p.31 #1 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
I went out again and tried some things and mine does in fact front focus sometimes at 75mm. I tried a variety of targets alternating between the Small Flexible Spot and the Magnifier in Auto Focus mode for a pin point spot and got some image pairs that matched up well and some that were front focused with the Flexible Small Spot, not sure why. It does seem like we are asking the small spot to do a lot accuracy wise, as it covers a fairly large area even at 75mm and up close.
p.31 #2 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
Had to read up on on sensor PDAF, seems like it could be a simple calculation issue, fixable via firmware... probably need to get more in the wild and see if it’s repeatable... I’ll check mine in the AM.
Will the camera fine tune AF with this lens?
Also, and doubt this is the issue here, but got me wondering, could a lens’ sharpness exceed the accuracy of on sensor PDAF? Ie the accuracy of the PDAF system is not high enough for the tiny circle of confusion from a given lens?
p.31 #3 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
Just remember all of Sony’s AF systems read the vertical lines to focus. Horizontal lines in a image are a non factor. So pick targets that have vertical lines in them for more accuracy when testing the AF side of it. Also the green square reads on the lines not the inside of the box. It’s seems more accurate to me to put one side of the green lines on the target.
p.31 #4 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
There is a thread about the A7III front focusing with eye auto focus. I believe Jordan is shooting A7III. i have not read the thread, but could be a connection
p.31 #5 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
This lens is nowhere near as sharp as the 90/2.8 macro, and there are no issues with accuracy there, even with super shallow depth of field at macro distances.
Mathieu18 wrote:
Had to read up on on sensor PDAF, seems like it could be a simple calculation issue, fixable via firmware... probably need to get more in the wild and see if it’s repeatable... I’ll check mine in the AM.
Will the camera fine tune AF with this lens?
Also, and doubt this is the issue here, but got me wondering, could a lens’ sharpness exceed the accuracy of on sensor PDAF? Ie the accuracy of the PDAF system is not high enough for the tiny circle of confusion from a given lens?
p.31 #6 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
Yea, I figured as much, was more musing if it’s possible. Seem it has to have its own technical resolution, wondering if it can be exceeded, or if it will always scale with higher res lenses and sensors... I guess it’s something Sony would work on.
Jman13 wrote:
This lens is nowhere near as sharp as the 90/2.8 macro, and there are no issues with accuracy there, even with super shallow depth of field at macro distances.
p.31 #7 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
Someone at Dpreview mentioned potentially changing AF priority, which might be a good idea, as I know I have mine set for fastest speed right now. I can't test it until tomorrow, though, as lucky me came down with appendicitis last night, so I'm enjoying the comfort of my hospital bed.
p.31 #8 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
Jman13 wrote:
Someone at Dpreview mentioned potentially changing AF priority, which might be a good idea, as I know I have mine set for fastest speed right now. I can't test it until tomorrow, though, as lucky me came down with appendicitis last night, so I'm enjoying the comfort of my bed.
Hi Jordan,
So sorry to hear that on a Holiday weekend to boot.
p.31 #9 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
If the misfocus is unique to AF-S and does not occur in AF-C then that sounds like a focus shift issue, just like what was discovered on the initial copies of the Sony 24-105mm. For the Sony it wasn't optical focus shift but instead algorithmic focus shift, ie the lens dynamically adjusted focus based on the dialed-in aperture and some copies went out with their aperture-to-focus look-up table misconfigured.
p.31 #10 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
I've been shooting more with my lens yesterday and today and haven't noticed any front focus issues. I also did some trials at 75mm with flexible spot (small) but didn't see any problems. I did notice after more use that the focus acquisition speed in AF-S mode (at least when using wide focusing area) is a bit slower than with the fastest focusing native Sony lenses, but it's still fast enough for my normal use.
p.31 #11 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
Jman13 wrote:
Someone at Dpreview mentioned potentially changing AF priority, which might be a good idea, as I know I have mine set for fastest speed right now. I can't test it until tomorrow, though, as lucky me came down with appendicitis last night, so I'm enjoying the comfort of my hospital bed.
Jordan -- Thanks for your tests, and get well soon!
p.31 #12 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
Loving the bokeh thus far.
This really would make an awesome vacation with a light long prime like Batis 135mm.
Jman13 wrote:
A few examples of the focusing errors I'm getting. At first I thought my lens was just soft, but if I manually focus, it's really quite good.
Small flexible spot, with the focus point placed on the point in the middle of the M here, 75mm, f/2.8...probably the worst example. I took multiple shots with the same result. Was bizarre almost.
Another at 75mm f/2.8 from a further difference, medium flexible spot. The differences here are a little more subtle, but the AFed shot is definitely notably softer, and in the full image it's focused forward in the AF shot.
Interestingly enough, when shooting indoors in dim light, I'm not seeing these focus errors...perhaps because the camera is relying more on contrast detection in dimmer light.
And a nice, properly focused shot to enjoy...when the AF hits, it appears to be a pretty good lens. Hopefully, they'll do a firmware update quickly, or I'll get my replacement lens without such errors. http://www.jordansteele.com/2018/columbus_tamron.jpg...Show more →
p.31 #13 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
Jordan, hope you’re better soon!
Did a bunch of testing on the R2 a bit ago and don’t see any consistency to focus error, though I also wouldn’t say it nails perfect focus every time. On the other hand, I’m more a MF shooter so could well be choosing the wrong mode for a given situation. Still with good light and contrast and obvious lines it was accurate. Someone with more AF knowledge than we would have to take a better look.
AF-C in the very corner with S or M flexible spot did just hunt back and forth. AF-S seemed to lock on fine though with both spots.
I’m still thrilled though, its IQ is good, in general focus behavior is good, it’s silent, light enough and convenient. Look forward to more findings but aim satisfied in its performance.
p.31 #15 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
From just a quick 30 minutes of testing:
Weight is great, you can really feel the 100 grams difference from the 24-105.
Focus seems as quick as any native zoom.
Super sharp in the center, definitely takes a couple stops to get really sharp at the edges and corners.
I don't seem to have any front focus issues at 75mm, tried different focus modes. I've always had AF as my focus priority setting.
I'm happy with the lens, but not blown away. The 12-24 and the 24-105 blew me away.
p.31 #17 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
If you're shooting landscape at 5.6 or smaller, I'd say you will get good results. But the 24-105 can do that with better focal length reach in both directions.
2.8 on this lens would seem to be useful for subject isolation, but not edge to edge sharpness. The center 1/3 of the frame is very sharp wide open.
I'm torn a little on whether to keep it. I really love the 24-105. I shot a band live a couple weeks ago at iso6400 and f4 the entire show, and the shots are awesome. I never said to myself "I wish I had that Tamron right now."
p.31 #18 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
Thanks maestro. Yes, I do shoot well stopped down for landscapes, usually at F/11. Everything I'm reading so far, is just nudging me away from this Tamron towards the 24-105. If I want shallow focus I will use the 55/1.8.
p.31 #19 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
Both modes are Balanced Emphasis. I'm sure I don't scratch the surface of the AF sophistication of even the R2. Few sets of crops below. First support the front focus, second set were as good with AF. I sure some could have been better on a tripod but I prefer to test how I shoot. Anyway, seems to me, at least in my case, it's just a matter of what the AF system is locking on, and it's not something I'm concerned about in real world use.
Jman13 wrote:
Mathieu, what are your focus priority settings, btw?
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As an aside to questions about landscape use, seems a no-brainer that the 24-105 is a better bet. Sharp with a more useful focal range. I've got other lenses for landscapes. But for people I'll take f/2.8, and I like that it starts at 28mm, I don't usually shoot people with wider, so I'd rather not always have to frame in from 24mm. That's me though...
p.31 #20 · In stock: Tamron 28-75mm f/2.8 E-mount ($799)
Thank you (all) for the great information.
For what it's worth, especially to those in the U.S., I pre-ordered one today from https://www.abt.com/ ... an electronics retailer near Chicago that's been around for several decades. A colleague led me to them. They were unbelievably helpful ... B&H helpful (I've always had great service at B&H). They ship for free, gave me a $50 immediate discount for Memorial Day weekend -- that they offered, I didn't ask, didn't charge tax (caveat: I'm not in that state), and assured me they could get one to me in 7-14 calendar days, stating "I checked to be sure and that's what our Tamron rep is saying". As an aside, perhaps that's also an indicator for when they'll be shipping in larger numbers everywhere.
$750 "out the door". Who knows, it may not make it for two months (facepalm). I'll try to update the board with my results, but thought I'd share here. YMMV.
