Regarding High Speed Synch - Lens Question

SLRdude

I'm still new to all this stuff, and I am VERY new to the world of somewhat fast lenses.

If you are shooting outside and you shoot wide open to get that nice bokeh, how the heck do you use the flash??
Every time I try with the flash on, it says HI and the images are severely over exposed. I tried negative EV compensation etc, you name it.

What's the secret in using fill flash while wide open?

Thanks a million guys!

jforbes

SLRdude wrote:

I'm still new to all this stuff, and I am VERY new to the world of somewhat fast lenses.

If you are shooting outside and you shoot wide open to get that nice bokeh, how the heck do you use the flash??
Every time I try with the flash on, it says HI and the images are severely over exposed. I tried negative EV compensation etc, you name it.

What's the secret in using fill flash while wide open?

Thanks a million guys!

I'm far from a flash guru, but here's what I'd start with:

Set high speed sync on the flash! If you don't have it set, you're limiting yourself to 1/160, 1/250 or so on shutter speed. This could be causing the overexposure. On Canon, you can't even set the shutter speed over that level - so if you're shooting with a flash at large aperture, it's actually very, very easy to overexpose the image, as the camera will refuse to go to a higher shutter speed. This is probably the case with most of the other manufacturers too.

Because you're shooting a really large aperture, that increases the flash exposure - remember that the flash itself is a near instant pulse, so a larger aperture will make the same powered flash shot brighter. If you're not using a TTL flash, this is a likely cause of results like this. Turn the flash power down. Way down! If you can't do that, it may be a problem.


If you're shooting an automatic flash (like the common Vivitars around), I'm not sure what you can do, as the flash does everything on its own, and you have to work around it - I used to have an automatic flash on my old K1000, and it worked by me moving a slider to tell it the aperture I was shooting at... I don't think it went down to F2.8.


What camera/flash setup do you have? They all work differently.

SLRdude

Thanks Jeff!

I am using a Nikon D90 with the SB-900, and the lenses in question are the Nikkor 35mm f/1.8 and Sigma 28-70 f/2.8.

I tried using TTL-BL while photographing some friends, but it was WAY too bright.
Going to negative EV on the flash did not do much good either. Going below 100 on the ISO produced similar results.

Manually lowering the power of the flash did cross my mind, but I did not try that yet.

adbsgicom

Are you not enabling the strobe to run high-speed sync? My Canon seems to not let you go past the max sync speed w/o setting the high speed, but your system might.

The basic solution to getting larger apertures, and lower shutter speeds outside is getting a neutral density filter to knock down the amount of light coming in.

jforbes

adbsgicom wrote:

Are you not enabling the strobe to run high-speed sync? My Canon seems to not let you go past the max sync speed w/o setting the high speed, but your system might.

The basic solution to getting larger apertures, and lower shutter speeds outside is getting a neutral density filter to knock down the amount of light coming in.

Yes, you need high speed sync.

Auto-FP seems to be the term Nikon uses. Here's a video that shows where the setting is:

http://www.youtube.com/watch?v=Sqf3TM-WGTE

SLRdude

adbsgicom wrote:

Are you not enabling the strobe to run high-speed sync? My Canon seems to not let you go past the max sync speed w/o setting the high speed, but your system might.

The basic solution to getting larger apertures, and lower shutter speeds outside is getting a neutral density filter to knock down the amount of light coming in.

Enable the strobe to run high speed sync -> Yeah... that I have no clue how to do. I am literally learning new stuff from trial and error every day. I guess I better dust off the book for that SB-800.

Neutral Density filter... did not think of that either, and probably because it costs money. And I just don't have a big budget. It took me over 3 years to end up with what I have right now.

Thanks for the advice, and I will try it next time! clap

adbsgicom

Remember that your strobe range goes way down with HSS. This is because instead of a pulse that is well contained within the shutter period, the HSS changes the strobe to basically create a bunch of little pulses to emulate a static on that encompasses the shutter period.

Normal sync:

---

| shutter open |

---

...................... /\
....................../..|
_____________/....\___________________ regular flash mode


High Speed Sync:

---

| |

---

shutter open
................._________
__________/..............\_________ High speed sync


Ignore the ".....". The editor deletes the excessive spaces if they aren't there.

SLRdude

thanks guys!

That's really good info, and I will try it soon!

jforbes

SLRdude wrote:

thanks guys!

That's really good info, and I will try it soon!

This should explain how to enable high speed sync on Nikon...

http://www.youtube.com/watch?v=Sqf3TM-WGTE&feature=PlayList&p=5968F151769654CF&playnext=1&playnext_from=PL&index=27

time2smile

FP is e5 under the pencil. It works very well with my D90 and SB-600, should work better with the SB-900. You will be able to increase your shutter speed. Try it with BL on and off.

TGAllen

jforbes wrote:

On Canon, you can't even set the shutter speed over that level -

Which Canon do you have? You can set your Canon (not sure which ones you can't, but the 50D and M5 IID you can) as I have found out through the fine people on this site. It's in your Custom Function settings, C.Fn 1-Exposure: Flash Sync Speed in Av Mode-Set this to 0.