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Author Topic: Do you test new lenses? How?  (Read 1727 times)
richarddd
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« on: May 02, 2013, 05:08:25 AM »
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Do you test your new lenses?  What tests do you run?
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Jason DiMichele
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« Reply #1 on: May 02, 2013, 05:53:42 AM »
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Hi Richard,

I typically trust photozone.de as I have found their lens testing results to be very accurate over the years. However the (relatively new I think) feature on the DXO Optics website which displays characteristics and sharpness ranges of lens and camera combinations looks good as well. I just ensure that a new lens isn't defective by taking a few shots and making sure the corners and other image qualities look consistent. I don't go crazy. Then I will use my lens align to ensure accurate focus.

Cheers!
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Jason DiMichele
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« Reply #2 on: May 02, 2013, 08:06:22 AM »
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For what they do, Photozone and DxO do good work...DxO's being a bit cryptic on the results.

Both of them have one similar fault....they only test one lens (or at most two).  If you have been following Roger Cicala's LensRentals blog, you know that "good" lenses have variability.  Therefore, when testing one lens, you have no idea if it is at the top or bottom of the "good" cluster.

As for testing a new lens, here are some writeups....

http://www.lensrentals.com/blog/2010/11/how-to-test-a-lens

http://www.canonrumors.com/tech-articles/this-lens-is-soft-and-other-myths/

http://www.lensrentals.com/blog/2012/05/testing-for-a-decentered-lens-an-old-technique-gets-a-makeover
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John
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« Reply #3 on: May 02, 2013, 08:37:34 AM »
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Generally I don't do any systematic tests or inspections.

I would say that for the first few months of usage, I spend a bit of time looking more closely at my results.  I'm not necessarily looking for lens defects. I think I am trying to understand the limits and strengths of a lens.  I think people expect a new lens to instantly provide a photographer with new capabilities, but I find it takes several months to fully flesh-out the usage of a new piece of gear.

I have made lens profiles, but mostly to deal with distortion and vignetting.  I have calibrated my telephoto lenses with the AF microadjust feature.  I generally do these things months after I get a lens when I understand what it's weaknesses are, and I am trying to eek more out of it.
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BartvanderWolf
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« Reply #4 on: May 02, 2013, 09:15:35 AM »
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Do you test your new lenses?  What tests do you run?

Hi,

Due to the local time limitations to being allowed to exchange a lens for a better copy, I shoot a test chart. That also allows to compare the quality to the known quality of the lenses I already own.

I shoot a carefully focused chart in the optical center, and 4 separately focused shots (to avoid the effects of field curvature and non-parallel positioning) in the corners. When all four corners are equal, then there is probably negligible decentering, and it already tells me how much loss of quality there is compared to the center shot.

When done for several apertures, it also allows to find the sweet spot of the lens (often, but not always, 2 stops from wide open). It also allows to later determine the optimal capture sharpening for the camera/lens combination. Shooting suitable targets in the beginning is going to save time later on.

I also shoot an image of a uniformly lit surface, or an LCC frame, wide open. That will allow to spot if the vignetting is symmetrical and central. If not, then there may be a decentered lens element. When repeated at a smaller/medium aperture, it may reveal issues with an asymmetrical aperture iris, although it's more accurate to make defocused images of a very small and bright point light. That will produce a usable image of defocus blur, and it will have the shape of the aperture and the quality of light distribution (bokeh) that you can expect. It showed me that my 85mm f/1.2 lens is partly shaded by the mirror box, which produces a vignetting that is hard to correct with anything else than an LCC.

Cheers,
Bart
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PeterAit
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« Reply #5 on: May 02, 2013, 09:30:38 AM »
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Sure I test new lenses. I take lots of photographs with them for about 6 months and see how the photographs turn out <g>.
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Rob C
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« Reply #6 on: May 02, 2013, 10:16:33 AM »
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Sure I test new lenses. I take lots of photographs with them for about 6 months and see how the photographs turn out <g>.


For myself, read some in place of lots.

As returns are pretty much impossible from here - can't find a way to insure, and the Post Office tells me that with them it can only be done via HQ in Palma, about 60 clicks away - I tend to buy manual, used AIS ones which I imagine were built before Nikon abandoned QC. Anyway, the sort of image that pleases me these days is peculiar by most standards, so I am happy enough with what comes out of the box.

(I'm not tempting you, Fate, baby, but so far so good.)

An example of what I feel like shooting is here, below. You see the different needs: manual 2/35mm Nikkor AIS wide open at 1/5000th. It might be useless for someone else - I don't know, but it shows that different takes on the problem depend, really, on different folks and their ways.

Rob C
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ErikKaffehr
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« Reply #7 on: May 02, 2013, 11:46:38 AM »
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Hi,

When I get a new lens I generally make a few shots of my bookshelf. This is initial check out. Are corners equally bad, do they clean up when stopping down.

After that I go shooting. Try to get naked tree branches and that kind of stuff in the corners. I may also shoot a brick wall.

Sometimes I shoot some table top arrangement and even calculate MTF from a slanted edge target.

Best regards
Erik

Do you test your new lenses?  What tests do you run?
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TMARK
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« Reply #8 on: May 02, 2013, 01:48:56 PM »
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I find something I want to photograph, then take lots of pictures, and look at the photos.  Try different F stops, different subjects, different shutter speeds, indoors, outdoors, lots of light, no light, strobes.  In about a week I know what the lens can or can't do on a particular camera.
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Telecaster
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« Reply #9 on: May 02, 2013, 02:40:55 PM »
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I take the lens (and a camera of course!) to my favorite state park and go on a long walk, shooting lots of photos of a wide range of subject matter at various apertures. Only if there's something in the photos that catches my attention in a negative way do I "test" more rigorously. Over decades of pic-taking I've only had to do this more rigorous testing twice. I do pay attention to what other people say about a lens, often based on their more formal tests, but there's no substitute for first-hand experience.

-Dave-
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WarrenRoos
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« Reply #10 on: May 02, 2013, 06:31:18 PM »
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Yes.. Always...I do three simple tests.
KISS
1.) A brick wall.. all apertures.
2.) A News paper(s) going away form the lens at a forty five degree angle. (for this I manually focus) and use a tape measure.
3.) A News paper(s) going away form the lens at a forty five degree angle. (auto focus) and use a tape measure.

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Ellis Vener
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« Reply #11 on: May 02, 2013, 07:52:59 PM »
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1) Use my eyes and ears to examine the lens to make sure there are no physical defects.

2) Set up a LensAlign Mark II and shoot from -20 to +20  find the correct autofocus micro-adjust setting using the FocusTune software for that specific individual lens on that specific individual camera body.

3) re-test those results

4) Shoot a solid color wall or a fair weather sky to see if there is any vignetting at all whole apertures. Like geometric distortion this easily can be corrected (if the vignetting is symmetrical) in raw processing software but I want to see what kind of problem I am dealing with. If it noticably assymetric I'll start to suspect that the lens is de-centered and needs to be collimated.

5) Start shooting real world subjects and see if I like what I am seeing.
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Ellis Vener
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Jason DiMichele
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« Reply #12 on: May 02, 2013, 08:18:24 PM »
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Ellis,

Thanks for pointing out the FocusTune app. I wasn't aware of it until you mentioned it. Looks brilliant! I've purchased it and am going to include it in my calibration workflow. Fantastic, thanks!

Cheers!
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Jason DiMichele
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spotmeter
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« Reply #13 on: May 02, 2013, 08:55:09 PM »
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Since my prints from my Nikon and Canon cameras are 5-10 feet in length, I test all of my lenses.

I just tested a Sigma 35mm 1.4 which has been widely touted on the internet. The entire right side was out of focus. Had to return it. Fortunately, I have a Zeiss 35mm f2 that can take its place.

With mass produced lenses, and especially wide angle lenses, there can be lots of variation from copy to copy.  If you want to do large prints, I recommend this test.

Print out five Word documents that have lines of type that range from 8 point up to 72 point.  Be sure to indicate the size of the typeface at the end of each line.

Set your camera up on a sturdy tripod and use a heavy weight (I use one of my backpacks full of photo gear) to weigh it down. Use a shutter release cable so that you don't touch the camera when tripping the shutter. Use the magnification in live view and a loupe to manually focus the lens.  Use Aperture Priority. Be sure to check focus with each aperture as there can be focus shift from one aperture to another.

Find a wall that is at least 10 feet across. Move your camera forward or back so that the wall fills the frame of your camera. Make sure your camera is the same height as the center of the wall. Put a double bubble on the flash mount and make sure the camera is level front to back and side to side.

Now mount one of the Word documents in the exact center of the wall and make sure it is also in the exact center of your live view. Also, make sure the back of your camera is parallel to the wall. On a post-it, write the name of the lens and make post-its with each aperture on them.

Using your live view, place the other four Word documents on the wall in the four corners of your frame.

Use the center document to focus the lens as best you can. Take a series of photos with every aperture of the lens. As you change the aperture, change the post-it so that you can easily see which aperture you shot.

Bring the photos into Lightroom.

On a  piece of paper, list the apertures on the left side of the paper.  Across the top write Center, Upper Right, Lower Right, Lower Left and Upper Left.

Double click on the photo to enlarge it to 100%.  Find the smallest line of type that you can read. Write that number down for each position, and go through all the apertures.

This may sound complicated, but it now takes me just 20 minutes to test a lens.

In many cases, you will see the center is sharp and clear with good contrast, but the corners are distorted, blurred, smeared, or full of chromatic aberration.  Since I want my prints sharp corner to corner, I return lenses with these characteristics.  Even some medium and telephoto lenses may have these characteristics, but it is more common on wide angle lenses.

Once you have all your numbers written on your piece of paper, you will see that there are some optimum apertures for each lens. For most of my lenses, this is usually 5.6 to 11, but it may vary from lens to lens.

I print a small piece of paper with the name and focal length of each lens and their optimum apertures.  I laminate this piece of paper with 2" wide transparent tape and stick it in my camera bag. When I am out shooting, I pick one of the optimum apertures, knowing that it will give me prints that are sharp corner to corner.

You can see my prints at http://www.photographica.us

Again, this seems laborious and complicated when written down, but it takes a short amount of time, which I find enjoyable and informative as I really get to know each lens before I take it out in the field. It also give me the opportunity to return a lens that is defective before taking lots of photos that I will never be able to print.
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EgillBjarki
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« Reply #14 on: May 02, 2013, 09:45:45 PM »
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I use two web pages before I buy the lens. This usually gives me a very good idea what I might be getting into:

http://www.photozone.de/canon_eos_ff

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx

There are differences between copies of each lens and I like to do some real world tests my self as well. If anyone is interested in the raw files from my recent Canon 24-70mm II vs. Tamron 24-70mm, I would be more than happy to share them.

That test was made from the 30th floor here in Shanghai.
Both lenses shot at 24mm, 35mm, 50mm and 70mm @ 2.8 - 4.0 - 5.6 - 8.0 - 11

Here is one frame @24mm
« Last Edit: May 02, 2013, 09:48:11 PM by EgillBjarki » Logged

DaveCurtis
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« Reply #15 on: May 03, 2013, 09:39:40 PM »
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Before I purchase a lens I read the reviews and see if they are all fairly consistent. Other than the technical reviews I like to no how the lens "draws",depth of field fall off, field curvature  etc. Diglloyd is quite good for the pixel peeping stuff and comparison with similar lenses.

Once purchased, this first thing I test for is left/right skew.

 

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