Digital camera accessories

[johntb]

I have a Pentax K100 digital camera. I also have a Sigma Zoom K11 Armsun lens It  is marked 1:45 f=70-210mm which I have used with some success. When I attach it to the body of the camera I am asked  what focal length should it be set to. I don't know but have been setting it to 200 and it seems to work but would it be better set to another focal length? I bought the zoom before I got my digital camera.

[bdery]

Hello and welcome!

The camera asks that question so the image stabilisation system will work correctly. It needs to know the focal length of your lens in order to stabilise it well. the general rule, for manual zoom lenses, is to set the focal length at the value you will use the most. If you plan on using the whole range, setting it at a medium value (something like 150 mm in your case) should be the safest bet.

I hope this helps!

[johntb]

Thanks for that, it makes things clearer. What is the maximum/minimum I can set it and what for? I am a bit of a novice so any help you can give would be appreciated

[bdery]

Don't apologize for being a novice, as you put it.

I'm not sure I understand your question. You mean what are the maximum and minimum values you should consider using with your lens? Given that your lens is a zoom going from 70 mm to 210 mm, these should be your boundaries. If you're not familiar with the focal length concept, you can read about it here:

http://www.digicamhelp.com/camera-features/advanced-settings/f-stops/

Please feel free to ask more questions if needed.

[johntb]

OK Now I understand. Many thanks.  Now perhaps I am not such a novice!!