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03-28-2008, 09:03 AM   #16
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I really think the flash is accounting for all the problems you are seeing. Browse or search the forums and you'll see cases where a photo of something reflective leads to underexposure. Too powerful of a flash setting will really flatten out an image and could possibly lead to under-exposure. How you have the metering set up could also be an issue (the previous poster mentioned spot vs. center weighted vs. the whole frame).

The nice thing about the problem you are having is that you can easily keep practicing it indoors until you get it right. That's actually what I had done. I strongly urge you to keep working at the manual settings too as you seem to have luck with it, and it will give you a better idea what will work. So will playing with the exposure comp and even the ISO settings. When you are using the flash, I don't think increasing the ISO settings is going to help much or is even needed. If you have a wide enough lens, which you probably would indoors, then the shake reduction is going to make up for slower shutter speeds (e.g. 1/30 sec or slightly slower) that might occur with the flash + camera exposure compensation.

For me, using a flash is a challenge. I can see why people don't like using it. It is a whole different parameter that fits into the equation, and I am not good enough to fit it in well, especially since I am still learning how to work with Shutter Speed, Aperture, and ISO without a flash. The nice thing with digital is you get to experiment without paying for film or developing.

Erik

03-28-2008, 11:46 AM   #17
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I have mostly been using center weighted average mode. And as far as the flash being too strong, I again refer to my brothers camera which if anything should be equal or brighter.

I am mostly using AV mode between f3.5 and 8. Without the flash shutter times go to a half second or longer and I am pretty much always in for a blurry picture that way. I believe I even went and did test shots with flash at different shutter speeds and could not tell a difference between the max 180 and something like 20...not sure if thats right either. My brother kept insisting that the K10 has a failed shutter because it sounds like its operating so slow, and I have to agree after hearing his A700 which is pretty much instant, whereas mine sounds the same all the way to 1/4000..not sure if this is a real issue though.


MJB: do you know generally what the difference is between what you end up using in manual versus what the camera would 'think' in the same situation? That would be good info.

Last edited by Oceanic; 03-28-2008 at 11:51 AM.
03-28-2008, 12:14 PM   #18
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Here are some aperture test shots...clearly the smaller aperture is brighter but I cant figure why..


200mm @ f5.6




200mm @ f9.5
03-28-2008, 02:01 PM   #19
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Metering for the correct exposure is a skill in itself - Bryan Peterson goes into this extensively in his book "Understanding exposure".

Sounds like you're getting good exposures with the M lens because you're in control of the exposure, but with the Sigma you're in 'camera-deciding exposure modes' and so the camera has been trying to work out how you want the scene to be exposed.

As explained earlier, the K10D tries to ensure no area in the picture is overexposed, so a less-well lit part of your photo will not be exposed well at all. The flash changes that because now the light has evenly spread throughout your picture area, so exposure is much easier for the camera to work out for you. Sorry if this is all basic stuff you already know.

In any case, once you've worked out metering ambient light on the K10D, it is a much more enjoyable experience shooting with the camera.

03-28-2008, 02:10 PM   #20
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Assuming all the settings remained the same for those 2 test shots (other than Av of course), and you used flash for both, it's hard to know what's causing this difference in exposure.

I do know that the AF540FGZ flash does tend to underexpose photos at the neutral setting, but this is for all apertures. So your case does seem different.

Would be interesting to know if you find out what's doing it. I doubt it's the camera - shutter curtains usually don't work OK in one aperture, then not OK in another. Have you checked your lens for freedom of its diaphragm to slide open and closed?
03-28-2008, 03:10 PM   #21
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QuoteOriginally posted by Oceanic Quote
Here are some aperture test shots...clearly the smaller aperture is brighter but I cant figure why..


200mm @ f5.6




200mm @ f9.5
It's the lens and shooting wide open forone and stopped downfor the other.....
I recommend (not thatit really matters) to try a different lens first. And shooting a white object w/ foil is not a good way to get a Pentax flash to work correctly.... Hard to explain.
03-28-2008, 03:28 PM   #22
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for what it's worth, 1 day into my ownership of a new k10, mine appears to be doing the same thing! not impressed at this moment.

lens is kit da 18-55. in aperture priority, with flash on, i set aperture to 5.6 - camera sets shutter to 1/60 and iso 1600. take picture. wind aperture down to f11. camera again chooses 1/60 and iso 1600??!! i take picture. now, the 5.6 picture is way underexposed, which is one issue, but the f11 is actually less underexposed than the larger aperture, with nominally the same settings otherwise! and if i go to fully manual, setting iso 1600 and f11 results in the meter telling me i need a half second shutter for correct exposure!!?

what the hell is going on here? there seems to be a serious gremlin or two in the metering and AE systems. the fact that it's happening to someone elses pictures is neither better nor worse imo. poor quality control, or do we both have a setting wrong somewhere?


i'm also convinced exposure is a bit hit and miss out doors without flash, but i'll stick to the topic in this thread.

PS-- this is with centre weighted metering.
03-28-2008, 03:52 PM   #23
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quick note: i just tried two shots with the flash off. naturally, this produced underexposure, but at least this time the camera selected a faster shutter speed for the larger aperture than for the smaller aperture. both pictures were underexposed by around the same amount. so whatever is going on, it seems to be a property of the flash and metering combined.

i'm not too fussed if it is a constantly underexposing camera. i can dial in exposure compensation. but if it's not consistent it will drive me mad. i've only had it for one day, so i'll keep experimenting, but i'll take it back if necessary. in all other respects, it's brilliant, it's just the damn metering that seems tricky.

03-28-2008, 04:36 PM   #24
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sorry to post yet again. i'm learning as i go, and hopefully some of this will make sense to someone, or even be of some help. the shutter speed when the flash is up seems to be constant irrespective of the aperture size - i can stop right down to f38 and the shutter doesn't change!. but the speed does get quicker as i wind the zoom out from 55mm to 18 mm (it comes down to 1/30 sec at 18mm). so i'd say the flash works by looking at the focal length of the lens, and then the objects distance ( guess that makes sense), then adjusts the intensity/timing of the burst to obtain what it thinks is correct exposure. to check this, i dialled in 1 stop of over exposure compensation. the shutter speed remained at 1/60 - as it appears it always will with the lens at 55mm - but the exposure definitely advanced to about right. so the flash is adjusting is output. it must obviously be applying relatively more light when the aperture is smaller than when it is larger - hence the brighter pictures at larger f-numbers.

now i am a novice really, so someone may be able to explain exactly why this is, and what i should do to shoot around it. i have not looked into flash compensation yet - not sure what that is actually doing - but could this be the answer?
03-28-2008, 05:37 PM   #25
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sick of me yet?

ok, here's what i did. i set the flash exposure at + 0.5. this had a noticeable effect on exposure levels - images are much brighter, and closer what i think they should be. i then took a photo at 6 progressive aperture sizes, starting with the largest possible. on my lens, at 55mm it is f 5.6 . this picture was much improved due to the flah compensation, but still slightly under exposed and dim. the next aperture up - 6.7 - was noticeably better again, the histogram looking pretty much right ( although my experience with histgrams is virtually nil, i'm assuming a nice single peak in the middle of the graph with even fall off both ways is good?). from there on up, not much changed - the next five aperture settings ( f8, 9.5, 11, 13 and 16) were all similar. perhaps exposure level went up a tiny bit across that range.

so what i would say, from all this, is that my lens is not all that flash when wide open. and indeed the pentax literature does mention that light fall off in the corners will occur at maximum aperture for the Da 18-55. i suspect that on mine, it's not just at the corners, the whole frame underexposes. but stop down by one or two levels and it brightens up considerably.

so to the OP, i suggest dialling in a positive flash exposure compensation, see what effect that has, then run a batch of shots at progressive App sizes. you may find that your lens is not great at extreme settings. But there also seems no doubt that the K10D is a chronic under-exposing camera at it's default settings.


well, it's my first day on the forum. this thread has already taught me a fair bit about my new camera. it's been fun, if nothing else. and if i've gone astray anywhere with all of this, please correct me. i want to learn as much about the camera as possible - no point having something you can't use correctly.

cheers, jason.
03-28-2008, 08:22 PM   #26
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I just went through and did some more test shots..still clueless as to whats going on though. I tried some shots with flash +.5 and +1 and couldnt really tell a difference on most. Tried it at the same time as +1-3 EV comp and sometimes got a better shot, other times got the exact same one with +3ev and +1.. Same ap and shutter speeds.. Really don't know what to make of it.

As it is, it would take pretty much the max EV comp in most situations to get close to the shot Im looking for, but thats unacceptable as far as Im concerned for what the K10 is supposed to be.
04-01-2008, 10:48 AM   #27
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Well for what I've found with digital cameras in general, the flashes don't have much range. I find myself constantly setting at the full flash compensation and still not getting things bright enough. That is just a typical limitation of on board flashes. Now, the Sony you refer to for your brother is probably partially due to Sony being a company that developed for point and shoot cameras first (my speculation) and not having much in the line for external flashes. If I remember back on the previous camera I purchased, Sony didn't have DSLRs.

A company like Pentax with a long history probably worries less about the on-board flash thinking that their target consumer will buy an external flash anyway.

I have noticed a lot of the problems Paladin has pointed out, and I find that setting all the settings on my own in M-Mode works a lot better than P-Mode and probably A or T mode (I tend to use P-Mode as my A or T mode)... You seem to find something similar with your manual lens, and I am guessing you would probably see that with your automatic lenses in M-Mode.

I have gotten more fond of M-Mode because I can use the Green Button to set the exposure settings and adjust it from there from my experiences. With flash, it is even easier as I find that I am typically using the kit lens and a standard shutter speed and aperture with ISO 200 (my favorite for flash shots) works well. I often have to tweak the flash compensation to brighten further objects or even reduce the flash compensation to darken close objects.
04-01-2008, 01:53 PM   #28
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Those are some good points, and yeah its becoming apparent that M mode will generally be better.

But Im still trying to figure out why both with and without flash I am getting brighter pictures at a smaller aperture like 7-8 than I am at 5.6 and under...I cant seem to find any info on why this might be happening...

I know that using a smaller aperture sometimes yields sharper photos..but I dont think thats it.
04-01-2008, 03:34 PM   #29
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keep in mind too, that the flash on the K10D is only rated GN11 at iso100. pretty sure a lot of it's competitors are Gn13 or better.

also, have you turned on the highlight/lowlight function in picture review? i found, and so might you, that there a highlights in shots that i didn't think held any when i took the shot. the camera metering will underexpose if it sees highlights. i am trying to train myself to see as the metering sees (this is not proving easy) in order to anticipate this effect.

if nothing else, owning a DSLR is fast tracking my knowledge build-up of photography - although i still have a long long long way to go.
04-01-2008, 07:36 PM   #30
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Brighter at smaller aperatue, hmm I'm afraid i smell a sticky aperatue , but theres no way i would try to fix it myself


edit: err never mind thats backwards

edit 2: thats not the link i wanted ether now thats a bad night

Last edited by Sanglant; 04-01-2008 at 08:02 PM.
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