Search results for 'back focus' - page 986
Sigma 50 1.4 from Microglobe
Yes. It does that with contrast AF, as in Live View. With phase AF it measures the difference between the out-of-focusness as seen by two sensors and calculates how much to tell the lens to move the focus. If the lens says it has got there it doesn't always mean it is perfectly focussed. How ...
Posted by Smeggypants on 17/07/2011 - 17:54
Sigma 50 1.4 from Microglobe
It got me too Smeggy but it's know that there is a focus tolerance in the lens as well, don't know precisely how it works though.
Posted by Anvh on 17/07/2011 - 18:01
Sigma 50 1.4 from Microglobe
It's an electronic instruction to a mechanical device. There must be feedback to say "I've arrived at the point of focus" but of course there will be mechanical tolerances. Deceleration also is a factor - nothing stops instantaneously. So a lens with a long throw may reach higher speeds and overs...
Posted by johnriley on 17/07/2011 - 18:08
Sigma 50 1.4 from Microglobe
It's an electronic instruction to a mechanical device. There must be feedback to say "I've arrived at the point of focus" but of course there will be mechanical tolerances. That's the point Smeggy is making. How does the lens say it has got there? Surely the camera decides when focus is achieved,...
Posted by Anvh on 17/07/2011 - 18:26
older Prime vs newer Zoom
OK I have a hankering to get a 24mm Sigma miniwide, or a 28mm Pentax A. I like prime lenses. I'm looking sub £100 older primes. However, frugal me thinks the Tamron 17-50mm I already have on the front of the camera is not a bad performer. I'm not bothered about manual focus or size as I'll be...
Posted by dougf8 on 17/07/2011 - 16:50
older Prime vs newer Zoom
Unfortunately, I don't have a "best of" modern zoom with which to compare, but I do have three sub £100 primes that definitely out-perform a Pentax 18-55mm ALII kit lens - though I couldn't guess how they would compare with a Tamron 17-50mm. You could do worse than have a look at the Sigma 24mm f...
Posted by andrewk on 17/07/2011 - 19:03
older Prime vs newer Zoom
I've got the Chinon 28mm f2.8 and it's a handy lens for close-ups from 200mm and can have nice bokeh and character. It's really soft though at the edges and corners, making it unusable for things like landscapes and buildings. I bought the Chinon only a few months back and it was almost permanently ...
Posted by andrewk on 17/07/2011 - 20:08
older Prime vs newer Zoom
Could be Andrew, but all my 28mm are soft at the edge apart from the Ensinor which cost a small fortune :mrgreen: ..... £5 Mint in box :mrgreen: This is a 100% crop of the extreme bottom left corner of a photo of Glenuig Bay (might not even have been in focus, as the grass was entirely incidental to...
Posted by andrewk on 17/07/2011 - 23:53
older Prime vs newer Zoom
Could be Andrew, but all my 28mm are soft at the edge apart from the Ensinor which cost a small fortune :mrgreen: ..... £5 Mint in box :mrgreen: This is a 100% crop of the extreme bottom left corner of a photo of Glenuig Bay (might not even have been in focus, as the grass was entirely incidental to...
Posted by Algernon on 18/07/2011 - 09:59
older Prime vs newer Zoom
If you can find a Sigma 24mm Super-wide II, then I would get it. I got mine, which is manual focus, for 30 quid and it's probably my best lens in terms of IQ. It's even very good wide open. I just missed an AF version on ebay for 15 quid....
Posted by aliengrove on 21/07/2011 - 23:02
older Prime vs newer Zoom
Sigma Ultra Wide II 24/2.8 (pravtako in C / Y bayonet) "I know a little bit strange choice at first glance, but does have aperture and focus manually, but the scan was made from a similar, if not the same design as the Leica model. Even before the test, I could see that this lens ca...
Posted by johnwhit on 22/07/2011 - 12:32
older Prime vs newer Zoom
Hi Algi, Do you not remember the AP cover Sigma beats Leitz? They tested all the 24mm lenses available and found the Sigma beat everything, another Dr Bell job:lol: Personally I think the Slovenian site has either a very beat up lens, a bad copy or a duff test. I have 2, one manual focus the o...
Posted by johnwhit on 22/07/2011 - 13:28
older Prime vs newer Zoom
Ok enough, best delete this thread or I'll never get a chance at a 24mm Miniwide. The Miniwide is the 28mm lens, I think. The manual focus Sigma 24mm f2.8 Superwide II that I have is a fine lens. Yes, you can demonstrate that it's sharper in the centre than in the corners by taking photos of tes...
Posted by andrewk on 22/07/2011 - 15:52
older Prime vs newer Zoom
The shot mountain underneath the church interior on the page I gave before looks really weird the way it's sharp in the centre and soft at the edge. There's no indication of aperture used, and the shot's on film... looks to me like the aperture was f2.8 and the focus was on the lamp post.... http://...
Posted by Pentaxophile on 22/07/2011 - 16:13
older Prime vs newer Zoom
Lovely images Will, yeah 1:4 at it's closest focus distance. John
Posted by johnwhit on 22/07/2011 - 16:14
older Prime vs newer Zoom
The Miniwide is the 28mm lens, I think. The manual focus Sigma 24mm f2.8 Superwide II that I have is a fine lens. That explains why I haven't found one on ebay!!:roll::roll::roll: And I have even less hope now.
Posted by dougf8 on 22/07/2011 - 18:59
older Prime vs newer Zoom
The Miniwide is the 28mm lens, I think. The manual focus Sigma 24mm f2.8 Superwide II that I have is a fine lens. That explains why I haven't found one on ebay!!:roll::roll::roll: And I have even less hope now. You have mail. John
Posted by johnwhit on 22/07/2011 - 19:39
Possibly FS: new DA18-55 WR
I have the DA 18-55 WR, unpacked, and unused, part of the two lens bundle from my K5. I don't think I need it as I have the wide end ( sigma 10-20), midrange (DA 50-200) and telephoto (DA*300) range covered. Just wondering what I would get for it. It won't be on sale until I come back from hol...
Posted by DaveN on 17/07/2011 - 17:11
Testing my 500mm Tamron Mirror
I just got a used Tamron 500mm mirror lens for my K-x from the classified section of the forum, and tried it out at the Cholmondeley Pageant of Power this last weekend. I was a bit worried at the requirement for a tripod, various web comments about it being f8, but I was quite pleased with the resul...
Posted by droopsnoot on 18/07/2011 - 10:38
Testing my 500mm Tamron Mirror
Problem is, there seems to be a prevailing attitude in some very noisy quarters that mirror lenses are always useless. I was recently given a Makinon 500mm f8. My assessment would be "Not too bad". Cropped shots from my 50-135mm are possibly better but that's comparing a £640 lens with something...
Posted by Dangermouse on 18/07/2011 - 15:00
