Mastering the Art of Lens Testing – Welcome

Welcome to this DearSusan course on lens testing in the field !

You have taken an important first step on a new path. One which will free you of biased opinions and make lens testing fun and super easy. All the team thanks you for your interest and wishes you a heap of fun running these tests through a collection of lenses, old and new, cheap and expensive. Trust us, you’ll be surprised by what you find on the way !

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We’re very fortunate, on DearSusan, to enjoy positive and constructive comments. It isn’t like that everywhere on the web and websites that deal with photographic gear often stage heinous flame wars between partisans of one brand and fanboys of another. It’s not a pretty sight and, amidst the anger, you also find a huge amount of misinformation.

It doesn’t have to be that way.

More than any other piece of photographic gear, lenses are open to personal investigation. These optical devices share two characteristics:

  • They serve to create a photographic look that plays an important role in a photographer’s signature.
  • They stay with you for a long time. Far longer than most camera bodies do.


Even today, on my late 2015 mirrorless camera, I’m using lenses that were created when film was still the only medium for recording photographic images. Made by Leica (for R-mount), they benefited not only from some of the best technical capabilities of the time but also from a vision of what photographic aesthetics should be. These days, they are also really cheap. These lenses are not neutral and impart a distinct look on my images.

My more recent purchases from other manufacturers carry a very different signature, one that is common through the range, yet much less visible on first inspection. Those purchases were made on conscious choices made knowing what to expect from each lens after only a short time with it. This is the look these new lenses give my recent photographs :






These photos are very transparent and contrasty, very direct. It’s a look that appeals to me. But you’ll notice the pronounced purple fringing on the cables running along the top of the frame. This is not a perfect lens, not by a long shot. But I can live with it’s aberrations and it’s 60% cheaper than rival lenses from prestigious companies.


This course is not about brands or designs. It is about understanding how to evaluate lenses for yourself, by defining your own criteria and finding situations which allow you to check the lens for each of them.

Note that I haven’t mentioned the term performance up to here. Brand marketing and the media have brainwashed us into thinking that the first requirement for a lens is optical perfection.

That mental implant helps sell the newer, better, lenses that constantly leave the production chains but also leads to sterile productions and the ironic revival of vintage lenses, digital filters that reproduce the look of old gear or film and whole systems built on the very idea of imperfection-as-a-feature (Lomo anyone ?).

As much fun as these neo-retro initiatives can be, they rapidly become every bit as limiting as the laboratory number-cruncher game. If you want to create a style that’s yours, you need to understand lenses and their rendering and learn how to test them for yourself. Just as any painter gets to know its paints, learning to evaluate the signature of your lenses will not only free you of outside opinions but also get you well on the way of finding a personal style you love.


Imagine you’ve ordered a lens from B&H and have to decide whether to keep it, borrowed one from a friend for a short spell, are meeting with a seller over coffee or have illegally entered your dream photo store through the roof in the middle of the night and have only 30 minutes before you need to retrace your steps and return it (because, as a DS reader, you’re a good person 😉 ).

Magazine reviews are not readily available and may present a biased judgement if you do find one. Most websites run tests using equipment that is woefully inadequate for significant lab evaluation and provide few useful test shots in real life situations. Forums can be theatres for fanboy flame wars and how do you tell the informed voice from the incompetent braggard?





When you have completed this free DearSusan course, you will be able to grab an unknown lens, run tests with it for less than 30 minutes and decide for yourself whether it is the sort of lens that will serve your vision and your type of photography. See that motorbike picture above. That lens is almost perfect. Almost. Notice the purple fringe running the along the cables? Is that serious? Does it degrade image quality significantly? Can it be cured? These are the questions answered in this Master the Art of Lens Testing tutorial.

Now, we’re not saying this will instantly turn you into a new Lloyd Chambers and allow you to set up shop. What this course aims to achieve is to provide the basic understanding to allow you to see for yourself. To let your eyes weigh into purchase decisions rather than relying exclusively on what others (or machines) have to say.

It made up of 8 very simple lessons, each dedicated to a specific aberration, each containing the follwing information :

  • What it is: a description of why the aberration happens in lenses. This is optionnal reading presented for backgrounf information and personal interest. You do not have to read this to learn how to test lenses.
  • What it does to the image: again, optional reading, provided for you to decide whether you mind about the issue or not. Some aberrations are a real pain for some types of photographers (mustache distortion, in architectural photography, for instance) while others won’t even notice it. If you have only a short time to test a lens and want to keep it reaaaally simple, just skip the parts that aren’t important to you 🙂
  • How to test for it: the name says it all. This section presents step by step instructions to provoke the lens and make the aberration obvious to you.
  • How to fix it: this optional reading section is precious.

The course is richly illustrated with examples from my own evaluation process. From this day on, you will be receiving a new lesson every 3 days, leaving you plenty of time to try each lesson on your current lenses, compact camera or even on your smartphone!


A new dawn - Sony A7rII uncompressed RAW & Zeiss Disatgon 1.4/35/ZM

Lesson one should be in your inbox now. Have fun!


How You can help ! Please comment and share this page.

This extensively researched and clearly presented course is totally free. It was lovingly created to help you on your way to self-expression. All that we ask in return is that you leave comments below or share with your friends on social media. Spread the love and let’s build a better photo world together.

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  • vincent bilotta says:

    reading this page, i feel fortunate to find this.

  • Andrej says:

    I’m a bit short on time these days so I don’t know if I’ll be able to test out my lenses before my exams are over. I am certain this course will be an intresting opportunity to learn something new and I’ll be sure to try and apply everything you teach me as soon as I find the time.

    PS. I really like the texts on this website and how you manage to both cover all important aspects of a reviewed product (technical and subjective alike) and note how it all translates into actual use and results. Those posts not based around gear are, likewise, a pleasure to read. Keep up the good work 🙂

    • pascaljappy says:

      Thank yo Andrej, that’s very kind of you and it encourages us to keep going. Don’t worry if you’re short on time, we’re keeping these pages up so you can access them whenever you feel like it. All the best, Pascal

  • Guido Van Leuven says:

    i am Guido from Belgium

    Sorry my English is not so well

    Thanks for your lessons . I bought a new samsung nx500 en for that reason I like to use
    lenses from canon en also a old 42mm lens with adapters. I was wondering that the cheap kit lens from samsung works very good en I make now photo’s with a cannon lens witch is more expansive en also with the native lens for comparisons
    So many thanks for your curses

  • Dan Peter says:

    Thanks Pascal, fantastic idea. I really appreciate this tutorial. I already own about fourty lenses mostly primes made by different manufacturers from the mid sixties up to now (Leica R, Voigtländer, Contax G Carl Zeiss and Contax Yashica Zeiss, Canon FD and EF, Nikon, Minolta and Sony FE) all in use on my Sony A 7. What a pleasure to revitalize some old darlings that worked 30 years ago on my Canon A1 or on my T90 or on my EOS 620 or D350. But sometimes it is really hard to decide which lens to take for a short trip. I always try to choose three or four that have a similar optical character to fit together. With your tutorial I hope to get some more and fast criterias, just an easy help for my own decision. And I think I have not finished my collection… Thanks again!

    • pascaljappy says:

      Dan, what a collection that is and what a great project ! Make sure to catalong your photographs, they will be a mine of knowledge. The course itself is about finding defects, so make sure to also make photographs of the aspects you enjoy, just to complement the analysis. We’ll be dealing with those subjective strong points in a second tutorial in a few weeks. Cheers, Pascal

  • Robert says:

    Hello Pascal, i am excited about your writing and your impressing photos. I am looking forward learning to examine my lenses. I have about 30 lenses. New lenses from Canon and Fuji and some fine old manual glass. In the last months i apreciated some manual lenses because of their rendering and how the pictures look. Its often more pleasing for my eyes than the newer ones. Thank you for sharing your experience and time.

    • pascaljappy says:

      Hello Robert, thanks so much for the kind words. 30 lenses !! I am so jealous. My collection has dwindled significantly. I think testing old lenses is particularly interesting because newer ones often have great results but lack soul. So the older ones can have a more pleasant look and, by testing them, you’ll find out the one or two situations you need to avoid where they behave in a way you don’t like. And, in all other situations, you’ll just enjoy the rendering. My Leica-R 19/2.8 was fabulous but hast strong ghost images against the sun, for example. Have fun and if you have interesting results, feel free to share them with us. Cheers, Pascal

  • Oleksandr says:

    Hello Pascal! I found your site by accident when I tried to find some information about new Zeiss Loxia 21/2.8, I was very glad to find so intersting and emotional review with mentions of other lenses in it. I have Nikon D800, Nikon F100 and Nikkor autofocus and manual lenses, few Carl Zeiss ZF.2 as well. Before that I had collected 8 best Soviet prime lenses with Nikon F mount but I sell it. Now I’m inerested in moving to Sony A7RII from Nikon because I’d like to have smaller weifht and size of camera and lenses and because I’d like to use any lenses of any brands on this camera. Unfortunatelly, I can not make it soon but I keep the hope. As for me, it is a great idea to can test lenses fast, to waist not long time to understad and get your own considered and weighed decision and to share it to other people. That is why I thank you for your open project and wish you success in your action. Sorry about my English.

    • pascaljappy says:

      Hi Oleksandr, thanks for the great message. I’m so glad you are finding this useful. If you ever move to Sony A7rII and still have one or two fo these Soviet lenses, I think you’ll find them very ineteresting and lovely. Please sendus some photographs you make with them, we’d love to see and share them 🙂 You English is great.Where are you from ? Cheers, Pascal

      • Oleksandr says:

        Pascal, thank you for your answer. I’m from Ukraine. All last year I stayed in Poland and I didn’t photograph at all. I wait for Spring to start shoot again. I’m a bit sorry that I sell all Soviet lenses but if I have A7RII, I will test many interesting old lenses of my friends. I need to wait one-two years when price of this camera will be lower, and for now I want to spend about 30 different films that I keep in refrigerator with Nikon F100 and Olympus Mju-II. Your site inspires me! Thank you!

  • Alistair Barclay says:

    Hi very please to have found this, looking forward to the lessons and testing. I have old Pentax lenses I use on My Sony A7r2 and this should be a very interesting exercise,
    Thank you!!☺

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