under exposure with spot AF/AE metering mode

in SPOT AF / SPOT AE metering mode my K-x underexposes, .. so that I've to tune up AE exposure compensation in order to get decent exposure; .. the problem occurs indoor; ... does anyone know why ?..

Hi Nuri, I also have a K-x and I have not noticed any issue with mine. It is strange that you say this as Trixie has mentioned a similar problem with her K-x, if this is the case it is puzzling as there should not be differences between individual cameras but it appears that there may be. Has anyone else noticed this?

Regards
David

I also have a K-x but I've not got enough experience to say if it's doing the same as it could be me not fully understanding what I'm doing with it. I'll see if I can figure out what's being said and try to recreate it. Sometimes my shots seem dark but I do live in a country where the sun shines in droplets.

without actually been there and witnessing the lighting conditions it would be very difficult to say.

Are you trying to use spot metering under conditions where it's not really suitable?
What does the camera expose like in matrix or centre weighted?

Hi Alan,
Yesterday I took some pics in a church, first with SPOT AF/AE metering mode and then with AF 11 points/multi-segment metering mode. Those taken with former mode prove pretty darker, so that, I need to push AE compensation 2 or 3 unit step up in order to catch the same level of exposure than with ms metering mode. I think the difference of exposure occurs in every context (I mean outdoor too)
Thanks
Kind regards,

The point of spot metering IS to produce different results from ms metering. You use the method to produce the "best" result, which only you can evaluate based on what you are trying to achieve.

The metering is a program and only recently are programs clever enough to guess what the subject is, e.g. smile detection systems on other brands.

After thinking about this. I was the same but discovered that if I point the centre of the screen to a darker area then lock AE with the AE lock button it works fine. You can also use a lighter area to lock the focus but you could get blown out highlights.

Will

Spot metering is taking the light reading from one small point of the image --- usually a 1degree or 5degree spot --- so where you point the camera makes a HUGE difference to the reading. It is a mode/technique which really requires one to know what one is doing. It will render whatever point is under the spot 18% gray so if you point the spot at something very dark, the whole image will be over-exposed and vice versa. It is most useful in very specific situations. For example, say you want to have a brightly lit object render correctly but the rest of the image crushed to black, then you can use spot metering to get a reading only from that object ignoring the rest of the picture.

Linking the AF lock with the AE lock is probably on the assumption that the part of your image you want 'correctly' exposed is likely to be the same part you want precisely focused.

Spot metering is also essential for using Adams' zone method of metering but that is mainly (although not entirely) a film based technique and the subject for another day. The prototype Spotmatic was going to have built-in spot metering (hence the name) but was released with a more generic average metering. My guess is that Pentax realised that most casual users wouldn't know what to do with it and would end up getting it wrong most of the time.

Best, Kris.

On the K-x I use the AE lock rather than locking with AF as well as I might need to re-focus. I'm still a beginner but did notice I could use spot to do this. Need lots more practice with it but one of my last pics in the gallery I used spot to lock AE on a darker part of the sky to bring out the beams. Made the grass very dark which I sorted out in Pse10. Never had my tripod or I could have use HDR or bracketing. I've learnt a lot on here reading the answers to others problems. Spot definitely allows good control on the results but I suppose it can take a long time to master.

Will

Centre weighted metering is the best bet if you have no experience of using a separate meter and/or the principles of light metering.

Spot metering as others have alluded to is best used with care

thanks a lot everyone for your judicious comments and enlightenments ..

best wishes