Using fill-in flash ?

Shimmyhill · 18 Apr 2006 at 16:13

Right this could potentially be a newbie question of the highest rate !

Im about to get a 550ex flash for the ol 300D and have been messing around with the onboard flash. Trying to take pics of the ickle one on her bike - its overcast here but quite bright so i just wanted some fill-in flash mainly for catch lights.

However all im getting is blown exposures, trying to use in AV mode - in manual i can get better results but what am i doing wrong in av mode ??

Im certain i should know what im doing wrong and i know its the exposure time but i dont understand why AV mode isnt compensating for the flash - i assume im overlooking something obvious !!!

SDK^ · 18 Apr 2006 at 18:12

Only think I can think of is - check you have the Flash unit set to ETTL mode.
Like you said - in Av mode the camera does adjust the flash for the scene but it won't adjust the shutter speed .

MajorPart · 18 Apr 2006 at 18:20

Can't remember the set up of the 300D but have you tried just using the centre AF point and centreweighted average metering or even better Partial metering..?

Reading your post again i'm not sure if your saying the background is over exposing or it's the wee un that is overexposed?

Sleepyd · 18 Apr 2006 at 19:20

To get effective fill in flash you have to add in some exposure compensation - minus 1 or 2 stops works well if you're close to your subject. Unfortunately the 300D doesnt let you set the flash exposure compensation via the camera interface but you can download utilities that enable you to set it via your computer.

Hope that helps.

Shimmyhill · 18 Apr 2006 at 19:39

I have the wasia firmware so i can use FEC and i did drop it by 2.

morgan · 18 Apr 2006 at 20:40

riiiiggghttt...

first of all - definately not a noob question. fill flash is very complex indeed and there isnt a right or a wrong way. I've found that most guides on the internet are either far too complicated or dont give the basic settings or details.

The variables you have:

FEC on the flash
Metering mode on the camera
Mode setting on the camera
Flash mode on Flash (high speed sync)

I played around last week after looking at a few guides and it takes a great deal of experimentation.

All I can tell you is the settings that worked for me:

First of all you have a setting on your camera, probably under custom functions, of high speed sync speed. The option will be 1/200 or auto - ensure this is set to auto. If this is set to 1/200 it will set the shutter speed to always be 1/200.

Heres my settings (and I'm not saying this is the best way, I'm just saying it works) - on 580EX and 5D

Av Mode
Evaluative Metering
Set Flash Exposure Compensation on the flash to -1 1/3

Keep an eye on the shutter speed. If 1/200 (fastest regular sync speed the flash can hanle in normal mode) flashes in the viewfinder you either need to:

a) stop down the aperature to get a shutter of less than 1/200 (otherwise you will get a totally overexposed shot.
b) Set your flash to HSS (High speed sync mode). This will allow fast shutter speeds, but will reduce the effective range of the flash.

Before anyone says 'read the flash manual' - it is totally useless.

Have a look at these documents:

This is a great guide to FEC settings/questions on fill flash (this is where the magic -1 1/3 came from!)

Have a look here for interesting techniques:

http://www.dg28.com/technique.html

if anyone else on here has any advice i'd love to hear it...its a very tricky subject that I am desperate to master!

AndyBorzi · 18 Apr 2006 at 20:51

morgan said:
Have a look at these documents:

This is a great guide to FEC settings/questions on fill flash (this is where the magic -1 1/3 came from!)

Great document this...i've seen it before and used it many a time as a crib sheet

SDK^ · 18 Apr 2006 at 21:05

You might already have this link but it covers pretty much all you need to knw

http://photonotes.org/articles/eos-flash/

morgan · 18 Apr 2006 at 21:45

SDK^ said:
You might already have this link but it covers pretty much all you need to knw

http://photonotes.org/articles/eos-flash/

it is a very comprehensive guide, but finding the relevant parts in the document is pretty hard work.

Shimmyhill · 18 Apr 2006 at 22:07

morgan said:
First of all you have a setting on your camera, probably under custom functions, of high speed sync speed. The option will be 1/200 or auto - ensure this is set to auto. If this is set to 1/200 it will set the shutter speed to always be 1/200.

Right this bit is mega helpful, i do have the setting under custom and it was set to auto. However it was always at 1/200 - and thus blown out images.

Now i assume that as i wanted f2.8 the onboard flash can not do it, will pick up the 550ex tomms and have another play.

Thanks to all who have replied its all brilliant info

Shimmyhill · 18 Apr 2006 at 22:14

Also just realised that i made idiots mistake number 1 - yes i had left the camera on iso 400 - no wonder it wouldnt work properly.

Im learning lots but i feel a little better now i realise i made a stupid mistake !!

Reading time ready for play time tomms.

morgan · 19 Apr 2006 at 08:59

you can use flash with high isos...thats not a problem. the flash will compensate for that too...

if you want a large aperature, giving you a shutter speed of greater than 1/200 ensure you set your flash to high sync speed mode.

Another good thing to do once you have finished playing in Av mode, is to put the camera in manual mode and try the same.

Theres a technique of metering off just the background (partial metering I belive) and using the FEC on the flash to dictate the fill in for the foreground. You can also use FEC lock '*' which will do a preflash and work out the metering of the whole scene.

This subject really is a minefield and it needs a whole day of experimenting to get it right. Maybe set up a test scene outside and have a play. A good test is keeping a sky correctly exposed against a flash lit subject...its not easy!

yak.h'cir · 19 Apr 2006 at 19:00

I've been playing with this recently. Practise is the key most certainly. At the moment i'm taking a few practice shots and quickly reviewing and then adjusting to get the right results.

Had some sucess in the end:

Gonna look up this pre flash thing, i knew it existed but never really new exactly what it did or how to make best use of it. Might dig the manual out!

morgan · 19 Apr 2006 at 22:15

^^very nicely done...do you remember the settings/method you used?

yak.h'cir · 20 Apr 2006 at 00:37

morgan said:
^^very nicely done...do you remember the settings/method you used?

Cheers!

I'd taken several pictures already and had been adjusting the settings according to the results I was getting. I was going for a nice obvious flash fill in with dark sky so i left the flash on 0ev compensation a just used auto settings, which was actually far better then any of my manual efforts (hopefully that will change eventually).

I took an exposure off the background and reduced by 2/3ev stops to get a darker sky, giving a shutter speed of 200, iso 200, apeture F8 at 22mm on my 10-22mm EFS. Didnt actually need much processing, I just gave it a very slight s curve and raised contrast a little.

The flash I use is the Sigma EF 500 DG Super which is quite similar in features to yours. Only problem I have is the flash can be quite slow to cycle. Which really gets on my nerves!

Shimmyhill · 22 Apr 2006 at 16:49

Right i have the 550EX now and its awesome, how did i live without it ??

However, im still having issued with fill in flash in sunlight @ F2.8 - as soon as im in AV mode and select F2.8 and prefocus i get the flashing 200 on the screen. I have high speed sync set to auto in the custom menu. If i move to f4 its fine but anything lower and its flashy 200 on the screen.

Is this a limitation of the 300d ? or am i still doing something wrong ?

Shimmyhill · 22 Apr 2006 at 16:56

Maybe ive found the answer !

If im using f2.8 and its sunny do i need to set the flash to high speed sync, im thinking i do now.

(cant try as im downloading images via usb 1 - i think it will be done sometime next tuesday

)

SDK^ · 22 Apr 2006 at 17:00

The max flash sync on the 300D is 1/200.
Use High speed Sync on the 550EX to enable a faster shutter speed.

:: EDIT ::
^^ You answered your own question

Gojira · 22 Apr 2006 at 17:03

Shimmyhill said:
Right i have the 550EX now and its awesome, how did i live without it ??

However, im still having issued with fill in flash in sunlight @ F2.8 - as soon as im in AV mode and select F2.8 and prefocus i get the flashing 200 on the screen. I have high speed sync set to auto in the custom menu. If i move to f4 its fine but anything lower and its flashy 200 on the screen.

Is this a limitation of the 300d ? or am i still doing something wrong ?

Daft question - if you set the aperture to f2.8 with the flash OFF, what shutter speed does it set? It may just be too bright for f2.8 and a shutter speed that slow.

<edit> looks like you've solved it while I snuck off for a Coke mid-post

</edit>

Alan Woodford

Shimmyhill · 22 Apr 2006 at 18:34

SDK^ said:
The max flash sync on the 300D is 1/200.
Use High speed Sync on the 550EX to enable a faster shutter speed.

:: EDIT ::
^^ You answered your own question

Gojira said:
Daft question - if you set the aperture to f2.8 with the flash OFF, what shutter speed does it set? It may just be too bright for f2.8 and a shutter speed that slow.

<edit> looks like you've solved it while I snuck off for a Coke mid-post </edit>

Alan Woodford

Cheers guys, i did work it out and it works fine

Lots and lots to learn but its all fun and the results are great.