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02-18-2013, 10:51 AM   #1
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Bouncing Flash underexposing in PTTL?

So I know there's some debate on the K5's exposure issues when using PTTL... Don't recall if the consensus is that is over or under-exposes. In any case, I'm using a Metz 50 AF2 and recently in a fairly small room with some partial lighting from lamps etc, I was having a hell of a time getting a decent exposure bouncing of a rogue flashbender... Now, perhaps I'm just using it wrong, but I found that even using the on camera flash exposure compensation and the on flash exposure compensation it would still seem to underexpose... In fact it seemed as it it barely changed...

So I switched the manual on the flash and shot at full power... At that point I got a reasonable exposure. But I seemed to need to shoot at full power.

Given that I'm only maybe 6-8 feet from my subject... the ceilings are low... There is some ambient light... It seems weird to me that this 'uppermid' level flash would be maxing out to attain an even exposure - even when bouncing.... Unless I'm screwing the pooch somehow....

Any suggestions???

02-18-2013, 10:59 AM   #2
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I also have a K-5 and Metz 50 AF 2. I use M on K-5 and A on Metz. Everything is well expose as long as you are not very closed to the subject.
02-18-2013, 11:05 AM   #3
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Couple of things. One is that even though your subject is 6-8 feet away - if your ceiling is 10ft high, the light from the flash has to travel closer to 15-25 ft (depending on whether you are standing up, or on the ground, the height of the subject etc). The other factor will be the nature of the ceiling (which I only started to think about because of my own flash challenges). In my living room it is a combination of white stucco (which will give a really uneven reflective surface) and the odd pot light, whose rim may lead to hot spots. I'm still learning how to use my Metz 58-2, but I'm finding it much more reliable on A or in M, where I adjust the power levels as need be. I very much miss the simplicity of the TTL I had with my 25 year old Minolta autofocus, and the very quick ways to adjust the power level even when using TTL mode.
02-18-2013, 11:20 AM   #4
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Try the following, alone or in combination:

  • Make sure camera and flash EV comp are set to 0 for starters, you can adjust from there, but know that camera EV comp has an additive effect on the flash EV comp (at least with Pentax), even if you're "adding" -3.
  • Shoot in Av or M mode. Open up your aperture. Indoors, you probably want to be at 5.6 or wider.
  • Raise your ISO, you've got a K-5, right?
  • Zoom the flash head manually to something like 75mm or more.
  • Make sure the wide angle diffuser isn't flipped down.
  • Bounce attachments MUST be attached at 45 degrees to send the light in the correct direction if the flash is on the hotshoe. Steeper and you're lighting the ceiling, shallower and you're lighting the floor.


02-18-2013, 12:42 PM   #5
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Interesting solutions,. I also only use M settings on the camera. I also set my flashes to M and either adjust the aperture or flash. I usually have the flash on half so I have a faster recycle time. I gave up stuffing around with PTTL back with the K10. I found the film version of TTL extremely reliable in both pentax and olympus. I did always set the aperture with these film cameras. (reading light from the film worked really well, but the reflection from the glass protecting the sensor messes things up and I believe pentax came up with a convoluted system hence the P in front of the TTL))

I am looking forward to other people's experience.
02-18-2013, 01:01 PM   #6
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QuoteOriginally posted by Bob from Aus Quote
Interesting solutions,. I also only use M settings on the camera. I also set my flashes to M and either adjust the aperture or flash. I usually have the flash on half so I have a faster recycle time. I gave up stuffing around with PTTL back with the K10. I found the film version of TTL extremely reliable in both pentax and olympus. I did always set the aperture with these film cameras. (reading light from the film worked really well, but the reflection from the glass protecting the sensor messes things up and I believe pentax came up with a convoluted system hence the P in front of the TTL))
One thing I read long ago (and likely have bookmarked somewhere) - the main difference between film and digital is that film tends to saturate so that you don't get blown highlights, but runs into trouble in low light. Digital tends to be the reverse is that it is easy to blow out the sensor, but a camera like the K5 has fantastic low light capabilities and dynamic range. This doesn't mean that flash can't work with digital - as you note I think most of the problem is a Pentax one rather than a general digital one. I haven't played with the photos I've taken with my flash, but I'm guessing that the ones that still look dark can in fact be rescued, but the blown out ones can't. So shooting at lower power has a lot of advantages, beyond just faster recycling.
02-18-2013, 01:46 PM   #7
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Not sure why, but the K-5 manual says P-TTL is available only with DA, DA L, D FA, FA J, FA, F and A lenses... See p. 187. Of course the manual also says it's only available with Pentax flashes but my Metz at least claims to support P-TTL...

I thought I remembered reading somewhere that bounce flash doesn't work with P-TTL (can't find that in the K-5 manual, possibly in the Metz manual or maybe I'm just mis-remembering). If it's a very dim pre-flash perhaps bounce just doesn't work...
02-18-2013, 02:09 PM   #8
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QuoteOriginally posted by nosliwmit Quote
I thought I remembered reading somewhere that bounce flash doesn't work with P-TTL
Mmm That would make sense. My understanding of PTTL is it makes calculations about the distance of the subject as part of what power it puts out. As I said before it is somewhat convoluted.

So I think we are still waiting for the genius out there who can explain it to us.

02-18-2013, 02:27 PM   #9
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QuoteOriginally posted by nosliwmit Quote
If it's a very dim pre-flash perhaps bounce just doesn't work...
That's a great point and one I hadn't thought about. I haven't read my Metz manual yet either though...
02-18-2013, 02:36 PM   #10
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QuoteOriginally posted by p38arover Quote
Would P-TTL metering work with a pre-flash
I thought PTTL was part of a preflash.
02-18-2013, 02:40 PM   #11
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There are a few other threads on the forum about this. From memory the problem is always over exposure when using bounce flash, not under exposure.
Here is one link; https://www.pentaxforums.com/forums/pentax-k-5/200387-k-5-pttl-bounce-flash-a...stories-2.html
I don't use flash very often, but I'm starting to think that manual is the only way to go.
02-18-2013, 03:47 PM   #12
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Me too

I had the same underexposure with my K10 and K5IIS when using the AF540 and a home made better bounce card. I wound up dialing in a bit of compensation on the camera and jacked the ISO up to 400 (sometimes 800 if its dark) and it works fine - beautiful exposures. How much compensation varies with the subject but over all this all takes a few seconds and I'm shooting. This works even in areas with highly reflective surfaces. Maybe not the best solution but it works for me.
02-18-2013, 06:06 PM   #13
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QuoteOriginally posted by Bob from Aus Quote
I thought PTTL was part of a preflash.
That's why I deleted my post. I misread a previous post - but you quoted me before I deleted mine.
02-18-2013, 06:09 PM   #14
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QuoteOriginally posted by rod_grant Quote
I don't use flash very often, but I'm starting to think that manual is the only way to go.
I don't use flash all that often either which is why I'm trying to decide whether to buy an AF540FGZ or stay with my TTL AF400FTZ I bought in 1990 for my SFX (it works with my *istD). My AF400FTZ has had extremely little use in the 23 years I've owned it.
02-18-2013, 06:21 PM   #15
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QuoteOriginally posted by p38arover Quote
I don't use flash all that often either which is why I'm trying to decide whether to buy an AF540FGZ or stay with my TTL AF400FTZ I bought in 1990 for my SFX (it works with my *istD). My AF400FTZ has had extremely little use in the 23 years I've owned it.
I'd say hold off on the purchase. I have an old Minolta flash which I was using in manual mode with a bit of success especially after I insulated a couple of the minor pins which seemed to be giving me problems. I still plan on using the flash, but may mount it on a bracket and attached a diffuser for doing close up work. I've also recently bought a Metz 58 as there was one at a good price available on the boards. With one exception the onboard flash was fine for those few times I needed it - except for the complaints that I kept blinding people. But as getting the Metz to work reliably is proving to be harder than I had hoped, and it does not have the most intuitive menus, I may end up selling it at some point. All the problems being discussed here and in other threads on the lack of reliable metering with the flash and the need to treat bounce and non-bounce situations differently makes it a less useful tool than I would like.
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