct exposure without the need to use green button metering (nb this is not the case for k-mount manual lenses).

Give this a try and see how you get on.

[DeanG]

When you look through the viewfinder and turn the aperture ring the scene should darken/lighten. So focus, then set aperture, then in M mode press the green button and you should get a correct shutter speed set by the camera. But with M42 lenses it is easier to use Av mode. Because the aperture actually stops down as you turn the ring Av mode will give you correct exposure without the need to use green button metering (nb this is not the case for k-mount manual lenses).

Give this a try and see how you get on.

Yes thank you, I have been following this procedure, but my question is why, given identical method, the K-S2 meters differently in Live View (correctly), but not when shooting with viewfinder . With Viewfinder the camera overexposes by about 2 stops.

---------- Post added 01-31-19 at 06:35 AM ----------

Yes thank you, I have been following this procedure, but my question is why, given identical method, the K-S2 meters differently in Live View (correctly), but not when shooting with viewfinder . With Viewfinder the camera overexposes by about 2 stops.

I meant to add that this only applys to the screw mount lens. I have verified that I am stopping down to meter. In any event if I metered wide open I would expect to get underexposure, not over exposure, after stopping the lens down to shoot.

[normhead]

What do the images look like?

[pschlute]

Yes thank you, I have been following this procedure, but my question is why, given identical method, the K-S2 meters differently in Live View (correctly), but not when shooting with viewfinder . With Viewfinder the camera overexposes by about 2 stops

Try this. In both M and Av modes, does the camera meter correctly wide open ? If yes then try at various apertures and see if there is a pattern....ie progressive overexposure the more you stop down ?

can I assume you have changed the two camera settings I mentioned ?

[DeanG]

I will post some examples later. Thanks!

[DeanG]

Well I never got around to getting some examples posted, but I checked again and the camera reads exposure differently in view finder operation vs Kive View all else being equal, for example Live View will read 1/40th while switching to viewfinder with no other changes reads 1/13th . And it happens that the LV reading is correct. I am wondering if somehow my screw mount adapter could have anything to do with the operation in viewfinder mode as it makes no contact with the flange leaving the electronic contacts exposed. Does normal viewfinder operation make use of these and not LV? I am just grasping at straws, and I think I should just shut up and use exposure comp! Thanks for all your input. 😐

[GUB]

Well I never got around to getting some examples posted, but I checked again and the camera reads exposure differently in view finder operation vs Kive View all else being equal, for example Live View will read 1/40th while switching to viewfinder with no other changes reads 1/13th . And it happens that the LV reading is correct. I am wondering if somehow my screw mount adapter could have anything to do with the operation in viewfinder mode as it makes no contact with the flange leaving the electronic contacts exposed. Does normal viewfinder operation make use of these and not LV? I am just grasping at straws, and I think I should just shut up and use exposure comp! Thanks for all your input. ��

One little thing that may be happening when you are using the green button -- The eyepiece needs to be covered to stop light pouring in it affecting the light meter. I don't think this will happen in LV.
Took me ages to work out why my exposures were naff - all because I pulled my head away to find the green button.

[altopiet]

Hi, I'm wondering if anyone might explain why I need a -2 stop exposure comp if I use my takumar 35mm f/3.5 screwmount on my K-S2, BUT no exp comp is needed if I use Live View. If I use my auto Chinon 28mm f/2.8 K mount, there isn't any problem. I have used Manual mode with green button, as well as Av with the Tak, same result. I am ok with using exp comp but I just don't get it. Is this normal? btw I do stop the takumar down before pressing for metering and it is in manual .

I had the same problem with my manual lenses and green button metering on my K-30, this was just after I had an aperture block repair, and I thought I'm not going to send it back but decided to assign one of the user modes to LV with a 2 stop exposure compensation, as a workaround, could never figure out why it happened, as it was a normal about 1/3 stop difference with my auto lenses...

[pschlute]

One little thing that may be happening when you are using the green button -- The eyepiece needs to be covered to stop light pouring in it affecting the light meter. I don't think this will happen in LV.

A good point but the OP is getting overexposed images. If light from the VF was affecting the exposure it would be under.

---------- Post added 02-01-19 at 01:20 PM ----------

Well I never got around to getting some examples posted, but I checked again and the camera reads exposure differently in view finder operation vs Kive View all else being equal, for example Live View will read 1/40th while switching to viewfinder with no other changes reads 1/13th . And it happens that the LV reading is correct. I am wondering if somehow my screw mount adapter could have anything to do with the operation in viewfinder mode as it makes no contact with the flange leaving the electronic contacts exposed. Does normal viewfinder operation make use of these and not LV? I am just grasping at straws, and I think I should just shut up and use exposure comp! Thanks for all your input. 😐

try the test I suggested at a number of different apertures and see if you get a pattern developing. Does it meter correctly at wide open ?

The reason I ask is that it could be the focus screen is the issue. Back when the K10D K20D cameras were released a new bright focus screen was introduced. This had the effect (with K-mount manual lenses K and M) of causing a gradual, progressive overexposure the more the lens was stopped down when metering using the green button. Perhaps your model camera has similar problems.

Some pictures would be good.

As was stated earlier LV will use its own metering system which is separate from the VF one. With a manual lens you can use CW or spot metering only when using the VF. Have you double checked theses settings ?

[UncleVanya]

Plus 1 for verifying metering settings in live view. These may be different from the ovf.

[DeanG]

The settings are both center weighted in either LV or VF. Oddly, I don't get an option for matrix metering as a choice for LV either. I should,correct?

here then FWIW:

manual mode, green button readings, center weighted avg metering...iso 1600

f/3.5
LV 1/40 VF 1/20

f/5.6
LV 1/15 VF 1/8

f/8
LV 1/8 VF 1/4

f/11
LV .4" VF .5"
(@ iso 6400: LV 1/10 VF 1/8 )

so about a 1 stop difference, with overexposure in VF mode, although by eye, I am favoring more like -1.7 or -2 exp comp in VF.

---------- Post added 02-01-19 at 08:28 AM ----------

As was stated earlier LV will use its own metering system which is separate from the VF one. With a manual lens you can use CW or spot metering only when using the VF. Have you double checked theses settings ?

On my K-S2, with manual lens I get spot or CW options in either LV or VF. I have been using CW for both...according to the info screens.

[Lowell Goudge]

although i cannot speak of the KS-2 or my new K1, i did a lot of work on metering issues with manual focus lenses about 5-6 years ago. the issue stems from the behavior of the metering system as a function of the "native aperture" of the lens.

for auto aperture (KA and later lenses) the camera knows the maximum aperture, and can adjust exposure for any general biases that a specific aperture has, for example, in many early cameras the tendency was to greatly under expose for large apertures (i.e. fast lenses) and over expose for small apertures F8 and higher,

if the camera did not know the aperture green button metering produced errors. newer cameras are better but still not perfect.

live view on the otherhand sets metering based upon what the sensor actually sees, so yes it may be more accurate, AND i would expect in an M42 Lens, you may need to have some exposure compensation when using AV mode for example. the trick is to know in advance, the compensation needed for each aperture because it is NOT constant over the whole lens aperture ranger