[GUB]

Nice total lack of chromatic aberration with the 400-600mm lens (as expected). To tell you the truth I prefer a softer image without the PF to a sharper one with it.

When it is at the centre of interest like the white paper it is a deal breaker. But controlling it and editing it are part and parcel of mucking around with legacy lenses.

[cyberjunkie]

Catadioptric lenses show other problems, but fringing is not one of them. Unfortunately the lack of sharpness can't be easily minimized. On the other hand, fringing is largely dependent on some characteristics of the image, like contrast, focusing distance, etc. So it's not always a problem like in the test pictures.
I'm not surprised by the good performance of the 400mm K, the 500mm big brother works the same (good sharpness but evident fringing with certain subjects).
The FA is better, but if we consider definition alone the simple Soligor 800mm doesn't do a lot worse. Quite the contrary!
I have the same lens, it was made by Tokina and also sold as Vivitar. There is some blueish diffused fringing but the Pentax logo is very readable. It could benefit from the different focusing distance (the caps are actually smaller, and not bigger, so the camera was much further away from the subject). Long focus achromatic doublets can work very well at the center of the frame, if the subject is not too close.
I can't see if the focus was significantly away from the paper. If that is the case, the fringing could be due to longitudinal chromatic aberration, not the lateral one. With such long focals a few cm difference in focusing can make quite a difference.
Last comment about the Soligor with "ears". It seems to be definitely better than the other. From my personal experience this series of lenses were all very well made. The optical performance varies a lot. Some were surprisingly (more than) decent, others are disappointing. Can't say if they were like that when new, or if it's just sample variation due to the level of use (and abuse) they have been through during all this time.

I appreciate this simple test. The results are quite interesting. Testing long focals is not so easy: the easiest way is to test the lenses very close to their minimum focusing distance, but many of them perform horribly that way, cause they were optimized for different conjugates. Their main use was sports or birding/photo safari. The subjects were always distant from the photographer. Modern objectives are more flexible because of AF and floating elements designs.

[GUB]

It could benefit from the different focusing distance (the caps are actually smaller, and not bigger, so the camera was much further away from the subject).

The 400mm was 40 metres from the Target and the 800mm 80metres (aka paces). The idea is to get a matching magnification. The 400mms cap (centre) are one or two pixels bigger yhan the 800s (110px vs 112px so pretty close).

I appreciate this simple test. The results are quite interesting. Testing long focals is not so easy:

Thanks for that. I also think it is important to not test at infinity because some lenses may fail due to simple mechanical adjustment error.

Their main use was sports or birding/photo safari.

That is why I am not too concerned about corner performance.

[GUB]

I realised that I had forgotten to test my Nestar 400mm 6.9 in this lineup so I did one today including a shot with the FA400 to match against. Result is a little shocking.
A 1960s Tamron

Tamron preset, T-mount ( Nestar ) 400mm f6.9. Lens Reviews - Tamron Lenses - Pentax Lens Review Database

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