Ken Strain

I wonder how variable the Tamrons are, as mine does the same with respect to resolving power on the D800. I can easily accept your comparison, as it agrees with test sites and general opinion, but...

At the time of buying a D800, I wanted a 70-200/4 but got the Tamron 70-300VC while waiting for the new zoom to be released.  The Tamron far surpassed my expectations, and my inclination to buy the...

Yes.  I am not convinced by Guichard's line of reasoning, though am prepared to accept that I could be misunderstanding or missing an important point.  In the general case there cannot always be...

First the comment: Detail Man wrote: "However, the idea that the 2nd derivative of the MTF response at zero spatial frequency corresponds with the "sharpness" of viewed images seems to contradict...

Is there a universal answer to those questions? Does the same character of blur, quantified by your suggestion of separating out the  departure from Gaussian, cause the same reaction in all...

Thank you for the thought-provoking post.  It helps to see, together in one post, those  non-Gaussian spectra.  That makes it seem even less likely that the Gaussian-based measure is a good...

Only a Gaussian "spectrum" can be characterised that way, so the question is really whether the result is useful for more realistic cases. In the 2004 paper there is an attempt in 4.2 to argue that...

I take it back: on comparing the tests for the 18-35mm and the 70-200/4 (both done with the D800E) the results look plausible.  The corners of the wider lens are not that great at 35mm, and that...

What I see, and find strange, are the results on the D800E at the smallest apertures.  Try setting 18mm, 24mm and 35mm at the aperture values f/22 (adjusting the f-no. slider as otherwise the f-no....

Absolutely right; those two comments point to the heart of the matter.  My aim was to find out, without investing too much effort, how hard it would be to make a balanced comparison. The answer is...

It is not clear what you mean by that phrase. 1/200th and 1/180th are surely close enough given the other uncertainties.  The significantly different exposure at 1/125th also represents a perfectly...

Attempt #2. Very overcast evening, PM2 and D800 shots taken within a minute of each other.  Lower light level permits exposure without ND filter etc. D800: Tamron 70-300VC 155mm f/5 (nearest...

OK, thanks for pointing that out.  I meant the same physical filter, and hence same risk to image quality, not the same attenuation - though of course it only varies for polarised light.   I could...

I'm replying here though the post relates to several points in the thread. Normally I stick to base ISO on either E-PM2 or D800, so I wondered how high-ISO noise compared, in the sense being...

Sure - I had intended to put `scaled' in quotes, as a surrogate for any transformation, but forgot.  I think we agree that conformal scaling does not work, ever due to the absolutes of aperture and...

It  depends on how the "scaling" from FF to MFT would be done.  Lenses could, in principle, be scaled in various ways: conformally (all dimensions halved, keeping same f/no.), eqivalently (half...

A number of good points have already been raised including the influence of diffration vs. other aberrations as a function of aperture or f/no which makes the task easier for FF.  But then again...