To go back to that, the plain AF screen as supplied is fine. I find it easy to focus manually and bright enough.

If it's too dark to focus manually then it must be some sort of night shoot where different techniques can be employed.

Nothing in this world is totally guaranteed Stefan.

Do I want an iPhone that is secure and virus free? Yes.
Do I want spurious Apps from all and sundry that can crash the system? No.

So for myself, the stance of Apple is just fine by me. Those who want to delve deeper into the software can buy an Android phone.

Mirror lenses do indeed have a fixed aperture.

The aperture on the Pentax 400-600mm Zoom Reflex only changes because the focal length does.

Opteka is another name for these lenses, and a few others too, but I've just found an Opteka 800mm mirror lens for Pentax:

http://www.amazon.co.uk/Opteka-Telephoto-Mirror-Digital-Cameras/dp/B00281IPXS/re...=sr_1_16?ie=UTF8&s=electronics&qid=1276950304&sr=8-16

Lokks interesting, I wonder how good it is?

gartmore has a copy of this lens for Pentax and has spoken very highly of it.

The new AP (out Tuesday) has a comparision test. The Samyang is apparently an update of the Nikkor design and actually out-performs it.

Looks like it's a very sensible buy for us Pentax Users, although don't forget it is a manual focus lens. That might not suit everyone.

Bump is just a post that puts the thread back to the top of the list.

Attention-seeking, you know....

I'm going to disagree with that. The faster the lens the easier manual focus is, for two reasons.

One, the image is brighter, so the eye can see better details.

Two, the limited DOF makes the exact point of focus very precise.

Talking to a lot of photographers, I get the impression that the art of manual focusing is being lost. Part of the problem may be incorrect setting of the dioptre adjustment on the viewfinder eyepiece. A very high percentage of those I talk to don't know how to do this.

Which is exactly right - if they say that and we don't follow their instructions then we won't sell any images.

Always read the instructions, and read them again from time to time as sometimes they change.

I notice Mifsuds have some longer Pentax fir telephoto zooms on offer at the moment, including a relatively inexpensive Cosina 100-400mm.

http://www.mifsuds.com/acatalog/Used_Pentax_AF_Lenses.html

I did mention this, and you can turn it off and have a fixed value.