When Should I Do An Automatic or Manual Lens Flange Adjustment on My XL H1 ?

[Mark Job]

Hi Shooters:
I have been shooting with my XL H1 camera now since late December of 2007 and getting excellent picture quality. However, I must confess I have never done the automaitic or manual rear flange adjustment. I understand this adjustment is important to overall image sharpness. Typically, when should this proceedure be carried out ?

Thanks,

Mark

[Robert Sanders]

Any time you add a new lens that hasn't previous been mounted to the camera. Once you perform the flange back it remembers that lens and re-adjusts itself every time you re-mount it.

So only once per lens.

[Mark Job]

Originally Posted by Robert Sanders

Any time you add a new lens that hasn't previous been mounted to the camera. Once you perform the flange back it remembers that lens and re-adjusts itself every time you re-mount it.

So only once per lens.

....OK, thanks for the heads up on this Robert :-) By this reckoning, I should go put the camera on the tripod and actually perform this proceedure, since I never did so before from the day I received my H1 brand new.

[Robert Sanders]

That's probably a good idea. It certainly won't hurt.

[Dale Guthormsen]

Good evening,

New to this camera I performed the lens flange not knowing what it really does. What exactly does it do?


Second, using an ef adapter does this come into account if I put a telephoto or soom on it?

[Marty Hudzik]

Originally Posted by Robert Sanders

That's probably a good idea. It certainly won't hurt.

Famous last words! :)

Seriously, this should not cause any issues....but sometimes that saying about "if it's not broke, don't fix it" really makes sense!

I do have to do periodic back focus adjustments on my 16x manual lens, but that is a different beast altogether. Still periodic adjustments to the non-manual lens could be beneficial as sometimes things shift on a microscopic level.

[Garrett Low]

How would changes in temperature affect the back focus? I'm thinking that under hot lights the materials in the camera will expand causing a change in distances between the lens elements and the sensor. Anybody every heard of any thermodynamic affects?

Garrett

[Mark Job]

Originally Posted by Robert Sanders

That's probably a good idea. It certainly won't hurt.

....OK. I did it. This was really easy and totally automatic. A real no brainer. :-)

[Robert Sanders]

Yeah, Canon's done a good job at making it as simple as possible.

[Dale Guthormsen]

Sense no one answered my question I did a little search and this is what i found about flange. (abstract found on the patent site)


A zoom lens barrel and a method of adjusting the flange back focal distance of the zoom lens barrel is disclosed. The zoom lens barrel includes mounting members for mounting the zoom lens barrel on a camera body; a zoom ring that rotates for zooming relative to the mounting members; an adjustment member that may rotate with or relative to the zoom ring; and a cam ring. The cam ring is screwed to the adjustment member and moves in the optical axis direction due to the rotation of the adjustment member when the adjustment member rotates relative to the zoom ring, and when the adjustment member and the zoom ring both rotate, the zoom ring and the adjustment member rotate together. Lens units move in the optical axis direction due to the rotation of the cam ring.


so I reckon it has to do with keeping things in focus simultaniously with the zoom.

[Mark Job]

Originally Posted by Dale Guthormsen

Sense no one answered my question I did a little search and this is what i found about flange. (abstract found on the patent site)


A zoom lens barrel and a method of adjusting the flange back focal distance of the zoom lens barrel is disclosed. The zoom lens barrel includes mounting members for mounting the zoom lens barrel on a camera body; a zoom ring that rotates for zooming relative to the mounting members; an adjustment member that may rotate with or relative to the zoom ring; and a cam ring. The cam ring is screwed to the adjustment member and moves in the optical axis direction due to the rotation of the adjustment member when the adjustment member rotates relative to the zoom ring, and when the adjustment member and the zoom ring both rotate, the zoom ring and the adjustment member rotate together. Lens units move in the optical axis direction due to the rotation of the cam ring.


so I reckon it has to do with keeping things in focus simultaniously with the zoom.

...Yeah. This adjustment is supposed to allow for both full wide angle at the end of the zoom out and the maximum telephoto position at full zoom in to retain an even focus.