Can zoom length change WB?

[kalibre]

For ages now I've been using the PRESET (Custom) WB on my D80 with various backgrounds. From my shooting position the background (white for example) doesn't fill the frame, so to get my WB set I zoom or move closer, set it under lighting then zoom out to my shooting spot.

So my question is; whilst zooming will modify the amount of reflective light seen by the camera, does it in any way affect the WB, bearing in mind that the light temp, strength and position is constant?

My shots have always been fine (ish) but I'm just curious?

 

[will69]

I do not think that focal length would effect WB. What will effect WB however is if your reference is not a mid tone grey.

 

[30psi]

Why isn't white better for preseting the custom WB?

 

[Byker28i]

If you're set for Auto WB, then I suppose it depends on the subject.
A landscape with green fields, blue sky may well change if you zoom into a sheep in a field?

 

[30psi]

By zooming in your not changing the light that's actually hitting the sheep though are you?

EDIT - I see what you mean in respect of auto WB...

 

[kalibre]

By zooming in your not changing the light that's actually hitting the sheep though are you?

EDIT - I see what you mean in respect of auto WB...

Exactly, obivously auto will apply an evaluative algorithm, which is why naturally it would change on zoom length because the composition is completely different.

With custom WB (PRESET) I don't think it would change, but I didn't know if anyone knew any different.

The manual (Shock horror, I've read it!) specifies either white or mid-grey as a the preset target, so obviously the camera is able to tell the two apart and understand which you were aiming for.

 

[StewartR]

So my question is; whilst zooming will modify the amount of reflective light seen by the camera, does it in any way affect the WB, bearing in mind that the light temp, strength and position is constant?

No, if you're setting a custom WB. End of.