CharlesH
LMF-Patron Gold
- Joined
- Mar 25, 2023
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- 1,213
Sorry to hear about the inadvertent Impact test.I’d be interested to hear if others have observed the same behavior in their own tests.
Sorry to hear about the inadvertent Impact test.I’d be interested to hear if others have observed the same behavior in their own tests.
Sounds like it's a bit decentered.As a continuation of my topic about the Panasonic 100–500, I carried out some additional tests today.
I tested autofocus using a target. The conditions were not ideal — lighting was far from optimal, which is clearly visible.
During the tests, I noticed the following:
at a focal length of 300 mm at f/6.5 and 400 mm at f/6.8, the left edge of the frame appears slightly softer than the right edge.
When stopping down to f/11, this effect is noticeably reduced and overall sharpness improves.
At a focal length of 500 mm, this behavior is not observed at any aperture — edge sharpness appears even across the frame.
300 mm f/6.5
400 mm f/6.8
500 mm f/ 6.8
Hi everyone, thanks for continuing this discussion — it’s really interesting to hear that someone else has also noticed a slight decentering. When a lens experiences a fall, it’s very easy to become overly critical afterward. You start checking everything very closely, and sometimes things can appear worse than they actually are. If a fall really caused decentering, I would normally expect it to be visible more or less across the entire focal range, for example consistently on the left side — not only at specific focal lengths like 300–400 mm. That’s why I can’t rule out that what I’m seeing might simply be a characteristic of my particular copy. To be honest, in the excitement of buying the lens, I didn’t properly test it for decentering from the very beginning — a lesson learned, and something I’ll always do in the future. At the same time, it’s also possible that this behavior isn’t unique to my copy. That’s exactly why I wanted to bring this up here and compare experiences. I’ve shared a link to a full test with a ZIP archive. The test was done at wide open apertures across the focal range, as well as at f/8, f/11, and f/16, so anyone interested can download it and take a closer look. It would be especially interesting if someone else could run a similar test and see whether any effect shows up specifically around 300–400 mm. I’m not suggesting this is a widespread or systematic issue — most likely it’s just my copy — but I’m genuinely curious to hear what others observe.Похоже, что здесь есть некоторая децентрализация.
Thanks for your detailed and thoughtful reply.I seem to recall a vlog post some years ago by Lensrentals, who have all the optical bench gear needed to test lenses thoroughly. Basically, their message was that almost all lenses are decentered to some degree; but of course some are worse than others. Anecdotally, I think that Panasonic lenses are worse than many others, but it's just an anecdote, I don't have the data.
What I do know is that most manufacturers do not perform QA tests on each lens that rolls of the production line. So there will be copy variation. The only exceptions I'm aware of are probably high-end Leica lenses, and Sigma who have built the necessary automation test ensure every lens gets a pre-shipping test.
Yes, the rubber-covered rings are dust magnets.Thanks for your detailed and thoughtful reply.
I’d like to clarify my position a bit. My particular copy shows a slight decentering at certain focal lengths, which I fully understand and will take into account when shooting. Most of my photography is landscape work, and I usually shoot stopped down — rarely wider than f/8, most often around f/11 or smaller apertures. Overall, I am very happy with this lens. I really like the stabilization, the way it works with Panasonic cameras, and the overall handling. I have used it not only for landscapes, but also for portraits, both with flash and available light. I like the rendering and the color reproduction it produces. For the L-mount system, Panasonic has made a genuinely good lens. It is possible that my particular copy has some minor imperfections, but they are subtle enough that in real-world images they are barely noticeable. As a former Nikon user, I have experienced much more serious quality issues with some lenses in the past — including lenses marked “Made in Japan”. Of course, I cannot judge the factory QA procedures or the technical tolerances involved. My only real complaint with Panasonic lenses in general concerns the rubberized rings — both the zoom ring on zoom lenses and the focus ring on prime lenses. Even when using clean hands, the rubber tends to look dusty or dirty very quickly, as if the lens had been handled with sandy hands. The material itself feels pleasant and provides good grip, but visually it picks up marks very easily.
I have the lens, I really like it, but unfortunately, I have only used it at 500mm. When I get a chance, I will check at other focal lengths.at a focal length of 300 mm at f/6.5 and 400 mm at f/6.8, the left edge of the frame appears slightly softer than the right edge.
Wrong. My company has really tightened up, and I can't see Flickr on this computer anymore. I'll check on my personal computer.my computer operates under really strict cyber security rules and 'm not able to open and view your test results. If you could post them on Flickr I can view them.
Got it, I can see the test charts. Dmytro, where did you get chart for testing?I'll check on my personal computer.
Bad Monkey is a really funny series. I didn't know there was going to be a Series 2, I'll watch for it to come out.or the new season of "Bad Monkey"
Cropping the image in camera (with either hybrid or crop zoom) has no effect on the light transmission through the lens to sensor unless a teleconverter is employed. The 750mm equivalent in an apsc ratio crop sounds right, so that would resemble an image same as a 750mm lens while only reducing the pixel count.Depends what you mean by “sacrifice light”. It’s still the same intensity/brightness in APSC as FF, so the exposure will be the same. Of course, you’ll lose half the sensor area so you’ll lose half (1 stop) of “total light”, but that only matters if you’re worrying about noise.
I would think cropping would have an advantage over a teleconverter concerning noise since the noise would not change in any way but only become more visible possible once reproduced and magnified.It would be good to get to some agreement on this (and I accept I may be wrong)...
- Cropping keeps the same image brightness so the exposure remains the same. But you crop away 50% of the pixels (APSC) so the "total light" is halved. This matters if you upscale to the original dimensions because you'll introduce noise.
- Using a TC reduces the image brightness so you need to up the ISO to keep the SS and f-stop the same. This also introduces noise.
I think in principle the end result for a given image size is probably the same in terms of noise, but of course there is also the option to increase the exposure using a TC rather than up the ISO which will get back what you lose in "total light" terms. You don't have this option with cropping of course.
But of course, all this discussion is paying no attention to fancy NR techniques which will potentially level the field.
This is a curious analysis for me. It seems like the teleconverter is reducing light by transmitting the entire image and stretching it to the full sensor giving a lower effective aperture because of the area it (the original image) is distributed over. An f/7.1 at the 750mm equivalent would be f/10.65 at 44mp in the S1Rii.You are loosing the same amount of light with cropping compared to using TCs. In both cases you are straching the image.
With TCs, you are doing it optically, with cropping digitally.
But with TC, you have the advantage of the finer scanning of the image produced by the lens.
I would think cropping would have an advantage over a teleconverter concerning noise since the noise would not change in any way but only become more visible possible once reproduced and magnified.
There is seemingly a mystery about noise which relates to having sufficient light over ISO, but I still do not have that comprehension. The ISO has always been an interesting translation from film grain and noise seems to relate to confused pixels.
Any thoughts on this would be much appreciated.