[ElJamoquio]

This is the friendly Pentax Forum!

I'm not stomping my feet. I had mis-interpreted those numbers as being normalized by distance rather than image height. That's my mistake.

Of course the results that they obtained are very non-conventional, so I wonder what was really the problem with their measurements. FWIW the comparison was fair. F/0.9 on APS-C is equivalent to F/1.4 on FF.

[jsherman999]

Actually that sentence is correct.

What is confusing you is the silly concept of "total light" which is nothing any real life photographer tends to care about, as they use exposure only and are not preaching theories.

"Silly"?

'total light' is important to any photographer who might like to get less image noise for a given exposure. You can't control total light for a given exposure in the same way you can control exposure itself - but you can make purchase decisions up front that will give you more total light for your typical shooting scenarios and available, affordable autofocus lenses - if that's what you're after. The majority of shooters who buy FF are after that. (As are the majority of aps-c shooters who choose that format over m43, or 1 inch sensors, etc.)

Has anyone reading his bought an aps-c DSLR system because you wanted (in part) better noise performance over a point n' shoot? Then you care about total light, and it's not 'silly'.

.

This sentence also explains why sensor size is totally irrelevant in most respects as explained by equivalence:
If you put a wide angle converter such as a speedbooster on your lens it acts like a funnel, concentrating all the rain on a smaller area, whereby this piece gets soaked much more, thus easily creating 16mm f/1.0 lenses on APSC (this is what you get when you attach a speedboster-like WAC to a Samyang 24mm F1.4 lens).

Sure, been talked about quite a bit, but then you need to buy $500 speedboosters and accept the increased astigmatism and distortion, and the big hit to your AF performance. Why not just buy a real FF, it's cheaper and better?

.

[Pål Jensen]

See the last few pages on this thread to clear up the confusion:

https://www.pentaxforums.com/forums/169-pentax-full-frame/258031-do-you-reall...ff-why-21.html

[Parallax]

I hate re-runs.