Advice please.

[mikeriach]

I have an A580 and recently noticed that when photographing aircraft side on, the nose and central fuselage is in focus but the tail drifts out of focus. It seems worse on telephoto lenses compared to wide-normal lenses. Could this be the sensor?

What is the best way to test the camera.
Also would the amount of out of focus be affected by the aperture?

Cheers,
Mike

[pakodominguez]

some reading:
http://en.wikipedia.org/wiki/Depth_of_field

[mikeriach]

Pako,

Thanks but it is not a DOF issue. Same photo with my A700 and same lens set to the same aperture has an even focus across the frame. I'm going to do a few sample shots tomorrow to illustrate. I had boought a new lens at the same time so was trying to identfy if it was the lens or camera.
I was really looking for some advice on what an image from an incorrectly aligned sensor would look like and what would show it up best. I'm guessing stopping down might improve it but wide open would make it worse.

Mike

[pakodominguez]

I was really looking for some advice on what an image from an incorrectly aligned sensor would look like and what would show it up best.

a brick wall?

[mikeriach]

No exposed bricks on our houses but was going to try a wooden fence which is straight.
Will give it a go at a couple of apertures to see if there is any difference.

Cheers,
Mike

[Argonaut]

Pako,
I was really looking for some advice on what an image from an incorrectly aligned sensor would look like ...
Mike

The only even mildly common problem with sensor "alignment" is back focus. The symptom is that the area you *thought* you were focused on is less in focus than another part of the frame. This can be tested for with a brick wall, shelf of books properly arranged, etc. BUT, your heli shot not being completely in focus is not proof of any kind of sensor alignment trouble. Everything else being equal (i.e. using your a700 with the same lens and same f-stop) it could be a different central focus point and nothing more. I think you need to do some more testing.

[gio67]

can I have some tips on this brick wall, I was focussing manually today and noticed it was a bit out of focus, put it on auto focus and it was perfect

it was the a700 and cz 16-80 combination

[David Kilpatrick]

Manual focusing on the A700 can be influences by the doptre setting for your eyesight. Make sure that is absolutely perfectly set.

David

[mikeriach]

Pako,

This one is fully side on with same distance to nose and tail.
The IQ varys as you traverse from left to right with the nose looking unsharp for want of a better word.

I'd appreciate comments on what could be causing this. I only seem to get this with the A580.

http://s19.photobucket.com/albums/b184/ ... C02034.jpg

Cheers,
Mike

[Atgets_Apprentice]

Although my a580 problem was due to sensor debris, it may be that your problem is of a similar nature, Mike, as my problem was down to the sensor being misaligned.

You could try downloading the Amateur Photographer lens chart for some test shots.

http://www.amateurphotographer.co.uk/downloads/

[mikeriach]

thanks for the link, try anything once!

Mike

[pakodominguez]

Pako,

This one is fully side on with same distance to nose and tail.
The IQ varys as you traverse from left to right with the nose looking unsharp for want of a better word.

I'd appreciate comments on what could be causing this. I only seem to get this with the A580.

http://s19.photobucket.com/albums/b184/ ... C02034.jpg

Cheers,
Mike

Hi,

I don't think I can really help you, I haven't have to face this kind of problem yet. And I'm totally ignorant about how to photograph aircraft.

What I see is the plane been sharp on the left side, and the windows on the right side looks blurry. But also some windows on the left looks blurry... at a first glace I'll say it is a motion blur issue -but, as i already told you, this is not my field of expertise (My longest tele reach 200mm, and I don't do sports or sailing or any those kind of photography where you need to deal with teles and sharpnes...

[mikeriach]

Pako,

Thanks for the comments anyway, I'm still looking for a big brick wall.
Will post a few when I find one.

Mike