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photography questions & answers (004)

October 3, 2010

photography questions & answers

I started the initial numbering of this serial topic with three digits. And since I thought of this being a monthly post, it would seem like we’re in for the long haul here if we’re ever going to reach the hundreds. So, continuing with this post where I check recent search engine queries, and answer a selection of 10 questions more directly …

01)  increasing flash will eliminate ambient light

It doesn’t quite work the way as stated there. If you have correct exposure for ambient light, then adding (correctly metered) flash to this, will just over-expose the photograph. To eliminate or reduce the ambient light, you first under-expose your available light to a certain extent, and then add flash to give you correct exposure. Now you can progressively eliminate the ambient light by changing your settings, but keep your flash exposure such that you get correct exposure.

You would change your shutter speed first to reduce the ambient light, but usually not higher than maximum flash sync speed. Then you need to juggle the aperture and ISO settings … and add flash to this. This is the usual technique when your available light is ugly. Think of tungsten lights in the ceiling, directly overhead.

This question then neatly segues into the next question and answer …

02)  what is the higher shutter speed to eliminate ambient light?

It’s not so much the higher shutter speed specifically, but a combination of your settings – aperture, ISO and shutter speed. By the time you under-expose by 5 stops, you’re not going to see much ambient light register. You could therefore eliminate your ambient light by changing to a small aperture and low ISO when you work in light levels that aren’t super bright.

Why 5 stops? Consider that changing your settings by a stop, double or halves the amount of light hitting the sensor (or film). Then, if you consider 18% as the middle tone .. then one stop down is 9% .. another stop down is 4.5% … another stop down is about 2% … another stop down is 1% … and another (the fifth stop down), isn’t much light at all.

03)  why is my bounce flash creating a shadow?

… because you insist on bouncing your flash forward at 45 or 60 degrees, or using a piece of plastic on your speedlight when you’re shooting indoors. More careful consideration of what you want to achieve with your light, is essential here.

04)  recommended aperture within situation

Your choice of aperture is usually dictated by the depth-of-field you need, whether shallow or deep. Anyone who isn’t familiar with depth-of-field and how aperture affects it, needs to stop being so lazy, and get a good basic book on photography and do some homework, such as Bryan Peterson’s book on Understanding Exposure. This stuff is one of the most essential basics in understanding photographic technique.

05)  is there a problem having two catch-lights?

You know what? It doesn’t bother me. I am sure the more classical portraitist will have a conniption at this, but it really doesn’t bother me. I know, heresy!

06)  how do you disable TTL flash?

Well, not so much in the way of disabling TTL flash, but the opposite of TTL (and Auto) flash is manual flash. With TTL flash, the camera and flash controls the flash’s output (with you nudging it either way with Flash Exposure Compensation). With manual flash, the output is constant.

07)  TTL flash is not accurate when photographing darker people

… and I have to add that neither will it be accurate when photographing pale people in light colored clothes. TTL flash, and any other automatic mode of your camera, is dependent on your camera’s metering system … which tries to evaluate the scene & subject as seen through the lens. Therefore the camera (in this case with TTL flash) will be dependent on the tonality of the subject / scene.

Your camera is always trying to expose for the subject / scene as a mid-tone, and whenever the subject / scene is darker than average, your camera will over-expose (trying to expose for the darker subject / scene as if it is a middle tone. You need to interpret your camera’s metering display, and adjust accordingly. My recommendation will always be to shoot in manual metering mode. Then you have control.

08)  why can’t I use aperture priority with flash

Well, you could use aperture priority with flash, if / when:
- you make sure you stay at or below maximum sync speed, or
- you set your camera & flash to high-speed flash sync, and know that your flash output will be considerably reduced when you do go into HSS mode.

One of the cries for help I often see, is a photographer saying they get great available light exposures, but the moment they switch their flash on, they get over-exposed photographs. The reason for this is that they are using Aperture Priority, and getting settings like 1/1000 @ f4 .. but the moment they switch the flash on (without HSS enabled), the camera limits the shutter speed to maximum sync speed .. and they get over-exposure.

09)  bring detail back in bride’s dress with actions

The actual query was about a specific action set. However, the answer remains the same. If you need to show detail in a bride’s dress – and generally you should – then the first place to start with this is in the lighting and positioning of the bride. Fixing blown-out areas is a second option … and for this, you have to work with the RAW file. You absolutely have to shoot in RAW anyway when photographing weddings. (And nearly any other situation I can think of.)

Back to the specific question – if you need to bring detail back in a JPG, then you have clear indication you need to adjust your lighting technique AND shoot in RAW. Always RAW. JPG is not an option if you photograph weddings. Fixing the JPG with an action in Photoshop already means you’re in a dead-end street.

As the final one for today is an oddity again:

what planet was first discovered by photographic methods?

apparently, planet neil!

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Stay informed of new articles via the monthly newsletter.
Also join us on the Tangents forum for further discussions.

If you need more direct help or instruction on flash photography,
I do present workshops & seminars and also offer individual tutoring sessions.

If you find these articles interesting and of value, then you can help by
using these affiliate links to order equipment & other goodies. Thank you!
 

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