BLACKOUT Posted September 3, 2016 Share Posted September 3, 2016 Prime - zoom,any format, film or digital.Just wandering what's out there that doesn't change focus/shape (too much). Stills taking lens only folks-NO CINES.Should be interesting. Quote Link to comment Share on other sites More sharing options...
BrorSvensson Posted September 3, 2016 Share Posted September 3, 2016 18-35 1.8, pretty much parfocal Quote Link to comment Share on other sites More sharing options...
Geoff CB Posted September 3, 2016 Share Posted September 3, 2016 Tokina 28-70 2.6. Quote Link to comment Share on other sites More sharing options...
cantsin Posted September 3, 2016 Share Posted September 3, 2016 There are AFAIK no true parfocal photo zooms - true parfocality requires complex optical constructions which are too expensive to make sense in a photo camera. On top of that, even parfocal cine zoom lenses need manual shimming adjustment because of mechanical tolerances of camera mounts. This isn't possible with photo zoom lenses either. Quote Link to comment Share on other sites More sharing options...
noone Posted September 3, 2016 Share Posted September 3, 2016 The Sony 28-70 FE (kit lens for the A7) is surprisingly close to being parfocal (it is for my purposes). On my A7s, I use it as a constant 5.6 lens for the most part. EDIT This might help too. https://www.lensrentals.com/blog/2016/03/mythbusting-parfocal-photo-zooms/ I actually only read it after posting. I think shorter range zooms may give greater consistency for those that are close to being parfocal. Quote Link to comment Share on other sites More sharing options...
sandro Posted September 3, 2016 Share Posted September 3, 2016 Someone mentioned the canon fd 35-70 f4. Quote Link to comment Share on other sites More sharing options...
TheRenaissanceMan Posted September 3, 2016 Share Posted September 3, 2016 Minolta Rokkor 35-70 Canon FD 35-105 Quote Link to comment Share on other sites More sharing options...
Geoff CB Posted September 4, 2016 Share Posted September 4, 2016 3 hours ago, TheRenaissanceMan said: Canon FD 35-105 I enjoy this lens, but it has some of the worst close focusing I have ever seen. Quote Link to comment Share on other sites More sharing options...
BLACKOUT Posted September 4, 2016 Author Share Posted September 4, 2016 1 hour ago, Geoff CB said: I enjoy this lens, but it has some of the worst close focusing I have ever seen. Surprised by the zooms getting mention,no primes yet! Quote Link to comment Share on other sites More sharing options...
cantsin Posted September 4, 2016 Share Posted September 4, 2016 7 hours ago, BLACKOUT said: Surprised by the zooms getting mention,no primes yet! Well, only zooms can be parfocal... Quote Link to comment Share on other sites More sharing options...
TheRenaissanceMan Posted September 4, 2016 Share Posted September 4, 2016 The definition of parfocal is that the focus point remains the same while zooming. Therefore, it doesn't apply to primes; they can breathe, but they can't be parfocal. Quote Link to comment Share on other sites More sharing options...
Marco Bentz Posted September 4, 2016 Share Posted September 4, 2016 Lomo Foton 37-140mm f4.5 lens Leica Vario Elmar R 80-200 mm f/4 Quote Link to comment Share on other sites More sharing options...
noone Posted September 4, 2016 Share Posted September 4, 2016 5 hours ago, cantsin said: Well, only zooms can be parfocal... Primes can be (sort of). With cameras that have a variable digital zoom you can use that. May have its uses for video though. Sony cameras can use Clearzoom (which is virtually lossless variable to 2x. For 2x to 4x digital zoom is not so good and obviously lossy). For the most part though, you are right. Quote Link to comment Share on other sites More sharing options...
TheRenaissanceMan Posted September 4, 2016 Share Posted September 4, 2016 28 minutes ago, noone said: Primes can be (sort of). With cameras that have a variable digital zoom you can use that. May have its uses for video though. Sony cameras can use Clearzoom (which is virtually lossless variable to 2x. For 2x to 4x digital zoom is not so good and obviously lossy). For the most part though, you are right. But then every prime is parfocal, since its plane of focus isn't involved in the digital crop process at all... Quote Link to comment Share on other sites More sharing options...
noone Posted September 4, 2016 Share Posted September 4, 2016 9 minutes ago, TheRenaissanceMan said: But then every prime is parfocal, since its plane of focus isn't involved in the digital crop process at all... Agreed. So long as you have variable digital zoom available. Not something for stills really unless focal length challenged (though it has its uses- but not needed to be parfocal) but for video, if I did anything other than record bands or had any actual ability to do it properly, I would certainly be using clearzoom with my A7s and 24 1.4/85 1.2 FD L lenses when I thought it would work. I posted a very lame demonstration of clearzoom on YouTube a couple of years ago (with a Nikon 50 at 5.6) but there are some better demos of it there. Quote Link to comment Share on other sites More sharing options...
noone Posted September 5, 2016 Share Posted September 5, 2016 Another quick (and lame) demo of Clearzoom with A7s and 55 1.8 Sony Zeiss and short extension tube. I think it would come in handy for short quick takes. Maybe a lens like a 24 1.4 would be useful. Quote Link to comment Share on other sites More sharing options...
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