SB-800 weirdness--focus assist

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Timm
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p.1 #1 · SB-800 weirdness--focus assist

I was attempting to shoot a group of people sitting in a tepee playing guitars by the light of a single candle the other night. I wanted to use the 10-20 Siggy from a high angle so I could get the whole scene, but, lo and behold, the damned AF assist light on the SB-800 DOESN'T WORK below 17mm! I mean it just refuses to light up from 10-16mm, but works just fine from there on up.

Unfortunately, the 10-20 Sigma isn't parfocal, so I couldn't just focus at a longer length and zoom out. Missed the shot.

Who thought this was a good idea? I'd think the flash unit was faulty, but I tried two others with the same results.

Sep 13, 2008 at 06:21 PM

GeorgeM
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p.1 #2 · SB-800 weirdness--focus assist

I'd be interested in the replies to your questions as well. I use the SB-800 and it works well with the 18-70, my main lens, but am very interested in the Sigma 10-20.

George

Sep 19, 2008 at 12:17 AM

sjms
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p.1 #3 · SB-800 weirdness--focus assist

well all i can say at this point is that it does on the SB900 with the 14-24/2.8 Nikkor using a D700 or D3

Sep 19, 2008 at 03:01 AM

GeorgeM
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p.1 #4 · SB-800 weirdness--focus assist

Was reading some Nikon literature, not the manual, and the SB-800 can only go out to 14mm. If you want more then the diffuser is the answer.

Too bad you lost the shot.

George

Oct 05, 2008 at 01:42 AM

hjanssen
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p.1 #5 · SB-800 weirdness--focus assist

The focus scale of a Sigma 10-20 goes from 0.25 to 1m and next to that is inf., so put your focus on 1m, aperture f8 and everything from 0.39m till inf.. is in the DOF.

What's the problem?

Oct 05, 2008 at 11:59 AM

Rodolfo Paiz
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p.1 #6 · SB-800 weirdness--focus assist

hjanssen wrote:
...put your focus on 1m, aperture f8... What's the problem?

For starters, I'd guess part of his problem was that "...a group of people sitting in a tepee playing guitars by the light of a single candle..." is not something you want to shoot at f/8. But his main problem appears to be that the AF assist light on his SB-800 wouldn't work if FL < 17mm.

I thought the question was pretty clear, actually...

Oct 05, 2008 at 02:02 PM

hjanssen
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p.1 #7 · SB-800 weirdness--focus assist

The question is pretty clear, but you can't change the design, but you can help with a solution.

OK, put it wide open and on 1.5m you, get:
Subject distance 1.5 m
Depth of field
Near limit 0.75 m
Far limit Infinity
Total Infinite

So everything grom 60cm from your front lens till inf. in the dof, why do you need a focus assist? Maybe Nikon made it this way, because the DOF is so big at these focal lengths.

Oct 05, 2008 at 02:22 PM

Rodolfo Paiz
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p.1 #8 · SB-800 weirdness--focus assist

Ah, I see your point... I misinterpreted your post as a smart-ass remark, but the real issue is that you don't believe it's "broken" but that it's designed that way. My apologies for the mixup.

Do you know for a fact that this is true (meaning, it's designed that way and cannot be changed)? That would answer the OP's question completely as well.

Oct 05, 2008 at 03:26 PM

Timm
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p.1 #9 · SB-800 weirdness--focus assist

I agree that there were several options for that shot that would not have required the AF assist--we'll put my failure to use any of them down to previous consumption of hand-crafted ales (hay, folks playing guitars in a tepee by candlelight--you think we were sober?). Aiming the lens at the candle would have been a no-brainer.

As for "endless DOF" at the wide end, unfortunately, I have several examples where this isn't enough. Besides, I was holding the camera above my head to get a nice perspective and I've gotten used to using the AF light to aim--yeah, another crutch.

Anyway, I'd be interested if anyone could try this with the SB900 and Siggy 10-20. As I mentioned above, I tried it with three SB800s and none of them would light up below 17mm. As the only other wide I own is a crappy 17-35 AFS, I haven't another ultra-wide to experiment with.

I read the SB800 manual f-b, btw, and found no mention of this--but then the manual isn't written in my native tongue (English).

This was on my D200--I haven't tried it on the 300 yet, come to think of it--could be the body. I'll give it a try when I get home.

Oct 09, 2008 at 01:48 AM

xof711
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p.1 #10 · SB-800 weirdness--focus assist

Question... Did you use the built-in/slip-out flash diffuser (not the diffusion dome)?
For some reason I think you need to have it pulled out to be able to work < 14mm but I might be wrong...

------
DigitalFreak.net

Oct 09, 2008 at 05:50 AM

panos.v
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p.1 #11 · SB-800 weirdness--focus assist

Timm wrote:
As the only other wide I own is a crappy 17-35 AFS, I haven't another ultra-wide to experiment with.

Can I have your crappy 17-35 please?

I've got one already but wouldn't mind another one. I'll pay you postage too.

Oct 09, 2008 at 10:47 AM

Timm
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p.1 #12 · SB-800 weirdness--focus assist

panos.v wrote:
Timm wrote:
As the only other wide I own is a crappy 17-35 AFS, I haven't another ultra-wide to experiment with.

Can I have your crappy 17-35 please?

I've got one already but wouldn't mind another one. I'll pay you postage too.

Darn it, it seems to be permanently affixed to one of my bodies!

Planning some stereo work?

Oct 10, 2008 at 03:12 AM

Timm
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p.1 #13 · SB-800 weirdness--focus assist

xof711: I tried that, too. Since I was bouncing the flash, I didn't really need the extra wide flash, but, yes, I tried it.

Oct 10, 2008 at 03:13 AM


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