No agreement is necessary. We disagree. Period.Originally Posted by MAubrey
No agreement is necessary. We disagree. Period.
We disagree to disagree? Uh, okay. I agree.
Drew, I'd like to point something important about Mr Pérez tets...
It is posssible that a DIY test underrates some performance value of a lens, but it is very difficult that the measuremet is overrated.
USAF 1951 test is a bit subjective, sometimes you can pick an element or the next, and this usually may bring on an uncertainty of some +/-6% in the Lp/mm value.
Beyond that 6% uncertainty, a Mr Pérez measurement could have a flaw, because alignment, film flatness, etc... but when he says that he saw 72 Lp/mm at least there were those 72 Lp/mm with that 6% uncertainty, because any flaw would degradate the reading rather than overrating the measurement.
Some f/11 readings perhaps may be flawed, but f/22 readings are very consistent because plenty of on film DOF allows for a wider margin. For example a 210mm test would have the target at 4.2m for the 1:20 magnitication of the tests, and at f/22 dof would be 1.5m DOF on the targuet, so way more than enough on film, if checking it. The 1:20 magnifications allows for an easy testing anyway.
He says in the "Please Note" section: "This is at best a relative (not absolute) comparison between these lenses. Kerry and I are simply looking for the Pick of the Litter.".
An important issue is that a reflective resolution target may deliver perhaps 1:50 contrast, but not 1:1000 or 1:1.6. At TOC 1:1.6 TMX delivers some 60 lp/mm, while at 1:1000 it delivers from 160 to 200lp/mm.
A grain of salt... yes, but also it is important to realize the actual value of that information.
Who cares about resolution tests and optical lab results. The Nikkor 450m proved itself to me years ago on 8x10 particularly and it produces amazing sharp and contrasty results consistently and without fail. The three Nikkor 450M lenses I use are all consistent performers between them as well. Indistinguishable between the lenses is the operative word that comes to mind. The other thing I love it is about the longest focal length that I can reach the f stop ring to stop down with while watching the GG. I also have and use the Fuji 450C which is my light weight alternative on 4x5 5x7 and 8x10.
You have three?
Yup. I really enjoy the lens and the price was right.
I have multiples of other lenses as well that i have come to appreciate and enjoy. Call it a natural hedge to discontinuance of the Copal Shutter as well as the lens manufacturers decision to exit stage left.
Pere - the is just so much about that particular lens test reference that doesn't ring quite right that I personally find it useless to consult. For Schneider and Rodenstock lenses, the performance data have actually been published including a much wider selection of parameters on actual charts or graphs than any one-shoe-fits-all approach on the web. There can be no doubt that Fuji and Nikon have done their homework just as well. And if Perez did take measurements from film exposed in an ordinary holder, it would void anything accurate. It has to done either with an aerial image or special film precisely flat in a vacuum holder, on a precision optical bench. But a lot of this gets downright silly. Lenses do differ in cost, weight, and minor personality differences; but nearly all modern ones are PLENTY sharp for sheet film use, even at substantial enlargement.
Drew, I never before thought of my 14" Commercial Ektar as the drunken sailor of Tessars, but since you bring it up, it sounds about right---especially since one night on McGilvery Creek in the Sierra I had to use vodka for lens cleaning solution LOL!
"I would feel more optimistic about a bright future for man if he spent less time proving that he can outwit Nature and more time tasting her sweetness and respecting her seniority"---EB White
The amount of quibbling over meaningless test numbers never ceases to amaze me.
The 450M is a great lens on 8x10 and just as good at much larger formats. Despite the earlier accusation of ULF only being "contact printed," I've also scanned some 8x20 negatives from the 450M and see no appreciable corner degradation at that size even with high magnification.
The OP will certainly have a top lens for 8x10 and at a better price than some of the other, rarer options.
John - vodka might also to change the way a print looks. You wouldn't need a separate soft-focus lens.
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