reading camera histogram/adjusting exposure

[photo_girl1]

hi guys, this might be an ignorant question, but while on a shoot today - found myself slightly stuck. if this

were to come up again, need to know how to adjust :)

 

had to shoot someone in their home with mostly ambient light and a touch of flash, that i used with a big soft

box. question is, after i took a reading of my available light... and lets say at ISO 400, i got... F1.4,

shutter speed 100. i brought in flash and got a measurement of F2.8 at shutter 100. when i took a test shot of

my assitant, the histogram on my camera showed up shifted to the left.. although there was quite a lot of black

in the image (piano etc).. i felt it was slightly underexposed. in the case that i need to add a bit more

exposure to the shot... do i , add more light from the flash/bring it in closer to subject? OR, slow down my

shutter speed? or ofcourse open up my aperture? i just thought if one is happy with a certain Fstop ... one

wouldnt touch it to add exposure.... say one is after a certain shutter/aperture combination..... how does one

add exposure..? do i adjust my ISO in that case?

 

thanks

[photo_girl1]

am i wrong in also noticing that the "blinking hightlights" addition in the D200 when one views an image on camera's LCD, is no longer there on the D700? i used to be able to see red tones on over-exposed highlights.... i dont see this on my D700...... am i missing something?

[richard_quindry]

Not sure I totally understand what your trying to ask in the first post. As far as the blinking highlight indicator, I don't own

a D700, but can't imagine that they would drop something that is so useful to so many people.

 

I think you can probably set it up in your camera's customization menus.

 

As far as the dark piano - the histogram just shows the relative quantity of each tone in your image. If your subject is

large and has primarily dark tones then your histogram will be very heavy on the right. I look to make sure that the

histogram isn't stacked up on the left side. It should taper off to almost nothing at the left edge. If you can't do that

without losing information on the right side of the histogram, you need to add light (or in the case of a dark shiny piano,

provide something bright for it to reflect.)

 

One of my clients is a piano manufacturer and I have a before and after lighting shot of one on my website if you want to

take a look.

 

Rich Quindry

[ellis_vener_photography]

http://www.ppmag.com/web-exclusives/2007/12/what-is-a-histogram-and-how-do.html

[photo_girl1]

thanks guys , that was helpful.... i tend to find myself just looking at the image on the display of my camera.. rather than the histogram.. and i guess that screen can be very misleading in terms of determining proper exposure... it always tends to look just right on the camera screen, but under-exposed on when i bring it into RAW...

 

so histogram it is :)

[photo_girl1]

so just to make sure i got this right, i adjust exposure by bringing in my flash head closer or further away from my subject, or adding power or bringing down the flast power.... correct? leaving my exposure settings as they are... am i right?

[Charles_Webster]

You can also adjust your exposure with FEC or by changing the lens aperture. Or by bouncing the flash off something like a ceiling.

 

<Chas>

[picturesque]

You're mixing up several things here. Besides reading a histogram correctly (which others have covered well), when you meter flash and use the same shutter speed you use for the exposure, your meter is taking ambient exposure into consideration too. Some meters will show you the percent of flash to ambient in the reading, some don't. When I meter flash, I set the shutter speed on my meter to the fastest--1/500th in my case, to cut out as much of the ambient light from the reading as possible. I want to meter the flash only, and I'll do my own calculation of EV to register the ambient light I want.

 

To add more exposure to your shot, you can do any of the things you mentioned, depending upon how you decide you want the scene to look--what combination of flash and ambient YOU want. In other words, don't follow the meter exactly, because the meter isn't going to read your mind. Use the meter, not the other way around.

[photo_girl1]

nathan thanks for your msg, but when you say to set the shutter speed on the highest possible when i meter my flash in order to cut out ambient light... do i do this in settings where i want ONLY flash effect ..? ie: in the studio etc.? OR, do i also do this when im in an ambient light setting, a nicely lit room, with nice ambient light coming through but where i feel i need a touch of flash to add? im confused.. :(

[henryp]

<i>but when you say to set the shutter speed on the highest possible when i meter my flash in order to cut out ambient light... do i do this in settings where i want ONLY flash effect ..? ie: in the studio etc.? OR, do i also do this when im in an ambient light</i><p>Some meters let you indicate a shutter speed on the meter itself. My Minolta meter for example has a 60/500 switch. When set to 60 (representing 1/60) the meter reading gives me an overall aperture taking into account both flash and ambient light, no matter where I'm shooting and no matter how much or how little ambient light there is. When I set the meter switch to 500 (representing 1/500) the meter's reply indicates flash exposure only. <p>My preference is to meter for flash and for ambient independently so I almost always use the 500 setting. If I intend to make my final exposure with the flash only, I'm all set. If I intend to blend flash and ambient in the final exposure I'll meter them individually and add or subtract one or the other to get the final blend.<p>

--<br>

Henry Posner<br>

<b>B&H Photo-Video</b>

[picturesque]

I agree with what Henry said. I also like to meter the flash and ambient separately and decide for myself what combination of the two I want. So yes, I set the shutter speed on my meter to 1/500th most, if not all, of the time to meter only the flash, even if I want a lot of ambient light recorded in the final exposure.

[brooks short]

You've gotten some helpful information on how to read a histogram and how to use a light meter. Balancing ambient

light with flash is a tricky exposure technique that's well worth learning.

 

One thing that helps is to use a flash meter that measures both ambient and flash at the same time and indicates

what percentage of the total exposure is from the flash.

 

An even better technique, and one you should be doing on any professional commercial/portrait shoot, is to shoot

tethered to a laptop so you can actually see the details of exposure, focus and posing/expressions on a large

computer screen. If you can see your capture on the laptop, read the density levels, adjust the white balance, zoom

in to check focus, etc. at the time that you're shooting the job, you wouldn't have any of these issues and questions.

 

The screen on your camera is less than adequate for anything other than reading a histogram.

[david_vickers2]

<p>Take a look at the 'Lighting 101' on <a href="http://strobist.blogspot.com/2006/03/lighting-101.html">Strobist</a>.</p>