[bygp]

I already had a bit the same "issue" with my K200D, but it seems even more obvious with my new K-5 II, mainly in low-light conditions using iso 400 to 1600.
When using the green button in M mode with M lenses (or A lenses but same issue in Av mode) the camera often sets shutter speed to 0.7" or 1" when it can easily hold 1/20 to 1/45 (giving a bit under exposed RAW shots but I prefer that than over exposed by far !).
I'm getting used now to this gap and by memorizing light conditions + iso can almost get manually the good speed, but then, metering becomes useless for me if I can't rely on it.

Any advice ? Is there a way to calibrate metering so it won't set so low speeds and I could rely on it ? I don't think this is a specific K-5 II issue as I have almost the same experience with the K200D even if this one would hold only lower speeds (1/10 to 1/20 when metering says 0.7" or 1").

It seems that lenses focal range have an impact, as I have a bigger gap with my 135mm than with my Cosina MC 24mm (A) or the Auto Chinon 50mm (M), the cosina has a A mount but Av or M metering gives same results when the lens ring is on A.

---------- Post added 12-10-15 at 02:36 AM ----------

But even in normal light condition, using camera centered zone (not the central spot & not the full frame) metering, always gives too slow shutter speed and so over exposed photos, the speed gap is just smaller in daylight conditions than by night.

This did not seem to occur with the 18-55 KAF2 kit lens in Av mode, so it seems to have to do with lenses types...

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Last edited by bygp; 12-10-2015 at 02:37 AM.

[Digitalis]

I personally haven't had any issues with the Manual metering on my K5IIs - but then again I'm using Pentax lenses, third party manual lenses might not have linear aperture mechanisms and this might be the cause of your exposure issues.

Low light metering is difficult, and a metering system attuned to 18% grey isn't much help with high contrast scenes. Have you tried shooting with you lenses in ordinary daylight, does the problem persist then?

[bygp]

I personally haven't had any issues with the Manual metering on my K5IIs - but then again I'm using Pentax lenses, third party manual lenses might not have linear aperture mechanisms and this might be the cause of your exposure issues.

Low light metering is difficult, and a metering system attuned to 18% grey isn't much help with high contrast scenes. Have you tried shooting with you lenses in ordinary daylight, does the problem persist then?

Well, I tested yesterday night with my SMC Pentax-M 135mm and there is definitely a gap in low light scenes, but almost no gap in daylight conditions and base ISO (100 or 200), although when it tells me 1/350 I can easily go to 1/500 (closed f8). It's not realy an issue for me as I'm a full manual methods fan and I post prod all my photos, but if there is no tweaking option for that (EV tweaking is not the answer here), I'll get used to take a test shot and than go to memorized manual settings, often 1/20 to 1/60 in the range iso 800-1600 by night, depending on aperture but I usually never go lower than f8 (range 3.5-8).


Ferry by night by Bruno Polleri, sur Flickr

this one was taken at 1/45, iso 800 although metering was telling me 0.7" ^^

[Digitalis]

there is definitely a gap in low light scenes, but almost no gap in daylight conditions and base ISO

That is unusual indeed, there may be something wrong with your camera settings or something physically wrong with the camera itself.

Considering all these manual focus lenses you are using, are you by any chance using a third party focusing screen? They are well known for causing issues with AE.

I usually never go lower than f8

Out of curiosity why is that?

[bygp]

Also found something very nice, need to digg further, but as everyone knows K-5 II gives a bit less sharp picture than K-5 IIs due to the AA filter, I did some test changing sharpness settings in the fast access picture tweaking menu, setting sharpness on +2 to +4 and setting it on F (fine sharp improvement), and got very nice test results on infinity focused crops, very close to what you can get from a K-5 IIs
Tried this this morning in daylight and iso 100, need to see if it is still doing the job in lower light and higher ISO...

[Digitalis]

setting sharpness on +2 to +4 and setting it on F (fine sharp improvement), and got very nice test results on infinity focused crops, very close to what you can get from a K-5 IIs

But the problem is with tweaking global image sharpening parameters increases the amount of visible noise in your images. I keep them zeroed out, by default. Due to the high quality lenses I work with, I find images from my K5II inherently need less sharpening.

[bygp]

That is unusual indeed, there may be something wrong with your camera settings or something physically wrong with the camera itself.

Considering all these manual focus lenses you are using, are you by any chance using a third party focusing screen? They are well known for causing issues with AE.




Out of curiosity why is that?

Not yet, it is the genuine focusing screen but I will change it quite soon for an MF optimized F.S. and I already know (as I did the swap on my K200D) that this old Pentax SLR (resized) focusing screen do not alterate metering, even brighter than the genuine one so it would only meter faster shutter speeds if there is a gap and that's fine to me.

Max F8 ? Because on all my lenses this is usually the smaller aperture giving sharp pics (often best results are in the 4.5-6.7 range), I could go higher for special reasons (DoF, movements effects, etc...) but I usually see IQ loss after f11 with these lenses.
(24mm, 50mm & 135mm primes).

---------- Post added 12-10-15 at 03:51 AM ----------

But the problem is with tweaking global image sharpening parameters increases the amount of visible noise in your images. I keep them zeroed out, by default. Due to the high quality lenses I work with, I find images from my K5II inherently need less sharpening.

I guess you are right, maybe this is less noticable at iso 100 and would be a bad choice at higher iso. IDK what you call HQ lenses, if they are modern high-end KAF lenses I don't have the budget for these^^ I'm very glad of my old primes results, the Auto Chinon MC 50mm 1.7 is my sharpest lens and the SMC 135mm is very good too. Enough for me ATM

---------- Post added 12-10-15 at 03:52 AM ----------

don't think it is a camera issue (the speed gap by night) because I had quite same results with my K200D.

[Scintilla]

Is this through the viewfinder, in Live View, or both? I find that using Live View on my K-30 seems to give more accurate exposures with manual lenses, if that's an option for your type of shooting.


(I just wish it wouldn't always stop down the lenses to some intermediate aperture that's not even the selected one for Live View focusing. If I can't focus wide open and I can't get real-time exposure preview, then why? Of course, this isn't an issue for non-K-mount lenses like M42 and C/Y.)

[bygp]

@ Scintilla :

Thanks for this advice but I've already tried some shots using LV and I... just hate this^^ This is why I use a reflex and not a compact or bridge, and accurate focusing is far much more important to me than accurate metering (under exposure is not an issue, bad focusing yes), the best focusing method I've ever used atm is using this screen in the viewfinder :


My new focusing screen by Bruno Polleri, sur Flickr

the splitted disk is realy accurate, and much easier to use in low light conditions than the genuine screen, perhaps if LV has a central crop option it could be nice but idk yet if I can do that with the K-5 II (got it a few days ago so I've not explored yet all its potential), focusing using LV viewing all scene is not realy accurate.

But maybe using LV just for metering once and then switching to VF could be a solution, I'll give a try to see if it gives other speed settings...

---------- Post added 12-11-15 at 12:03 AM ----------

what I may also try is to use the central spot metering, choosing an average light level in my scene, just because with the above MF focusing screen, center zone is not mate at all, it is cristal clear and gives a brighter view so perhaps I can get a better metering with this method... I'll test that and give a feedback here