Macro + random Qs

[Innocence]

Hello,

I've started playing with a macro lens, and I'm wondering

1/ What the effective fstop means? Why is it there?
2/ How to calculate EV number? Say ISO 100 and f/2.8 1sec = EV # ?
3/ Is there something a ring flash can do that a normal sit on top of my camera (or even on board) flash can't?
4/ Can I use a non ring flash for macro photography?

Cheers! =)

 

[Big Mike]

3/ Is there something a ring flash can do that a normal sit on top of my camera (or even on board) flash can't?

A ring flash sits on the end of the lens so that it can evenly illuminate a small subject. If you tried to light up a small subject that is only a few inches in front of the lens...the lens might be in the way, the flash won't point in that direction and it would be very directional light, rather than even light.

4/ Can I use a non ring flash for macro photography?

You can try...it would be best if you could move the flash off of the camera.

 

[el_shorty]

1/ What the effective fstop means? Why is it there?

a quick goggle search gave this.

When you use macro lenses in the close-focusing range, the barrel extends considerably. This is like having variable built-in extension tubes in the lens, to enable you to focus close. And like extension tubes, there is light loss when the lens is extended.
For example, I am using my 105mm f/2.8 Micro. The aperture is set to f/2.8, and I extend it to closest focusing distance to achieve 1:1 magnification. Although the aperture ring reads f/2.8, because of the long extension, there is light loss of around 2-stops. So my effective aperture is only f/5.6. If you're using a camera with TTL meter, the camera automatically takes into account this light loss, and compensates accordingly.
If you're using a hand-held meter, beware of this light loss. You must add the light loss into your calculations when you set the aperture or shutter. For example, you know that there is a one-stop light loss at a certain magnification ratio. So if the hand-held light meter recommends 1/60 sec at f/8, you should add in one-stop worth of light (eg. exposing at 1/30th sec at f/8).

4/ Can I use a non ring flash for macro photography?

Yes you can, and I do it a lot, but like what Big Mike said, you get better results with having your flash off camera, here you can see photos of frogs i took a few months ago, I used flash on all of them.