Canon EOS 10D/20D/...
Majitel: Pepa Ouředník |
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ALEX LÍŠKA | 00:47:37 15.05.2004 |
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| [Canon EOS 10D/20D/...]
Vlado Burjan | 23:10:37 14.05.2004 |
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Zdenek Felix | 19:10:21 14.05.2004 |
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17-40/4L
24-70/2,8L
70-200/2,8L IS
50/1,4
100/2,8 macro
a všude je ostrost ok.
Stejně tak u 28-135 a 16-35, co jsem měl předtím...
Jiří Kejdana | 17:10:48 14.05.2004 |
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Zbyhněv Ćmiel | 17:07:12 14.05.2004 |
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Jiří Kejdana | 16:52:15 14.05.2004 |
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Jiří Kejdana | 16:48:17 14.05.2004 |
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Sigma 15-30, f/3,5-4,5 EX DG ASPHERCIAL
Canon EF 28-135, f/3,5-5,6 IS USM
Canon EF 100-400, f/4,5-5,6 L IS USM
SIGMA 105mm F2,8 EX MACRO
Canon EF 50/1,8 II
Canon EF 28/2,8
a nejlepší ostrost mám u pevné 28 a 50.
Jiří Cvrk | 16:11:13 14.05.2004 |
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Jiří Cvrk | 16:10:41 14.05.2004 |
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mám:
EF 28-105 1:3.5-4.5 II USM 28,0-105,0mm
Canon EF 100mm f/2.8 Macro USM
Sigma AF 15- 30mm f/3,5-4,5 EX
Sigma70-200mm f/2.8 EX APO HSM
žádný z těchto objektivů netrpí popisovanou potíží v kombinaci s mým 10d, pokud to já amatér dokážu posoudit. Při nákupu objektivů Sigma jsem zdůrazňoval, že to chci pro 10d.
Jiří Kozubík | 15:48:18 14.05.2004 |
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Pavel Lexik Kulička | 15:23:08 14.05.2004 |
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Zbyhněv Ćmiel | 15:18:14 14.05.2004 |
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| 12:26:42 14.05.2004 |
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Pepa Ouředník | 12:25:15 14.05.2004 |
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Kamil Toman | 12:09:46 14.05.2004 |
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Tomáš Houda | 12:09:37 14.05.2004 |
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Docela by mne zajimalo, jestli by se lidi, co si kupujou ty kanoony, nechali treba naverbovat na nejaky letadlo nebo neco podobnyho...
Hej, mam fantastickej tip... poslete mi vsichni svoje uspory, a do roka vam zarucuju renditu 45%... supr obchod, nevahejte :-D
Kamil Toman | 12:09:18 14.05.2004 |
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This is a very common and very pitiable reason for messing up a photo! Picture the following scene: You want to take a candid shot of your girlfriend lying in a flower field. You know that it doesn't look good to have the main subject centered in the picture. But your split-image focusing tool is in the center! So, you center the finder on your girlfriend's eyes, focus to perfection on her using the split image, then turn the camera slightly away so that she is on one side in the field, and you press the shutter. And when the film comes back from the lab, you are terribly disappointed: Your girlfriend is out of focus, while the flowers behind her are sharp! And the worst thing is that she laughs about your misfortune!
Many hobby photographers do this mistake time and again, and fail to understand it. The reason for your unsharp girlfriend is that photographic lenses have a reasonably flat field, not a spherical one. Suppose you were 4m away from her. When you focused on her, you adjusted the lens to 4m. When you then aim to place her on one side of the picture, your lens will be focused for the plane that is perpendicular to the lens axis, and 4m away. That plane is considerably behind your subject! If your girlfriend is at 30 degrees from the picture center, then the distance ratio is 0.86 (the cosine of the angle). So, your lens should have been focused to 3.46m, which is the distance along the lens axis to the plane which is perpendicular to the axis and passes through your girlfriend's face!
What can you do without using math in the field? Simple: Compose the picture first, and focus after that, while keeping the camera in the exact position at which you will shoot. That means, on most cameras you need to use the matte screen instead of the split-image tool. The reward for the slightly bigger effort will be a sharp girlfriend!
The more expensive autofocus cameras may be able to take care of this problem, as long as they provide some way to decide correctly where you want the focus to be. The cheaper autofocus cameras simply can't take this kind of photo correctly using autofocus, since they measure focus only in the center. If you have such an autofocus camera, switch off the autofocus and focus manually. With a point-and-shoot camera that does not allow manual focusing at all, the only hope is to look for an object that is at the correct distance, focus there, and then compose. That object needs to be closer than your subject is. And you will need some math, or at least some guesstimation!
Tomáš Houda | 12:04:05 14.05.2004 |
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Jiří Kozubík | 12:02:08 14.05.2004 |
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http://www.digitalkamera.de/Info/News/17/58.htm
Petr Hořice | 11:59:13 14.05.2004 |
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Jakub Slížek | 11:35:08 14.05.2004 |
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Michal Duchek | 11:33:19 14.05.2004 |
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Tomáš Houda | 11:23:33 14.05.2004 |
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Ja si jeste dobre pamatuju, jak pred prichodem digitalni techniky byly delany testy kamer... to se zkoumalo pomalu pod mikroskopem jak jsou udelany a merilo se na setiny procenta jak presne jim jdou zaverky a podobny picoviny, ktery na foceni prakticky opravdu nemaj vliv. Docela se musim smat pri predstave, ze by si tehdy nejakej vyrobce dovolil dat na trh fotak, kterej neostri, nebo ostri jenom s jednim objektivem a s jinym nekam jinam... to by byl bugr :-D
Jiří Kozubík | 10:45:23 14.05.2004 |
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Tak jsem dohledal ty testy: http://www.hkdotnet.com/FrancisPhotographyChannel/AF_Test/index.htm
Conclusion
The methodology introduced here lets every camera owner test the focus accuracy of their camera easily without the need of sophiscated testing instrument. I've tested my Nikon FM3A, F100, CP995 DC and the Canon EOS 33, EOS 1V with some lens combination. The manual focus of the FM3A and F100 is nearly dead on, the F100 AF is quite accurate. The manual focus of EOS 1V is OK but not as good as the F100, the EOS 33 is not good enough, both EOS 33 and EOS 1V showed more pronounced degree of AF focus shift than F100, EOS 1V AF is a little better than EOS 33 but it is not satisfactory for a camera aimed for the professional.
An interesting result is found in testing the EOS 1V with the EF70-200mm f2.8 usm lens, the focus shift is quite a bit backward at the 70mm side, the focus is good in the 100-135mm range and OK at the 200mm end. This showed that both the camera AF accuracy as well as the lens sharpness play a part in final image sharpness.
Overall Nikon F100 AF and MF is more accurate than Canon EOS 33 and 1V, also the AF accuracy of F100 is more consistant with different lenes.
Kamil Toman | 10:31:30 14.05.2004 |
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nektery vlastnosti AF jsou dany, napr. rozliseni senzoru AF (typicky matice CMOS senzoru), kterych je moc malo na to, aby pri mensi DOF
rozeznaly detail, na ktery ma byt zaostreno (typicky napr. oko).
Tr. Ianus Germanicus | 10:17:13 14.05.2004 |
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Jiří Kozubík | 09:38:56 14.05.2004 |
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Petr Staněk alias šnek | 09:25:58 14.05.2004 |
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Tvuj problem je spise prinutit servis aby zjednal napravu. Znam jedno profi fotografa ktery je nestastny majitel Sigmy 70-200 + Eos5 + Eos3. Sigma mu slape s Eos5 a on jiz foti s Eos3. Na Eos3 Sigma dosti zlobi, jine skla OK. Takze chyba objektivu v komunikaci s Eos3 (a Eos 10D). Dotycny fotograf ma znameho v AWH a Sigma tam byla celkem 3x. Vysledek Sigma zlobi dale a AWH tvrdi ze je to OK. Pokud jsem do AWH volal ja, tak mi rekli po popisu projevu zavady Sigma ze ta sigma je vadna at ji poslu do servisu, to netusily ze po 4-te. Vysledek? Dotycny fotograf si Sigmu nemuze vynachvalit a taji ze vlastne obcas nefunguje a ze vzpomina na Eos5 :(










