Hi Ian and Cowan, thank you for commenting. First: I only shot about 6-7 sheets on 8x10 with the PSVQ IV so far, but generally, I agree with the opinion that it's softer, in a very nice way, than the Cooke's PS945 rendering. I think if one were to look at a set of prints from each, they should be able to pick up their differences. As for Cooke's referencing the PSVQ IV, "it's close enough for government work", as one might say. Certainly, it's nice to have such choices.
The Cooke PS945 is definitely sharper. By F8, the soft focus is already very subtle, whereas the PSVQ IV still glows. Format matters of course but regardless, it just means that I will need to find the sweet spots for my preferences for each lens. Also, the Cooke excels with colors. Not sure about the PSVQ IV. Unlikely I can afford color 8x10 films, ha ha.
Ian - the Cooke PS945 images were on 4x5, so yes, the format size is different, as is the DoF based on distance, apertures, etc., so for sure, this is just a "hey they look pretty good" "comparison" rather than a detailed report. The PS945 actually does cover 8x10, at least around 6 feet or so, and probably around other distances as well, but currently I do not have an 8x10 that can take the Cooke, as the Kodak 2D uses its own size lensboard and not the Sinar size one. When I have my own 8x10, which hopefully would be within 4-6 weeks, I would do another comparison but on 8x10 films. That would be interesting as well.
As for comparing with other Cooke's. I have 3 small brass Cookes, 6 1/2" series II, 7" series II and 8" series VI. I have them mounted on Copal 3 and use them on the 4x5 some times. The 7" supposedly has some soft focus adjustment by unscrewing the back cells a few turns. Generally, they are very pleasing lens. The contrast is quite a bit lower than the modern Cooke PSp45.