SB800 expert required

[simpo two]

I was using an SB800 + D70 last night at an awards ceremony, mostly in the 150-200mm focal length range. The SB800 was in TTL mode.

Although I had up to +2/3EV dialled in, a lot of the photos are underexposed. I guess this is because I'm 'off the end' of the SB800's max zoom of 105mm, and I was in shutter priority mode at 1/400th sec and at max aperture, so the camera couldn't help.

I'd hoped that the SB800 would use its TTL facility to realise the underexposure and use more power to compensate. Evidently it didn't, and it certainly wasn't using full power as it was ready to fire again almost instantly.

Can anyone tell me what I did wrong?

Also, has anyone used 'flash extenders' for use beyond 105mm? There's plenty of power there, it's just not concentrated enough.

[luca brazzi]

Can't help (nothing new there ) but I've had similar issues in the past with my stuff.

I now leave the histogram function turned on as part of the auto image review after taking each shot, and glance at the bars to check for overall coverage.

What metering did you use, eval, partial, centre?

And what was the ceremony, and show us your results good and bad....especially if there are any 'nice' ones

LB

[dcw@pr]

if the flash wasn't firing at full power then it must be a metering problem. was there anything especially reflective in the photo that may have thrown it off? maybe have a go using centre metering next time

[V6GTO]

When using flash I allways shoot in apature priority, allowing the camera to use it's vast amount of shutter speeds automatically, and would have gone down to as slow a speed as needed.
To use shutter priority @ 1/400th is asking too much of the limited f-stop range, it couldn't get down to the f1/f2(nominal figures) that it needed.(Assuming the flash is working correctly)
BTW - what is the flash sync speed of a D70/SB800?

Martin.

It's early and I've got flu so if I got it totally wrong please don'e be too hard on me!

[simpo two]

luca brazzi said:

What metering did you use, eval, partial, centre?

Centre-weighted

luca brazzi said:

And what was the ceremony, and show us your results good and bad....especially if there are any 'nice' ones

I'm tempted but it's for a client so not for public release, at least not yet, sorry!

dcw@pr said:

was there anything especially reflective in the photo that may have thrown it off?

Good point, the b/g was cream - the people obscured most of it but it can't have helped. Next time we'll use a cyclorama to cover the wall up.

V6GTO said:

To use shutter priority @ 1/400th is asking too much of the limited f-stop range, it couldn't get down to the f1/f2(nominal figures) that it needed.(Assuming the flash is working correctly) BTW - what is the flash sync speed of a D70/SB800?

You're quite right. The D70 synch speed is 1/500th; I used 1/400th to avoid any risk of camera shake at longer focal lengths. In hindsight I think I could have used a bit slower, especially as the flash is doing most of the exposure.
So whilst I agree that 1/400th at f4 is a recipe for underexposure, why didn't the SB800 use more grunt to compensate and give me the correct exposure?

Or maybe try one of these chaps:
www.warehouseexpress.com/photo/flashguns/nikon.html

[mmertens]

How far were you away from the subject? Even with the SB800 I routinely have to dial in a bit of positive compensation as I tend to get underexposure otherwise - you know the D70 is slightly infamous for underexposing to presrve highlights. If you used centerweighted, the background shouldn't have mattered that much (as long as you didn't have large wads of cream or white in the centre). Could you save the pics in PS or so or were they too dark for such an effort? You had it on TTL, not BL-TTL, right?

[simpo two]

mmertens said:

How far were you away from the subject? Even with the SB800 I routinely have to dial in a bit of positive compensation as I tend to get underexposure otherwise - you know the D70 is slightly infamous for underexposing to presrve highlights. If you used centerweighted, the background shouldn't have mattered that much (as long as you didn't have large wads of cream or white in the centre). Could you save the pics in PS or so or were they too dark for such an effort? You had it on TTL, not BL-TTL, right?

Range was 30-40 feet: I could get a tight head and shoulders at 300mm. Setting was TTL, theory being that the flash would do the lighting. They're coming up quite well in PS though.

[Bacardi]

[redacted]

[ehasler]

The SB800 controls a slave flash with wireless doesn't it?

How about using a 2nd flash nearer to your target next time?

>> Edited by ehasler on Friday 4th February 11:00

[dcw@pr]

simpo two said:

You're quite right. The D70 synch speed is 1/500th; I used 1/400th to avoid any risk of camera shake at longer focal lengths. In hindsight I think I could have used a bit slower, especially as the flash is doing most of the exposure

I can;t understand why the D70 goes to 1/500 and the "superior" D2x only goes to 1/250? Bizarre and very irritating, I use the 1/500 all the time on my D1x.

simpo two said:

So whilst I agree that 1/400th at f4 is a recipe for underexposure, why didn't the SB800 use more grunt to compensate and give me the correct exposure?

I agree, which is why i think there must have been a metering problem

[dcw@pr]

Bacardi said:

At the risk of putting on the same old record I could mention RA..... , no must resist, must resist

RABBIT? is that a new Canon format?

>> Edited by dcw@pr on Friday 4th February 22:20