540 let me down Christmas Day

Started Dec 26, 2007 | Discussions
(unknown member) Veteran Member • Posts: 6,759
These shots are already

nosnoop wrote:

Try doing a test with Link AE with AF with Matrix metering, and you
will see a difference.

My camera is permanently with "Link AE with AF" but it makes no practical difference. I keep it on anyway.
--
Alan Chan
http://www.pbase.com/wlachan/random_shots

OPTMEKX7 Senior Member • Posts: 1,668
Re: Here are examples...

Michael Perham wrote:

Both frames @ ISO 200 1/60 and f/5.6 ...as you can see one is a bit
overexposed compared to the other.

The camera was hand held so framing is not exact, but I don't think
the subject is such that it should cause this difference in exposure.

Mike.

Could it be that the second shot is underexposed because of the reflection from the copper urn and the wider white wall to the left, thus the camera is preventing blownhilight as shown on the example by manual focus.

Cheers,

Rene

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(unknown member) Veteran Member • Posts: 6,759
Link AE/AF shots here

I have done another set of tests which test the Link AE/AF in P-TTL mode. The first 2 shots were taken with the chosen AF point (+) on the left-hand-side (pointing at the white colour wall). The last 2 shots were taken with the chosen AF point (+) on the right-hand-side (pointing at the black colour paper). At least from this particular results, the Link AE/AF feature makes no difference whatsoever on P-TTL flash exposure.

Link AE/AF - off, (+) AF point left

Link AE/AF - on, (+) AF point left

Link AE/AF - off, (+) AF point right

Link AE/AF - on, (+) AF point right

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DS_Dave Senior Member • Posts: 2,261
Re: Wow Brilliant!

Huh?

A total of +1 EV comp for the flash (implying some user knowlege of exposure) and it is still underexposed...hmmm I think you proved my point.

I know how to meter, and I still get seriously underexposed pics with my DS and flash - unless I dial in loads (more than I should have to) of +'ve comp...and it aint always the obvious miniscule specular highlight that is to blame. Best results are obtained at ISO 400 and better (even in a small room filled with a myriad of different colours etc), even with a fully P-TTL flash.

I rarely had any issues with tranny's using my Z-20 and an auto thyristor Metz-45 or Vivitar 283..

I really dont like people leaping to the old chestnut of implying that a poster is dumb as a first response. Perhaps wording the same message in a less accusatory way might be better for the future?

Dave
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LesMizzell
LesMizzell Contributing Member • Posts: 517
Pentax Flash System for Dummies?

If somebody writes it, I'll buy it!

If not a "Dummies" book, a good solid web tutorial posted somewhere with pictures and diagrams with lines and arrows everywhere, and a little tongue-in-check humour would be an amazing thing!

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(unknown member) Veteran Member • Posts: 6,759
Frustrating isn't it?

DS_Dave wrote:

I really dont like people leaping to the old chestnut of implying
that a poster is dumb as a first response. Perhaps wording the same
message in a less accusatory way might be better for the future?

The urge to defend really made constructive discussion impossible.
--
Alan Chan
http://www.pbase.com/wlachan/random_shots

Paul Hunt Contributing Member • Posts: 784
Re: 540 let me down Christmas Day

A little fragment I read in the K10D manual (p. 180) says that when the flash mode is set to P-TTL Auto, the flash pre-fires using the 16 segment metering, to allow "more precise control".

This possibly occurs irrespective of the metering mode set for the camera?

Paul

(unknown member) Veteran Member • Posts: 6,759
My answer is yes

Paul Hunt wrote:

A little fragment I read in the K10D manual (p. 180) says that when
the flash mode is set to P-TTL Auto, the flash pre-fires using the 16
segment metering, to allow "more precise control".

This possibly occurs irrespective of the metering mode set for the
camera?

Just see the post above.

http://forums.dpreview.com/forums/read.asp?forum=1036&message=26175203
--
Alan Chan
http://www.pbase.com/wlachan/random_shots

Alfisti Veteran Member • Posts: 6,649
Super post

I love the brutalness yet accuracy of your rantings

Steve_ wrote:

... because if Pentax could even spell refinement, you wouldn't have
to. That's why you pay somebody hundreds of USD to make a flash for
you--in theory the complications become theirs, not yours. But of
course if the Pentax faithful can make constant excuses for
unimpressive exposure metering, lame AF, and essentially no telephoto
lenses I guess anything is acceptable.

I have Panasonic P&Ss that nail the flash exposure every time, as did
my old Nikon coolpixes. I don't care why Pentax can't do it right,
DSLR or not. Until Pentax similarily doesn't care, they will remain a
bit player in this market. When you design both the camera and the
flash, you have every opportunity to try the two together and
optimize the results. Unfortunately Pentax leaves this to the user,
an unnaceptable lack of refinement considering their flashes cost as
much as those that really work as well as they promise.

It's pretty easy to make a flash work. I have 30-year old ones that
work fine, and without the benefit of a dedicated communication with
the camera. With them, you have to know a bit about what you are
doing and run a good bit of the show yourself. That's supposed to be
the whole point of all the complexity of something like an AF540
flash--to automate all that rather than just produce enough settings
to allow it to be set up very, very wrongly.

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Updated November 2007

DS_Dave Senior Member • Posts: 2,261
Yep!
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tigrebleu Senior Member • Posts: 2,060
Bounce on ceiling?

I used my AF 360FGZ on my K10D (or set on wireless) on december, 24th and 25th and I bounced it on the ceiling at least 95% of the time.

The results were very good, with only a few shots underexposed (because I was further away from the flash). My settings? Av mode, ISO 400, somewhere from F/4 to F/6.7, with no exposure compensation. The flash was set on a small tripod using a hot-shoe to tripod screw adapter and was aimed at the ceiling, most of the time straight up. The flash itself was set to +1.0 EV compensation. Wireless mode, of course.

The best part is, it doesn't look much like a flash was used at all.

A word of advice, though: watch were you aim the camera. If you focus in the background, the flash will deliver more output, resulting in all close subjects being overexposed. The opposite is also true.

Unless you have a colored ceiling, your pics should have a good WB. If you have a colored ceiling (I once did a shoot in a bar with a yellow ceiling), try changing the WB using the K degrees presets. It should work well enough.

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OP FuzzyUno Regular Member • Posts: 114
Bingo!

I started this thread not to bash the 540, but to see if I could get some help. I knew the problem was with me "mostly" and not the P-TTL system. I really do not think it is too much to ask for a camera with a full auto setting and a flash with an auto setting to operate....well....automatically.

I have a lot to learn and do so with each picture. Tonight was my second round of family holiday gatherings where I needed to get it right after blowing it Christmas day. Thanks to GaryDeM, I was able to keep about 75 of 90 shot that were pretty good.

I printed out the following and stuck it in my bag, then made some changes after a few test shots.

GaryDeM wrote:

with that said try the following-camera in manual mode, matrix
metring, multiple auto selection of meter points. iso200. flash set
to P-TTL, auto zoom. no exposure compensation used on flash and
camera. turn camera on first then flash. on camera set shutter speed
to 1/125 to 1/180sec and fstop to f8.0. if you are using a lens with
and intial fstop near f3.5-4.0 the chart on the back of the 540
should be reading near 13meters. focusing on camera in auto. do not
change any settings. take some test shots in a dim area of your home;
dark interior hallway or basement.
with the above the camera/flash should be full auto to about 13meters
or 39ft. it is not necessary to change any settings for your shots
the flah will do all the calculating and adjust accordingly.
i use the above on my dslr and it works. took me 6eails and 5 phone
calls to boulder colorado pentax tech and repair center before i
found and got someone who worked with me to get it to work. i have a
360 flash and it works with same setup though with slightly less
range at any fstop(the 360 is not as powerfull).

note-if you need more flash range you can get it by upping the iso,
but you will be eliminating some short range ability to take a
picture. for at f8.0 39ft is plenty in full auto flash. you cna also
get more range by lowering the fstop you have set in M mode from f8.0
but you will be sacrificing dof. the reverse is also true.

I ended up shooting the majority of my pictures at the following with no changes:

manual mode
320 iso
matrix/pattern
1/125
0 exp. comp.

+.7 flash comp. (I think this may have been because I bounced with the Stof-fen???)
multiple auto focus points (can't remember what the proper terminology is)
P-TTL with auto zoom
link AE with AF

Was every shot perfectly exposed? No, but they were 100% better IMHO and good enough for this newbie. Here are a few straight out of the camera. The first being the worst:

You can see in the 3rd and 4th images the tree lights and window flash glare . This would have totally fooled or thrown off the P-TTL system before these changes were made. I think the key is the pattern metering and auto selection of focus points. But hey, what do I know, it was my original thread/question. LOL

Thanks to all those, especially GaryDeM, who provided input.

OP FuzzyUno Regular Member • Posts: 114
Re: 540 let me down Christmas Day

GregT wrote:

Hi:

The flash manual states that if you have not used the flash for a
while to pop the flash in test mode to fully discharge it.
Apparently this resets the flash and can then be used reliably. Hope
this is of some help.

I didn't read that. It's good to know as I leave my flash on for longer than I should. Thanks for the input.

(unknown member) Veteran Member • Posts: 6,759
This is interesting

FuzzyUno wrote:

You can see in the 3rd and 4th images the tree lights and window
flash glare . This would have totally fooled or thrown off the P-TTL
system before these changes were made. I think the key is the
pattern metering and auto selection of focus points. But hey, what
do I know, it was my original thread/question. LOL

So the "Auto Select AF' seems to be the key as this is the only feature that I have never used. I just tried the suggested setting with my DS but without much success. Anyway, the reason that the 3rd shot was not fooled by the blown window could be that it was located at the edge of the shot (as the picture below has shown). I would have guess that the top & bottom large portons of the meter would be given less priority. As to the 4th shot, could the blown highlights were too small to make any meaningful contribution? These are my speculation of course and I will need to run more tests with the suggested setting to find out if it really worked. But one question remains. Assuming the suggested setting works, why not with other settings? Did the designers programmed it to work in a specific setting only due to limited resource or time? I guess I will never know.

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nosnoop Senior Member • Posts: 1,694
Re: Link AE/AF shots here

wlachan wrote:

I have done another set of tests which test the Link AE/AF in P-TTL
mode.

The main difference could be the camera used. I assume you did the test with *ist DS? Because it definitely shows at least 1+ stop difference with my K10D.

nosnoop Senior Member • Posts: 1,694
Re: This is interesting

wlachan wrote:

So the "Auto Select AF' seems to be the key as this is the only
feature that I have never used. I just tried the suggested setting
with my DS but without much success.

Actually, it works with manual selective AF point. It could be a difference between the DS and K10D though. They may have changed the metering behavior since then; because it really does show a significant exposure bias in the K10D in using Matrix metering + Selective AF + Link AE to AF.

(unknown member) Veteran Member • Posts: 6,759
Ok I believe you

nosnoop wrote:

The main difference could be the camera used. I assume you did the
test with *ist DS? Because it definitely shows at least 1+ stop
difference with my K10D.

since I don't have the K10D. And I guess I won't be able to own one to see for myself anytime soon.
--
Alan Chan
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manual_focus Senior Member • Posts: 1,345
Re: Bingo!

Glad you finally had some success.

The use of 0.7 ev while using P-TTL is a good compromise setting as many of the underexposed images from P-TTL are only 0.5 to 1.0 f-stops off.

My reading of your four posted images are as follows.

  1. 1. White box on table determined the flash duration and the wide angle view ate up the extra ev setting.

  1. 2. This is what P-TTL is geared for. Nothing unusual and just slightly overexposed.

  1. 3. Poster "wlachan" has a good point. The reflection is outside the area of matrix metering.

  1. 4 Lights from x-mas tree are too dim (too far back) to make much influence (I shot a similiar scene with similar results) although your lovely wife's face is slightly overexposed. It's mostly when the reflective surface is in front of or at the same plane of your primary focus point that the light meter seems to get fooled.

Keep practicing and reviewing your work. Flash is a very difficult type of light to work with due to its small size (even with various flash diffusers). Bouncing helps spread it out but the issues of light fall off, and harshness still come into play. The benefit of P-TTL over just Automatic is to help improve on the harshness of flash, as its trying to reduce light hot points. Automatic mode uses a single small eye to determine overall light output. P-TTL seems to use the light meter's various segments to ensure preservation of highlights and no segment being under- but primarily over-exposed. As a lot of posters have stated, all the various reflective surfaces one encounters in a living space can be tough on a light meter.

I'll try the tip of using an exposure adjustment of 0.7 (a little bit but not too much) and see how it works under these types of environments.

Nice pictures and nice family. Looks like everyone was enjoying themselves.

manual_focus Senior Member • Posts: 1,345
Re: Here are examples...

OPTMEKX7 wrote:

Could it be that the second shot is underexposed because of the
reflection from the copper urn and the wider white wall to the left,
thus the camera is preventing blownhilight as shown on the example by
manual focus.

Cheers,

Rene

Good eye. I think you might be correct.

OP FuzzyUno Regular Member • Posts: 114
Re: Bingo!

manual_focus wrote:

Glad you finally had some success.

The use of 0.7 ev while using P-TTL is a good compromise setting as
many of the underexposed images from P-TTL are only 0.5 to 1.0
f-stops off.

I agree with your perspective on the pictures. I bet if I only had dialed in +.3 flash comp., I would have had better results.

On a side not, I was trying natural mode................and will be returning my setting to bright mode/.

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