p.1 #1 · D800 back focus with SB900 & SB700 AF assist
Received my D800 a few hours ago
Ran some out doors test and all is well.
Tested indoors with SB 900 and SB 700 and the camera back focus with all my lens using AF assist on the flash. Dial in -20 AF fine tune helps but focus still not as good as without AF assist.
Googled the problem and found a thread on DPReview with others having the same problem. One person said they did not experience the problem withe the SB 600 only with the SB 900 and SB 700.
I remembered that I have a SB 800, ran some more test and the focus is perfect with the SB 800 AF assist.
Anyone else have a similar experience? Hopefully a firmware update will fix the problem.
I seem to remember something similar with the D3 but I am not certain.
Apr 12, 2012 at 11:20 PM
mshi Offline • • • • [X]
p.1 #2 · D800 back focus with SB900 & SB700 AF assist
No, I have eight SB-900s and AF-assist is always spot on in AF-S mode, which I seldom use. Did you lock the camera down a set of sticks? Make sure you understand AF-Assist doesn't work in AF-C mode. What was your shutter speed used? What was your AF mode on camera? How far was your subject to sensor distance? What was the flash mode on SB-900?
p.1 #3 · D800 back focus with SB900 & SB700 AF assist
Camera was hand held. AF mode was AF S. When I used AF C focus was perfect without AF assist. Flash was on ttl. Tested at various distances. Shutter speed was 1/250. Same situation works great with SB 800 AF assist.
I am a wedding photographer and I depend on flash AF assist when shooting the reception. I have used D3 and D3s but sold those D700's which I have been using for about 2 years. I never experienced this with any other camera I owned.
Will just have to start using my SB 800 again and hope for a firmware fix.
p.1 #4 · D800 back focus with SB900 & SB700 AF assist
Which AF sensor(s) did you use, and which lens / focal length ?
With the other flash unit were you shooting exactly the same thing from the same distance and position ? I'm wondering if the camera could be focusing on a shadow line instead of the intended subject. That would require the subject to be reasonably close to a background surface such as a wall for the shadow to be obvious.
p.1 #6 · D800 back focus with SB900 & SB700 AF assist
Center AF point. 24-70 at various focal lengths, 35 1.4g and 85 1.4g. Shooting the same thing, different things, just about anything and the same results every time. Back focus with SB 900 and SB 700 AF assist. In focus photos without the AF assist and in focus photos with the SB 800 AF assist.
p.1 #7 · D800 back focus with SB900 & SB700 AF assist
I've long had the same problem with both of my D3s bodies and both D700 bodies as well. Happens with the SB900, but not with the SB600 (I don't have an SB800 to test), and also happened with the SB700 (which I returned after it displayed the same issue). It's most noticeable with primes and at longer focus distances.
p.1 #9 · D800 back focus with SB900 & SB700 AF assist
Just posting here to mention my own issue. I was hoping to avail myself of the small size of the sb700 for wedding work to offset the weight of the D3.
The D3 would back focus with a Sigma 50, Sigma 85, 35G, and 50G by up to 1 or 2 feet when using the sb700's flash assist beam. Focus would be spot on using the sb700 without the beam enabled. Focus was also spot on using an sb800 with flash assist beam enabled. Tried this out on a buddies D3 and it performed the same re: back focus with the sb700.
