Yet another autofocus problem...

Hi... my problem is pretty similar to the one posted in https://photography-on-the.net/forum/showthre​ad.php?t=329359 and at least one other thread, but it's not exactly the same so here goes...

I have a Digital Rebel XT (EOS 350D) which I'm pretty sure was autofocusing fine in the beginning, but now can't properly autofocus when in the creative modes. I've cleaned the mirror but to no avail... AF mode is set to One Shot (no AI SERVO) and all the custom functions (including 4) are off.

This is a more specific description of the problem:

When I put the lens in AF mode and the camera in total auto mode, it looks like AF is functioning ok. However, when I put the lens in "P" mode (programmed auto exposure), only the rightmost autofocus dot ever blinks red, and only it seems ever to really be able to focus on anything. I hope I'm making myself clear... when you look through the viewfinder, there's a cross formed by 7 points, and the points on which the lens is actually autofocussing blink red. So, yeah, only the rightmost point ever works when the camera is in P mode. Tv, Av, and M modes suffer from the same problem... but A-DEP is ok, as is full auto and all the "image-zone" modes (portrait, landscape, etc.).

I'm sorry this is so verbose... I'm hoping against hope that there's a quick easy fix to this (yeah, right...). Help!

Thanks!


Li.

In all Creative Modes except <A-DEP>, press the AF point selection button (top right, looks like a cross inside the rectangle) and turn the Main Dial (or press appropriate Cross key) to select appropriate AF point.

Then, read pages 73, 74 of your camera’s User Manual.

Welcome to POTN!

Oh, my, it's a feature! How embarrassing! Hermeto, you are officially my hero. Thank you sooooo much!

Li (placing the User Manual next on her reading list).

lmarkakis wrote in post #3989789
I've cleaned the mirror but to no avail...

Very bad idea to clean the mirror itself, especially on an xt. If you used a blower, it should be fine, but anything else can mess it up. hopefully your problem is only the af point selection, but remember to never clean the mirror with anything other than air

lmarkakis wrote in post #3989989
Oh, my, it's a feature! How embarrassing! Hermeto, you are officially my hero. Thank you sooooo much!

Li (placing the User Manual next on her reading list).

No problem, my dear, you are welcome!

Read the Manual cover to cover, with the camera in front of you.
Make sure you identify every button, try every mode, change every setting..
What you read in the manual, try on the camera.

If you still have any questions, feel free to ask for the explanation..

Ah, no, I did use a lens tissue (the mirror looked like it had crud on it), though I did try to be extra careful. Hopefully I didn't break or scratch anything. I do have a blower--I'll stick to that in future. Thanks!

I like your sig btw, basroil--I was discussing that exact idea with a friend just last week.

Hermeto wrote in post #3990102
No problem, my dear, you are welcome!

Read the Manual cover to cover, with the camera in front of you.
Make sure you identify every button, try every mode, change every setting..
What you read in the manual, try on the camera.

If you still have any questions, feel free to ask for the explanation..

Will do--thanks again!

lmarkakis wrote in post #3990107
Ah, no, I did use a lens tissue (the mirror looked like it had crud on it), though I did try to be extra careful. Hopefully I didn't break or scratch anything. I do have a blower--I'll stick to that in future. Thanks!

I like your sig btw, basroil--I was discussing that exact idea with a friend just last week.

All SLR mirrors are front-surfaced mirrors, and that surface is EXTREMELY delicate. You are quite likely to damage the surface if you wipe with anything. In addition, the mechanism that supports and moves the mirror is quite delicate in itself.

As said before, it is best to use nothing but a squeeze-bulb blower to clean a mirror and never physically touch the mirror with anything but the stream of clean air. The only exception to this "rule" would be if the person cleaning the mirror has both appropriate training and appropriate tools.

SkipD wrote in post #3990160
You are quite likely to damage the surface if you wipe with anything. In addition, the mechanism that supports and moves the mirror is quite delicate in itself.

Gotcha, thanks. I'll just have to hope that I've been lucky enough to avoid the irony of having "fixed" something that wasn't broken... Will be more careful in future.