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rustyair
8-Apr-2013, 00:18
Hi,

Will I see a difference in sharpness or etc when I upgrade Fujinon w 150mm f/6.3 upgrade to Rodenstock 150mm Sironar-n? Number says it would but would I see it in print size 32x40"? Thanks!!

Fujinon w 150mm f/6.3
f/11: 60 60 48
f/16: 48 60 54
f/22: 54 60 54


Rodenstock 150mm Sironar-n
f/11 76 57 27
f/16 76 76 30
f/22 60 60 43

vinny
8-Apr-2013, 06:06
skip that and get a sironar-s, about as sharp as modern len$e$ get.

IanG
8-Apr-2013, 06:49
Those test results are an indication of the relative sharpness of two individula lenses, similar Fujinon or Sironar-N lenses might give quite different results. Kerry Thalman states the Fujinon 150mm f6.3 are good sharp lenses.

It's often a case of working to get the best from the lenses you have, based on those figures I'd prefer the Fujinon at f22 which is generally regarded as the optimum aperture for over-all sharpness.

My main 150mm lens for the past 27 years has been a Sironar-N, I'd take Vinny's point and if I started again perhaps I'd get a Sironar-S but I'm more than happy with the Sronar-N and similar Symmar-S lenses (135mm & 210mm). In addition I get excellent results with a 150mm Tessasr or Xenar indistinguishable in final prints from the more expensive Sironras and Symmars, but of course with minimal room for movements.

Ian

MIke Sherck
8-Apr-2013, 07:19
There's enough individual variation, I think, that you really can't go with published specs. You need to try a lens and see if it does what you need to do: specs tell you what it's supposed to do, not what it does. Does your current lens not provide what you need in your enlargements? Make sure that you have return privileges on potential replacements, then give them a try by photographing with them and making prints of the size you need. When you find a lens that does what you want, buy that one.

Mike

E. von Hoegh
8-Apr-2013, 07:39
There's enough individual variation, I think, that you really can't go with published specs. You need to try a lens and see if it does what you need to do: specs tell you what it's supposed to do, not what it does. Does your current lens not provide what you need in your enlargements? Make sure that you have return privileges on potential replacements, then give them a try by photographing with them and making prints of the size you need. When you find a lens that does what you want, buy that one.

Mike

I agree. You could have tested a pair of Fujis, or a pair of Rodenstocks, and got similar results.

Bob Salomon
8-Apr-2013, 07:49
Since neither lens was designed to photograph a flat chart at near distances and the results can vary with exposure, atmosphere, development, quality of the loupe and how tired your eye is.

test lenses for what they were designed to do. Or check their MTF, color and distortion curves.

Leigh
8-Apr-2013, 13:09
Since neither lens was designed to photograph a flat chart at near distances...
I will challenge that statement and the philosophy behind it.

Magazines and internet fora are full of people claiming that photographs of test charts are somehow invalid.
Rubbish.

Suppose your customer is Stouffer or Edmund Optics, who make and sell resolution charts.
If they want you to take photos of those charts for advertising, they're perfectly legitimate subjects.

Photographic lenses are designed to make accurate images of whatever subject is placed in front of them.
Period.

Performance at closer subject distances is certainly a function of lens design (macro vs. non-macro), but
that has nothing to do with the nature of the subject.

- Leigh

Nathan Potter
8-Apr-2013, 15:02
I use a simplified assessment for a lens capability for resolution at a particular enlargement. The degree of enlargement under most conditions of best focus (a big if) is limited by diffraction effects. For your test data above, and if we equate a diffraction limited airy disc to a line width (approximately valid) the limits at the f/stops listed will be:

f/11 = 14 Ám linewidth = 35 lp/mm. = 70 l/mm
f/16 = 21 Ám linewidth = 24 lp/mm. = 48 l/mm
f/22 = 30 Ám linewidth = 16 lp/mm. = 32 l/mm.

Don't know where that test data came from but it is improbable that it is relevant for determining what you want to know. Clearly at f/16 and f/22 those results are suggesting resolving power well above the diffraction limit for that aperture.

A 32 X 40 is a big print and if your film is 4X5 your enlargement is 8X. That means a line appearing on your print is 8X the width on film. Taking the best case of f/11 at at 70 l/mm diffraction limit (14 Ám linewidth) 14 X 8 = 112 Ám resolved (a bit over 4 mils) which generally is OK for critical viewing).

At smaller aperture of f/22 the diffraction limited linewidth is about 32 Ám so at 8X that becomes 256 Ám or about 10 mils and will show very discernible blurring in a 32 X 40 inch print.

The practical limit in resolution for most LF lenses comes from the diffraction limit. In fact test data that shows significant resolving power much above a diffraction limit should be considered somewhat suspect. A more useful measure of resolving performance would be the image contrast at the diffraction limit. Thus MTF data yields a more complete picture as Bob Salomon has indicated.

I guess what I would say is choose either of those lenses because the limit in resolution will be diffraction, the same for both lenses despite what the test data says. I could believe that the Rodenstock might have a bit more contrast.

Nate Potter, Austin TX.

rustyair
8-Apr-2013, 15:15
Don't know where that test data came from

Thanks guys. I got the test data from link below.

http://www.hevanet.com/cperez/testing.html

Fuji W f/6.3 150mm Seiko #0

Rodenstock Sironar N f/5.6 150mm Copal 0

Bernice Loui
8-Apr-2013, 19:11
Moving away from these numbers which have a large number of variables and is subject to individual variations of each production lens,

Would it be possible to be more specific about the motivations and observations of why a "shaper" lens is required?

It is so easy to be mis-lead by simplified numbers like this to make judgments about what is a complex subject of optics performance. It goes far, far beyond LPM or MTF and...

Overall performance must be considered as a system including film (or digital imager), camera precision, image plane (film or digital) flatness/alignment and more. A "better_shaper" lens is not the only link in the system that makes a difference in the overall result.


Bernice



Hi,

Will I see a difference in sharpness or etc when I upgrade Fujinon w 150mm f/6.3 upgrade to Rodenstock 150mm Sironar-n? Number says it would but would I see it in print size 32x40"? Thanks!!

Fujinon w 150mm f/6.3
f/11: 60 60 48
f/16: 48 60 54
f/22: 54 60 54


Rodenstock 150mm Sironar-n
f/11 76 57 27
f/16 76 76 30
f/22 60 60 43

Nathan Potter
8-Apr-2013, 19:52
Bernice as you point out there are many other factors that affect the performance of a camera "system" even more than you alluded to above. But the OP has specifically limited his choice to sharpness which is defined by the industry in terms of lp/mm and contrast via MTF plots. These are pretty precisely defined metrics along with diffraction limits. The diffraction limits are a particularly good way to determine the approximate resolving power of a lens as a function of f/no and that is what is critical in the field if one is after resolution especially for large prints as the OP desires.

Lp/mm and MTF plots are not variables if the method of recording is delineated. That means, for instance, that the distance of the target is recorded, the target contrast is known and whether the recording of lp/mm is from an aerial image or from a piece of film. The modern method is to use digital capture (I hate that word) and analyze the data using Imatest software, for example. This is all pretty precise stuff and provides the best metric for determining sharpness without actually taking pictures and trying to quantify and compare sharpness from a set of images.

Yes in the real world we take pictures, but then we are not talking about lens resolution but about a complex photographic "system" of which the lens is but a small part. The OP is specifically talking about the sharpness between two lenses with no mention of film.

It would seem that talking about resolution in precise terms bothers a lot of people and I think I understand that, but many of us have also moved up to LF for the very purpose of achieving greater "sharpness" in our images. There are of course a whole host of other applications where "sharpness" doesn't matter a hoot. Certainly with many of the antique lenses talking resolution is near nonsense, since the real glory is in the multifaceted distortions that are unique to each lens type.

Nate Potter, Austin TX.

rustyair
8-Apr-2013, 20:14
Would it be possible to be more specific about the motivations and observations of why a "shaper" lens is required?

It is so easy to be mis-lead by simplified numbers like this to make judgments about what is a complex subject of optics performance. It goes far, far beyond LPM or MTF and...

Overall performance must be considered as a system including film (or digital imager), camera precision, image plane (film or digital) flatness/alignment and more. A "better_shaper" lens is not the only link in the system that makes a difference in the overall result.
Bernice

Watch the wind blow, sturdy tripod and head, use cable release, focus...etc...I think I got other parts down and it's because shaper lens means less blurry in large print image I guess. It's true that A "better_shaper" lens is not the only link in the system that makes a difference in the overall result but it's definitely one of them. :) Btw, It's portra 160 film and an ebony I'm using.

Nathan Potter
8-Apr-2013, 20:14
I should point out the dilemma of resolution variation between samples of the same lens. This is sometimes quite large, as mentioned above - possibly 30% difference. However when using a diffraction limit criteria the resolution limit is a fixed function, (2.44 X wavelength X f/no). It's not a function of the glass unless the glass is particularly bad.

Y'al can't change 2.44 X wavelength so to improve resolving power you have to use larger apertures.

At f/8 you get an airy disk diameter or about 10 Ám
At f/4 that drops to about 5 Ám
At f 1.2 it drops to about 1.5 Ám

Of course at some lower f/no optical distortions will swamp the diffraction limit but for most LF lenses that is below f 5.6 to f/8.

Nate Potter, Austin TX.