photography questions & answers
Continuing with the monthly theme where I look at search engine queries,
and answer a selection of 10 questions more directly…
01) why two flashes with rear curtain sync?
TTL flash exposure is calculated with a pre-flash signal that the flashgun emits before the main burst of light. The main burst of light is what gives you (hopefully) correct exposure. But the camera needs some way of determining what that correct exposure should be. In order to do that, the camera measures the amount of light returned from that pre-flash. Looking at this diagram of the sequence of events when your shutter opens and your flash fires, you will see the pre-flash there:
Now, if you set your camera to first curtain sync, then the pre-flash and main burst are so close together, that you can’t distinguish these as two discrete bursts of light. It looks like one blitz. Now, if you go to rear-curtain sync, and set a slower shutter speed … then there is a discrete time interval between when the pre-flash is emitted, and the main burst is emitted. You will see this pre-flash then as distinctly separate pulse of light.
You can test this for yourself by setting your camera to any aperture (but let’s say f4), and any ISO (but let’s go to 800 ISO just for this exercise) .. and set a 1 second shutter speed.
Set your camera to first curtain sync, and fire your shutter. You will see one burst of light. But when you now set your camera to rear curtain sync, you will see two separate blasts of light.
02) benefits of 1/500 flash sync speed
A higher flash sync speed is a real boost when working in bright ambient light. The higher shutter speed implies a wider aperture, and hence more range on your flash.
An alternate way to look at it, is that in bright light, you have a better chance of over-powering the sun with a higher flash sync speed. The higher flash sync speed cuts more of the ambient light for the same aperture.
03) how can I take photos at a slow shutter speed and not over-expose?
The problem experienced here is that the photographer asking this question, most likely did not keep an eye on his camera’s built-in meter. Whatever shutter speed you choose, the combination of aperture / ISO / shutter speed needs to be such that you’re not over-exposing the ambient light.
04) stopping zoom lens from changing aperture
If you’re using a variable aperture zoom, and you find the change in aperture annoying, then don’t set your flash to the maximum aperture for the widest zoom setting. In other words, if you are using an f3.5 – f5.6 zoom, then use f5.6 as your maximum aperture. Or use a smaller aperture. Now if you zoom, your aperture won’t change on your. This is of course assuming a modern camera. On older cameras with a mechanical link between the lens and the camera, the aperture would change regardless.
05) will my exposure settings change if I move my position?
It depends on how you are moving in relation to the light. If you are moving towards or away from your subject, then your settings will remain the same. If you are moving around your subject, then your exposure settings will need to change. (This is of course assuming a single directional light source.)
The essential difference of course is that with E-TTL / TTL flash, the camera is calculating your flash exposure. With manual flash, YOU are the one calculating the flash exposure. This of course implies a whole bunch of other things, and this is where flash photography becomes
07) Canon service and repair
For any Canon repairs (in the USA), Toshio is the man!
Contact him at: (732) 238-8806
Toshio; TF Camera Repair; 27 Brunswick Woods Dr; East Brunswick, NJ
08) Chinese UV filters any good?
A cheap filter is never a good idea. While I seem to be the lone proponent of the idea that using a filter is sometimes a good thing, I would agree that using a cheap filter is always a bad idea. Stick with the known name brands. And if you’re looking at a filter that seems horribly over-priced, then you’re probably looking at the kind of filter you should be using instead.
09) tutorial for pop-up flash photography
Here’s my complete tutorial: I have good news for you – you’re going shopping!
the final one for today:
Oh dear. No. Just a no. It’s not negotiable. If all you have is a pop-up flash, then wedding photography isn’t in your immediate future. If you decide it is, I believe that Judge Judy will also be in your immediate future.
Just like this person who is considering something very dangerous:
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!