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Roger Cicala tests Lomography's Petzval lens
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PostPosted: Mon Jul 21, 2014 10:51 am    Post subject: Reply with quote
Gerald wrote:
...
What happened to the soft-focus lenses which were so popular in the past? Well, it seems they were simply outdated. Smile

Another conclusion we can draw is that the "theory" that a good portrait requires a low-resolution lens is questionable. But if a photographer really wants to do a portrait with soft focus, he just uses a high-resolution lens and softens the photo with post-processing...


This thinking "Lets do it in Photoshop" is quite normal at the moment.
I still wait for Photoshop enthusiasts to create a good Trioplan like soap bubble bokeh in post processing Smile
There are tools for this, but not very good one from what I have seen up to now.

And the under corrected Spherical Aberration often used in soft focus lenses is just the other way round - I think there is no way to add this in post processing with good results in all situations. Ok, one could paint every picture one can imaging in Photoshop, pixel after pixel, but I rather take the right lens and see nearly the end result live in the optical viewfinder.

But I agree that MTF measurment is a great tool for lens manufacturers. It allows fast and reliable image quality control both for mass production and for development.
Years ago I applied for a job in the laboratory of a well-known lens manufacturer, there my work would have been MTF measurments at their own lenses and competitor lenses as well. Seems they don´t want to compare their own lens MTF results with results form competitors datasheets.


PostPosted: Mon Jul 21, 2014 11:25 am    Post subject: Reply with quote
dan_ wrote:
To come back to the Petzval portrait lens, have a look at this Petzval-made portrait by Jim Galli:
http://tonopahpictures.0catch.com/JesusAt100.jpg
The fine gradation of tones, the mild transition from sharp to unsharp, the ponderate contrast - all are pointing to what's important in the portrait and have a very strong power to express both the inner life of the old man and the photographer atitude on the subject. These, the swirly bokeh and a mild vignetting are the optical qualities one should expect from a Petzval lens.
Used well, as Mr. Galli did, they could be very expresive tools.

Could that be obtained with a modern clinically sharp and contrasty lens and post processing? I very much doubt of it.
Could all this optical qualityes of the lens be intuited by reading its MTF chart? No. If you'd read the MTF of this Petzval your conclusion should be that it's a crappy lens.
Not saying that MTFs are useless. If done properly they succeed well in describing sharpness, contrast, etc. but they can't properly describe all the optical qualities of a lens. And therefore they are quite an improper way to see, for instance, if a Petzval lens is better or worse than other Petzval lens.

In this case (and a lot of other cases) the '500 photos rule' of Erwin Puts seems much more appropriate.
I don't have to make all those photos by myself - I just surf the internet for as many samples as I can find before buying a lens.
They'll reveal the potential of the lens. If what I see is what I want then I'll buy it and use it extensively for a while to get used to it.
If I feel comfortable with it I'll keep it, if not I'll re-sell it (well, that's theoreticaly - in fact, in most cases, my greedy nature makes me keep it anyway Smile ).

And, as always, there is a shortcut : just ask Attila (or other trustfull and experienced members of this forum) and if he says it's a good lens, buy it. Wink


I wanted to take part in this conversation some time ago, but was really busy. Now Dan has said most I wanted to mention and in a much nicer way, than I could have expressed it.

For me personally old lenses are like wine: They come in many different flavors; some fit better for an occasion than others; and there is a substantial component of personal taste involved. Reading about the alcohol content on the label tells you something, but choosing your wine based purely on the measured alcohol content, or claiming that the highest alcohol level is the best wine (after all you could water it down if you wanted) does not really do justice to the rather more complex matter at hand.

And I support the Puts approach not only for lenses but also for wine. Tasting, tasting, and more tasting.

Cheers.


PostPosted: Mon Jul 21, 2014 5:30 pm    Post subject: Reply with quote
Wow, how many interesting comments! So, as Jack the Stripper liked to say, let's go by parts! Razz

RSalles wrote:
Gerald wrote:
Another conclusion we can draw is that the "theory" that a good portrait requires a low-resolution lens is questionable. But if a photographer really wants to do a portrait with soft focus, he just uses a high-resolution lens and softens the photo with post-processing.

Yes, but the charming of these lens is that it comes with "pos-processing" built-in!


A disadvantage of using lenses with built-in "hard-wired special effects" as Petzval and similar lenses is that the effect cannot be canceled or transferred to other lenses. In contrast, focus softening by post-processing is much more flexible:

1) It can be applied to images taken with any lens and any aperture. How about applying softening focus on a fisheye or a super telephoto lens working at F16?
2) The effect can be varied by changing the appropriate parameters.
3) The effect can be applied subsequently; photographer does not need to make the decision at the time when taking the picture.
4) The effect can be undone or modified if the result is not satisfactory.
5) It is cheap.

It is important to note that digital post-processing is a fairly recent technique and therefore is far from being fully developed.

I will now present an example of focus softening using DXO Film Pack 4. The original "portrait" of the tennis player Maria Sharapova was captured with a Canon 500mm F4 lens wide open (even in a dream there is a Petzval equivalent).

The original picture is very sharp but the natural lighting was not good: the white balance is wrong (the image is too redish), and even though Sharapova is a very pretty woman, you can see imperfections and blemishes on her skin. The post-processed picture does more justice to the natural beauty of Sharapova.

I just spent about 5 minutes with the DXO Film Pack 4. I'm sure many of you with more skill and more time than I could do a much better job.

Original picture:


Post-processed picture:


PostPosted: Mon Jul 21, 2014 5:43 pm    Post subject: Reply with quote
Quote:
I just spent about 5 minutes with the DXO Film Pack 4. I'm sure many of you with more skill and more time than I could do a much better job.


I prefer to have the job rather done in 1/125 of a second than in 5 minutes by choosing the right tool. Wink

P.S.: Now is the Canon 500 f4 the right tool to take shot of a Tennis Player? Or Not? If yes, why did it not work? I did not really understand your point.

Last edited by bernhardas on Mon Jul 21, 2014 5:53 pm; edited 1 time in total


PostPosted: Mon Jul 21, 2014 5:48 pm    Post subject: Reply with quote
That processed picture of Sharapova is nothing like the rendering of a Petzval lens at all.

The argument about doing it in PP is like saying 'hey, let's not bother to make cheese the traditional way anymore, now we can make it cheaper in a factory'.

Anyone who has eaten factory-produced cheese knows why they still make traditional cheese - it's 1000x better!


PostPosted: Mon Jul 21, 2014 5:56 pm    Post subject: Reply with quote
iangreenhalgh1 wrote:
That processed picture of Sharapova is nothing like the rendering of a Petzval lens at all.

The argument about doing it in PP is like saying 'hey, let's not bother to make cheese the traditional way anymore, now we can make it cheaper in a factory'.

Anyone who has eaten factory-produced cheese knows why they still make traditional cheese - it's 1000x better!


Haha my brother in law was VP for cheese in a large food multi-national. He never bought the stuff they produced. Very Happy


PostPosted: Mon Jul 21, 2014 5:58 pm    Post subject: Reply with quote
scsambrook wrote:
Whilst not demeaning the value of scientific testing in a carefully controlled environment, I'm not sure why it's 'dumb' to test a lens by taking plenty of photographs - at least not for hobby photographers as opposed to the professional journalists or self-publishing bloggers who pontificate on how 'good' a lens is.
...
Erwin Puts's 'rule of 500' is neither new nor foolish.
...


I do not know where Erwin Puts found the magic number 500 (why not 1000 or 5000 or 10000?). Certainly one does not need to take 500 pictures to discover all the qualities and shortcomings of a lens. Taking 500 pictures to know how a lens performs is a waste of time in my opinion. Today, with modern computational resources, a photographer can know the performance of a lens with only a few dozen test photos.


PostPosted: Mon Jul 21, 2014 6:13 pm    Post subject: Reply with quote
Puts is right, you need to use a lens for a while, shoot it in different settings with different subjects, different conditions, get to know it, learn it's character, it's strengths, it's weaknesses.

MTF charts are mainly for advertising purposes, they don't tell a photographer very much at all about a lens.


PostPosted: Mon Jul 21, 2014 6:13 pm    Post subject: Reply with quote
Gerald wrote:
..
Today, with modern computational resources, a photographer can know the performance of a lens with only a few dozen test photos.


As long as one is statisfied with a bunch of data yes.
But cause MTF for a good but not ideal wideangle and a tele lens construction are a bit different, it is not easy to judge wheter a lens is good or not. One need still some comparison measurments.
And this MTF performance says nothing about bokeh, glow, color-transmission...
MTF is only one single part of a lot of lens properties.

I sometimes like vignetting, distorsion, bad MTF values in some image parts, not exact corrected Spherical Aberration. This is very hard or to most parts not expressed good in MTF values.


PostPosted: Mon Jul 21, 2014 6:24 pm    Post subject: Reply with quote
dan_ wrote:
To come back to the Petzval portrait lens, have a look at this Petzval-made portrait by Jim Galli:
http://tonopahpictures.0catch.com/JesusAt100.jpg
The fine gradation of tones, the mild transition from sharp to unsharp, the ponderate contrast - all are pointing to what's important in the portrait and have a very strong power to express both the inner life of the old man and the photographer atitude on the subject. These, the swirly bokeh and a mild vignetting are the optical qualities one should expect from a Petzval lens.
Used well, as Mr. Galli did, they could be very expresive tools.
............

Galli's photo was clearly manipulated ("photoshopped") to give the impression that was taken with an ancient lens.

Anyone who has ever seen as the process of image formation by a lens is, knows that the focus gradually decreases with increasing distance from the focal plane. Plus, when the lens is bad or partially corrected aberrations, this variation of the sharpness is still slower than a perfect lens.

The photo manipulations in Galli's picture are almost crude. I show in the crop below some areas where changes of focus are abrupt and unnatural. It gives the impression that Galli wanted to leave the ears of the model more blurry than it should.



PostPosted: Mon Jul 21, 2014 6:30 pm    Post subject: Reply with quote
bernhardas wrote:
...Haha my brother in law was VP for cheese in a large food multi-national. He never bought the stuff they produced. Very Happy


Seems to be common Smile
I heard people who work for plastic food packaging prefer glass and ceramic for their own food.


PostPosted: Mon Jul 21, 2014 6:44 pm    Post subject: Reply with quote
Tedat wrote:
Gerald wrote:

Sony publishes MTF for its 135mm F/2.8 [T4.5] STF lens, but only for the F8 aperture. I suspect it would be a little embarrassing to publish the MTF for wide open. Laughing


sorry but this is completly bullshit!

The STF is very sharp wide open (and as mentioned not a soft focus lens).. I suggest you to get some more information before you guess the performance or character of a lens. Even if there are no MTF charts, it would be easy to find out how sharp this lens is wide open.

You are also talking about "extreme croppings".. just get the right lens and the right distance and you don't have to crop at all.



Maybe you should complain to BH Photo Video that lists the Sony 135mm F/2.8 [T4.5] STF lens as a soft focus lens:







Tedat wrote:

The STF is very sharp wide open (and as mentioned not a soft focus lens).. I suggest you to get some more information before you guess the performance or character of a lens. Even if there are no MTF charts, it would be easy to find out how sharp this lens is wide open.

Sharp lens? Kurt Munger found out that the Sony 135mm F/2.8 [T4.5] wide open is poor in the center and crappy at the corners. A Pentacon 135mm F2.8 blows the Sony out of water in the sharpness department. Even the CZJ 135mm F3.5 has more transmission than the Sony (and certainly is sharper, too).



PostPosted: Mon Jul 21, 2014 6:54 pm    Post subject: Reply with quote
Gerald writes that " . . . Taking 500 pictures to know how a lens performs is a waste of time in my opinion. Today, with modern computational resources, a photographer can know the performance of a lens with only a few dozen test photos."

We are, indeed, all entitled to our opinions - "chacun à son goût" as the saying goes. I accept that a photographer may well have knowledge of the optical properties of a lens after only a few dozen test photos using 'computational resources', but s/he certainly won't yet be well acquainted with it. My experience in using and selling lenses since the 1960s has convinced me that time and experience are at least as important as worshop or laboratory testing in deciding whether a lens is satisfactory or not to its owner.

I have owned more than one lens which 'computational resources' demonstrated to be optically first class, yet which for one reason or another proved disappointing to me. And similarly, I continue to get satisfying results from a lens which laboratory testing shows to have MTF curves which look dispiritingly woebegone. I have another lens which although optically beyond [ my ] reproach has 'ergonomic issues' which take much of the gilt off its operational gingerbread. My initial optics-based euphoria wore off steadily in consequence and now it gets left at home as often as not . . . it certainly took me more than a couple of hundred exposures to reach that point.


PostPosted: Mon Jul 21, 2014 6:54 pm    Post subject: Reply with quote
Gerald wrote:

Galli's photo was clearly manipulated ("photoshopped") to give the impression that was taken with an ancient lens.



Edit: for me there is nothing wrong with the picture. there is a very slim DOF and the transition from in focus to out of focus is sharp in all areas.

It was taken with a large format camera and we do not know what kind of movements were involved.

Have you looked at his website? If you post a link I am happy to look at your collection of large format pictures?
What makes you an expert in how they should look like?

A couple more can be found here http://tonopahpictures.0catch.com/MichaelandYousef.html and here http://tonopahpictures.0catch.com/Downings/Some%20uncommon%20portaiture.html


I am very sad and disappointed that you accuse a person of manipulation and deception, without doing your research and homework properly. Please take time to have a good look at Mr. Galli's website and have an informed opinion before you post such preposterous accusations.


PostPosted: Mon Jul 21, 2014 7:21 pm    Post subject: Reply with quote
Gerald wrote:

Sony publishes MTF for its 135mm F/2.8 [T4.5] STF lens, but only for the F8 aperture. I suspect it would be a little embarrassing to publish the MTF for wide open. Laughing

Have you ever visit Sony's site to see the MTF of the STF? Sony have publish the MTF of 10/30 LP/mm for both wide open and F8.
http://www.sony.jp/ichigan/products/SAL135F28/feature_1.html#L2_90

You can find a larger version of the MTF diagram here http://allphotolenses.com/lenses/item/c_980.html .

From many reviews and comments from other members I have heard, the STF have very high sharpness in the center at wide open. Take a look at the samples on photozone http://www.photozone.de/sony-alpha-aps-c-lens-tests/390-sony_135_28?start=2 .


PostPosted: Mon Jul 21, 2014 7:51 pm    Post subject: Reply with quote
Here is the original Minolta 135mm STF lens' measured tables, done independently by the group of people
at the japanese photo magazine "Asahi Camera".



Left two MTFs tables in the bottom were published by Minolta Co. LTD itself.
Upper left defocus character and lower right MTF tables were measured at 2m position at wide open.
lp/mm data indicates a pretty sharp lens.


PostPosted: Mon Jul 21, 2014 8:35 pm    Post subject: Reply with quote
Gerald wrote:
...
Maybe you should complain to BH Photo Video that lists the Sony 135mm F/2.8 [T4.5] STF lens as a soft focus lens:
..

Likely they have not much knowledge - or they want to sell lenses to people with not much knowledge.

Gerald wrote:
...
Sharp lens? Kurt Munger found out that the Sony 135mm F/2.8 [T4.5] wide open is poor in the center and crappy at the corners. A Pentacon 135mm F2.8 blows the Sony out of water in the sharpness department. Even the CZJ 135mm F3.5 has more transmission than the Sony (and certainly is sharper, too)...


Do you understand the apodization filter principle? There is a circular gradient grey filter in the iris - this takes light away. This is the reason why Sony states a 4.5 behind the f-stop 2.8. 4.5 is the T-stop.


PostPosted: Mon Jul 21, 2014 8:58 pm    Post subject: Reply with quote
bernhardas wrote:
I am very sad and disappointed that you accuse a person of manipulation and deception, without doing your research and homework properly. Please take time to have a good look at Mr. Galli's website and have an informed opinion before you post such preposterous accusations.


+10

Jim Galli doesn't photoshop his pictures, he has a vast body of work you could have looked at.

Ever since Gerald appeared here he has been trying to preach at people like he has superior knowledge.

Clearly he underestimates the skills and experience possessed by the members of this forum.


PostPosted: Mon Jul 21, 2014 9:01 pm    Post subject: Reply with quote
ZoneV wrote:
Do you understand the apodization filter principle? There is a circular gradient grey filter in the iris - this takes light away. This is the reason why Sony states a 4.5 behind the f-stop 2.8. 4.5 is the T-stop.

Yes, I understand the apodization principle, but that does not mean I like it.


PostPosted: Mon Jul 21, 2014 9:07 pm    Post subject: Reply with quote
koji and calvin83,

Thank you guys, but unfortunately I cannot read Japanese ... The MTF curves appear to be decent, but…

One of the things that has prevented people to believe in lens measurements is the unreliability of MTF curves published. I do not have a Sony 135mm STF lens to measure it, so I will not contest the curves published by Minolta or the Japanese magazine, but certainly they are in contradiction with the review of that lens by Kurt Munger:

http://kurtmunger.com/sony_135mm_f_2_8__t4_5__stfid268.html

Trying to understand better if the Sony 135mm STF is a good lens, I did a search on the site pixel peeper looking for pictures taken with the Sony 135mm STF lens operating at F4.5:

http://www.pixel-peeper.com/lenses/?lens=1003&perpage=30&focal_min=none&focal_max=none&aperture_min=4.5&aperture_max=4.5&res=3&p=37

Most pictures are of flowers (!) at short distance. Pictures of 3D objects at short distance are not suitable for evaluation of sharpness because the depth of field is very shallow and so most of the subject is out of focus. The best pictures to evaluate the sharpness of a lens are distant landscapes, when the focus is set to infinity.

How is the sharpness at corners in those pictures?

Answer: The same as found by Kurt Munger: crap, crap, crap, crap, crap....

If you do not believe me, check out here:

https://www.flickr.com/photos/tnanba/10527468246/sizes/o/
https://www.flickr.com/photos/tnanba/10527743163/sizes/o/
https://www.flickr.com/photos/tnanba/11003137595/sizes/o/
https://www.flickr.com/photos/tnanba/8254273799/sizes/o/
https://www.flickr.com/photos/tnanba/8254273799/sizes/o/


PostPosted: Mon Jul 21, 2014 9:23 pm    Post subject: Reply with quote
Gerald wrote:
Galli's photo was clearly manipulated ("photoshopped") to give the impression that was taken with an ancient lens.


bernhardas wrote:
I am very sad and disappointed that you accuse a person of manipulation and deception, without doing your research and homework properly. Please take time to have a good look at Mr. Galli's website and have an informed opinion before you post such preposterous accusations.


Mr. Galli is, probably, the most important man responsible for the revival of the use of very old lenses, and in particular of projection Petzvals, in today's large format photography. He has a huge collection of ancient lenses. To accuse him of photoshoping his images in order to give the impression that were taken with an ancient lens is an insult, Gerald. And he doesn't deserve it.


PostPosted: Mon Jul 21, 2014 9:42 pm    Post subject: Reply with quote
Gerald wrote:
...
One of the things that has prevented people to believe in lens measurements is the unreliability of MTF curves published....


Thats what I wrote several times, you can not compare your own MTF measurments with manufacturers MTF measurments. They are reliable each in their system, but not between several testing setups (MTF-software, light, sensor, image processing, chart,..).

Gerald wrote:
...
Answer: The same as found by Kurt Munger: crap, crap, crap, crap, crap....


Yes, the edges look bad - but you must realize it is not a soft focus lens.


PostPosted: Mon Jul 21, 2014 9:48 pm    Post subject: Reply with quote
Gerald wrote:

Most pictures are of flowers (!) at short distance. Pictures of 3D objects at short distance are not suitable for evaluation of sharpness because the depth of field is very shallow and so most of the subject is out of focus. The best pictures to evaluate the sharpness of a lens are distant landscapes, when the focus is set to infinity.

How is the sharpness at corners in those pictures?

Answer: The same as found by Kurt Munger: crap, crap, crap, crap, crap....

If you do not believe me, check out here:

https://www.flickr.com/photos/tnanba/10527468246/sizes/o/
https://www.flickr.com/photos/tnanba/10527743163/sizes/o/
https://www.flickr.com/photos/tnanba/11003137595/sizes/o/
https://www.flickr.com/photos/tnanba/8254273799/sizes/o/
https://www.flickr.com/photos/tnanba/8254273799/sizes/o/


That was the lens intended for - portraits and close-ups with 3D effect and creamy blur. Corner sharpness is not essential in this kind of photography. And is one of the best lenses for for this kind of photography. To ask it to do sharp landscapes too is absurd.
To evaluate its sharpness on distant landscapes is completely pointless and therefor to evaluate its quality by the MTF charts with infinity focus is improper.
Is just like evaluating how good a bus is by its performance in a formula I race competing against race cars. Or saying that an apple is a crappy orange.

Last edited by dan_ on Mon Jul 21, 2014 10:13 pm; edited 2 times in total


PostPosted: Mon Jul 21, 2014 9:51 pm    Post subject: Reply with quote
I did not make a moral judgment of the character of Jim Galli. I just made a technical analysis of one of his photos. I did not say that his picture is forged as it was done in the era of Stalinism, when political figures that fell in disgrace were deleted from the official photographs and books.

Yes, I continue to think that Galli's photo was "cooked" to achieve a certain effect that his audience likes. Even Ansel Adams manipulated pictures (not with Photoshop, of course, because Photoshop did not exist in his day) and everyone enjoyed and prized Adam's pictures.

Why people get outraged when someone says that a photo has been manipulated with Photoshop? Maybe be because Photoshop is modern.


PostPosted: Mon Jul 21, 2014 10:05 pm    Post subject: Reply with quote
Gerald wrote:
Why people get outraged when someone says that a photo has been manipulated with Photoshop? Maybe be because Photoshop is modern.

It's not about a picture being manipulated in PS. I like PS and manipulated pictures quite a lot, if well done.
It is about accusing a honest man of fake(= pretending that he is doing something when, in fact, he is doing something else). And this is a moral judgement of the character of Jim Galli, therefor people got outraged.
His photos are printed on photographic paper and optically enlarged or contact copies from LF sheet film. What one can see on internet are scans of classically processed photos.

Last edited by dan_ on Mon Jul 21, 2014 10:44 pm; edited 4 times in total
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