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| bio | website | jonrista.com |
|---|---|---|
| location | Denver, CO | |
| age | 33 | |
| visits | member for | 2 years, 10 months |
| seen | 2 hours ago | |
| stats | profile views | 1,762 |
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 300mm f/2.8 L IS II (Periodic rentals)
- EF 500mm f/4 L IS II (Periodic rentals)
- EF 600mm f/4 L IS II (Periodic rentals)
- Canon EF 1.4x TC III
- Canon EF 2x TC III
- Kenko 1.4x Teleplus Pro 300 DGX
- 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
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Apr 30 |
comment |
For MTF, why does 10 represent contrast while 30 represent resolution? Resolving power drops because the lens is causing a lot of blur wide open. The MTF chart doesn't contain enough information to tell you why it has a lot of blur, or what kind of blur it is...there is not enough information in an MTF about whether blur is caused by diffraction or optical aberrations specifically. The only measure of optical aberrations is really whether the lens produces identical image quality across its total surface area (the "rotational" factor...astigmatism, and focal plane...field curvature, neither of which are really affected much by aperture, not like CA et. al.) |
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Apr 30 |
comment |
For MTF, why does 10 represent contrast while 30 represent resolution? @erotsppa: Resolution is lost as blur increases, and as blur increases, microcontrast at those fine detail levels drops. A loss of global contrast can be due to poor transmission by the lens, which cannot fully transfer the original signal in total accuracy. Again, it IS all about "contrast", but multiple things can have an impact on contrast, and affect contrast at different levels. At 10lp/mm, the lens has good to excellent contrast midway to the edge, you read that correctly. At 30lp/mm, the lens has poor to good resolving power, you also read that correctly. |
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Apr 29 |
comment |
For MTF, why does 10 represent contrast while 30 represent resolution? @mattdm: I've rewritten my answer. Hopefully this is better |
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Apr 29 |
revised |
For MTF, why does 10 represent contrast while 30 represent resolution? Explained MTF chart with sample from Canon |
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Apr 29 |
revised |
For MTF, why does 10 represent contrast while 30 represent resolution? added 8782 characters in body |
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Apr 28 |
comment |
Why are Zeiss lenses heavier and larger for Canon EF than Nikon F mounts? I would like to know the same thing Matt asked. Could help a lot in offering a valid answer. |
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Apr 27 |
comment |
What is “correct” exposure? So, the skies look good in your photos. What about the landscapes themselves? Do they simply become silhouettes? Do they have any detail or color remaining? Are you using a D800/D600/D3200, in which case you have two additional stops of DR over any other camera, and can lift those shadows and still retain some detail? |
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Apr 27 |
comment |
How do you find out the “sweet spot” of a lens? BTW, it should be noted that I've had plenty of time to test Eruditass' statements that higher density never means worse IQ (all else being equal), and I completely agree. |
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Apr 27 |
comment |
How do you find out the “sweet spot” of a lens? It should also be noted that if I change the phrasing to "raises the question", the circular nature of the statement remains unchanged. Only the phrasing changes, but the impression that I am making one argument to further my original argument remains...so why bother nitpicking the phrasing itself? Better to nitpick the circular argument in general, no? ;P |
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Apr 27 |
comment |
How do you find out the “sweet spot” of a lens? @luser: Perhaps. I think the wiki article you linked is inappropriately assuming the use of the phrase "begs the question" means "assuming the initial point" (petitio principii), when in fact in general usage, "begs the question" quite literally means "raises the question". The sole difference is that the former is simply more slangish, and if you wish, "sloppy". Slang or not, I do not believe it is in the average speakers nature to go around saying "assumes the initial point", which makes the notion that "beggs the question" is a direct translation of "petitio principii" a stretch at best. |
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Apr 26 |
revised |
For MTF, why does 10 represent contrast while 30 represent resolution? added 687 characters in body |
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Apr 26 |
revised |
For MTF, why does 10 represent contrast while 30 represent resolution? added comparison of typical MTF chart and my plot |
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Apr 25 |
awarded | Good Answer |
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Apr 25 |
comment |
For MTF, why does 10 represent contrast while 30 represent resolution? Modern real-world tests always test optical systems. MTF charts produced for lenses tend to be theoretical, generated by computers from the computer models used to actually manufacture the lenses. They are quite accurate, and extrapolating them theoretically is really the only way to determine the actual resolving power of a lens. Trying to use any kind of equipment, especially digital equipment, will limit the results, as the resolving power of an optical SYSTEM is the RMS of all the system components combined (which tends to be quite a bit lower...~20-55lp/mm most of the time.) |
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Apr 25 |
comment |
For MTF, why does 10 represent contrast while 30 represent resolution? Also recognize that the most recently released modern equipment is capable of resolving FAR more than 30lp/mm. To put things in perspective...the Canon 7D sensor, and 18mp APS-C, is capable of resolving at its best, 116lp/mm (luminance only). Factoring in the bayer CFA, it can resolve ~80lp/mm in full color, interpolated detail. A new Canon L-series Mark II lens such as the EF 300mm f/2.8 L IS II, can resolve around 160-170lp/mm at f/4. On a relative scale...10lp/mm would be like the big fat lines to the left of my chart, while 30lp/mm would be like the lines in the middle. |
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Apr 25 |
comment |
For MTF, why does 10 represent contrast while 30 represent resolution? It should be noted that my sample image is particularly "exaggerated" compared to an actual 10lp/mm + 30lp/mm test chart. If you think about those measures...ten line pairs PER MILLIMETER. The highest frequencies in my sample image probably don't even meet the requirement for 1lp/mm, let alone ten or thirty. Also keep in mind, a line pair is one white and one black line...so you actually have 20 or 60 lines total per millimeter. |
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Apr 24 |
comment |
Do good lenses really last a lifetime? @MichaelNielsen: Compatibility is really, I guess "natively", determined by registration distance. If a lens is designed for a mount with a larger registration distance than the EF mount, it is natively compatible, with a glassless adapter. The whole point about EF is that it has one of the shortest registration distances of any DSLR, which is why it is natively compatible with so many lenses. Overall compatibility is also benefitted by a variety of adapters. My point there was that the EF mount has adapters for EVERYTHING. Not every mount has that range of compatibility, glassless or else. |
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Apr 24 |
answered | For MTF, why does 10 represent contrast while 30 represent resolution? |
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Apr 24 |
comment |
Do good lenses really last a lifetime? I think I mentioned that you have to use a lensed adapter to get FD working.... |
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Apr 24 |
revised |
Do good lenses really last a lifetime? Added update regarding new Canon L-series lenses and their unparalleled quality |
