Pentax AF140 Ring Flash

I recently bought a Pentax K20D which takes great pictures and uses all my old Pentax lenses, but my Pentax AF140 ring flash will not work TTL (Through The Lens) with the digital camera; it fires, but only at full power. A ring flash fits on the end of the lens for extreme close ups, so that the lens shadow does not get in the picture. I have found a way around this by using a neutral density filter (cuts down the light transmitted, but does not change the color) to cut down the light from the subject. A 3-stop neutral density filter is just right at the closest distance to the subject (ie. 1:1) with my Tamron macro lens at f32 and the camera sensitivity at ISO100. This is fine for very small insects, and for larger subjects such as moths I either increase the ISO or go to a larger aperture, such as f22, or f16. I was using ISO200 and f16 for a praying mantis a month ago.

Lovely to look at but toxic to touch, as a friend of mine found out. This caterpillar lives in the Panamanian coffee growing town of Boquete.

I have no idea what the moth or butterfly looks like. Notice the false eye spots on its behind.


Pentax is bringing out a new ring flash, the AF160FG, which I suppose will work TTL on their digital products. Adorama describes it but says it is not currently available. Meanwhile, I am glad I can make my old one do the job.