50mm f1.7 lens and flash

[Eyesthruthelens]

Hi,
This morning I tried few shots with the KM5D lens and all shots are totally overexposed!!
Is this normal?

[Drudkh]

what flash? pls state model.
settings used on cam & flash.

[Eyesthruthelens]

Originally Posted by Drudkh what flash? pls state model. settings used on cam & flash.

Sorry.. build-in flash on my camera..
aperture priority setting with f setting at 1.7.

[dynaxattack]

Funnily, I experience that too. Also inconsistent exposure metering when using F/10 and above.

Is that common, or needs to be serviced?

[Ecclesiasm]

Last night, I did some testing with my minolta system. Here are my findings:

ADI, pre-flash TTL works when I underexpose in-camera by 1-2 stops.

Images are overexposed when I use normal settings. Did not try compensation on flash as I assume that it'll have the same effect.

Any experts would like to comment?

[leeshock]

Originally Posted by Eyesthruthelens Hi, This morning I tried few shots with the KM5D lens and all shots are totally overexposed!! Is this normal?

Yep, got the same result. That is why I always go for manual when using flash. At least I roughly can gauge how it will turn out.

Not sure about others here on the forum and how they tackle the problem.

[Eyesthruthelens]

Hi,
So far, I only experienced this totally overexposed problem on this 50mm f1.7 lens.. no issue with the kit lens.. 17-80mm..

[dynaxattack]

Originally Posted by Eyesthruthelens Hi, So far, I only experienced this totally overexposed problem on this 50mm f1.7 lens.. no issue with the kit lens.. 17-80mm..

I suspect is the compatibility issue of the ADI vs TTL. You noticed the 50mm f1.7 connector has only 5 contact points instead of 8 on the camera body?

I have serious exposure problem when on P/A/S mode when set at higher than F/10. From F/1.7 all the way to F/10 is good, creamy stuffs. When goes to F/11, all hell break loose... .

I m sending it for service. Hopefully it can be rectified.

[mpenza]

Originally Posted by Eyesthruthelens Sorry.. build-in flash on my camera.. aperture priority setting with f setting at 1.7.

what's the shutter speed? maybe the shutter speed is limited by the flash sync speed and hence resulted in overexposure.

[Eyesthruthelens]

Originally Posted by mpenza what's the shutter speed? maybe the shutter speed is limited by the flash sync speed and hence resulted in overexposure.

Hmm..
Never take notes on the shutter speed.. So, I should try higher f setting, f/3 or f/6..

[mpenza]

or lower the ISO.

[megaweb]

Originally Posted by mpenza what's the shutter speed? maybe the shutter speed is limited by the flash sync speed and hence resulted in overexposure.

mpenza is right. If the shutter speed is faster than sync speed, you will get overexposed.

[Eyesthruthelens]

Originally Posted by megaweb mpenza is right. If the shutter speed is faster than sync speed, you will get overexposed.

thanks.. never experienced this problem before, never thought speed is an issue..
Will try out tonight..

[dynaxattack]

Originally Posted by Eyesthruthelens thanks.. never experienced this problem before, never thought speed is an issue.. Will try out tonight..

Have you tried A mode of S mode before and experience the same problems? Because if u use that, shutter speed shouldnt be a problem at all because what ever ISO or A value you set, the camera will set the correct shutter speed based on its meter reading.

I'll post up some overexposed shots and EXIF tonight.

[mpenza]

Originally Posted by Eyesthruthelens thanks.. never experienced this problem before, never thought speed is an issue.. Will try out tonight..

Originally Posted by dynaxattack Have you tried A mode of S mode before and experience the same problems? Because if u use that, shutter speed shouldnt be a problem at all because what ever ISO or A value you set, the camera will set the correct shutter speed based on its meter reading. I'll post up some overexposed shots and EXIF tonight.

An attempt to explain further.....

He already used aperture priority where the camera will determine the right shutter speed to use based on the metering. However, the actual shutter speed used will still be limited by the flash sync speed (for KM D7D, this is 1/125 or 1/160s depending on whether AS is on).

Eg, the camera determines that the right shutter speed to use is 1/320s, but because flash is used, the actual shutter speed used is limited to 1/125s or 1/160s which will result in overexposure (by the ambient lighting).

If the overexposure is really due to this, besides making sure that the metered shutter speed is within the flash sync speed, you can also enable high speed flash sync (should be available) which allows shutter speeds faster than the flash sync speed at the expense of more limited flash range.

[dynaxattack]

Originally Posted by mpenza An attempt to explain further..... He already used aperture priority where the camera will determine the right shutter speed to use based on the metering. However, the actual shutter speed used will still be limited by the flash sync speed (for KM D7D, this is 1/125 or 1/160s depending on whether AS is on). Eg, the camera determines that the right shutter speed to use is 1/320s, but because flash is used, the actual shutter speed used is limited to 1/125s or 1/160s which will result in overexposure (by the ambient lighting). If the overexposure is really due to this, besides making sure that the metered shutter speed is within the flash sync speed, you can also enable high speed flash sync (should be available) which allows shutter speeds faster than the flash sync speed at the expense of more limited flash range.

Thanks for your indepth explanation. I'll try out the HSS. But funnily, this doesnt happen to my Minolta xi 28-105mm (which has 8 contact points instead of 5 in the AF 50mm f/1.7).

Also, what if flash is not activated and you still get an overexposure?? I'll post up photo sample tonight.

[mpenza]

Originally Posted by dynaxattack Thanks for your indepth explanation. I'll try out the HSS. But funnily, this doesnt happen to my Minolta xi 28-105mm (which has 8 contact points instead of 5 in the AF 50mm f/1.7). Also, what if flash is not activated and you still get an overexposure?? I'll post up photo sample tonight.

could be compatibility issue between body and lens, metering issue (e.g. light areas overexposed in predominantly dark scene), body problem or host of other issues.

[Eyesthruthelens]

Originally Posted by dynaxattack Also, what if flash is not activated and you still get an overexposure?? I'll post up photo sample tonight.

Hmm.. Never experienced this on my 50mm lens.. without the flash.

[doremonx]

I have the same experience of overexposed using the flash. I noticed that when I set the ISO to a particular high value, e.g. 800, this may happen. I need to set the ISO to Auto.

Setting to high speed sync is one way but I believe HSS will not work when bounce.

[TME]

I did extensive testing on the 50mm f/1.7 at various ISOs and using 5600 and built-in flash + 7D... I was trying to obtain a close-up shot of a soft toy. All testing done on tripod with 10sec timer... the issue is many-fold...

1) *most important* Distance between subject and flash... must factor the flash coverage... if u are outside the range but closer than what is allowable then u get overexposure. Eg. At f/1.7, 1/90s, ISO400, 75cm subject-camera distance, the flash coverage on the 5600 is 3.0-28 metres. Sure overexpose. I think cos the distance is so short, the flash cannot cut the flash pulse in time. At the same setting but at subject-camera distance of 3.0 metres, the subject was ok. With the built-in u dun quite know your flash coverage. Testing with built-in flash replicates what I got with the 5600HS.

2) ISO affects the exposure. At the same setting above in (1), ISO100 gave ok exposure although the highlights were still blown. At ISO400, everything was blown... no difference between built-in flash and 5600HS except that the 5600 overexposes more.

3) Because of (1), no amount of flash exposure compensation works. Manual flash at 1/32 power is worse. I get complete white out. Did not try built-in flash power ratio. Apparently the TTL is able to pump out power lower than 1/32??


Also tried without flash, no overexpose at any of the following apertures: f/1.7, f/5.6, f/8 and f/16
Will post all the shots for everyone to exam later when I have the time tonight...