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03-31-2017, 10:11 AM   #1
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How do you assess lens quality?

I have acquired more lenses than is useful due to some of them coming with other things I bought. Nothing particularly interesting but I would like to work out which are the opnes to keep.

Other than just noting my general impressions over an extended time is there a method people use to assess lenses against eath other that would be a faster and more scientific approach ?

03-31-2017, 10:19 AM - 2 Likes   #2
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join the Single or Daily challenge and shoot with a lens for an entire month - you'll find any shortcomings and decide what to keep....
03-31-2017, 11:17 AM   #3
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I like to do some kind of controlled comparison test if I have comparable lenses, say a number of 28mm lenses. But I only test because I like to. Often I find one lens that is pretty bad, one is OK and maybe six are pretty good. Then it really does not matter whether one of the good ones is slightly sharper in the corners at f5.6 on a flat subject. I always end up using the good lens that I like for other reasons. That might be "looks cool on the camera" or "fits in my pocket" or whatever. So testing doesn't do anything for me than shooting for a while with the lens would.
03-31-2017, 11:26 AM - 1 Like   #4
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If you want to be super scientific, then you'll want to download an image of a resolution test target, print a bunch of copies, paste them all over a big cardboard sheet and mount it on a large blank wall so you can take carefully controlled shots at each aperture. (For extra credit, use pixel shift mode!) This is a lot of bother and a good way to fill up a hard disk if you have a lot of lenses, test every aperture setting, and test different zoom settings. But it is scientific and lets you really compare lenses side by side.

If you want to get a quick-and-dirty assessment of resolution, point the camera at large, full book shelf, put the camera in live view, zoom to the max, focus carefully, and take a little tour of the image. That will show you overall softness in the center and corners in terms of how blurry the book titles are. You'll also see evidence of chromatic aberrations and, if you are careful you can check for field curvature in which the lens focuses at a sligthly different distance in the center versus the edges or corners. As a bonus, the straight lines of the shelves will make any pincushion or barrel distortion obvious. Digital preview snapshots can be used to test the lens stopped down.

If you want to convince yourself that almost every lens sucks (but some suck more than others), then point the camera at a nighttime skyline with lots of tiny bright lights and take another live-view-zoom tour (when you visit the corners, you'll probably need to angle the camera to get horizon lights in the magnified view). That test will strongly show all the aberrations that most lenses have wide open. A similar test is to take an astrophotograph if you have good dark skies.

A quick and dirty test for flare and contrast issues is to point the camera so that the sun is just out of the frame (be careful not to blind yourself) and then use your hand to block the sun from falling on the front elements. If the scene in the viewfinder goes from slightly foggy to nice and contrasty, then the lens probably has some flare, internal dirt, or shiny internal bits that will reduce contrast in backlit situations.

Of course, as many will note sometimes the worst lens (from a scientific standpoint) has some redeeming quality in which it's softness or low contrast actually improves certain kinds of the images.

03-31-2017, 11:51 AM - 2 Likes   #5
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The best way is not to pixel-peep :-)

There are so many factors that go into a "good" image, and it's all mostly relative and personal preference.

There are some members who know all the ins and outs of fancy lenses and I believe everything they say about gear, though in many cases I have no idea what they are saying :-)

You can do all the lens measurements and testing for numbers, but for me it boils down to smiling or frowning when you use it.

Last edited by SpecialK; 03-31-2017 at 03:30 PM.
03-31-2017, 11:55 AM   #6
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The book shelf test , the night scene with tiny bright lights. Play around with enough lens because you have LBA and you end up with the same conclusion. Not certain if it is, great minds think alike ;or the lens arrives, unpack, wonder if it is any good, the alcove bookcase is just 10ft away.
03-31-2017, 12:05 PM   #7
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QuoteOriginally posted by pepperberry farm Quote
join the Single or Daily challenge and shoot with a lens for an entire month - you'll find any shortcomings and decide what to keep....
QuoteOriginally posted by Frosty66 Quote
I have acquired more lenses than is useful due to some of them coming with other things I bought. Nothing particularly interesting but I would like to work out which are the opnes to keep.

Other than just noting my general impressions over an extended time is there a method people use to assess lenses against eath other that would be a faster and more scientific approach ?
I'm a terrible one to talk since I tend to buy and keep a long time and sometimes regret sales.

I really honestly think you should read this:
Nikon's 'Worst' and 'Best' Zoom Lenses Compared

The point of the article is that while spending money on a new "better" lens did allow the photographer some additional shot opportunities, the old lens held up rather well despite being one of the worst ever made. The moral of this is that pixel peeping may be fun but it has very little real value. Shoot your lenses (as Pepperberry Farm suggests) a lot. Decide if you like using them (not just the images, the ergonomics, etc.) and then decide what to keep and what to toss.

I have sold things like my A* 85 f/1.4 - which I miss but I don't second guess because it was the gateway to affording an FA 31 and an FA 77. The FA 77 proves to me (on crop) to be as capable and as lovely. The A* is superb and special but my failing eyesight wouldn't do justice to it anymore. I have also sold things like my old 18-55 and 50-200 that went to Paris on my first trip there. You would think the sentiment might make me miss them. I don't miss the 18-55 but the 50-200 was such a tiny light package for 200mm I kind of pine for it when I don't need it!

Just proceed with care and thought and don't get hung up on lens charts and resolution tests. Take pictues, view them, decide what you like and see which lenses you come back to over and over.

03-31-2017, 12:11 PM   #8
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QuoteOriginally posted by UncleVanya Quote
I really honestly think you should read this:
Nikon's 'Worst' and 'Best' Zoom Lenses Compared
He lost me at "Ken Rockwell is no slouch when it comes to lens reviews and the guy knows what he’s talking about so I was interested to see how bad Nikon had screwed up here."

I hope a donation was made to support Ken's growing family...
03-31-2017, 12:19 PM   #9
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QuoteOriginally posted by boriscleto Quote
He lost me at "Ken Rockwell is no slouch when it comes to lens reviews and the guy knows what hes talking about so I was interested to see how bad Nikon had screwed up here."

I hope a donation was made to support Ken's growing family...
I read that part and laugh but the points in the article have nothing to do with Ken's accuracy of opinion.
03-31-2017, 12:19 PM   #10
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QuoteOriginally posted by Frosty66 Quote
I have acquired more lenses than is useful due to some of them coming with other things I bought. Nothing particularly interesting but I would like to work out which are the opnes to keep.

Other than just noting my general impressions over an extended time is there a method people use to assess lenses against each other that would be a faster and more scientific approach ?
You might want to start with the lens reviews, to get an idea which lenses are worth evaluating further. Next, follow the advise that has been provided by others in the thread.
03-31-2017, 12:24 PM - 2 Likes   #11
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QuoteOriginally posted by Frosty66 Quote
How do you assess lens quality?
Take it out into the real world and use it. If it gives me "good" images it's a good lens - done.
By that method, right now, my "best" glass is the FA 35.followed by the Sigma 18-250 because they, for some reason, give me the most keepers.

This is for normal photo purposes not for my birding long glass which is entirely different.

The FA 35 wide open...

Last edited by wildman; 04-06-2017 at 11:05 AM.
03-31-2017, 02:46 PM   #12
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QuoteOriginally posted by wildman Quote
Take it out into the real world and use it. If it gives me "good" images it's a a good lens - done.
By that method, right now, my "best" glass is the FA 35.followed by the Sigma 18-250 because they, for some reason, give me the most keepers.

This is for normal photo purposes not for my birding long glass which is entirely different.

The FA 35 wide open...
+1. Everyone has different needs / desires. While its true that lenses with higher optical quality are capable of performing better than cheaper lenses, there are many other factors to consider (bokeh look is subjective, weight, size, focal length, colour rendition, balance, feel, flexibility etc etc) which you can only really find out by trying the lens out for yourself.

BTW - love my FA35 on the K-1 - its just such a great combination and really suits me.
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