PROIETTORI E LUCI PORTATILI - proiettori luci

 2024-09-09 20:20:12

focallength中文

That isn't what they do. They make it clear that they are testing lens/camera systems. OK, they don't repeat it every single page, but they are clear enough.

They rank lenses with sensors (really lenses with cameras, the AA filter, if fitted, has a significant effect). DxO overall scores are always to be taken with a pinch of salt, the individual measurements less so. However the ranking always says which camera the lens is being tested on:

So I can slap an OTIS lens on an old Nikon D200 and have it pronounced "poor" by DXO. Since it is impossible to rank this way without using the very same camera, it's a bad way to rate lenses.

but I have seen now some of the stuff in their website and it looks pretty dope. Why would they go all about with a lot of expensive stuff and high tech equipment and don't deliver live reliable results? This is stupid.

That isn't what they do. They make it clear that they are testing lens/camera systems. OK, they don't repeat it every single page, but they are clear enough.

System resolution is the convolution of the resolution of all the components in the system. A lens will perform better the more pixels you place behind it.

I just pointed out how that won't be the case because of HOW they do their tests and they are conflating camera performance with lens performance.

Up to you if you want to run your life by infantile rankings. They don't matter. DxOmark and other reviewers only provide them because a certain type of nerd is obsessed by rankings and thus they drive hits their way. Best to ignore the rankings, or just treat them as a bit of fun, and look at the data that actually matters to you.

I just pointed out how that won't be the case because of HOW they do their tests and they are conflating camera performance with lens performance. Is that too much for your brain to absorb?

If you want a compact camera that produces great quality photos without the hassle of changing lenses, there are plenty of choices available for every budget. Read on to find out which portable enthusiast compacts are our favorites.

A faster sensor, improved autofocus and video see Nikon's third-gen mid-range full-framer go toe-to-toe against Canon's EOS R6 II and the Sony a7 IV. We feel its all-round ability lifts it to the top of the pile.

If you put them both on a better camera, both will become better. The ordering of the goodness will not change, just the scores. Your quandry is based on a false premise. A good lens is always good, whichever camera you put it on.

It's of interest to know how the lenses do perform on different cameras. The only site performing camera independent lens tests is Lens Rentals, so picking out DxoMark and Optical Limits (they have other problems) is a bit off the mark.

Focal distancevsfocallength

It's like Photozone.de or whatever they are called now. Some of the lenses they tested were on 10mp cameras back in the Dark Ages so of course they'll perform differently on a 45mp camera but it has nothing to do with the lens changing its characteristics and it can't go from "ok" to "great."

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I just pointed out how that won't be the case because of HOW they do their tests and they are conflating camera performance with lens performance.

The front focal distance of an objective is the distance between the front surface of the objective (the vertex point of the first lens) and its front focal point. The back focal distance is the distance between the vertex of the last lens and the back focal point.

They rank lenses and that rank is variable depending on the camera. So, how does lens "X" suddenly become "better" than lens "Y?" They put it on a better camera. So I can slap an OTIS lens on an old Nikon D200 and have it pronounced "poor" by DXO. Since it is impossible to rank this way without using the very same camera, it's a bad way to rate lenses.

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In any case, no-where does DxOmark say a lens becomes 'bad' by putting it on a low resolution camera. Their rankings (which as said above, really should not be bothered with too much) simply give the best each lens performs on any camera they have tested it with. Generally, when tested on high resolution cameras without AA filters, this will be pretty close to the absolute performance of the lens, since the slanted edge method they use is inherently oversampled and there is not low-pass filter in the way. You'll note that everything at the top of their list comes into this category.

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Above $2500 cameras tend to become increasingly specialized, making it difficult to select a 'best' option. We case our eye over the options costing more than $2500 but less than $4000, to find the best all-rounder.

FOV tofocallength

That isn't what they do. They make it clear that they are testing lens/camera systems. OK, they don't repeat it every single page, but they are clear enough.

What’s the best camera for around $2000? This price point gives you access to some of the most all-round capable cameras available. Excellent image quality, powerful autofocus and great looking video are the least you can expect. We've picked the models that really stand out.

35mm equivalentfocallength

That isn't what they do. They make it clear that they are testing lens/camera systems. OK, they don't repeat it every single page, but they are clear enough.

Leica has announced the Q3 43, a variant of its full-frame fixed lens compact with a 43mm F2.0 normal lens. We've had the chance to use and test it, to produce an in-depth review.

Focallength camera

Focal distances should not be (but are sometimes) confused with focal lengths. The latter are measured from the principal points and are the same on both sides if one has the same refractive index on both sides. In contrast, the front and back focal distance can be quite different, even if there is air on both sides.

What’s the best camera for around $1500? These midrange cameras should have capable autofocus systems, lots of direct controls and the latest sensors offering great image quality. We recommend our favorite options.

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We don't usually test a product for ten years before reviewing it, but after a decade of using the Lowepro Photo Sport 300 AW II on an almost daily basis, Managing Editor Dale Baskin tells us why he loves this pack.

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What this is telling us is that these lenses perform better on a high resolution camera, not that they become worse lenses on a low resolution camera.

What's the best camera for travel? Good travel cameras should be small, versatile, and offer good image quality. In this buying guide we've rounded-up several great cameras for travel and recommended the best.

That isn't what they do. They make it clear that they are testing lens/camera systems. OK, they don't repeat it every single page, but they are clear enough.

Focallength

The results are the results, but their wording for lack of a better description is silly. A lens is a lens. It is built to a specific optical standard, lets say 90% Strehl ratio. Putting it on different sensors does not change that. All you are changing is the sensor and IT'S performance, not the lens. So you can't say one day, "the lens is ok" then change sensors on another day and say "the lens is great!" Which is exactly what they do. It's like Photozone.de or whatever they are called now. Some of the lenses they tested were on 10mp cameras back in the Dark Ages so of course they'll perform differently on a 45mp camera but it has nothing to do with the lens changing its characteristics and it can't go from "ok" to "great."

Sure they do. Some of the Olympus pro lenses are sharper across the board than some of the pro lenses from Canon and Nikon and because they test them on 16 and 20mp m4/3rds cameras, they score low according to DXO. Which is ridiculous.

That isn't what they do. They make it clear that they are testing lens/camera systems. OK, they don't repeat it every single page, but they are clear enough.

People deride DxOmark because it doesn't produce the results they don't. Mostly it's quite good, and they do tell you how the make their measurements if you hunt hard enough. They do sometimes make some quite bad mistakes, there is bad data there, but it's identifiable as being bad and mostly it's good. What he's referring to as 'stupid' is the reality. Lenses deliver more resolution with a high MP sensor behind them. It's a good example of DxOmark being blamed for someone else's ignorance.