what i should believe for lens of Nikon 450M and G-claron?

[originalphoto]

I read some thread and people suggested to use G-claron 355 and Nikon 450M for 11X14 or even 12X20. I made a simple calculate that for cover 11X14 the image circle should be 452mm or bigger, 590mm or bigger for 12X20. But based on the chart of http://www.largeformatphotography.in...LF11x14in.html, both of lens have 440mm image circle. why?

[UlbabraB]

I assume that the suggestion is based on personal experience. I use both on 14x17, usually stopped down and without extreme movements and haven't noticed any appreciable vignetting or image degradation (I contact print Kallitypes)

[Lachlan 717]

I run out of movements on a 7x17 with both.

I suspect that the link shows Manufacturers' figures.

[Vaughn]

I have used the 355mm for 11x14 -- never ran out of movements, but then I do not usually use much...just a little front tilt.

[Drew Wiley]

The manufacturers calculate the image circle based on a particular optimized or "typical"
f-stop as well as on the hypothetical usage for which that lens was designed. LF photographers often use smaller stops, hence the usable image circle increases. And
in the case of G-Claron, extremely conservative coverage values are published because
this lens series was once marketed for copy and graphics applications, where they wanted
very strict apochromatic standards well in excess of what ordinary photography demands.

[Leigh]

The IC on the Nikkor M 450/9 is 440mm, which Nikon rates adequate to cover 10"x12".

- Leigh

[John Kasaian]

Lenses can't read published data, so they don't know any better.

[Leigh]

It's all a question of quality.

Manufacturers publish an IC within which the image quality meets their specs.

That does not mean the image ends at the circle, only that the acceptable quality
does not extend beyond the circle.

- Leigh