I am currently in the process of testing the Nikkor 400mm f/2.8E FL lens in my Imatest lab and I am simultaneously also measuring the performance of the new Nikon TC-14E III teleconverter and comparing it to the older TC-14E II. Although I am planning to review the teleconverter separately, I decided to give our readers a glimpse of the teleconverter performance when compared to its predecessor in terms of sharpness. To make it easy to compare differences, I converted all numbers to percentages (detailed numbers will be posted in the reviews).
The Nikkor 200-400mm f/4G VR is a very versatile and sharp lens and those that own it or previously used it know that is a great choice for close action photography, such as photographing bears in Alaska. I recently saw a comment by a photographer, who claimed that the lens gets even sharper if its front protective filter is removed. Both the Nikkor 200-400mm f/4G VR and its newer VR II version have a removable front protective element, as well as a 52mm drop-in filter that most other super telephoto lenses have. While I was testing my 200-400mm f/4G VR in my Imatest lab, I decided to compare the performance of the lens with and without the front protective and the 52mm drop-in filter to see if the above claims were true or not. It turned out to be an interesting study. I apologize for the geeky nature of this article!
The subject of using or not using protective lenses can invoke heated debates among photographers, with both sides often fiercely defending their choices. I am not going to debate whether it is right or wrong to use protective filters – that’s certainly a personal choice. I have been using them for a number of years now to protect my higher-end lenses and make it easier to clean lenses with recessed front elements (such as on Nikon 50mm f/1.4G / f/1.8G). Having had bad experience with purchasing a low-quality no-name brand filter when I just started photography (it was sold to me as a “must-have” at a local photo store), I learned what such a filter can do to my photos the hard way. Since then, I have only been purchasing multi-coated B+W filters that use high-quality Schott glass. I have been very happy with these filters and have been telling our readers to either use the best they can find, or not use filters at all.
Just like the old “film vs digital” or the “Nikon vs Canon” debates, lens filters often create endless discussions on the Internet. Some people argue that one should never use protective filters, since it is another piece of glass in front of the lens that reduces resolution and emphasizes other optical problems such as ghosting / flare, while others argue that filters make it easier to protect the front element of the lens and make it easier to clean that element. I personally have been recommending use of protective filters for years, as long as they are of high quality. The filters that I have been using do not seem to affect the resolving power of lenses they are mounted on and mostly do not seem to heavily affect ghosting / flare either. Having spent the last couple of weeks in a lab testing many lenses, I wondered if I could actually measure the resolution of a lens with and without a filter. I recently purchased a used lens that came with a crappy plastic filter, so I decided to run two separate scenarios – one without a filter, one with a high quality B+W filter (more on B+W products below) and one with a cheap plastic filter. The results of the study came out very interesting!
A lot of our readers have been asking me about the new Nikon 18-35mm AF-S lens that was recently announced. I had a chance to use this lens a while ago for over a month and I never got a chance to fully review it. Ahead of the upcoming Nikon 18-35mm review (posted on 07/27/2013), I would like to provide some data for our readers and compare the lens performance to the Nikon 16-35mm f/4G VR. The below information only contains sharpness numbers and does not include all other optical tests such as vignetting, distortion, chromatic aberration, etc. – I will only provide a summary of my findings for now. The full data with illustrations and sample images will be provided in the full review.
When my article on field curvature was published a while ago, where I talked about how one could do a quick analysis of lens MTF data and determine if it exhibits any field curvature, some of our readers expressed interest in understanding how to read MTF charts. Since we talk quite a bit about lens performance and MTF data here at Photography Life, I decided to write a detailed article on the subject and do my best to thoroughly explain everything related to MTF curves, charts and all the verbiage that comes with them.
A fellow photographer recently asked me how much image degradation one would see with each Nikon teleconverter. As a nature photographer, I have been wondering myself about this for a while, but never had a chance to actually quantify what the image degradation figures would look like when using the TC-14E II, TC-17E II and the TC-20E III with Nikon lenses. I have been relying on field use and my vision so far and here is what I have thought about each teleconverter.
A couple of weeks ago I had an opportunity to visit Norman Koren, founder of Imatest, LLC. I have been fascinated by his software for a while now and after evaluating the software, decided to purchase it to use in our lens reviews. When I found out that his company is right here in Boulder, Colorado (where I lived for over 5 years), I gave him a call and asked if I could come over and interview him. Despite his busy and hectic schedule, he was able to accommodate me for an hour during his lunch time. Below is the text version of the interview.