Here's a diagram of the 10-mile, 5-mile situation to show how you can calculate the amount of blurring you'd expect if the ocean is out of focus. The diagram assumes the object is in focus. It's based on this Wikipedia section which you can use to check my work.
Can you link this manual?
The focal length is not needed for the calculation. The hyperfocal distance is an approximation based on setting a maximum noticeable size for the circle of confusion (little c in Wikipedia's diagram). That's explained in the section I linked.That diagram represents nothing in optics.
And even if you got the lens to be a converging one (it's acting like a diverging one the way you've drawn the lines), there'd still not be enough information on the fixed version of it to calculate anything. Where are the focal length, the aperture, the hyperfocal distance?
:-O thirded? That's huge.@Mick West Seconded? I was not aware of this for some reason? It would be very helpful.
The focal length is not needed for the calculation.
The size of the blur at distance 5 (e.g. in meters) only depends on the aperture size. If you were to have a real disc at distance 5 with half the aperture's diameter, its image would be the same disc as a point behind it at distance 10. If you make the distances 50 and 100 with the same aperture size and focus on 50, the disc size is still A/2 in the object plane but it covers 1/10 the angle because it's 10x farther away (sharper image).Consider the fact that I've provided a scenario where an item at distance 10 is insignificantly blurred, and another where it is significantly blurred, when you are focussing on an object at distance 5, and that your diagram makes no distinction between these two cases.
People on Twitter, etc, still keep arguing that you can't have two objects at different distance in focus at the same time.
:-O thirded? That's huge.
if you already know the size of something in the object plane then you can convert between meters and pixels in that plane proportionally.
Thanks for the comments and examples. If I ever deploy the argument in a wider forum I will try to guard against the misconception you mention. As you say, 'more distant' does not imply 'more focussed'. My point, which I hope still stands, is that if an object is well focussed at 5 miles, it will still be well focussed at 10 miles. If it isn't well focussed at 5 miles, it won't be at 10 miles either - assuming the same camera set up, obviously. No lens, so far as I know, would be able to distinguish between the two cases, so far as focus is concerned. Of course, other factors such as resolution of detail might come into play.One reason I fear that your smaller-range-of-angles analogy won't work with such people is that it could be misinterpreted as implying that more distant things will always somehow be more focussed than near things, which is of course nonsense, and not what you said, but that matters not. Never underestimate the ability of those who don't understand simple concept to misinterpret simple explanations and draw bizarre illogical conclusions, that's probably how they picked up their wrongthink in the first place.
My point, which I hope still stands, is that if an object is well focussed at 5 miles, it will still be well focussed at 10 miles.
I'm using "object plane" to refer to the plane of the object at 5 miles, which I'm supposing to be in focus. I changed from saying focal plane to avoid ambiguity. I'm not talking about the plane inside the camera, because the focal length doesn't matter.{edit: adding} First - when you have a plurality of objects - what do you mean by *the* object plane? There's a good chance we're talking at cross purposes.{end edit}
But you can't do that with the information you claimed to have - you're presuming the distance from the lens to the focal plane. That distance isn't fixed, as the lens moves relative to it as you focus - that's what focussing *is*.
You'll note that the lens moves relatively less in order to change focus between two far distances (say having the objective to focal plane distance at f*1.01 and f*1.02, a movement of f*.01) than it does to change focus between two nearer distances with a similar distance ratio (say f*1.11 and f*1.25, a movement of f*0.14). And that is precisely why the depth of field is wider - as a ratio - for farther objects. than for nearer objects.
I'm using "object plane" to refer to the plane of the object at 5 miles, which I'm supposing to be in focus. I changed from saying focal plane to avoid ambiguity. I'm not talking about the plane inside the camera, because the focal length doesn't matter.
Here's a simple experiment that would test what I'm saying:
1. Open a camera's aperture fully.
2. Cut a disc shape out of something with the half the diameter of the camera's entrance pupil.
3. Put the disc at any distance and focus the camera on it.
4. Put a tiny light source at twice that distance.
5. In the photo, the bokeh of the light source has the same size as the disc.
Doesn't matter what the distances or focal length are as long as the distances are at a 1:2 ratio and the disc is in focus.
Another focus example. Plane (~5 miles) and Moon (~239,000 miles) both in acceptable focus.
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This might be a more fruitful source of examples. If the Moon is high, then there will be far less atmospheric distortion - in fact, it will be similar to the minor distortion in GoFast
holy gsus. what camera setup is this? looks insaneAnother focus example. Plane (~5 miles) and Moon (~239,000 miles) both in acceptable focus.
This might be a more fruitful source of examples. If the Moon is high, then there will be far less atmospheric distortion - in fact, it will be similar to the minor distortion in GoFast
holy gsus. what camera setup is this? looks insane
I imagine it's probably one of the big Canon primes 5/6/800mm on an extender like the Canon 2x then cropped in post.
You can get 1000/1200mm at f/8 or 1600mm at f/11 with this setup.
These are £8000-13,000 lenses.
No need for anything that fancy just for the pixels, it's basically the same resolution as my cheaparse (200e 2nd hand) Canon 55-250mm on D550: http://fatphil.org/images/moon.jpg (no processing only crop, I think that was a 'supermoon', 1 day before full, but the next day was forecast rainy. Oh - no tripod, because hardcore/stupid!)
I do live near a small international airport, I should see what flight paths they follow, and whether that's compatible with any moon flightpaths, snagging a photo like that would really make me chuffed.
Planes at cruising altitude are not that big/detailed even a A380 on my crop sensor with 400mm, the moon isn't the issue, it's getting the plane that big.
However those planes in the shots may have been on approach/egress from an airport and thus lower.
Planes at cruising altitude are not that big/detailed even a A380 on my crop sensor with 400mm, the moon isn't the issue, it's getting the plane that big.
However those planes in the shots may have been on approach/egress from an airport and thus lower.
One is leaving exhaust contrails, so probably over 30,000 feet.
But yeah, if you can get the moon is that big, then the only challenge is waiting for a plane to fly in front of it. Probably he's by some consistent air routes. Lots of waiting would be involved.
I got one in front of the sun once. Really far away plane though.
Nikon P900, 2000mm (cropped to about 60%) 1/250, F6.5
thats actually not the sun. its a glare. from a bug. reflecting sunlight. /sFriend of mine captured this one near Greenville/Spartanburg, SC, during the eclipse of 2017. Not perfectly focussed, but pretty close for the various distances involved... and just a neat picture.
That's not an aura, it's an unsharp maskthats actually not the sun. its a glare. from a bug. reflecting sunlight. /s
HOYA PROND100000 (5.0)What filter did you use? ND?
Thanks.HOYA PROND100000 (5.0)
The manual states:
"7. The ATFLIR provides two air-to-air modes: pointed, and autotrack. Air-to-Ground and air-to-air laser range finding is also provided."
Apparently it DOES use the laser for A/A range finding.
So why does Chris say (paraphrasing) no one uses the range value in A/A or the laser is only used for ground targets?
So, Chris Lehto says that the RNG data in the GOFAST video is unreliable. Fine. I wondered what a different approach could tell us, without relying on the RNG data. So I created a model of the scenario in Blender, in order to simulate the camera's sightline, using all other available data.
Not sure how wave size would be relevant, what matters is the time it takes for features to cross the screen, not how big they are.A few factors could make the ocean appear to move slower or faster in a sim than in the actual video
Wave size i.e. the size of the ocean surface texture features, wind blown waves, causing an apparent speeding up or slowing down of the sea surface, the FOV of the camera etc.
If 10 waves go by in a second it matters if they are 1 foot waves or 10 foot waves.Not sure how wave size would be relevant, what matters is the time it takes for features to cross the screen, not how big they are.
And while I doubt waves from the wind would have much effect given the speed of the panning, even if they did that would mean it would be a mistake to adjust FOV to compensate for what is not an issue.
Of course it could be a combination of FOV/waves/wind, I just think the change to 0.5 FOV is perhaps overkill if there is reasonable certainty that 0.7 is the correct FOV. Not a huge issue but would effect the potential sizes/speeds of the object a bit.
EDIT: Of course turn speed is another potential factor