p.2 #1 · Falling in love with Sony 28-70 f2 GM again !
Xysterz wrote:
Have you compared this to a 2.8?
Compare to 2470GM2? The only real advantage is lighter which I personally don't mind anything less than 1kg. The 24 is wider yes, but 2870GM is ess blurry with the same ISO (higher shutter speed) or same shitter speed (lower ISO)
p.2 #2 · Falling in love with Sony 28-70 f2 GM again !
gordonyz wrote:
Compare to 2470GM2? The only real advantage is lighter which I personally don't mind anything less than 1kg. The 24 is wider yes, but 2870GM is ess blurry with the same ISO (higher shutter speed) or same shitter speed (lower ISO)
How different are the lenses at various focal lengths as far as ability to capture light? Has anyone tested your theory?
p.2 #3 · Falling in love with Sony 28-70 f2 GM again !
chez wrote:
How different are the lenses at various focal lengths as far as ability to capture light? Has anyone tested your theory?
You mean the T stops. I never touched a 2470GM II
There is at least 2/3 difference. I tested against Tamron 17-28mm f/2.8 and the same brightness the 2870GM is a full stop brighter.
p.2 #4 · Falling in love with Sony 28-70 f2 GM again !
How Sony buried the telecentricity argument in lens design:
I came to this fast mid-zoom lens genre while researching telecentricity - the ability of lenses to deliver light rays that are perpendicular to the sensor's outer reaches. You may recall the promotion of wide lens mounts at the beginning of Z and RF mounts. AI listed Canon's 28-70/2 as an example lens of the advantages of wide mount throats. Nikon Z is 55.0mm and Canon RF is 54.0mm, while Sony E is 46.1mm.
"Canon RF 28-70mm f/2L USM: A constant f/2 zoom for full-frame is historically impossible on tighter mounts like Sony E or Leica M. The wide 54 mm RF throat allows a huge rear nodal footprint, creating an oversized image circle that forces light rays down perpendicularly across the frame. (from G/AI)"
I had believed that telecentricity was highly desirable and valuable - it just seems logical that if you can fill sensor photosites at 90 degrees you will be delivered a demonstrably better image.
Sony's entrant is obviously a response to the earlier released Canon of the same configuration. Before a closer examination, the main advantages touted for telecentricity (and wide mount throats as the enabler of it) are: low to no focus breathing and low outer frame shading or vignette. Other claims are made but in sotto voce, rather quietly. Such as smaller physical size, better bokeh.
But Canon's lens is, to put it bluntly, a lemon. And this is why you don't hear much about the superiority of the wide mounts any more. There is virtually no evidence for it in the years since RF/Z first appeared, in the form of great new C/N lenses that were clearly better than the Sony equivalents, let alone being impossible for Sony to emulate.
Here, the Sony 28-70/2 is smaller, takes 86mm filters (not 95mm); has better AF, is sharper, and is a massive 500 grams lighter. And to cap it all off, it has very low vignette and extremely well-controlled focus breathing. Regarding the Canon, technical reviewers were shocked at its severe focus breathing, and aggressive vignette (2.5-3 stops). It seems telecentricity is a feature we can well do without! So that is a victory for optical science over long-established beliefs.
Sony's 28-70/2 is a fabulous lens, a genuine technological achievement. Below are lens block diagrams of the 19/13 Canon lens and the 20/14 Sony lens. How did they trounce Canon so completely, against all odds, against all expectations?
High tech, in a nutshell. Superb matching of six aspheres - three of highly variable centre-edge thickness; and four ED elements with ten regular optical elements. Canon used four aspheres and three ED elements, along with a dependence on their coatings. I sympathise with their users.
p.2 #5 · Falling in love with Sony 28-70 f2 GM again !
Here is a fine explanation of the focus breathing phenomenon. It's not only an issue with video in a lens designed for event work and portraiture, where close focus distances are common.
Used at close range (MFD) the Canon 28-70mm f2 is actually a *25-54mm lens*..let that sink in. At 2m or so, the shift to wider angles of view will be not so dramatic but still very serious. It's not a landscape lens top be used at infinity, is it?
70mm is already a little short for people photography. Close focus headshots will be strange. It's amazing they would release it, and it's equally surprising it is not roundly condemned. This is a $3400 lens. The horror show banner says it all. At least it will work well for large group shots, I guess.
p.2 #9 · Falling in love with Sony 28-70 f2 GM again !
There is an image thread of this lens posted earlier although it didn't start out that way: https://www.fredmiranda.com/forum/topic/1928366/. Some images posted there are truly amazing, making me droll 😜.
