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Chrissie

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Everything posted by Chrissie

  1. There are basically two cases to consider: the resulting resolution may either be limited by the available pixel count of the sensor (lens could deliver more, but sensor does not have enough pixels to take advantage of the lens's capabilities - or: the resulting resolution may be limited by the focussing capabilities of the lens. (The image of a "point size" object on the sensor is larger than one sensor pixel.) If you want to exhaust the pixel count of your sensor as far as possible, you should pick any lens that has a higher "perceptual pixel count" (to use dxo's terminology) value than the sensor. In their lens database there are only five lenses that come close, if you include 40 pMP as being close enough to the 42 actual MP od the 7Rii.
  2. I would assume, that the camera has low-light autofocus capabilities. "EV" being the abbreviation of "exposure values". So it would still be able to auto-focus, even if the lighting conditions are "X" exposure values below proper exposure. However, I'm only guessing.
  3. I have experienced the shooting of birds in flight to be one of the most demanding benchmarks for shooting at all. Looks like you are underestimating its requirements in terms of long focal reach (which in turn requires short exposure times), erratic, i.e. unpredictable movements of the birds, along with advanced continuous AF capabilities (forget manual focus with birds). In very broad terms, selling used equipments rarely gets you an adequate return on the initial investment. Therefore I would keep the A7iii and buy a used a9, to turn that bad ROI for the supplier into an advantage for you. 😉
  4. Pieter, thanks for your openness. To give Wally the Unspeakable the benefit of any doubts possible, I took the worst of all possible assumptions. The 15 Newton resisting force would only be reached, if all of the following conditions would be met. In particular, if the sample lense: had a barrel diameter of 70mm a fully compressed length of 200mm a fully extended length of 280 mm was completely hollow inside had been manufactured and sealed at the fully extended (400mm) position (i.e. rendering a pressure differential of zero between inside and outside of the lens at this position). Compressing this volume by fully zooming out (100mm position) would shrink its internal volume by 28.5%, resulting in an increase of internal pressure up to 140% of ambient pressure. So we are talking about a pressure differential of 0.4 bar, acting upon the full front surface (diameter 70mm), and this is where the 15 Newton comes from. And this is, btw, only the force acting axially, while the user would only have to apply his force to the zoom ring, which has a friction brake in itself. What I'm implying by this is, that holding this zoom lens in any position is effortless, regardless of pressure differential. We can discuss ad nauseam whether this force is difficult to overcome or not. This of course is very much subject to everyones physical capabilities and individual perception. I'm not going into that. But the initial claim, that is definitely nonsense. It states in absolute terms, that regardless of the force applied, no movement would be possible. Being a mechanical engineer by education and profession, I tend to take such statements as verbatim. Having to overcome a maximum resisting force of 15 Newton just does not qualify as a blocking obstacle whatsoever. To put this a little into perspective: Whoever handles a Sony alpha and the 100-400GM lens combo is dealing with a combined weight (force) of 21 Newton already, and nobody in their right minds would claim, that this weight is impossible to lift. This, btw, is the factual background, against which I qualified Wally's initial claim as nonsense. Thanks to everybody for their patience. I'm leaving the last word to whoever wants to have it. I'm not going to elaborate this any further.
  5. Wally, this is your initial claim: Even as you are backpedalling now, conceding the possibility of only a little movement, before being overwhelmed by air pressure forces, this still remains nonsense, as the undisputed forces generated by the pressure differential between inside and outside don't exceed 15 Newton on a zoom lens with dimensions similar to a 100-400GM. This minuscule force does not qualify as making any zoom action difficult or even impossible. Any claim to the contrary does however qualify as nonsense.
  6. Since this was a low-light situation (exposure time 30 seconds), my guess is, that the AWB did not find a proper reference point for "whiteness". If you've shot in raw format, you could correct this during postprocessing. To avoid this in future shots, you may want to experiment with manual white balance settings. Note the 2nd bullet point in the "Note" section of the above linked section of the user guide: It looks like the street light (which cast your shadow on the sidewalk) may have been one of those mercury or sodium lamps.
  7. https://www.meike-canada.com/product/meike-mk-28mm-f2-8-large-aperture-manual-focus-lens-for-sony-e-mount-nex33n56/
  8. The 70-200 GM lens is known for noticeable (actually: worst in comparison) vignetting of -1.7 EV, according to comparative measurements at dxolabs: Using a lens hood certainly doesn't help with this.
  9. I'll second that, from personal experience. And according to dxomark.com's lens database, it's actually one of the sharpest lenses around. (9th rank out of more than 7000 tested lenses).
  10. It seems like you don't plan your pictures at all. A good picture doesn't happen by accident. It consists of various aspects, including (but not limited to) the following: proper exposure (brightness, contrast) proper focus (including depth of field) proper composition (point of view, focal length, foreground, background, position of main subject within frame) Proper timing (with or without motion-blur, depending on your intention; waiting for the "right" moment, etc.) If you don't aim at anything, you're sure to hit - nothing. On a positive note: study pictures which you really like, and try to mentally decompose into each of the above aspects. Then try to imitate. This requires a solid proficiency with your gear, which you can only acquire by lots of practice. You need to plan, then act according to plan, then compare the results with your initial goal. Adjust the means as necessary. Don't adjust your goal! 😉
  11. Please answer my question regarding your 1st picture.
  12. What did you intend to show, and in which way is the result different from your intention?
  13. I tried to look it up, and my most relevant finding is this: This is the only occurrence of the word "limiter" in the linked user guide, btw.
  14. Google gives no results for "internal couting". The most likely replacement in this context would probably be "internal coating". There are a few suggestions given on how to deal with problems like yours, like this one on stack exchange.com. Warning: not for the faint-at-heart though.
  15. If you don't want to upgrade you MacOS, you have several options: maybe you have access to somebody's Windows computer, maybe friends, or at work? you may have a bootcamp partition on your Apple computer, to boot into a native Windows on your Mac you may have a virtualisation environment for MacOS, like VMware Fusion, where you could install a Windows OS
  16. They say: "Time heals all wounds". And it's amusing to see, how the passing of less than a year papers over in some people's minds the reasons for why username got kicked out of this forum. I would have liked to link some of his "fresh perspectives", but they have been purged as well. SO SAD. SCNR
  17. What kind of "luck" are you expecting?!! In your first post, which was only 13 hours ago, you didn't bother to introduce yourself - you didn't even tell your name. This forum has, in my personal view, a sore surplus of first-time posters who just pop in and ask questions which require actual effort of actual people to answer. This forum is not an automated, Sony related search engine. Many people don't even bother to say "thank you" for any effort expended on an answer that was given to them, even if it was a correct one. If you don't like that, the only advice I can give you is: Be the change you want to see in the world! Become a contributor, instead of a "drainer". And eventually, over time, you'll be part of a real discussion. Including: receiving answers.
  18. I think, this is for you. Set Focus Mode to DMF.
  19. Knowing the width of a Sony A7iii body (from Sony tech specs) of 126,9 mm, you can derive the height of 20.0 mm from this foto: Base image source: https://epicelectronics.dropgecko.com/shop/Meike-MK-X1EM-Metal-Bracket-Hand-Grip-for-Sony-GP-X1EM-A9-A7MIII-a7RIII-a7RII-a7II-a7SII-Camera-Free-Shipping-19#gItem_3 Measurement by Chrissie.
  20. Wally, please don't spread this kind of nonsense claims. Without an opening, micro or not, you would simple just be changing the internal air pressure, which would definitely not block the lens from moving. If you want to read up on physics, this would be a good start.
  21. That's odd: I couldn't find this function for the a9 (running on v 5.0) but did find it for the a7r3. To me it sounds like it has been specifically designed for the very artificial lighting situations that we're talking about. I'd definitely give it a try if I had it on my camera too. (Note my tag line...). Note also, that Sony recommends taking tests shots beforehand. Shooting under artificial lighting conditions seems to be tricky business:
  22. I consider this to be the proper answer, and not some lame excuse by Sony. Also their advice, to avoid short exposure times, goes into the right direction. This would help to "average" out any effects of LED flicker. With the spreading of more and more LED-type lighting, this problem can be expected to become more frequent, and not only the a9 will be affected. Reason being, that LED type light sources emit light in a pulsating fashion at a frequency unknown to the camera body, while the sensor readout also occurs at a frequency, which the LED has no knowledge of. These frequencies are likely to be different, and shooting at artificial light becomes prone to some kind of interference, superpositition, cancelling or whatever you might call this. Even though the human eye generally cannot realize the flickering nature of LED lighting, the sensor of a Sony alpha sure can. The faster the sensor, the better it is at capturing distinct phases (i.e.: darkness, color variations) of this flicker. You just can't beat physics.
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