Regarding the crop factor and image distortion, although a 50mm lens remains a 50mm lens that has nothing to do with perspective distortion. Perspective relies entirely on the distance we are from the subject, nothing else. A 50mm lens will require us to move back to get all the subject in (compared to using it on a film camera) so the perspective will change.

The classic portrait lens would be the 55mm f1.4 (equiv 85mm approx) or the 70mm (equiv 105mm) or the 77mm (equiv 120mm) - I've rounded those comparison figures to actual focal lengths that used to be available as portrait lenses.

Why would we? PPG has no connection to PU....:

My feeling is that you're totally misunderstanding something basic. The purpose of adjusting the eyepiece dioptre has nothing to do with the lens focusing, so forget that for a moment. To focus accurately on anything manually, that is by looking to see when it's sharpest, your eye needs to be at rest at the correct "virtual distance" from the focusing screen inside the pentaprism housing. This distance is around 1 metre, so your eye needs to be able to focus comfortably on something 1 metre away. That is where the viewfinder image is. So we look at a blank wall and thenadjust until we can see the etched lines in the viewfinder at their clearest.

Now we can focus on a subject. The distance from the lens to the focusing screen (via the mirror) must be the same as the distance from the lens to the sensor, so when something looks sharp in the viewfinder it will be sharp on the sensor. This basic collimation you can do nothing about and usually cameras are spot on or so close it doesn't make any difference.

Now in its simplest form manual focusing is dead easy. We turn the focusing ring on the lens and when the image is sharpest it is in focus. Always focus after zooming by the way as shifting the zoom setting will alter the focus point with all but the most expensive zoom lenses.

The AF system also seeks the sharpest point, but errors in lens manufacture and calibration may mean it's slightly out with a particular lens. I haven't found a lens yet where it is, but some seem to find fault with every lens they have. Anyway, whatever the reason if you want to adjust you can do and each lens (up to 20) can be individually calibrated the AF adjustment.

I would feel a lot happier that you were doing the testing right if the images you were posting were better technically, being brutally honest, so the newspaper one was the best but it should be done in daylight, at various zoom settings and you should be more specific about where you were aiming for. The letter T was a big letter - where on the T were you focusing?

Get it right for daylight, starting with factory defaults to make sure there is a problem and you're not just chasing in circles.

Hope that helps!

I would always say if you can afford the Pentax get the Pentax. Equally applies to all marques by the way - the maker's own products usually gel best together.

No idea Bob, it could be a waste of money, but you'd have an Asahiflex IIa and one decent lens out of it. I know I wouldn't pay very much at all as a repair could be quite expensive, if it's possible at all.

Personally, I wouldn't pay more than £20 or £30 for the package, but I've not seen it so it's not written in stone. I'd be thinking I might have to add £100 or so in repairs, maybe more, and depending on the condition wondering if I would have something viable after all the expense and effort.

It depends upon the price you will end up paying. The camera is relatively rare in the UK and might be worth repairing. You have one decent lens. You might be able to get your money back later and find a better one.

Only you can decide if the price is worth it. The theoretical value of a mint camera + 58mm is $300-450 according to McKeowan's guide, but a damaged one would be much less.

The camera dates from 1955.

Perhaps picking up a second hand weatherproof body would be a good start - look at the Classified Ads section of the forum and see if there's a K10D or K20D at the right price.

The WR 18-55mm lens is available at quite a low price new from www.srsmicrosystems.co.uk and that would suit you well to start off with.

Yes, I did indeed read the post. The fact that the error was consistent suggests the adjustment was not being made as per the instructions, as the eye tends to compensate. Thtat's why it's necessary for there to be a blank or defocused image. Removing the lens is another way to achieve this.

A typical tungsten exposure might be more like 1/60sec at f5.6 using moderately powerful photoflood lighting, but I suspect that we're thinking here more about wanting to use ordinary room lighting.

To be honest, that's dreadful lighting for a portrait, if indeed that's what we are talking about. Images that appear to be natural room lighting are probably extensively augmented by additional hidden lights, thus giving reasonable exposures.

An EV table, taken from Carl Shipman's Pentax SLR Cameras book. These tables are based on ISO100 and an f1.4 lens.
[IMG]http://i240.photobucket.com/albums/ff250/johnriley1uk/001EVTable.jpg[/IMG]
Any combination of aperture and shutter speed that is equivalent to the ones given will give the same EV number.