# metering the sky at Apeture 2.8 and recompose



## hao (Jul 28, 2009)

I have been reading "Understanding Exposures" , which is a good book btw. 
In the book, the author metions a technique for shooting backlight, snow, or sunset. What you do is that you meter the sky to get your aperture and shutter speed first then recompose to get a proper exposure. 

What confuses me is that he likes to meter the sky with an 2.8 aperture, and adjust the shutter speed accordingly. Then it comes to recomposing. A bigger aperture number, say 16, is neededfor landscape, so aperture is adjusted to 16 (5 stops) and the shutter speed needs to be decreased by 5 stops accordinly for the correct exposure. 

My question is: 

Why do we need to meter the sky at aperture 2.8 instead of the aperture we need, 16,at the first place? Does it give a better metering result?
thanks!


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## Tiberius47 (Jul 28, 2009)

I have no idea why he would do this.  You can set your aperture to whatever you want and then adjust your shutter speed to correctly expose for the sky.


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## PhotoXopher (Jul 28, 2009)

He just uses the sky to meter the light, aperture has nothing to do with it other than coincidence that he's shooting wide open with his 35-70 a lot in that book.


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## Josh66 (Jul 28, 2009)

N0YZE said:


> He just uses the sky to meter the light, aperture has nothing to do with it other than coincidence that he's shooting wide open with his 35-70 a lot in that book.



Yeah, but he's metering, then adjusting his settings (that he just got done setting) by 5 stops!

I think I would just meter in whatever aperture you plan on taking the picture at...  Less to remember that way.  "Now, how many stops did I change the aperture...?  Oh, crap - what did it say the shutter speed was before I started changing everything...?"


I'm sure he has a reason for doing it his way, but I have no clue what it could be.


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## Josh66 (Jul 28, 2009)

The ONLY time I do something like what he's doing is if I'm going to have to go into Bulb.

Let's say I want a picture of an old barn in the middle of the night...  (That I _still_ haven't made it back to, BTW...)

You can't really meter past 30 seconds, so you have to do a little math in your head to figure out what it needs to be.

Let's say f/1.4 is 2 stops underexposed at 30 seconds.  That means you need an exposure of 120 seconds (30*2*2).  But - what if you don't want to shoot at f/1.4?

Let's say you want to shoot at f/8.  That's another 5 stops.  120*2=240*2=480*2=960*2=1920*2=3840.

Get your watch ready, because that's 64 minutes.

OK, so you don't want to sit there that long...  f/4 (2 stops less) sounds more reasonable.  That would be 16 minutes (960 seconds).  You could drop down to f/2.8 and only sit there for 8 minutes too.


Anyway...  I think it's important to know how to figure it out - but don't make it harder than it has to be.


edit
(Maybe that's why he says to do it that way in his book - so you'll know how when you need to.)


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## Big (Jul 28, 2009)

I actually saw a guy do this one day. I was taking a walk on the coast and he was photographing a girl at the ocean and I noticed he kept pointing it up at the sky and then back to her.


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## PhotoXopher (Jul 28, 2009)

That'll be the next big feature - exposure preview


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## Dao (Jul 28, 2009)

Here is the reason why Bryan Peter do that in the cityscape type shot.

He metered the sky. Then change to F/11 and 10s shutter speed based on the metering.


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## bhop (Jul 29, 2009)

Dao said:


> Here is the reason why Bryan Peter do that in the cityscape type shot.
> 
> He metered the sky. Then change to F/11 and 10s shutter speed based on the metering.
> ...



Actually, in the video he mentioned that since the subjects were far away, f/stop didn't matter, so he chooses f/8 or f/11, then adjusts his shutter speed (in this case 10 sec), he never actually said *why* he was metering the sky.

As a side note.. fancy hairstyle he's got.


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## Garbz (Jul 29, 2009)

N0YZE said:


> That'll be the next big feature - exposure preview



Ha sucker. My D200 has this feature already. I click the shutter button and on the screen comes an exposed preview.


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## musicaleCA (Jul 29, 2009)

Considering it's a cityscape, metering off anything else is kinda useless. If you meter the buildings, you might get a reading that turns the lights to neutral, except that's not what you want at all. He's just deciding that the sky should be in the middle of the dynamic range of the image. If you think about it, the why becomes clear.


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## KmH (Jul 29, 2009)

bhop said:


> Dao said:
> 
> 
> > Here is the reason why Bryan Peter do that in the cityscape type shot.
> ...


But, everyone here understands *why* he metered the sky, right?

The exercise with calculating a change in stops the OP mentiones was just to show the relationship of aperture to shutter speed. To maintain the same exposure, if you change one, you have to change the other an equal amount.


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## musicaleCA (Jul 30, 2009)

KmH said:


> bhop said:
> 
> 
> > Dao said:
> ...



I wonder: does anyone else just count the number of notches you travel on the dial, and then go the other way with the other setting, ignoring calculating stops altogether? Works a heck of a lot faster with me (I mean, I guestimate first where my shutter speed or aperture is going to land, and adjust ISO to compensate if either goes somewhere I don't want, but still).


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## Garbz (Jul 30, 2009)

Exactly. I only ever calculate things when i'm sitting here posting on this forum. Every other time it's 3 stops ok that's 9 clicks on the wheel.


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## musicaleCA (Jul 30, 2009)

Garbz said:


> Exactly. I only ever calculate things when i'm sitting here posting on this forum. Every other time it's 3 stops ok that's 9 clicks on the wheel.



Yeah. Or when the exposure is super long, but then it's a piece of cake to keep multiplying by 2.


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## UUilliam (Jul 30, 2009)

Honestly.. i have no idea how to calculate stuff, I just know What Aperture does and i know the basic settings to put it at e.g. sunny sky, f16 with ISO 100 at shutter 1/125 or if im on iso 200 f16 shutter 1/250
and other basics i can roughly guess the needed aperture, I personally use Aperture for DOF more than calculating light (for just now) but reading up on exposure...


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## Dao (Jul 30, 2009)

musicaleCA said:


> Garbz said:
> 
> 
> > Exactly. I only ever calculate things when i'm sitting here posting on this forum. Every other time it's 3 stops ok that's 9 clicks on the wheel.
> ...




Yes, that is what I usually do as well.


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## usayit (Jul 30, 2009)

My two cents

1) Sky (back towards the sun) is often the brightest dominating thing in a subject that can easily throw off simple metering that was common in older film cameras.  The results are similar to a handheld ambient meter in broad daylight.  
2) It doesn't matter what you meter off.  Just as long as you adjust exposure placing the reading in the appropriate place within the dynamic range.  

I do something similar but I meter off palm of my hand pointed up at the sky and adjust 1 stop.  Others have told me that metering the sky (or grey card of course) provides a more consistent readings but old habits die hard.  My camera doesn't have complex metering.. lending itself to metering once-in-a-while.


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## usayit (Jul 30, 2009)

musicaleCA said:


> I wonder: does anyone else just count the number of notches you travel on the dial, and then go the other way with the other setting, ignoring calculating stops altogether? Works a heck of a lot faster with me (I mean, I guestimate first where my shutter speed or aperture is going to land, and adjust ISO to compensate if either goes somewhere I don't want, but still).



Your post reminds me of this discussion we had recently:

http://www.thephotoforum.com/forum/photographic-discussions/170672-aperture-rings-gone-good.html

It is exactly why I miss aperture rings on lenses... Left hand == aperture, Right hand == shutter.


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## PhotoXopher (Jul 30, 2009)

usayit said:


> musicaleCA said:
> 
> 
> > It is exactly why I miss aperture rings on lenses... Left hand == aperture, Right hand == shutter.
> ...


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## Sn00bies (Jul 30, 2009)

I didn't quite hear an explanation from the video guy of how metering the sky creates an evenly exposed image.  I'm just at the beginning of studying light and metering, but doesn't this idea only work when your sky/foreground are of similar brightness?  Otherwise, if you metered for the sky and took your composed shot, wouldn't the foreground be underexposed?

I was out taking some photos of wheat fields being harvested, and the only thing I could think to do was to point down and meter the foreground so I get that correctly exposed, hold AE-L, compose my shot by including more of the sky, take the shot (metered for foreground, sky blown out), and then after taking that shot, letting go of AE-L to quickly re-meter for the sky(which was already in the position to be metered) and take another shot.  Then I end up with a shot metered for foreground, and a shot metered for the sky, and I would have to blend the two in PS.  

Am I missing something major here?


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## KmH (Jul 30, 2009)

Was it after sunset like in the video?


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## Sn00bies (Jul 30, 2009)

KmH said:


> Was it after sunset like in the video?



Yeah, but now that you mention it, I only waited until just as soon as the sun fully vanished behind the ridge rather than 10-20 minutes after the sun disappeared.  

So is that his main point, that typically from 20-26 minutes after sundown the light will be perfect so you can meter from the sky and have a balanced sky/foreground?


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## musicaleCA (Jul 30, 2009)

Sn00bies said:


> So is that his main point, that typically from 20-26 minutes after sundown the light will be perfect so you can meter from the sky and have a balanced sky/foreground?



Yup. That's his point. That and it has nice pwetty colours.


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## KmH (Jul 30, 2009)

Sn00bies said:


> KmH said:
> 
> 
> > Was it after sunset like in the video?
> ...


In photography, the devil is in the details.

The difference between a pro shooter and an amateur shooter is the pro monitors 20 details per image the amateur never considers.


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## musicaleCA (Jul 30, 2009)

And size of their trash bin.


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## usayit (Jul 30, 2009)

N0YZE said:


> Left hand, zoom/focus
> Right hand, aperture/shutter



More like

Left hand zoom in AF
and
Right hand aperture in Av
or
Right hand shutter in Tv


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## JerryPH (Jul 30, 2009)

Nikon users:
Left hand zoom
Right thumb shutter
Right 2nd finger aperture
Right 1st finger shutter button

Right eye glued to the eye piece and the stars align... lol


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## Big (Jul 30, 2009)

The guy in that video could have a sick mullet if he trimmed off the sides...


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## Josh66 (Jul 30, 2009)

usayit said:


> N0YZE said:
> 
> 
> > Left hand, zoom/focus
> ...





JerryPH said:


> Nikon users:
> Left hand zoom
> Right thumb shutter
> Right 2nd finger aperture
> ...



OR...

Left hand, hold the camera.
Right hand, everything else.

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I don't use very many zooms, so "zoom" is rarely an option for me (with my hands anyway).

When I use manual focus (rarely), I would do that with the left hand.


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## KmH (Jul 30, 2009)

* 
"The guy in that video could have a sick mullet if he trimmed off the sides..."
* 

As many millions as he's made off photography, I don't think he really cares.

You should see his villa in Tuscany.

You know that book every photographer recommends to newbies _*"Understanding Exposure"*_? The guy in the video wrote it: Bryan Peterson.


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## musicaleCA (Jul 30, 2009)

Millions? Yeesh.


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## Garbz (Jul 31, 2009)

N0YZE said:


> usayit said:
> 
> 
> > musicaleCA said:
> ...


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## usayit (Jul 31, 2009)

O|||||||O said:


> Right hand, everything else.



eeeeewww... way too much info....   Way Too Much Info.... 

:Joker:


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