How is this lens for 4x5? Image quality? Can get for 269. Image circle is 187mm at f22. Is it as good as the f4.5? Or better? See picture for a side view.
How is this lens for 4x5? Image quality? Can get for 269. Image circle is 187mm at f22. Is it as good as the f4.5? Or better? See picture for a side view.
It is fine but not near as good as the 4.5!
It can be added that a sample of this lens was measured here: http://www.hevanet.com/cperez/testing.html
f/11 67 60 42
f/16 60 60 24
f/22 54 54 38
This is optical performance measured in the center, the mid an in the corner.
The pointed measure at f/16 in the corner, 24, probably comes from a camera alignment or film flatness miss, it's not consistent with 42 and 38.
This was a DIY test, not an absolute Lab test, but it can be very useful to see some trends, see disclaimer at the bottom of the linked page, but if those 67 Lp/mm were seen by Mr Pérez, at least that was there.
Also there is the sample to sample variation... but this test points that, as Bob says, this is a very competent glass, no doubt.
I've tested the old GD 90 a friend has, single coated, also very good but not MC in that case...
It is extremely misleading to rely on their tests, they did those tests at different times and under different conditions each time so their results can not be duplicated. Further, their test of photographing a test chart plastered on a wall at closer distances does not show how the lens will perform at the distances the lens was designed for or on the subjects it was designed for. Unless one is buying a wide angle lens to copy new print!Originally Posted by Pere Casals
Bob I fully agree this is a practical test that may have pitfalls like the pointed "24" value, but let me make a reasoning.
What I say is that (IMHO) while that practical test have severe limitations still it's enough to say that in general the Grandagons are 1st class glass.
I'd say that to interpret well that test we have to keep in mind 2 things:
1) The actual performance of the tested sample could be better than the measured one, but not worse, because it's very difficult that a pitfall in the test ends is a higher measurement
2) Another sample we are to purchase may be better or worse than the tested one, even we may get a pretty dog lens
Note:
This is a 1:20 consistent test, so 67 Lp/mm at f/11 center says that Mr Pérez saw 3.35 Lp/mm in the test chart.
Group 1 Element 5 is 3.17 Lp/mm and Group 1 Element 6 is 3.56 Lp/mm.
The final 3.35 Lp/mm can come from doubting if the visible patern was the 5 element or the 6... ..or he averaged something.
Well, perhaps the shot was not good enough and with a better focus he could even been reading 73 Lp/mm... but we know he was viewing element 5 or 6 at 1:20, and this corroborates that sample of the Grandagon N 75/6.8 was a very good glass.
Manufacturers never specified Lp/mm at extintion for their taking lenses, but showed "average" MTF graphs that have more technical sense ...but not many understand well. At the end the USAF 1951 is practical test from military, and military wants very practical things.
Al interesting. One could just buy it and try it. If not liked then sell it. my other cboice is the Nikkor 75mm with a bigger image circle. Or for around 1000 bucks the 72mm Schneider lens.
IMHO you won't find a bad 75mm choice from the 4 principal manucaturers.
Just you have to know what circle you want, if not doing architecture you may sacrifice circle for weight and price. At the end you will have a lot of fall off in the boundary of the larger circle...
When deciding, I prefered a 65mm and a 90mm, IMHO the 75mm replaces both, so it saves one glass in the bag, being more polivalent ...at the expense of not having 65mm wide. From the 75mm shot you allways can crop the 90mm framing.
Perhaps the 75 is a better choice than hauling the 65 and the 90.
This is all true. I definitely want a large image circle. I do use shift and rise in landscape and shoot architecture. A center spot maybe pricey, but worth it especially for night/long exposure stuff.
Just look at the factory curves for MTF, distortion, color, fall off, etc. and you will see how well they perform. And you won’t be mislead by chemistry, atmospheric conditions, eyesight, loupe quality, exposure, lighting, how tired the observers eyes are, etc., etc., etc..
Have both f4.5 & f6.8 and used them. Essentially, the difference comes down to size and what the imaging needs are. The f6.8 is smaller with a slightly smaller image circle, the f4.5 is larger with a slightly larger image circle. f4.5 has slightly less distortion ONLY visible in straight line architectural images of critical examination and slightly brighter on the GG. The f6.8 does most everything the f4.5 does but smaller. In real world image making, they are essentially the same with the f6.8 being more compact.
Compared to the Schneider 72mm SAXL, the SAXL has a larger image circle easily covers 5x7 with similar image quality and it is a MUCH larger lens than the 75mm f6.8 Grandagon. With all these WA optics, light fall off can be an issue depending on imaging need.
Nikkor 75mm f4.5 has the SAME image circle as the Rodenstock 75mm f4.5 (yes, disregard those published sheets) except for higher contrast and reduced contrast gradation.. it is a look common to Nikkor SW series, it is a different image result, different set of trade offs.
As for those "On Line" lens test... the variables that affect any given example of optic can vary a LOT and as previously mention too many times, images made by any given optic is a LOT more complex than LPM.
Bernice
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