Red AF light with hot-shoe-mounted flash: is it the reason for not-so-sharp shots?

[ZapoTeX]

Hi everyone!

I have a Metz 50 AF-1 and Nikon D90. I was at a birthday party last night and I must say thank God for white walls, tiltable flashes and TTL I took some photos that look like it was daylight

However, I have one problem: the AF assist light from the Metz is very different from the one from the camera and, I believe, far less effective:
1) It is a striped pattern rather than just a beam. Theoretically it should help, but does it?
2) It is red, rather than white
3) It looks significantly less bright than the camera's light
4) Given that it comes from a source that is MORE DISTANT FROM THE LENS than the camera's built in AF-assist light, it is not always at the right place

For these reasons, I got some shots that seem to be out of focus. Here are two examples of one photo that turned out well and one that did not:

1) A good photo: this is a 100% crop and... wow, it does not even look like a 100% crop. Incredibly sharp and pretty awesome

2) A bad photo: I'm posting both the full photo and a 100% crop. Even in the full size one, it is completely obvious that the photo is soft. It sucks! It had never happened to me with the built-in flash (and built-in AF light).

For both photos, I did exactly the same thing: I focused on somebody's eye with AF-S mode, recomposed and shot.

Anyone had this problem? How did you guys fix it? Thanks so much for your help!

ZT

 

[Big Mike]

Typically, the pattern that a flash put out for the AF assist light, is meant to match the pattern of AF points on the camera. There may be an issue because you're using a Metz on a Nikon...but who knows?

 

[ZapoTeX]

Hi Mike! Thanks for your reply!

I thought the main thing was that the light is weak (I can hardly see it on a wall), but maybe the pattern matters.

It would be nice to program my camera to use the internal AF-light even when there's a flash on it. But I have no idea how

Thanks a lot!