Image stabilization (SR) & focal length?

[jaycai]

I have a Pentax K100D Super with SR, and was thinking of getting a manual focus

zoom lens, which means it won't know the focal length for the SR. So I have to

enter it manually every time I turn the camera on. I assume I enter the actual

focal length instead of the cropped focal length (i.e. 50mm instead of 75mm for

the f2.0 50mm prime lens). My question is on a zoom lens, what focal length do

I use? Do I have to constantly change the setting in the menu as I change the

lens zoom?

[a few images]

Yes. That is what the manual outlines to do. Some have different methods for dealing with this however. From picking the FL in the middle to only switching to the thirds to turning SR off, each person deals with it their own way it seems.

[mountainvisions]

What Tom said.

 

And...I'd say go with either the average FL or the long FL on the zoom.

 

I'd simply not turn the camera off all the time. It mostly wears thes switch out. The camera uses near nil battery power in sleep mode so just leave it on.

 

Dealing with "having to enter" the FL is a personal thing. Consider it a bonus, the flip side is you could have to ditch all those lenses and buy nice new ones that you don't have to bother with entering FL #'s.

 

Hmm, little hassel = lots of savings.

[hinman]

Disclaimer: Justin & others, I don't know this well. Hope that helps you all to read my response with grain of salt. I learn it from another forum discussion that suggests to use the lower FL value of your zoom or fixed length prime lens. Say you have a 230mm odd zoom and the FL for SR selection only has 200mm and 250mm, I use the lower one for fear of over-compensating in the SR.

 

And about changing FL in a manual Zoom, I use the following short cut menu option to adjust to a closer focal length number that is below the actual zoom FL that I am in.

 

1. Press Menu

 

2. up arrow will get to the FL selection for SR

 

3. select a lower or equal number to the FL for the shot

 

I tried to stay away from powering on/off though that will prompt you again fro the FL selection on manual lens. I don't have any test or any experience to back up the claim that over-compensating can be a problem in dialing in a bigger value such as 250mm for an actual length of 210mm being used

 

It is for the MC2 scientist to figure it out.

[hinman]

I always enter the actual length that is indicated on the zoom. I don't add the crop factor. Again, others please verify. I saw discussions before and I recall other people pointing to use the actual FL as in 50mm SR selection for 50mm FL to be used.

[miserere_mei]

You definitely need to enter the focal length of the lens because...well, because lenses only have *one* focal length, and it's always the same, no matter what camera they're mounted on.

 

When using an old zoom, I enter the smallest focal length if I know I'm going to be using the full zoom range. If I know I'm going to be using it mostly at the long end, then I enter the longest focal length.