Pentax 100d will not power off when turned off but will power off with auto power off with timer.

SOURCE: pentax k 100d

Try this -

Connect the camera to the PC via a USB cable.
Download and install the firmware from Pentax's website
http://www.pentaximaging.com/customer_care/show_firmware?firmId=7717476

Follow the upgrade instructions propoerly.

Good Luck!

SOURCE: t is possible to use sigma dl zoom 75-300mm on

Best option is to go to photogrphic shop with the camera and lens and ask for converter that will fit on both ( if available ).

SOURCE: How to download manual for

Search for Pentax web site and look for manual for your Camera. If you have printer click and print pages then you don't have to save on HDD of computer. Good luck

SOURCE: I have Pentax 100D and

I had the same problem and found a way to solve it.

Clean the batterie contact within the camera after removing the batteries, with a electrical contact spray lubricant and swab the internal plastic parts after.
Replace new charged batteries, it should work.
There is 4 batteries wich correspond to 8 contacts wich create with along the time electrical resistances that lower the tension supllied to the K100D