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  #1  
Old 03-25-2013, 01:16 PM
Jorda75078 Jorda75078 is offline
Larry Jordan
 
Join Date: Apr 2011
Location: Inverness, FL
Posts: 17
Default Testing a newly acquired lens with FoCal ver. 1.8.1

While attending the NANPA Summit in Jacksonville earlier this month, my friend Phil and I met a couple who shared many of our photography interests. It seemed like Walt and Nancy were stalking us; we kept turning up in the same presentations. In the end, we became friends with Walt and his wonderful bride, and we shared some photo opportunities after we left the summit.

I have always been into landscape and nature photography, but I have never done much with close-up and macro photography. However, I developed an interest in getting up close and personal with my subjects while attending two summit presentations made by Mike Moats. I was amazed at the results he gets within walking distance of his house.

After attending Mike’s “Beyond Flowers and Bugs” pitch, I ran into Walt during a break, and I mentioned that I was considering getting into macro work to see if I could get results like Mike gets. I also asked Walt what gear he uses for close-up and macro work. Walt gave me a lot of tips but the best one was a suggestion that I look at a lens Nikon quit making in 2004. Walt said that he and his wife like Nikon’s 200mm f/4 Micro prime lens, but they prefer the older Micro-Nikkor 70-180mm f/4.5-5.6D ED lens. He went on to say that Nancy particularly likes the zoom lens because she does not have to use rails with it; she can do close-up work while hand holding.

After further discussion, Walt told me that he and Nancy like the 70-180mm Micro Zoom so much that they bought two of them through eBay so they would not have to share the same lens when out on a shoot. He even offered to let me try one that he had in his camera case so I could judge the lens for myself. I did not borrow the lens, but I did take a close look at it later that day.

Even though the micro zoom appeared to be well made, I still had my doubts after looking at Walt’s copy. I also discovered that folks were asking a pretty penny for their 10-15 year old copies on eBay. The asking price for most of the copies classified as mint condition was higher than the price of a new 200mm prime micro. I was dumbfounded by that until I ventured to Thom Hogan’s ByThom website and read his review of the 70-180mm micro. While there were things he did not like about the lens such as the slow autofocus and lack of full 1:1 magnification, he still rated the lens as highly recommended. In another article, Thom rated the 70-180mm higher than the newer Nikon 200mm f/4 micro prime.

With some hesitation, I decided to take the plunge and try to buy a good copy of the lens. I have sold a number of pieces of camera gear through eBay, but I have bought no used camera gear through them. I have bought used and refurbished gear from other reputable dealers with 100% success, but I have always been leery of eBay because of rumors I hear and read. After a futile search for a used 70-180mm on Nikonians and FredMiranda, I started focusing on eBay. It took me a couple of weeks to find what appeared to be the perfect fit for my camera bag, but the owner was asking too much for the lens. The description sounded great and the images of the lens appeared to say mint condition as well.

To make a long story short, I negotiated a fair price for the lens and additional close up filters the owner had. When the package arrived last week, I was pleasantly surprised at how well it was packed and how well the lens looked. There were a few ware marks on the lens collar knob, but that could be expected for a 12 year old lens that did not just sit in a bag. I was eager to try it out, but first I wanted to be sure I had a lens that could deliver results if used right.

I downloaded and installed the latest version of the FoCal testing and calibration software from Reikan Technologies. As I indicated in a previous post, I had not used the software since last fall, and Reikan had added several new and improved features. However, I was interested in running the same tests I ran last year with all of my lenses – lenses I had originally purchased new. I wanted to see how the 70-180mm measured up in both autofocus consistency as well as image sharpness.

After some hiccups with FoCal which I have learned to expect, I was able to do my autofocus fine tuning. I also ran another test that I felt was a key indicator of lens quality—the autofocus consistency test. I have attached those test results. The AF consistency of 96.7% for the lens falls within the range that I got with my other lens last year, and is pretty close to the consistency I got with my 24-70mm zoom. That test gave me confidence that the 70-180mm lens would produce good autofocus results even though the autofocus is slower than it is with my newer lenses.

The last test I ran was Aperture Sharpness. I wanted to see how sharpness changed with aperture change over the full aperture range. I seldom shoot above f/11 with any of my lenses, but the depth of field is so short for a macro lens that I knew I would be tempted to raise the aperture when light allowed or when using a flash. Those test results are also attached.

I was happy with all of my testing, but the proof is always in the images you capture. Last night I had the opportunity to see what the 70-180mm could do. While I sat watching TV, I found a Tussock Moth Caterpillar crawling up my shirt. I see them outside all the time, but that was the first time I had seen one in my house (we have some strange creatures here in Florida). My first thought was, “where are my camera and the new macro zoom?” My second thought was, “how can I get this little guy to hold still while I capture some images?”

You can see the results of my actions with the camera and lens attached. I used a flash because the light was too low in the bathroom where I moved the little guy, and he refused to stop moving. As he crawled across the edge of the vanity, I kept my AF-On button pushed, kept the focus point on his head and snapped about 20 images while hand holding. I had the ISO on 400 and the resulting shutter speed was 1/60. As you can see, the depth of field on this one inch long caterpillar was about twice the depth of his head and that was at f/13. I knew I was losing sharpness at that aperture from the earlier tests I had run, but I needed the extra DOF. I was also confident that my autofocus was dead on his head because of the AF fine tuning I had done with FoCal, and these results show that accuracy.

After all of the testing, calibration and initial image captures, I have decided the lens is a keeper. FoCal helped me achieve the results, but having a good camera and lens to work with in the first place also made a big difference.
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  #2  
Old 03-27-2013, 10:20 AM
ericbowles ericbowles is offline
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Join Date: Sep 2011
Location: Atlanta, Georgia
Posts: 57
Default

Nice post and explanation. Very nice image of the rapidly moving caterpillar.

I was curious about how to interpret the test results. The Quality of focus test shows pretty widely ranging results by focus point. Is this typical? And how to you know which focus points are 1, 3, and 5 (with the good results) and 10 (with the poor results).

The chart with different aperture settings seems to confirm the conventional wisdom that f/8-f/9 is the sharpest, but other apertures are usable if DOF is required. Where is the point that you would be reluctant to stop down further?

Eric
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  #3  
Old 03-27-2013, 01:05 PM
Jorda75078 Jorda75078 is offline
Larry Jordan
 
Join Date: Apr 2011
Location: Inverness, FL
Posts: 17
Default Replu re testing 70-180mm

"I was curious about how to interpret the test results. The Quality of focus test shows pretty widely ranging results by focus point. Is this typical? And how to you know which focus points are 1, 3, and 5 (with the good results) and 10 (with the poor results)."

I believe the test you are referencing is the Focus Consistency Test. Those numbers 1 - 10 are just the shot numbers. They are not focus points. I used the same center focus point for each shot...in fact, FoCal used the same center point. With this test, you push the start button, and FoCal executes the entire test while you watch. The test just shows you how consistently the camera/lens combination performs autofocus. The Quality of Focus on the left side of the graph indicates how well the camera/lens was focused. It is meant as a relative indication of focus quality.

You may have this test confused with the multi-point sensor test that compares the quality of focus of all autofocus sensors. I have not posted an article about that test yet.

"The chart with different aperture settings seems to confirm the conventional wisdom that f/8-f/9 is the sharpest, but other apertures are usable if DOF is required. Where is the point that you would be reluctant to stop down further?"

I try to stick with the peak quality setting on f/9. However, I do go as high as f/13. I shot flowers today that you will soon see on Facebook. I shot some at f/9, but I also shot about half at f/11 to get some additional DOF. I did use the CamRanger and performed focus stacking for these flower shots to give me a HUGE DOF compared with a single shot. I probably could have stuck with f/9 for all shots, but I wanted some DOF between me and the first focus stack shot in each sequence. CamRanger stacks from where your focal point is backwards away from the camera. (This may be too complex to explain here.)
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