[tyke]

Hi.
First post here, athough I've been an avid reader over the years.
I've recently bought a flash which I seem to have avoided for the last 20 years but I've a bit confused to what's going on.
From scouring the net it seems that it is the k5 pttl system what seems to be the problem but who knows it might be my novice tender step into the world of flash.

First picture
[IMG]Photo: http://flic.kr/p/Aq8bbQ[/IMG]

Second picture shows angle of bounce
[IMG]Photo: http://flic.kr/p/AsqL2k[/IMG]

Fourth picture
[IMG]Photo: http://flic.kr/p/Aq84R5[/IMG]

The flash was slightly turned clockwise just enough to turn
the focal length of the lense off on the flash
[IMG]Photo: http://flic.kr/p/B54P3t[/IMG]

Anybody any ideas how such a few millimetres can yield such different results?

[WPRESTO]

Cannot see any of the images. Check how you posted.

[tyke]

Pictures not displaying for some reason,so I will try to explain....
Taking a picture with the flash in a vertical position bounced at 80 mm with the focal length displayed on the flash itself produces a extremely underexposed picture.

The second one of the same subject at the same focal length produces a much better result,but all I did was turn the flash head a couple of millimetres to the right ,just enough to register the focal length of the lense disappears from the flash display .
Hope this makes sense

[rullrich]

Hi.
First post here, athough I've been an avid reader over the years.
I've recently bought a flash which I seem to have avoided for the last 20 years but I've a bit confused to what's going on.
From scouring the net it seems that it is the k5 pttl system what seems to be the problem but who knows it might be my novice tender step into the world of flash.

First picture


Second picture shows angle of bounce


Fourth picture


The flash was slightly turned clockwise just enough to turn
the focal length of the lense off on the flash


Anybody any ideas how such a few millimetres can yield such different results?

Hi,

could you please reedit your post and remove "Photo" from within the IMG tags? Maybe this keeps the forum software from resolving the flickr links.

[WPRESTO]

OK. General observations
1) make sure the flash is fully charged before the next exposures (I get caught by this sometimes when the batteries are getting weak)
2) IF the flash output were determined by the distance to the subject as recorded by how the lens is focused, then in theory every exposure at the same distance would be the same. BUT the pTTL system works by metering light reflected from the subject, SO any small change in what is reflected to or detected by the meter can change the exposure. For example, if a bit more background is included, the flash is likely to overexpose the main subject because more flash output is required to illuminate that distant background. This is a classic problem with all metering, flash or not, when the background is much brighter or darker than the main subject. Spot metering in theory can correct the problem, but only if the spot is placed on something near neutral gray and for a sequence of shots, only if the metered spot is exactly the same for each exposure (example: if the the subject is wearing a dark jacket over a light-colored shirt, the exposure will be profoundly different if the spot is first placed only on the shirt, then shifted to pick up the edge of the jacket), For absolute consistency in a series of flash exposures, use manual flash and don't change the flash-to-subject distance. This is basically the standard way studio photography is done with monolights or power-pack strobes. Once the flash units are set up and the exposure determined, the photographer can move the camera anywhere and still get exactly the same exposure.

[mcgregni]

Its difficult to understand the issue yet .... in general, when bouncing, you can get more light onto your subject by increasing the Flash Head Zoom when it is striking a large surface, rather than using a wide zoom position which will spread the light more before it strikes the surface (wall or ceiling for example).

There does not need to be any connection between the lens focal length and the Flash Head Zoom setting .... in bouncing situations it could be advantageous to increase the zoom setting for the reason I said above, but the actual effect on the subject will depend on the angles involved. Its a good idea to visualise a line of light going from the flash head up to the bounce surface and then down again to the subject (like a snooker ball) in order to judge exactly where to point the flash head.

To take advantage of any extra light available from longer flash head zooming you would need to use Manual zoom control.

Flash units that display a Range & Distance indication (depending on the aperture / ISO / Flash Head Zoom) in P-TTL can be useful to assess if you're in the right ball-park for getting good bounce exposures. First, keep the flash pointing straight at the subject using realistic camera settings, in order to get a range readout ... (eg 2m - 10m). If your subject is already near the far limit of this range then you will struggle to get enough power for bounce at the same distance ..... move the subject closer to the flash, open the aperture or increase the ISO. Ideally you want to have about '2 stops' worth of additional power up your sleeve for a successful bounce exposure. A subject that is placed no more than half way along the range distance indication (eg 6 meters max with an indication of '2m-10m') stands a good chance of being able to be illuminated OK with a typical bounce so long as the ceiling is not too high.

(You don't get the distance / range indications with the head in a bounce position, so the assessment needs to be done with the flash pointed straight at the subject firstly). By using this sort of methodical approach you can ensure that your camera /flash configurations are technically within limits and automatic flash exposures become much more accurate. And don't be worried about using plenty of Flash Compensation .... you might need to dial in +1.0 or even +2.0 stops of FC if needed .... tell the flash what you want from it!

(Apologies if your Metz doesn't have the range indication, I'm assuming it does)

[Class A]

The images of the OP can be seen in his Flickr stream.

@tyke: You would have to access the BBcode for the images through the "share photo" option in Flickr, one by one and paste that BBcode into your post. You are currently using the links to the Flickr pages, not the images (and have extraneous "Photo: " text in the <img> tags).

P-TTL underexposure can be the result of elements in the frame directly reflecting the light of the flash.

Perhaps you can improve the exposure of the first shot by excluding the reflective structure in the left part of the image.

You'll have to live with some wonky exposures from the K-5 in any event, though. The few times I tried using P-TTL, I got underexposure from bounced flash and overexposure from direct flash (some of this may be caused by the known K-5 flash problem). I much prefer using manual flash power control. If I have to fiddle with flash exposure compensation when using P-TTL, I'd rather use manual control and then enjoy the predictability and consistency of fixed power output.

BTW, I'm not sure why you are seeing the "70mm" zoom setting despite the flash head not pointing forward. On my Metz 58 AF-2, the automatic zoom setting is disabled once I move the flash head away from the basic straight-on position, which makes sense to me. Anyhow, the fact that you see a change most likely coincides with the camera using a different approach to obtaining the correct flash exposure so that's most likely the reason why you are seeing a huge difference, despite the light output being very similar. Just go manual.

---

Last edited by Class A; 11-14-2015 at 09:03 PM.

[reeftool]

I'm also a K5 & Metz 48 user. I find the Pentax pttl mode a crapshoot at best. My normal routine is to take a couple of shots, check my exposure and make the necessary + or - EV adjustment on the flash or camera. It does a pretty good job much of the time

[mcgregni]

It's really unfortunate that there seems to have been problems with both the K5 and P-TTL with some third party flash models. I hope the camera issue was solved with the firmware update a long time ago. I have found P-TTL automatic exposures to be very good with the K7, including with 2 off-camera flashes set with a Wireless Lighting Ratio balance, and Flash Compensations if needed. Plenty of K3 users have said things are much better, so lets hope its a thing of the past.

It would be a great pity for people to miss out on the many benefits, practicalities and versatility of a dedicated system flash setup, just because of the idea that P-TTL auto exposures are unreliable. There's a lot more to a full featured dedicated system flash than P-TTL mode. It's a multi functional device that is well adapted to quick changes in shooting situations and offers different workflow approaches to match those situations. It also offers manual exposures if needed. I know its more expensive ...('a LOT' more ClassA ...I did put that in the guide ) but in my view for many kinds of Pentax photographers it is a very good value solution.

[reeftool]

I've been reading gripes about p-ttl for years. I bought my Metz 48 back several years ago for my K10D. It may benefit from a firmware update. At the time however, the Metz flashes were considered considered better performers than either the the Pentax AF540 or AF360. I would say most of the time, my Metz 48/K5 combo exposes close enough only a slight exposure tweak is needed in PP. I just used mine yesterday shooting a wedding in awful lighting conditions and around 400 of the appox 600 shots I took were with the flash. I did have to make occasional + or - adjustments and most of my shots require some exposure adjustments in Lightroom although mostly less than 1 stop either way. It's something I've just grown used to dealing with and you're right, there's more to a good flash than just auto exposure mode. Out of all those shots, very few were lost and of the ones that were, it wasn't the fault of p-ttl.

I don't like to use flash much and when I do use it, it's because I'm in difficult lighting conditions that require it. It's also a tool that requires some practice and skill to use and if I used it more often, I would probably improve. Besides, I shoot in Raw and I'm certainly not going to whine about slightly tweaking an extra slider or two in Lightroom.

[mcgregni]

That all sounds quite good really, and I don't think anyone can expect to shoot RAW images that don't need some brightness and contrast adjustments, with or without flash, automatic flash or manual .... no difference in that respect really. Same with minor colour balance issues.

Take a look at this Blog article from the Pro 645z user, Chris Giles ...... The flash system options for the Pentax 645z ....

1 paragraph to quote ... "For starters though, the Pentax proprietry TTL system (P-TTL) is highly accurate and just as good, if not slightly more accurate in metering than the Canon system. I currently use the MkI Pentax 540 FGZ and it’s very good. If you want to use a full wireless system then Pentax had wireless before Canon did. And that’s true wireless, not infrared "

[Class A]

It's really unfortunate that there seems to have been problems with both the K5 and P-TTL with some third party flash models. I hope the camera issue was solved with the firmware update a long time ago.

The K-5's (and probably K-7's as well) overexposure problem are not fixable via a firmware updated, as reported by Adam a while ago:

"Pentax was very conservative with their response. What they said does imply that the problem has been fixed [for the K-3], however. They were aware of the old bounce flash issue and said it wasn't fixable via firmware due to some hardware limitation in the K-7/K-5's metering system."

Plenty of K3 users have said things are much better, so lets hope its a thing of the past.

Fortunately, the K-3 does not have the same overexposure problem anymore, but unfortunately it has a nasty flash delay issue of its own that makes capturing action with flash more challenging that it already was with the regular P-TTL delay (due to the need to pre-flash and meter). So one can pick the lesser of two evils, but there is no ideal implementation (yet?).

It would be a great pity for people to miss out on the many benefits, practicalities and versatility of a dedicated system flash setup, just because of the idea that P-TTL auto exposures are unreliable.

Well, it isn't just an idea. The K-5's overexposure bug is well-documented. It is also true that reflective elements in the scene can throw off P-TTL big time. This may even be the OP's problem.

P-TTL exposures may work in many cases to a satisfactory degree, but it isn't a fool-proof system.

There's a lot more to a full featured dedicated system flash than P-TTL mode.

What are you referring to?

The two nice features that are unfortunately tied to P-TTL are second-curtain sync and HSS, but they require P-TTL mode. So I wonder what you have in mind when you say there is "a lot more".

I know its more expensive ...('a LOT' more ClassA ...I did put that in the guide )

Well done!

As to Chris Giles' statements:

"For starters though, the Pentax proprietry TTL system (P-TTL) is highly accurate and just as good, if not slightly more accurate in metering than the Canon system."

That's certainly not true for the K-5 (and probably K-7).

"If you want to use a full wireless system then Pentax had wireless before Canon did."

Of what relevance is that today?

Today's shooters don't need to wonder when a wireless (optical triggering) system was introduced. They are rather concerned about what functionality is supported and Canon's E-TTL apparently is ahead of P-TTL with more control over multiple flashes.

"And that’s true wireless, not infrared"

In this context "wireless" just means "optical". What is the advantage of "visible optical triggering" over "infrared triggering"? Canon's system also uses visible pre-flashes, so what is this talk of "true wireless" about?

[mcgregni]

It's not my words about that, it's Chris Giles. I carried the quote through to the end of the paragraph for tidiness. It's good to see someone working at that level who is making such positive comparisons with Canon equipment. As I said before, lets hope any flash metering issues are well behind us with newer models ....K3 and 645z sound ok.

I don't find any inconsistencies with bounce on the K7 .... If we're expecting perfect exposure first time in every bounce situation, that is a high expectation. It is a normal part of the workflow to use Flash Compensation and take positive control to tell the system what you need.

You pay more for a dedicated flash, yes, and for those who will take advantage of its features then its well worth the money I feel. The detailed summaries of differences are now in that new section of my guide, which I felt was a positive addition, and I've tried to make it unbiased. It's mainly about the communication aspects between camera and flash (and that mostly benefits on-camera work, yes, but there is wireless communicated compensations there as well if needed).

I wrote 6 new pages for the guide exactly about this sort of discussion, and that was mainly in response to your feedback and questioning ClassA, so I'm not going to try and detail it all here again. It's on pages 14-19 for those interested (in the new edition) .... And yes, I think there are lots of benefits detailed about radio triggered manual systems as well. There is no side by side comparison that could indicate one approach is better than another ... It's about the person, their needs and approaches. So probably you and I should not lock horns on it, and instead just accept that an automatic dedicated system will suit some, and a radio manual system will suit others.

[Class A]

It's not my words about that, it's Chris Giles.

That's why I wrote "As to Chris Giles' statements:". I'll tidy up the post to avoid confusion.

It's good to see someone working at that level who is making such positive comparisons with Canon equipment.

Except that his comments do not make much sense ("...true wireless..." vs "...infrared..."?).
Apparently you don't know what this (and other statements) is supposed to mean either.

I don't find any inconsistencies with bounce on the K7

Well, good for you but there are many, many threads about users complaining about P-TTL exposures on the K-5. Given that Ricoh admitted to a hardware limitation shared with the K-7 I can only assume that the same problems existed on the K-7 already. Maybe there are differences, as I believe the real P-TTL complaints came with the K-5; perhaps I missed the K-7 ones, I don't know.

It is a normal part of the workflow to use Flash Compensation and take positive control to tell the system what you need.

If that's the case then that severely diminishes the utility of automatic exposures, AFAIC. If one has to take a couple of attempts to find the right compensation value, one does not appear to be quicker than someone finding their correct manual level (guessing the right ballpark is not hard with a bit of experience).

It's mainly about the communication aspects between camera and flash (and that mostly benefits on-camera work, yes, but there is wireless communicated compensations there as well if needed).

But any camera/flash communication relies on P-TTL. Perhaps you meant "automatic exposure" instead of "P-TTL"? I don't understand to what end "communication aspects" could be useful; perhaps you mean the indication of flash reach on the flash display which only works for direct flash? I wouldn't count the latter as a noteworthy feature because of the bad quality direct flash has.

I wrote 6 new pages for the guide exactly about this sort of discussion, and that was mainly in response to your feedback and questioning ClassA, so I'm not going to try and detail it all here again. It's on pages 14-19 for those interested (in the new edition)

OK, thanks for the pointer.

So probably you and I should not lock horns on it, and instead just accept that an automatic dedicated system will suit some, and a radio manual system will suit others.

I don't see anyone "locking horns".

I regard it as entirely normal on a discussion form to ask questions about something someone else wrote. I didn't understand what you were referencing when alluding to things on a dedicated system beyond P-TTL mode, so I asked. One of my speedlights supports P-TTL and if I may learn anything about how I may exploit its functionality better, why shouldn't I ask?

EDIT: I agree that different approaches suit different people / preferences. Agreeing to disagree on some aspects is fine.

That shouldn't stop us, however, to probe whether some perceived benefits are actually helping and whether the price to pay to obtain them may be too high (no pun intended).

[mcgregni]

I think there's been some good advice in this thread on what may be interfering with good bounced flash exposures. And I fully accept that there are times that manual flash mode is the way to go, and fortunately the dedicated system flashes include that.

A lot of the choice comes down to workflow approaches and the level of dynamism needed. I do a lot of on-camera flash in fluid, and outdoor, situations. Also, indoors, I often use an on-camera flash bounced with a Gary Fong diffuser as a fill, while a slave in a softbox provides main light near the subject. I find I get easy, good exposures this way in P-TTL (with manual camera mode) and a Lighting Ratio set on my flashes, 1/3 - 2/3. I get instant total flash exposure adjustment from the cameras flash compensation.

I also appreciate the range and distance indicator as an instant flash calculator, even in manual mode, for assessing subject distance and power settings needed. It's an on-camera thing, yes, but then it can still be used even for bounce with a quick judgement on the bounce factor.

So most of this comes down to personal approaches, and style of flash working. It's the sort of things that people should consider before committing to any particular system kind. I hope in the Guide I have given a fair overview of what each kind of system offers.