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[OM] Re: Advice from Dr. Flash LONG (was [photo] berkshire hill fog)

Subject: [OM] Re: Advice from Dr. Flash LONG (was [photo] berkshire hill fog)
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Thu, 14 Dec 2006 21:28:54 -0500

Mike Lees wrote:

> Chuck,
> 
> Thanks for the advice - I really appreciate it.
> 
> You guessed right - I was using battery powered flash. I had the big
> 580EX on a bracket immediately above the camera with a pocket bouncer
> and a smaller 430EX on a stand shooting through an umbrella.

I'm not sure about the master slave relationships in Canon flash units 
so in ETTL mode you may have to mount the 580EX on the camera as the 
fill flash as you have it.  But the power output relationships between 
fill flash and main light are backwards here since the 430 is less 
powerful than the 580.  Probably doesn't matter since you're not likely 
needing full power in close quarters but normally the fill light would 
be 1/2 to 1 stop less power than the main... at least as measured at the 
subject.

> 
> The setup was less than ideal. I think I only had about 6 feet in total
> from the front of the camera to the background, with a wall immediately
> behind me. It was also so dark that the autofocus was struggling. I take
> your point about the background colour.

I suspected you were in close quarters and less than ideal conditions. 
It's times like these that I always remember the amonishment of my photo 
mentor.  During a class years ago I was trying to take a very tough shot 
with a model in mixed full sun and deep shade and struggling with the 
OM's 1/60th second flash sync speed and trying to compensate with ND 
filters.  I approached him for advice and he said: "Don't take the 
picture there".  Well, that didn't solve any technical problem for me so 
I said: "You know, I think if I just... " and he cut me off with "Don't 
take the picture there!"  Being a natural techie I just had to know how 
to solve the problem so I said: "But I think maybe I can do it if I 
only..." and the immediate response was:  "Don't take the picture 
there!!!!"  You know, he was right.  That wasn't a very good spot to 
take the picture.

As to the autofocus there is an easy solution.  Put the camera on a 
tripod, use an aperture of about f/8, focus (auto if you like) on a 
bright object held by the subject and then turn the autofocus off. 
Don't move the camera and don't toudch the focus again.  Everything is 
in a fixed or near fixed position.  All will be in focus with no errors 
or focusing delays.  Another option is to set Custom Funciton #4 to 
option #1.  This will remove the autofocus from the shutter button and 
move it to the "*" button on the back of the camera.  Then the camera 
won't be continuously trying to autofocus in the dark whenever you press 
the shutter button.  Only when you want it to by pressing the "** button.

> 
> I think you are probably right about the recycling too. I could see the
> 580 charge light (which recycles faster and was set to less output) but
> not the 430 - I remember a couple of times the 430 didn't fire because I
> was too quick. I retook shotw when that happened, but I hadn't
> considered the "not fully charged" case.

The not full charged case covers a lot of ground.  It's not yet fully 
charged even when the ready light comes on.  If it recharges and turns 
on the light in, say, 8 seconds it's probably still 1/2 or even one stop 
from full power.  Do some measurements or, to be on the safe side, wait 
at least double the spec time.  The T-32 spec says 10 seconds to 
recharge from a full dump uaing alkaline batteries.  I'll tell you (by 
flash meter measurement of 4 separate T-32's) it takes more than 20 
seconds to get completely charged even using brand new batteries.  And 
if you use NiMH batteries it will recharge faster but won't reach the 
full power level delivered by fresh alkalines because the MiMH voltage 
is too low. (1.2 volts vs. 1.5 for alkaline)

> 
> When you say "manual mode" do you mean the camera in manual or the flash
> in manual. I have been learning much more about the Canon flashes this
> week (more on that later) and I am now more confident with the camera in
> manual but the flash still in ETTL mode.

I mean everything in manual mode.  You're in a fixed position with 
nothing changing to affect exposure or focus.  Turn the automation off 
and don't give the camera a chance to screw it up.  Trying to balance 
the power output of the two unequal flash units without a flash meter 
will be a bit problematic but not insurmountable.  Start by setting the 
main light exposure for, say, f/5.6.  Leave the fill flash off and 
adjust power output and/or distance on the flash until you get a nice 
histogram without any flashies on that white card.  Now turn the main 
light off and work with just the fill.  Find a proper power level and 
distance such that the fill flash is making a good histogram with no 
flashies when the aperture is about f/4.5 - f/5.0  (you're really 
looking for about 1/2 stop differential but the camera doesn't have 1/2 
stops).  The greater the differential the more dramatic the shadows. 
Less for children and women and more for men.  Then turn on both flash 
units and adjust the aperture upwards from f/5.6 to account for greater 
total light.  Adjust the aperture until you get another good histogram 
without flashies.

This whole thing can be made easier and with more freedom to place the 
camera if you remove the fill flash from the camera and put it on its 
own light stand nearby.  Not much higher than the camera but not in 
front of the camera where the lens can pick up flash glare.  The main 
light should be about 45 degrees away from you as seen by the subject 
and about 45 degrees up.  The main light has to simulate the sun which 
is why it should be higher than the fill.
> 
> My clients were actually my wife's parents and they understood that it
> was my first time doing anything like this and they were pleased with
> the results. 40 years ago when they got married, they hired a
> professional photographer but he sent his assistant since he had got
> double booked. Then it snowed (despite it being April) and exposing for
> snow was beyond the assistant so they ended up with no pictures.

Yikes.  Too bad.  The exposure error for the snow using a meter would 
only have been about one stop which should have been within the dynamic 
range of the negative film that was probably being used.  Maybe the 
assistant overcompensated in the wrong direction.  Now, here is where 
you might need to turn on program mode.  It might not be perfect but 
it's probably close.

> 
> While I have the attention of Dr. Flash, could you spare a minute to
> offer advice on another situation?

> 
> I like taking candid shots at parties, so I'm often working with not
> much light. So for Christmas I was allowed to treat myself to the Can*n
> 24-70 f2.8 - I was given special dispensation to use it on exactly 2
> specific occasions before it got wrapped and then not opened until the
> 25th. The first occasion was my son's nativity show and the second was
> my daughter's nativity show.
> 
> The two shows were quite different in many ways, but I was quite
> disappointed with the results in both cases. I am quite sure the blame
> lies with me and not my equipment.

I think you're being a bit harsh on yourself.  I think most of these 
shots are pretty good.  And don't feel bad about not shooting in raw.  I 
*always* shoot raw too... except when I forget.  And there has been some 
notable forgetfulness.

None of the stuff I see here is awful from a color balance perspective 
and I'm quite sure there's plenty of room to fix it up in the JPEGs if 
you want to do that.  You might follow Moose's advice to convert to 16 
bit before messing with the color but I'm sure it will be fine.

For your 8-10 meter shots I think you did well.  That's a long distance 
even for the 580EX with flash head zoomed for 70mm coverage.   My 
reference table tells me the guide nubmer for a 580EX at 70mm coverage 
is 50 meters.  Therefore at 10 meters and ISO 100 you'd have needed to 
shoot at f/5 for the flash or f/7.3 at ISO 200 of f/10 at ISO 400.  I 
think I'd have taken the exposure at f/10 and ISO 400 and then used a 
longish shutter speed (like 1/15 sec) to allow the ambient light to fill 
in the area outside the flash range.

You didn't mention what ISO rating you used on these shots.  Perhaps you 
could have just cranked the ISO up to 400 or 800 and dispensed with the 
flash.
> 
> The first (http://photo.whizzkid.co.uk/KGS/SleepyShepherd2006/) I was
> sat on the front row, nice and close and I experimented with and without
> flash. The disappointment here was the white balance was way off when I
> didn't use flash. I haven't experimented using anything other than auto
> WB yet. This disappointment was further compounded when I got home and
> realized that I hadn't been shooting raw (I always shoot raw). It was a
> strange light - it was in a gym which had florescent lights and also had
> translucent yellow panels in the ceiling which obviously coloured the
> daylight coming in. The white balance for the flash shots wasn't great
> either. I was just using the built-in flash for a bit of fill - the kids
> are only 3 or 4 years old and I thought the DSLR was probably
> intimidating enough without adding a 580EX and a pocket bouncer.
> 
> For my daughter's show
> (http://photo.whizzkid.co.uk/KGS/HoityToityAngel/) I was around 8-10m
> away a sat much higher. The room was quite brightly lit with artificial
> light, but not bright enough to not need flash. None of the pictures
> were at all sharp - the ones in the gallery have really been over done
> with USM. So I am now wondering how I got it so badly wrong. I have come
> up with a couple of reasons:
> 1) Not keeping the camera steady - Camera + grip + 24-70 + 580EX is
> quite weighty and I'm not used to such a heavy lens yet. I couldn't have
> used a tripod if I had wanted to, but I am now going to buy a monopod.
> 2) Ratio of flash to ambient - maybe I should have used a smaller
> aperture to force higher flash output? Would this have reduced motion
> blur I can see in some of the shots? Would it have made the camera shake
> less evident?
> 
> Any advice or comments gratefully received.
> 
> Thanks,
> 
> Mike.
> 
> Chuck Norcutt wrote:
> 
>>Hi, Mike.
>>I checked your gallery and liked it.  You've got a couple really great 
>>shots of the kids.  Presumably the parents are happy.
>>
>>But Dr. Flash can't help but offer some advice on the formals for the 
>>wedding shots.  It may be that where you were at simply didn't afford 
>>the luxury of more room.  But I believe you'd get better results with 
>>your subjects further from the backdrop.  At least 4 feet and maybe a 
>>bit more if you've got the space.  I'd also suggest a more neutral 
>>backdrop (like a gray or soft brown) when you have to take lot of shots 
>>with people who are going to be in clothing with an unknown but 
>>guaranteed mix of colors.
>>
>>Now to exposure and lighting.  I don't know what you're using for lights 
>>but I see the camera is set to program mode and that the exposures vary 
>>quite a bit from shot to shot.  The program mode may be partially 
>>responsible for that but I have a sneaky suspicion that you're using 
>>battery powered flash and you may be outrunning the recycle time; ie, 
>>the flash wasn't fully charged when you fired the shutter.  If that's 
>>not the case then the program mode on the 350D doesn't work as well as I 
>>would have guessed.
>>
>>Whether it does or not I would recommend that you abandon the program 
>>mode and (at least for the formals where things are slower and more 
>>under control) use manual mode only.  Ideally you'd have a flash meter 
>>but a real cheap substitute can be had in the form or a white card or a 
>>collapsible reflector or even a piece of A4 size paper.  Have someone 
>>hold it at chest level in the position where your subjects will be 
>>relative to the background and make a few test shots.  Adjust the 
>>exposure with the aperture until you get a good histogram and you don't 
>>get any over exposure "flashies" on the white card in the picture.  If 
>>you have to go smaller than f/8 or larger than f/5.6 then adjust the ISO 
>>or move the flash units or adjust their power level.  That's to keep 
>>within a reaonable range for depth of field without sharply imaging the 
>>backdrop.  With a 350D maybe even f/4 is OK due to the small sensor.  A 
>>little experimentation with a willing subject should answer all your 
>>questions.  Once you get the exposure set there will be no further need 
>>to worry about it for that setup and all your shots will be perfectly 
>>exposed... assuming you don't outrun the recycle time on the flashes. 
>>Just keep in mind also that the spec sheet for recycle time is likely a 
>>big lie.  Give it at least 50% more time than it says.
>>
>>Chuck Norcutt
>>
>>
>>  
> 
> 
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