Alley in Pisa, Italy

by Lars Kotthoff

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53,429 reputation
7103241
bio website jonrista.com
location Aurora, CO
age 34
visits member for 4 years
seen 14 hours ago

I am a relatively new photographer, having been at if for only a few years. I chose Canon gear when I finally took the plunge into DSLR. I am an avid hobbyist now, and love everything about photography, from the gear, to the science, to the art. I spent years reading about the technology and photography theory, so I am very well versed in the technical aspects of photography. My artistic skills are moderate, but improving. You can see my work @ the following sites:

My interests lie primarily in nature photography:

  • Birds
    • Songbird Setups
    • Shore Birds & Waders
    • Raptors
    • All others
  • Astrophotography
    • Moon
    • Wide Field
    • Deep Sky
  • Landscapes
  • Wildlife
  • Floral Macro
  • Insect Macro
  • Abstract

I currently use the following gear:

  • Cameras
    • Canon EOS 7D
    • Canon EOS 450D (Rebel XSi)
  • Lenses
    • EF 16-35 f/2.8 USM L Wide
    • EF 50mm f/1.4 USM
    • EF 100mm f/2.8 USM Macro
    • EF 100-400mm f/3.5-5.6 IS USM L Zoom
    • EF 600mm f/4 L IS II
    • Canon EF 1.4x TC III
    • Kenko 1.4x Teleplus Pro 300 DGX
    • Periodic Rentals:
      • EF 300mm f/2.8 L IS II
      • EF 500mm f/4 L IS II
      • Canon EF 2x TC III
  • Filters
    • Lee Foundation Kit (x2) + Tandem Adapter
    • Lee .3/.6 ND
    • Lee .3/.6/.9 Soft Grad ND
    • Lee .3/.6/.9 Hard Grad ND
    • Lee CPL
  • Tripod
    • Gitzo Systematic GT3532LS 3S. Series 3 Tripod
    • Jobu Pro 2 Gimbal
    • Gitzo Mountaineer GT0541 4S. Series.0 Tripod
    • Gitzo GH1780QR Series.1 Mag. Center Ball Head

May
26
comment Human perception in color mixing
There is research in this area, from the standpoint of the human perception of color. That's all of CIE's work. There are decades of studies and mathematical modeling and refinement of models in CIE's body of work that covers human visual perception in quite a bit of detail. There is also some fairly extensive study of human color perception by other bodies as well, from medical institutions to universities. In terms of matching human visual perception to computer color models, some work has been done (i.e. RGB->XYZ->Lab transforms), but I myself kind of threaded the pieces together here.
May
25
comment UV Filter Coating
If it's dust on the filter, I'd just clean the filter. Pick up a pack of kimwipes and a soft brush (either camel hair or something synthetic like a lens pen). Brush off the filter, clean it with the kimwipe (dry, they work like magic, and don't worry about the rough feel, it's by design and WHY they work so well.) If that does not fix the problem, then it's probably a nick in the glass or coating, and you'll probably need to replace the filter to get rid of the problem.
May
25
revised Human perception in color mixing
added 2315 characters in body
May
25
answered UV Filter Coating
May
25
answered Human perception in color mixing
May
24
comment How to use TC's with Canon lenses
This question is pretty vague. If your just looking to know what TC to use to double your focal length, that is quite literally self explanatory. If your asking about something else, you need to be a lot clearer.
May
23
comment Aperture priority images are all severly underexposed
@Jon: Normally, that would be correct...however your situation is not normal. Your using a lens that does not communicate with the camera, which is forcing the camera to make incorrect assumptions about what settings IT should set to get a correct exposure. You NEVER get a correct exposure, as light changes or otherwise. Your solution is manual mode. Don't fear it...with a little practice, you'll be a wizard at changing settings on the fly as needed to get the right exposure.
May
23
comment Is the format for the distortion and chromatic aberration correction of µ4/3 lenses documented?
@bronger: Actually, it does answer the question, as best as was possible at the time. The OP asked for documentation, and indicated the goal was to ultimately implement lens correction functionality in OSS. The information I provided was the best information available FOUR YEARS ago. I think your downvote is unwarranted and your comment missed the point of the question.
May
23
awarded  Notable Question
May
22
comment How can an amateur print high gamut images?
Finally, papers that have a nice dMax and high L* very frequently achieve that via OBAs. OBAs can definitely improve your gamut, color reproduction, dynamic range, etc. Just beware that OBAs are uv-sensitive (they absorb UV then reflect it back at a lower energy), so they fade over time. If you want brilliant prints, especially brilliant matte prints, you SHOULD choose a paper with OBAs (Moab Lasal Photo Matte is a wonderful example), and you'll get some of the best gamut you can find. If you need "archival" longevity, then acid free natural fiber papers are usually best.
May
22
comment How can an amateur print high gamut images?
In the case of Lucia II, Lucia EX, UltraChrome HDR, etc. you definitely have wide gamuts, and often on a wider range of papers. It should be clearly noted, however, that if you use matte papers in general, and certain natural fiber luster/semigloss/gloss papers (there are a few, such as from Moab), that your gamut is likely to be quite restricted. That's due to lower reflectivity, dMax and offtone white points, all of which affect gamut. Gamut isn't everything in print, however. There are very specific reasons to choose a matte or natural fiber paper, for their specific aesthetic.
May
22
comment How can an amateur print high gamut images?
Gamut in print largely depends on which papers you are using. I know that my old PIXMA Pro 9500 II and Lucia inks can print wide gamut (around AdobeRGB size) on specific types of luster and gloss papers. Same generally goes for Epson printers with their UltraChrome inks. Wide gamut in print usually doesn't extend beyond AdobeRGB size, although some parts of the print gamut may extend outside the bounds of either sRGB or AdobeRGB in specific hues...such as purples/skintones (Epson) or greens and reds (Canon).
May
22
comment Aperture priority images are all severly underexposed
...meter correctly.) There isn't any magic going on with pixel wells or anything like that, because the sensor literally is blocked by the shutter until the shutter opens...at which point there is no longer any time to do metering, as you are ACTUALLY taking an exposure. I would also offer that bracketing your shots is only a bandaid for your problem, it is not a solution. Your BY CHANCE possibly, maybe, getting a better exposure, but you will never get the right exposure until you go full manual. Full manual is your only option here.
May
22
comment Aperture priority images are all severly underexposed
@Jon: I find it unlikely that's the case, since the sensor is not exposed to light prior to actually opening the shutter. The metering sensor, however, which is an entirely different sensor housed in the upper part of the camera where the pentaprism is, does get light, and it is responsible for determining exposure. I am quite certain my description is correct...the lens is not communicating with the camera, so the camera is assuming an aperture, and that aperture is incorrect for all but one aperture setting (i.e. if the camera assumes f/4, and you choose f/4, ONLY then would the camera...
May
22
comment Photos messed up after copying from a usb drive
Take a screenshot of the photo on your screen, and upload the screenshot. It's likely this question is a duplicate, but having an example of what your seeing will help us make that determination, and decide which existing question will answer yours.
May
22
revised How can an amateur print high gamut images?
added 751 characters in body
May
22
answered How can an amateur print high gamut images?
May
21
comment How can I make the text in this photograph of an ancient column more readable?
@Revious: Photoshop uses a pretty wide variety of algorithms, and over the years they have become quite advanced and complex. Are they neural networks? Dunno, likely not. Are neural networks REQUIRED for this kind of image processing? Again, probably not. You have to understand here, Revious, that the burden of demonstrating WHY the product you are recommending is valid and will solve the problem at hand is ON YOU. You need to make a more valid argument about why PV is the right tool for the job, the better tool for the job, than the tool most every photographer already has.
May
21
awarded  Nice Answer
May
21
awarded  Nice Answer