[pentax360]

Do KAF zoom lenses communicate their current focal length to the camera?

Will IS on KAF lenses that aren’t on the start up “focal length input list” work optimally.
I’m specifically looking at a KAF 90mm, and if it were K/KA I would only be able to select 85-100mm, which the IS would work but not optimally.


I’m sure this would be self-evident if I had any KAF lenses, but currently all mine are K and KA. (spent a total of $66 on my 3 lenses )


thanks.

[Adam]

Do KAF zoom lenses communicate their current focal length to the camera?

Yes and yes, anything with AF does.

Are you talking about the Tamron 90mm?

Also, you probably wouldn't be able to tell a difference even if the camera thought it was an 85mm. SR will still work well.

[stevebrot]

Do KAF zoom lenses communicate their current focal length to the camera?

The interface supports focal length update, but whether a particular lens supports the feature and how granular that support is varies by lens and maker.

Will IS on KAF lenses that aren’t on the start up “focal length input list” work optimally.

Edit: Most lenses will report actual focal length and the camera will act appropriately.* For non-AF lenses, convention is to choose the next lowest focal length and not worry about whether the performance is optimal. I enter 85mm for my manual focus Tamron 90/2.8 (72B) and it works fine.


Steve

* Example: My FA 77/1.8 reports as 77mm and SR behavior is normal.

[pentax360]

Thanks a lot, just what I needed to know.

-

Are you talking about the Tamron 90mm?

Yes I am.
---------------------------

The interface supports focal length update, but whether a particular lens supports the feature and how granular that support is varies by lens and maker.

What kind of wording would I look for to make sure a zoom lens can do focal length update?
Are there very many lenses that don't do it?

Thanks.

[Adam]

Are there very many lenses that don't do it?

As long as they are autofocus, they will automatically update. Manual focus lenses won't.