Exposure Lock

[Primal Eye]

Hey guys

I'm new to this so I may well be miles off the correct technique, but I was hoping for some advice.

I was trying to take a portrait shot last night at dusk. The sky behind the subject was incredible, and I wanted that exposed correctly. I aslo knew that I'd have to use my flash to light the subject.

I turned off the flash, pointed the the lens at the sky, depressed the shutter button half way down to take an exposure reading from the sky, then recomposed the shot on the subject, and turned the flash on. Now here's my question: since the subject is alot closer to me than the sky should I have manually focused on the subject once more? Or is there a way to keep exposure lock active while refocusing on a subject that's closer, or further away than the area/item you have obtained your exposure lock from?

Does that even make sense? :eek: Really enjoying playing with the exposure lock, makes for some really interesting shots - just not sure I fully understand what I'm doing to be honest.

I have a Canon 50D

Thanks

[swifty]

You should have a dedicated exposure lock button, something like a AE-L button.
Use that instead of the shutter half press.
On Nikon models, half press usually only lock focus, not exposure but u may be able to configure it to lock both on your model. Check whether a half press locks both focus and exposure or just focus.

But yea, you can AE-L background, recompose and AF lock subject with half press and take shot with flash.
Or even simpler, go into manual mode. Adjust exposure for background only.
Once you have it, you don't need to touch the exposure setting too much (sunset light changes quickly though). Turn on your flash and set to ttl, focus on your subject as normal and your flash with light your subject correctly. Use flash compensation to adjust how much you want your subject lit.

[Wayne]

Some Nikon bodies have an AF-L / AE-L combined button. It's default operation is to lock both focus and metering, but it can be programmed to lock just one or the other.

You could use it in the default mode, by;
Place focus mode in single servo and focus on subject > now compose to meter the sky (don't touch shutter button, so do it straight away before meters turn off) and while pointing at the sky, press and hold the AE-L / AF-L button > compose back to your subject ensuring your focus point falls on exactly same place as it did when you originally acquired focus, otherwise use manual focus (assumes AF-S lens for Nikon) to tweak it, then shoot away.

My bodies (D3s & D800) have dedicated AF-ON buttons and I use them for focus, I have set the AE-L / AF-L button to lock meter only with a single press (no need to hold down - it resets after meters turn off or you fire camera) and can simply;

Meter background>Press AE-L / AF-L button>compose and press AF-ON to focus then shoot.

There are also function buttons on my bodies which can be programmed, and I know some who choose to use one of them for locking the meter only.

[William W]

I’d have used MANUAL Camera Mode.

I would have made a Meter Reading of the Sky – and used FLASH EXPOSURE COMP for the FLASH as FILL.

I would not have used Exposure Lock.

To use Exposure Lock, it means one MUST be using an Automatic Camera Mode, such as: Av, Tv, P - and in those CAMERA MODES, one does not have (as easily) the full control over the Flash Fill: and in some situations one cannot have full control over the Flash as Fill.


***


Also you are confusing "focusing on" (i.e. using Auto Focus) with making a Light Meter Reading by using the Half Depress Shutter Release position.

You can separate these two functions by using “Back Button Focus” – i.e. setting the AF to the <AF-ON> button.
The method of achieving this is in “CUSTOM FUNCTIONS” in your user manual –
It is C.Fn IV-1, for a 50D.
Selection 3 would be good to meter and lock, for the purpose of the shot you described.

But as already mentioned, I wouldn’t do that for the shot you described: because I would be using Manual Camera Mode.








WW

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Canon User Manuals are sometimes “ho-hum” have a read of this:
http://www.learn.usa.canon.com/resources/articles/2011/backbutton_af_article.shtml

WW

[norwest]

As William says. Manually meter the background, recompose and focus without touching the manual settings and use fill flash with flash exposure compensation according to need. If needed take as many shots as necessary to get the fill flash level you require.

[Primal Eye]

Thanks guys

Some great advice, much appreciated - even if i don't understand it all fully :o .

I'll have a go and see if I can use the manual mode.

[William W]

i don't understand it all fully

What?

WW

[MarkChap]

Primal, yes the 50D has an exposure lock button.
You have 3 buttons on the back, top right, near your thumb, from the right -
Button 1 - Focus Point Selection
Button 2 - Exposure Lock (symbolised with a star)
Button 3 - Af- On

So in your situation, provided you were shooting in Av, Tv, or P (won't work if green box auto), yes point at the sky -> depress the shutter button half way, this will both set the meter and auto focus, then whilst still point at the sky depress the middle button on the back top right, turn your flash back on, recompose your shot and depress the shutter button halfway to re-focus and then take your shot.

In Av mode the canon system expects that you are using the flash as fill and will get your exposure pretty right for you.

As mentioned, there are better different ways (shooting modes) to do the same thing.

The advice by others above will work, but if being so pedantic as to say that you should have used manual, then you also should have had the flash off camera, and that is a whole new world of confusion for you.
Your theory is correct, and with the use of exposure lock you will get some pleasing shots

[ricktas]

What?

WW

Remember you are dealing with a BEGINNER here.

[norwest]

The advice by others above will work, but if being so pedantic as to say that you should have used manual, then you also should have had the flash off camera, and that is a whole new world of confusion for you.
Your theory is correct, and with the use of exposure lock you will get some pleasing shots

I can't see anyone saying he should have used anything, Mark, only "I'd have used manual mode". Personally and the reason I agreed with William, most certainly not for the purpose of an idealistic pedant regarding the manual operation of a camera but in my opinion, a simple and accurate method of achieving the particular exposure of both the sky and subject wanted by Primal.

[fess67]

Hi Primal,

Another thing that may be worth mentioning, turn your speedlight to high speed sync setting. That way you will be able to use shutter speeds above 1/200 with the flash. That will help to get the background sky well exposed, and not overexposed, while still allowing the flash to be used.

[William W]

Remember you are dealing with a BEGINNER here.

I was specifically remembering that this is a BEGINNER'S Forum.

The OP stated that not everything was understood.
I asked "what (was not understood?)” – so that I (and others) might have a better opportunity to explain those particular areas in depth.

My question: "What?" - pertains specifically to the quote of the OP's which I referenced and that’s why I referenced that particular quote.

It occurs to me that you have misinterpretted the meaning of the question, beacuse of the brevity of the response.

WW

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I can't see anyone saying he should have used anything, Mark, only "I'd have used manual mode".

Yes.

And that's exactly why it was written that way - because I would have used Manual Mode and I was offering that as another option to the OP to doi the job as described.

Note the question of how to use Exposure Lock was answered in detail, also . . . without having to turn the Flash On and Off. :)


WW

- - - Updated - - -



turn your speedlight to high speed sync setting. That way you will be able to use shutter speeds above 1/200 with the flash. That will help to get the background sky well exposed, and not overexposed, while still allowing the flash to be used.

If you use HSS, you'll need to watch out for WD (Working Distance - how far the Flash is located, away from the Subject).

In simple terms, usning HSS robs the Flash of Effective Power and LESSENS the MAXIMUM working distance from the Subject.

So it is a balance - using HSS means you can use fast Shutter Speeds, but the Flash might have to be located closer to the Subject.

WW

[dodgyexposure]

If OP is truly a beginner, then using fill flash in Av, and evaluative metering will probably obtain a usable result, because the camera is likely to predominantly meter for the background anyway.