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06-18-2013, 01:00 AM   #46
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EarlVonTapia's Avatar

Join Date: Oct 2012
Location: Vancouver
Photos: Gallery
Posts: 1,150
Hi PhotoMike. I appreciate your thoughtful replies to all of the questions in this amazing introduction thread.

Fantastic collection! My jaw dropped as I scrolled through the thread and the picture of your lens collection appeared. It dropped further when I read that it only represented 3% of your entire lens collection.

Having tested every Pentax lens, what would you say are the best autofocus lenses for Pentax DSLR's available for purchase new right now? What are the best autofocus lenses that are no longer in production?

Thanks.

Earl

06-18-2013, 04:30 AM   #47
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Join Date: Jun 2013
Posts: 30
Original Poster
Hi Earl,

Thank you for your comments.

In my work, placing commercially available lens with clients that need certain tasks accomplished, the following AF lens have been very good performers:
28mm F/2.8 FA, 50mm F/1.4 FA, 85mm F/1.4 FA and the 100mm F/2.8 FA macro. Over the years of production, few design changes were done including the coatings.
The newer A* and EDIF lens follow the older releases, but testing shows little if any advantage on most of these released. I do not emphasize lens "features" as much as I examine
lens performance issues. Most of my "user" Pentax collections are manual lens, with few exceptions for the upper end of the Penatx EDIF line up like the 300mm F/2.8 400mm F/4,and the 560F/5.6.
Beyond the 35mm format, I find the Pentax 645 and Pentax 6X7 lens offerings to be quite good, especially adapted to the DSLR format camera bodies.

The best lens that I own across all my collections are those that are manually controlled. The critical focus requirements for such lens is best met by manual focusing means. These lens are always shot wide open, so the DOF is limited depending upon the working distance and focal length, but with a precise point of focus, the resutts are excellent.

Best Regards, Mike

Last edited by PhotoMike; 06-18-2013 at 04:37 AM.
06-29-2013, 11:49 AM   #48
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Join Date: Jun 2013
Posts: 30
Original Poster
For this nighttime shot of a lizard under a cover, I used the Sony Nex 7 with a 21 mm extension tube and an adapter for M-39 threads that allowed me to mount the APO Rodagon 50mm F/2.8 enlarging lens onto the camera.
Since enlarging lens do not have focusing mechanisms, other than the bellows systems used on enlargers , the focus point is preset to a specific close range. Focusing is done by moving the camera and the lens in and out from the subject until the subject appears focused. I did this shot hand held at night, using a small headlamp as my illuminator for focusing. Since the lizard was much more dormant during the evening hours, he did not move from his position .
I used the enlarging lens because they are designed for a close range , across a flat film subject. They focus the film by projecting the image down to the photographic paper that forms the print upon development.
The APO Rodagon lens line are outstanding in their color correction and high definition at wide open aperture.
This shot was done at ISO 100 , 1/60 second exposure using the Nex 7 pop-up flash.
While I have all the finest macro lens for film and medium format cameras in my collections, I also have special collections (like the enlarging lens) that can be adapted to any format camera for work like this.
I usually work on still subjects, with a fixed camera/lens setup to assure a straight forward way to obtain the proper shooting angle, lighting, and precision focus.
This image was taken in the field as a challenge to myself and to demonstrate to my friends that were curious to see what my results would be like.
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06-30-2013, 07:47 AM   #49
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Join Date: May 2011
Location: Santa Cruz, CA
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Welcome aboard and I am looking forward to seeing some actual technically well developed and exectured - and possibly independently verifiable, lens test results. For starters, how about results from comparing fast lenses from the different manufacturers - f1.2 or faster, in terms of resolution? Perhaps macro lenses or telescopes? TIA.

06-30-2013, 10:47 AM   #50
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Join Date: Jun 2013
Posts: 30
Original Poster
HI TIA,

Thank you for the greeting.

All my laboratory tests are certified to a highest level of professional standards available anywhere in the world. The level of sophisticated instrumentation assures that every test provides the most accurate results which set a standard of excellence that few labs can match. The average experienced level person that contributes to my business in the optical design and testing fields exceeds 40 years. Now, we are an independent lab tied to no manufacturer, so we are not ever influenced by any company to "push" their products. lens. I do consultation business with many lens companies on a signed contract basis. On the commercial level (not custom systems), we have had over 7000 lens tested across most lens of every design, focal length , f-number in existence. However, much of this information is sensitive to the development groups , special clients that I work with and the off the shelf designs from the leading manufacturers. I do not disclose data sheets or charts of test results without the proper authorization.To do such an action would jeopardize my business relationships that are in excellent standing over the past 40+ years.
I will answer specific questions relating to the lens performance as it relates to an image that was taken (and that I have reviewed) or to a specific task that a user needs assistance in choosing the best lens with in his budget.
My personal collection of over 650 lens is based upon me hand picking the best of the best samples for each lens that I have. The laboratory has several hundred test lens and "standards" that I have no interest in for my collection. To this , I also have a significant number of telescopes , each representing the best design and implementation possible . Many of these telescopes are located at my Observatory, where the state of the art tracking systems are used to hold such assemblies. The Observatory is independent from my optical lab facility, and I am not a dealer or resale outlet for any brand of lens of any era.

Best Regards, Mike
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