F-stop limits with 39MP sensors

[Ray]

Wait a minute!!!! Does that mean that you have actually tested a P25?
[a href=\"index.php?act=findpost&pid=206909\"][{POST_SNAPBACK}][/a]

No it doesn't. It means that no-one else on this forum has done the test (properly) and that I therefore have to deduce the results from my understanding of theory.

I'm always open to correction if someone shows me their tests carried out with impeccable methodology.

[Jack Flesher]

And here we go. Again...

[Ray]

And here we go. Again...
[a href=\"index.php?act=findpost&pid=207009\"][{POST_SNAPBACK}][/a]

And we shall continue to go again untill you get it right. These issues are not difficult. If you can't get simple issues right such as sensor size, appropriate F stop, lens specifications etc, then we've got no hope.

We're in a world crisis of climate change and we cant't even decide if a P21 has significant advantages over a 1Ds3.

[Jack Flesher]

I've got it all sorted out just fine Ray, but thanks for your concern.

And best wishes as you continue trying to convince the world of the veracity of your theoretical extrapolations to qualitative performance characteristics of gear you've never even used.

 ,

[BJL]

If an MF lens with high resolution sensor such as the P45 or Aptus 75 appears to be virtually as sharp at F16 as at F8 ...
[a href=\"index.php?act=findpost&pid=206848\"][{POST_SNAPBACK}][/a]

If you had studied the examples linked earlier in this thread, you would see the irrelevance of this hypothetical: there is clear evidence that lenses like the Rodenstock HR 180/5.6 are noticeably sharper at f/8 and even f/5.6 than at f/16 or even f/11. I would say that resolution close to diffraction limits at f/8 is a reasonable hope with the right MF lenses, and maybe even to f/5.6.

By the way, Hasselblad provides MTF graphs at up to 40lp/mm for four lenses combined with the new tilt-shift adaptor and its 1.5x mag., and these can be no better than MTF at 60lp/mm without that mag., so we have an estimate of the 60lp/mm performance of those lenses.
In a nutshell: about 50% at center of field, less elsewhere. (Not bad, but not as good as any Olympus FourThirds lens at 60lp/mm and wide open; maybe close to the kit zooms. It does seem that format size matters with attainable resolution in l/mm.)


By the way: with 6 micron pixel pitch and Hasselblad touting 83lp/mm sensor resolution (the Nyquist limit), how about publishing MTF data at higher than 40lp/mm? Ditto to Canon and Nikon, which stay at a maximum of 30lp/mm and 40lp/mm respectively despite offering even higher sensor resolution.

[Ray]

I've got it all sorted out just fine Ray, but thanks for your concern.

And best wishes as you continue trying to convince the world of the veracity of your theoretical extrapolations to qualitative performance characteristics of gear you've never even used.

 ,
[a href=\"index.php?act=findpost&pid=207039\"][{POST_SNAPBACK}][/a]

It's a sad state for humanity if, in this modern age of computers and excellent jpeg compression, the average consumer cannot arrive at a state of understanding of image quality without getting the gear and testing it for themselves.

[Ray]

If you had studied the examples linked earlier in this thread, you would see the irrelevance of this hypothetical: there is clear evidence that lenses like the Rodenstock HR 180/5.6 are noticeably sharper at f/8 and even f/5.6 than at f/16 or even f/11.
[a href=\"index.php?act=findpost&pid=207040\"][{POST_SNAPBACK}][/a]

BJL,
If you read my previous thread, you would see that I mentioned the fact that Sinar and Rodenstock lenses specifically designed for DB are the exception.

The trouble is, we don't have any independent authority, such as Photodo, to test such lenses.

We're well and truly into the bull shit age of hyperbole and unsubstantiated claims.

[gss]

We're well and truly into the bull shit age of hyperbole and unsubstantiated claims.
[a href=\"index.php?act=findpost&pid=207053\"][{POST_SNAPBACK}][/a]

This is an amazing statement from someone who refuses to substantiate any of his claims by performing an actual experiment.

[Ray]

This is an amazing statement from someone who refuses to substantiate any of his claims by performing an actual experiment.
[a href=\"index.php?act=findpost&pid=207057\"][{POST_SNAPBACK}][/a]

This is an amazing statment from someone who apparently hasn't bothered to check out my history on this forum. I've posted hundreds of image experiments and comparisons testing particular characteristics of lenses and system resolution.

However, I'm not prepared to spend thousands of dollars renting equipment for the purpose of testing. But I'm very obliging when asked to provide tests of the equipment I own.

[BJL]

... I mentioned the fact that Sinar and Rodenstock lenses specifically designed for DB are the exception.
[a href=\"index.php?act=findpost&pid=207053\"][{POST_SNAPBACK}][/a]

Did you miss my comments abut the Fujinon H system lenses?

In fact, they need clarification. The 50% figure is for the lenses wide open. MTF is also given for f/11 with 1.5x mag., which means the lenses themselves are at f/7.3, and there the MTF is about 60% central. As I noted in another thread, the real sensor resolution limit for 6 micron pixels with Bayer CFA is probably about this 60lp/mm.

So it seems that even those nasty Japanese lenses can keep up with the new wave of 6 micron pixels, and thus I am sure that the inherently superior German MF lenses can too! (Not a dig at you, but at posters for whom certain German brand names are a guarantee of superiority over any Japanese product at any price.)

[Ray]

Did you miss my comments abut the Fujinon H system lenses?

In fact, they need clarification. The 50% figure is for the lenses wide open. MTF is also given for f/11 with 1.5x mag., which means the lenses themselves are at f/7.3, and there the MTF is about 60% central. As I noted in another thread, the real sensor resolution limit for 6 micron pixels with Bayer CFA is probably about this 60lp/mm.

So it seems that even those nasty Japanese lenses can keep up with the new wave of 6 micron pixels, and thus I am sure that the inherently superior German MF lenses can too! (Not a dig at you, but at posters for whom certain German brand names are a guarantee of superiority over any Japanese product at any price.)
[a href=\"index.php?act=findpost&pid=207081\"][{POST_SNAPBACK}][/a]

BJL,
I accept there are a number of MF lenses that have excellent performance at wide apertures. I mentioned the Digitar lenses with reduced image circle as an example.

However, the point I make is still valid. If image resolution at F16 appears no worse than at F8, using a high resolution sensor (such as the 40D, 1Ds3, P45 etc) then there's an implication that the lens is not particularly sharp at F8, or as sharp as it could be, or as sharp as some other lenses at F8.