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Forum: Travel, Events, and Groups
07-10-2018, 10:52 AM
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Managed to drag myself to Waterloo and onto the South Bank of the Thames for the fly-past. A bit colder than I expected, and fairly cloudy, but I got some reasonable pictures - 178 of them, plus a lot of duds and duplicates I deleted!
They're all on line here
RAF 100th Anniversary Fly Past 10/7/18 | Flickr
I need to go through and identify the aircraft types etc., and I'm not the world's best at aircraft ID. Any and all help will be appreciated, just add to the comments on the photos if you know them.
Some samples below:
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Forum: Lens Clubs
06-24-2018, 06:51 PM
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That is a beautiful image, Dave. It is impressing how f2 works.
I was exploring my new Classic Carl Zeiss 100mm, f/2 lens. I was hunting for it over two years and recently won one on e-bay, ZF version. Fenwoodian (Dave) excellently adapted it for Pentax. I am very thankful to you, Dave! It is a great joy to use this lens. Below are some examples shot habdheld on k-3 at f2. Almost no post-processing, some cropping only. I am not a pro but critique is welcome.
 00026247 by Joseph Dubrovsky, on Flickr
 00026240 by Joseph Dubrovsky, on Flickr
 00026198 by Joseph Dubrovsky, on Flickr
 00026165 by Joseph Dubrovsky, on Flickr
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Forum: Lens Clubs
06-30-2018, 12:14 AM
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An image I forgot to share here when I posted it in the K-1 thread last night. It's five images captures in portrait orientation with the K-1 and the Zeiss Distagon T* 2/35, and merged as a pano in On1 Photo RAW.
 End of the working week by noompty, on Flickr
If anyone is thinking of shooting their Zeiss lenses for panos, something I wholeheartedly recommend BTW, I'd suggest you consider the Zeiss characteristic of vignetting at wider apertures. I love how they Vignette, but the vignetting will be too hard for some software to manage properly. I found out how bad a problem this was with the Zeiss Makro Planar T* 2/50 when I captured a series of shots for a pano at f2. I combined the images in the Gigpan Stitch software and the vignetting effect was noticeable and completely ruined the image. As it was multiple layers I needed Gigapan Stitch for the merge, but maybe newer software will be good enough to compensate especially if you prepare your images with a good lens profile before stitching. Anyway, my point is, know what the Zeiss lenses will do when shot wide open if you intend to stitch into a pano later on. Especially if it's full daylight in the sky with little cloud to mask the variation in luminance.
Having said all that, this image was shot at f2 due to the fading light and my inherent aversion to dragging around a tripod if I don't have to. The vignette is still influencing the image but with the low light conditions the program did a decent enough job to not ruin the sky. I managed that by adding a vignette in post. :lol::o
Tas
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Forum: Lens Clubs
06-30-2018, 01:46 AM
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Forum: Pentax SLR Lens Discussion
08-16-2012, 01:40 PM
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I have a lot of the same lenses and then some. i managed to justify it by giving the wife a K-r and saying half the lenses are for her.
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Forum: Pentax SLR Lens Discussion
06-30-2012, 08:11 PM
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This has to be one of the most asked questions here on the Forum. There is already a lot of information in threads out there, just move your cursor up to the search box and type in "wide angle lenses". Having said that, here are some questions that you really need to ask yourself - as only you can answer them:- Zoom or Prime? - What type of lens do you think you want?
- Rectilinear (normal) or Fisheye? - You probably are looking for a Rectilinear, but it is always worth asking. Fisheyes are usually 180 degrees wide (Field of View) diagonally corner to corner.
- How wide? - Zooms go down to 8mm (112 degrees FoV), 10mm (100 degrees FoV), 12mm (90 degrees FoV) while Primes are at 14 (81 degrees FoV) and 15mm (77 degree FoV). FoV calculated from Angular Field of View Calculator. Also this question also essentially asks how much distortion are you willing to have? The wider the Field of View the more distortion you are going to get, especially along the edges.
- Sharpness & Resolution - As you put wide angle lenses on your camera body, the shorter the focal length, the more view or information you are focusing on the sensor. The sensor is not getting any larger, so each pixel will be representing an ever larger amount of area. This will lead to reduced sharpness. For instance, a image from a 85mm lens will be sharper than an 8mm lens. However the 8mm lens will have a much wider view than the 85.
- How much do you want to spend? - There is wide angle and ultra wide angle. The wider the lens the higher the price. It takes a lot of optical engineering, fine quality optical glass, and manufacturing techniques to build a wide angle lens. The wider the lens the more view along the edges (top, bottom and sides) it needs to pull into the lens and then bend the light and get it aligned so as to hit the sensor.
- Physical Size - Most of the zooms can be somewhat physically large. The primes tend to be small (for a f4 aperture) and larger for a faster f2.8 aperture.
- Aperture - Most of the wide angle lenses tend to be somewhat slow - f4+. To get something faster you go to a f2.8 prime or a fisheye that tends to be faster.
For the most part your choices are going to be from:- Pentax - Pentax has the DA 12-24/f4 - a good lens, noted for its well controlled distortion. It is large. Pentax also has 2 primes the DA 14/f2.8 and the DA 15/f4 limited. Pentax also has the DA 10-17 Fisheye. The Pentax lenses tend to cost a bit more than the rest....
- Sigma - Sigma has several zooms, the 8-16, 10-20, and a 12-24. The problem with Sigma is getting a good lens. Once you find a good lens (with out problem), folks really like them.
- Tamron - Tamron has a 10-24 that folks also like. It is well priced, and they appear to deliver lenses that work well out of the box.
After having written all of this - I am going to assume that you are looking for a moderately priced zoom, and your choice will probably be the Tamron 10-24.
I would suggest scooting over to the lens clubs and taking a look at what the various lenses produced in terms of images.Also, here are a few links on wide angle lenses:
:cool:
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Forum: Pentax SLR Lens Discussion
08-01-2012, 08:04 AM
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The DA70 is a wonderful wee lens. I know the 77 is future proof should Pentax ever bring out a ff but I have been using the 70 more or more for landscape shots.
Couple of recent ones.
You can't go wrong with a 15 either - very nice little lens. The 15, 40 and 70 made a cracking little lightweight set that I could carry in a little waist bag. The 70 is comparable in sharpness to my 60-250. Too many nice lenses out there at the moment. The 40 &70 see far more action than my 31.
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