ND Filters - Can I get some info on them?

Hey guys, I've got a question on ND filters, but first, let me tell you how I'm and why I'm going to use them.

I don't shoot landscapes, or at least don't intend to always shoot landscapes with the ND filter. I shoot portraits with off camera flash, strobist style.

The thing is, on a bright and sunny day, I can never ever get as low as 1/200 ISO100 while shooting wide apertures. I'll always get something like 1/400 while shooting f/2, and this means that the flash will only be present in the upper half of the image, sometimes even less.

When shooting off camera flash, I always aim to underexapose the bg by at least 2 stops and use flash to light my subject properly. Can't do this in the day with fairly small apertures (f/5.6) and definitely not at f/2.

So anyway, I know an ND filter will solve the problem. My question is, how many stops of ND filter should I get, and will I be able to retain AF on them?

Oh, I know there are Singh Ray VariND filters, but I can't afford them Cheap 58mm to 77mm ND filters are under SG$50 over here.

Cheers,
Zexun

EDIT: And I know this thread is about ND filters, but are CPL filters supposed to give a slight colored hue to your pictures? I don't know if it's WB, but I personally feel that when shooting on a green field with trees, my Hoya cpl makes everything slightly cool.

Just as an aside as you haven't mentioned it... You know there's a high speed sync mode on your 580EX II that allows you to use whatever shutter speed you like? You need to trigger the 580 using Canon's own system, though, so an off-shoe cord ($10 modification to make it take Cat5 extension cables, dead easy), ST-E2, 580EX etc.

There are some tradeoffs such as reduced range and whatnot but for close range work it can work well.

No sorry, I'm using the Impact ebay triggers, and I like the range I can get. I never liked Canon's IR system. And I said that I do off-camera flash without any mounted flash!

Thanks for the response, though =)

Cheers,
Zexun

Headshotzx wrote in post #6602253
No sorry, I'm using the Impact ebay triggers, and I like the range I can get. I never liked Canon's IR system. And I said that I do off-camera flash without any mounted flash!

Thanks for the response, though =)

Cheers,
Zexun

Off-camera flash doesn't necessarily mean that you're not shooting with one on - I have one 580 on-camera that does nothing but trigger two off-camera!

Well... I use a 3-stop GND filter and the AF still works when the AF point is covered by the ND section... if you're using it in bright light I reckon you'd be fine. If you were talking one of the much stronger ND filters you might start hitting trouble.

Jim G wrote in post #6602287
Well... I use a 3-stop GND filter and the AF still works when the AF point is covered by the ND section... if you're using it in bright light I reckon you'd be fine. If you were talking one of the much stronger ND filters you might start hitting trouble.

That's great to hear! Thanks for the info =)

Cheers,
Zexun

Just remember that the ND filters will cut the available light from your flash(es) as well.

CPs shouldn't give colour shifts, but remember that they cut reflections and boost saturation so the colours may appear shifted just because you've killed a lot of the scattered light that tones things down.

Jon wrote in post #6602639
Just remember that the ND filters will cut the available light from your flash(es) as well.

CPs shouldn't give colour shifts, but remember that they cut reflections and boost saturation so the colours may appear shifted just because you've killed a lot of the scattered light that tones things down.

Good info. Thanks. Yeah I know ND's are just sunglasses. I rarely shoot above 1/4 power on my 580EXII, I'm sure I could up it some more.

Cheers,
Zexun

If you are always getting something like 1/400 then a 1 stop ND will bring you to 1/200, I think you can try with a 1 stop and 2 stop ND. Buying a set of 1,2,3 stop NDs is going to be cheaper than the Vari-ND. The Vari-NDs also polarize the light so that is not always what you want.

Luigi