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11-13-2013, 03:23 AM   #1
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thank you for the help.

the title? oh, i'm annoyed but not that annoyed. I just wanted you here. now that you're here, please try to help me.

The problem:
my K-5 messes up the exposure completely randomly every once in a while.
example: today I was photographing a leaf outside (overcast, after rain, plenty of light). I had a close up macro filter, a CPL and the ring flash ring on the lens. First I photographed the leaf without turning the flash on. Then I turned the flash on (on constant light mode, not flash mode). The first couple of pictures were fine at shutter speeds around 1/500-1/1250 and ISO around 100-400. Then the next picture was black. I reduced the shutter speed to 1/400 or so. Still black. I reduced it to 1/15 at ISO 400. Almost perfectly exposed picture. I didn't touch ANYTHING, didn't change any settings. I took the next picture. Completely white. I set the shutter speed to 1/500 or so. Still way too bright. I reduced the ISO to 80 and set the exposure to something like 1/640 and the exposure turned out fine (at this point the camera wasn't messing up the exposure, the shutter speed and the iso seemed to match the environment and the aperture).

Any idea why the camera is behaving like this?
I still have plenty of warranty left, will it help if I send it to be fixed or is this some bug in the Pentax software?

One of the reasons I use manual lenses without P/A settings and only ever shoot in M mode is because I don't need the camera to pretend to be smarter than me. I don't want it to set the exposure for me, I want to set it myself. Why does Pentax seem to make this so difficult? What are these glitches? I have been getting them ever since I bought the camera, usually rarely, but lately it seems to be more often.

The only "lens" with which the camera didn't mess up the exposure was when I taped aluminum foil on the lens mount, poked a hole with a needle and took some pictures. I had no problem with over/underexposure then.
8-15 sec exposures worked just fine.

What is the problem? any idea? it's happened with an external flash and the internal, with and without LV on... there doesn't seem to be any pattern. Am I the only one? I've hardly found any other posts about this. Is this some rare problem or don't people just talk about it?

Another question: after these problems the "forced flash mode, flash not fired" in the EXIF is really starting to annoy me. What is that supposed to mean? how can a picture in sunlight with more light than any pentax flash can produce say "forced flash mode" whatever?
is that some kind of inside joke of Ricoh?

I've sometimes read something about "forced flash mode" here, what is it supposed to be? no matter what flash you have on the camera or what you press, the flash menu only has 2-4 options: flash on, flash curtain sync, flash red eye and flash wireless. There is no "flash off". After I discovered that, I left the menu alone since it's obviously completely useless, unless you want to set up a wireless flash or use curtain sync.

Any insight into any of this?



Last edited by tripodquest; 11-13-2013 at 07:08 AM.
11-13-2013, 03:47 AM   #2
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First thing - Unless you are using a flash with High Speed Sync (HSS) you are limited to 1/180th of a second as the fastest shutter speed you can use with a flash.

For some of the photos the flash was probably not firing because the speed was too high.

Depending on what series of lens you have on the camera (DA FA F A M K), and what mode you are in the flash options will change. See the manual.

Also what type of flash are you using? Is it a P-TTL flash, ordinary TTL, automatic, manual? You don't say. The K-5 will only meter direct flash properly with a P-TTL flash.

Regards

Chris
11-13-2013, 03:48 AM   #3
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Could it be a problem with aperture setting?

If you are not shooting fully open (and don't use a M42 lens), the body will close the aperture to the set value. If this action is not working consistantly, it could explain the behaviour. Specially if you are working with the 'green' button.

Please add information about the lens used and aperture values.
11-13-2013, 03:49 AM   #4
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QuoteOriginally posted by seventhdr Quote
First thing - Unless you are using a flash with High Speed Sync (HSS) you are limited to 1/180th of a second as the fastest shutter speed you can use with a flash.

For some of the photos the flash was probably not firing because the speed was too high.

Depending on what series of lens you have on the camera (DA FA F A M K), and what mode you are in the flash options will change. See the manual.

Also what type of flash are you using? Is it a P-TTL flash, ordinary TTL, automatic, manual? You don't say. The K-5 will only meter direct flash properly with a P-TTL flash.

Regards

Chris
I don't want my k-5 to meter anything, ever. are you saying i need to switch brands or switch to film to make this happen? I wasn't using the flash in flash mode, I was using the Meike ring flash in the "constantly on" mode. I don't use any Pentax lenses at the moment, all my lenses are manual and absolutely have no contacts for electronic anything which is the way I prefer it. if the k-5 knows it's not a p-ttl flash, shouldn't it just ignore it and not try to meter anything? ps. i think my flash works even if it's not mounted on the camera, i've used it like that at least once. I just mount it on the camera so i don't have to hold it, and just in case i want to use the flash (since using it as a flash won't use up the batteries as much as having it on at 1/1 power for several seconds at once.)

11-13-2013, 03:53 AM   #5
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QuoteOriginally posted by RKKS08 Quote
Could it be a problem with aperture setting?

If you are not shooting fully open (and don't use a M42 lens), the body will close the aperture to the set value. If this action is not working consistantly, it could explain the behaviour. Specially if you are working with the 'green' button.

Please add information about the lens used and aperture values.
Today I was shooting with a Petri 55mm f/1.2. it has manual aperture. I'm taking out the lens now to check. Okay, it has no pins, no holes, no electrical contacts of any kind. Unless the camera has a mechanical arm changing the aperture, I don't think the aperture is the problem. The body hasn't known what aperture I'm using probably ever, it always shows F--

I appreciate you both for helping me figure this out. I hope I'm not sounding snarky or anything, I'm only trying to describe my expectations. I don't understand why this is happening. I think if I set the ISO, set the aperture on the aperture ring and set the shutter speed and take a picture, it should come out fine if the settings i used are correct. I don't think the camera should do anything about it other than use the numbers I gave it. Am I missing something?

About the green button, I don't press any green buttons on the camera. I always have it in M mode except when I'm shooting video.
11-13-2013, 04:04 AM   #6
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QuoteOriginally posted by tripodquest Quote
I think if I set the ISO, set the aperture on the aperture ring and set the shutter speed and take a picture, it should come out fine if the settings i used are correct. I don't think the camera should do anything about it other than use the numbers I gave it. Am I missing something?
If you are in full manual mode this is correct. If you take a series of shots and the exposure is different between them, without the light changing (not using low frequency CFL are you?) then there is something wrong. If you are using a native K mount lens then it is possible the aperture is sticking and not closing down consistently.
11-13-2013, 04:10 AM   #7
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QuoteOriginally posted by elliott Quote
If you are in full manual mode this is correct. If you take a series of shots and the exposure is different between them, without the light changing (not using low frequency CFL are you?) then there is something wrong. If you are using a native K mount lens then it is possible the aperture is sticking and not closing down consistently.
I'm always in full manual mode. I shoot in M mode. Can any menu settings screw up the M mode somehow? I don't think I have anything "Auto" on... oh wait! I just noticed the lever next to the lens was on "AF.S", can this have any effect? That was pure negligence, I forgot I tested the kit lens for the first time a couple of weeks ago (when I remembered i had one and I wanted to compare the angle of view of 18mm, 20mm and 21mm) and while testing it I also enabled the Autofocus, I don't remember why, I think I wanted to test it. I must have forgotten to turn it back to MF. I don't think this can be the cause though because I had the problem even before I tested the kit lens.
11-13-2013, 04:13 AM   #8
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Is the Petri a K-Mount or M42?

For your problem, this could make all the difference. With a K-Mount, the body may try.to close the aperture of the lens to whatever value mechanically set on the lens (without knowing which value this would be).

If that coupling works inconsistantly, it could explain the over-exposure. If you had used the green button, also the under-exposure.

11-13-2013, 04:14 AM   #9
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You said you said you checked the lens, did you also check the lever that controls the aperture? I have had with a lens that the lever wasn't alligning well with the lever in the camera (it was too loose). So I also had random exposed pictures (and that was with film and slide, so lot of material wasted). When i went back to the store I bought the lens, they told me about the lever. That sometimes the allignement is not fine, and therefore the camera lever can completely miss it,The trick was to bend the lens lever a bit, and problem was solved (and now I still use this lens without any problems).
11-13-2013, 04:17 AM   #10
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QuoteOriginally posted by RKKS08 Quote
Is the Petri a K-Mount or M42?

For your problem, this could make all the difference. With a K-Mount, the body may try.to close the aperture of the lens to whatever value mechanically set on the lens (without knowing which value this would be).

If that coupling works inconsistantly, it could explain the over-exposure. If you had used the green button, also the under-exposure.
Thank you for the info. But how can that be, when it has no contacts? It's a K-mount, could be a native K-mount? The mount matches the rest of the lens perfectly but I don't know if that's any indication. https://en.wikipedia.org/wiki/Pentax_K-mount#Petri Wikipedia talks about Petri to K-mount adapters. I don't know if this lens was made in K-mount or if someone put one on it. It's hard to find any information about it. (I personally like the lens a lot!)

Okay, you got me curious so I checked the lens thoroughly. The aperture lever which is the only part that can be manipulated from inside the lens/near the mount allows the complete opening of the aperture regardless of the aperture, if you pull it. The lever does not allow the closing of the aperture even wide open, only opening it.

I was mostly using f/8 and f/5.6 (I stopped down for the macro).

Does this help in troubleshooting?
QuoteOriginally posted by Macario Quote
You said you said you checked the lens, did you also check the lever that controls the aperture? I have had with a lens that the lever wasn't alligning well with the lever in the camera (it was too loose). So I also had random exposed pictures (and that was with film and slide, so lot of material wasted). When i went back to the store I bought the lens, they told me about the lever. That sometimes the allignement is not fine, and therefore the camera lever can completely miss it,The trick was to bend the lens lever a bit, and problem was solved (and now I still use this lens without any problems).
I described the lever above, I just checked it. Do you have any suggestions?
11-13-2013, 04:28 AM   #11
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Now that you see that lever, set the lens at the smallest aperture, pull the lever to open the aperture and then release it, does the aperture snap closed quickly?
11-13-2013, 04:29 AM   #12
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Before anyone asks, Menu C1-7: Auto EV Compensation is Off. I couldn't find any other menu settings that would be of any help.
QuoteOriginally posted by elliott Quote
Now that you see that lever. Set the lens at the smallest aperture, pull the lever to open the aperture and then release it, does the aperture snap closed quickly?
It does.
11-13-2013, 04:35 AM   #13
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Now try with it on the camera, mount it on the camera and pull the DOF preview to stop down the lens, is the viewfinder getting dark every time you pull the lever and bright when you release it?
11-13-2013, 04:44 AM   #14
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QuoteOriginally posted by elliott Quote
Now try with it on the camera, mount it on the camera and pull the DOF preview to stop down the lens, is the viewfinder getting dark every time you pull the lever and bright when you release it?
i tried it. I have the LCD turned off, but the brightness indicator (the -.....|||......+ between the MF (shutter speed) and the RAW and aperture indicators when you look through the viewfinder changed according to the aperture. at 1.2 it showed slightly overexposed with 1/60 and ISO 160 in dim inside lighting (3 dim ESLs and windows not letting any light through) but when I took a picture it was normally exposed. I closed down the aperture step by step and the indicator showed normal exposure, underexposure and then more and more underexposure as i closed it down further. so seems to work fine? too bad, I thought you might be onto something but I didn't see anything wrong with this test...
11-13-2013, 04:45 AM   #15
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I just realized you are using a Meike ring "flash". I myself own this LED ring light, and use it occasionally.

As it is LED, it may beam pulsating light. If so, you should try to avoid very short exposure times, as you may just randomly hit moments when the ring light is dark (not visible by the eye).

Also try elliotts suggestion. When shooting with short shutter times, the body will move the lever from aperture fully open to set value and back in a fraction of a second. When the lever moves to allow for closing the aperture, it will not force the lens to do this! The lens must follow the movement of the lever just by the force of its own built in suspension! And this action must follow the lever movement immediately without delay.

EDIT: Some time ago, I wrote a review about the Meike. Have a look at it. To avoid any possibility of problems, I suggest not to use shutter times shorter than 1/60 second.

Last edited by RKKS08; 11-13-2013 at 04:53 AM. Reason: Grammar
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