Quote:
Originally Posted by bratislav
Those old cameras were designed for film, and would be rather mediocre by today's standards.
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Hi B,
Whilst I'm not wedded to anything (film or digital) I'd just comment that:
Yes of course they were designed for film, it was the film era. It's just that,
THAT FILM was a whole lot larger than the typically used 35mm film. (121 times the surface area of normal 35mm film). I feel that despite the passage of time, that given the application to which they were applied, their precision and the expense involved in their design and manufacture that they may be of some use today. Objectively I couldn't say without any testing, but my thoughts/leanings follow.
Given that no expense was spared on these spy/surveillance systems there is every reason to expect that the film used would also have been special and certainly likely to be up to the task, certainly as good or better than commercial film stock. Given the increase in film size and that the film used would have been equal or better quality to readily available commercial film stock, that would mean a significant increase in observable detail/sharpness (resolution+contrast)
on a per picture height or width basis compared with the commercial consumer cameras of the time.
Without some form of objective test it would be difficult to say by just how much the sharpness improved, but given that the film used was 9 x 18 inch surveillance film, compared with typical 35mm or smaller film. That's 121 times the area or between 9.5 to 13 times larger in height and width. Ergo from a sensor (film) standpoint one could expect something probably like 10 times the resolution
on a per picture height/width basis compared with typical commercial film systems of the time based on 35mm film.
Of course the lens then had to play its part.
Leaving this extra large spy film aside, I would certainly be guided by the increased resolution available
on a per picture height/width basis between say a 35mm film
camera system and larger format film
camera systems, as demonstrating the sort of sharpness (Resolution + Contrast) improvements possible with larger sensor (film) size camera systems and that should be observable in equal sized output images (of sufficient resolution) from such systems.
Quote:
Originally Posted by bratislav
To the right are MTF curves, also 10 to 50 lp/mm of a 450mm f/1.8 (yes, that is 250mm aperture (!)) Strange-Jones astrograph. It has only 4 elements (3 lenses and a mirror), and uses ordinary BK7 glass. It also has zero vignetting, near zero distortion, and it has perfectly flat field.
But it can't do IS, can't be stopped down instantly and can't autofocus.
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Do you have a link/pics etc or some further info on that design?
Thanks and
Best
JA