p.1 #1 · How sharp / less sharp should a G lens be compared to a GM?
Just got a 20-70 and am taking some test shots at 35mm to compare with my 35 GM, and I'm noticing a fair amount of sharpness lacking with the zoom at 100%. See examples. Wondering how much is this expected vs. potentially a copy issue with the lens? In the center, both lenses are comparable sharpness but the GM of course has more microcontrast. But my concern is at other areas of the frame.
These are shot at f8 focused on the same point with both lenses. 20-70 G on left, 35 GM on right. These are 100% crops.
p.1 #3 · How sharp / less sharp should a G lens be compared to a GM?
msadat wrote:
What you have done is not a test between a g and gm lens, you are comparing a f4 wide zoom lens with one of the best 35mm 1.4 ever made.
Yeah fair point. I’ve always been incredibly impressed with my 35 GM. But I guess I’m surprised just how much sharpness falloff there is with the zoom.
p.1 #4 · How sharp / less sharp should a G lens be compared to a GM?
msadat wrote:
What you have done is not a test between a g and gm lens, you are comparing a f4 wide zoom lens with one of the best 35mm 1.4 ever made.
The amount of people that cheerlead the 20-70 here as if it's one of the sharpest zooms ever made has been a little goofy, though...glad to see some reality for once with this lens.
p.1 #7 · How sharp / less sharp should a G lens be compared to a GM?
RoamingScott wrote:
The amount of people that cheerlead the 20-70 here as if it's one of the sharpest zooms ever made has been a little goofy, though...glad to see some reality for once with this lens.
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BigBabyMoses06 wrote:
That image quality seems a bit, rough to me on the 20-70. I was in the market for one and now need to re-evaluate my options.
Yeah I'm a little concerned and maybe should send this back. I had bought it as a travel lens for a trip in a couple of weeks, but at 100% I would've expected sharper. I'll compare it to my Tamron 17-28 and decide if I need to take that + the GM and lose out on the range. I also bought a Sony 16mm 1.8 - that one is a bit harder to compare against, but I'll compare it to the Tamron.
Yeah I'm a little concerned and maybe should send this back. I had bought it as a travel lens for a trip in a couple of weeks, but at 100% I would've expected sharper. I'll compare it to my Tamron 17-28 and decide if I need to take that + the GM and lose out on the range. I also bought a Sony 16mm 1.8 - that one is a bit harder to compare against, but I'll compare it to the Tamron.
It's known that zooms are almost always less sharp than primes, but, would you rather capture more moments during your vacation or would you rather pixel-peep?
p.1 #10 · How sharp / less sharp should a G lens be compared to a GM?
nepali wrote:
It's known that zooms are almost always less sharper than primes, but, would you rather capture more moments during your vacation or would you rather pixel-peep?
Of course the flexibility of a zoom is why I want to take one (otherwise, I would likely just take my much smaller M11 + APO 35 kit). I'm just wondering if this performance is expected from the 20-70 or if I might have a below average copy. The 35 GM pics are more as an upper benchmark. I wasn't expecting the zoom to meet those exactly.
p.1 #11 · How sharp / less sharp should a G lens be compared to a GM?
I have both a 20-70/4 (rather recent purchase) and 28-200. Both extremely popular, highly convenient, etc. I've been a bit surprised at times with some of the descriptions offered up of their performance.
Just from "experience," controlled expectations, limiting my wishful thinking, etc., I wouldn't expect a $1200 (or $700-800) zoom to perform like a $1400 prime or $3000 zoom. However, they could be more than good enough for someone's interests.
And, in the right hands, they can be used to get some impressive results. They work well for me. Others need a higher level of technical performance, and, like any lens or tool, that user needs to be more critical in evaluating the item or the "reporting."
p.1 #12 · How sharp / less sharp should a G lens be compared to a GM?
I ran similar test with 20-70 G against 35 GM and the results were similar to yours. The issue with most zooms, even the first gen GM zooms was the inconsistency in performance at all FL ranges. For example, I had a copy of the 20-70 that was quite strong at 35mm but 60-70mm range was weaker. After 5 copies , I gave up. This isn't to say for general shooting you can't get amazing images, just technical gear OCD. The newer gen GM zooms seem much more even throughout the range though. The newer 50-150 for example I tested was pretty much perfect all the way through.
p.1 #15 · How sharp / less sharp should a G lens be compared to a GM?
No doubt about it, a prime typically has better image quality than a zoom. I think he (and I and probably many others) expected the results of the 20-70 to be a liiiiiiitle better. Even like, 10 - 15% better.
That said, I would like to see the entire image to get a better understanding of where the spot is exactly that we are looking at. If this is literally the edge of the frame, I'd be much more understanding. But if somewhere in the left 1/3rd line, I'd want better.
p.1 #16 · How sharp / less sharp should a G lens be compared to a GM?
Keep in mind others including me have noted that the 20-70G can exhibit some field curvature particularly in the 35-50mm range at certain distances, even at f/8 (check the 20-70 thread if you're curious). Don't know if that's the case here, but where you chose to focus can be somewhat important.
That being said though, it's still not going to be anywhere close to a 35mm GM. Just one of those cases where the word "sharp" is thrown around too loosely to describe a lens.
p.1 #17 · How sharp / less sharp should a G lens be compared to a GM?
According to these tests both lenses should be fairly similar near the center. Also, it just so happens that this zoom is the weakest in the corners at 35mm:
p.1 #18 · How sharp / less sharp should a G lens be compared to a GM?
old-gregg wrote:
According to these tests both lenses should be fairly similar near the center. Also, it just so happens that this zoom is the weakest in the corners at 35mm:
Thanks for sharing those - very informative and actually matches my findings.
I took a number of additional test shots focused to infinity with no buildings too close and overall, I'm happy with the 20-70 and will be keeping it. There is corner sharpness and microcontrast variation across the zoom range, but that is expected for a zoom. At 20mm / 50mm / 7mm, I found f8 to be the sweet spot for corner sharpness. At 35mm however, f5.6 was sharper. At 100% crop, even 20mm is quite fine.
This shot is at 70mm and is sharp enough for me.
ILCE-7CRFE 20-70mm F4 G lens70mmf/8.01/80s200 ISO-0.7 EV
