/p/ - Photography » Thread #3159232

[29 / 8 / ?]

1MiB, 2048x2048, earthmoon.jpg

Anonymous Thu 28 Sep 2017 03:45:24 No.3159232 View View Reply Original Report

Ok /p/, please help put this to rest.

Everytime somebody posts the images in pic related, claiming NASA can't decide how big the earth is,
another anon will always cite focal length as the reason for the discrepency.
I've read arguments and watched videos, but I've never seen anyone address the the topic directly.
Essentially, "it's caused by focal length" is the argument.
I've never seen the focal length argument refuted.

This is NOT a flat-earth/moon-landing/conspiracy thread.
This is a thread about focal length and what is and is not possible with new and old technology.
Full disclosure: This is my first post on /p/, so if anon can be specific, explain with detail, and maybe give me some schooling on focal length, I would appreciate it greatly.

Anonymous

Anonymous Thu 28 Sep 2017 03:48:45 No.3159234 Report

Quoted By: >>3159237

fun fact: 99% of NASA photos are "artist's representations" aka. photoshops.

Anonymous

View Same Google ImgOps iqdb SauceNAO the perfect death.webm, 910KiB, 720x480

Anonymous Thu 28 Sep 2017 03:50:57 No.3159235 Report

Quoted By: >>3159236

>>3159232
Here are a few numbers provided by NASA (with estimations):
>The Earth's diameter is 7,917m (8,000m)
>The Moon is between 225,623m - 252,088m away from Earth (250,000m)
>The Moon's radius is 1,079.6m (1,000m)

If we scale down and you were standing in the center of the moon, you would be 251' away from an 8' wide Earth.
>Earth diameter 8,000m -> 8m -> 42,240' -> 8'
>Moon radius 1,000m -> 1m -> 5280' -> 1'
>Distance 250,000m -> 250m -> 1,320k' -> 250'

The top-left image is supposedly taken from approximately 1 million miles away.
After scaling it down, it becomes 1,000' away from "Earth" and 750' away from the "Moon."
>pic is to scale, but it's too large..

Anonymous

View Same Google ImgOps iqdb SauceNAO focal length.jpg, 851KiB, 1920x729

Anonymous Thu 28 Sep 2017 03:52:29 No.3159236 Report

Quoted By: >>3159240

>>3159235
Everything is too big and too far away.

Here are my questions for you /p/:
On the basis of focal length, are the OP images legitimate?
Is it possible to recreate similar images from ground level, or other vantage point?
Is the quality of the images presented in OP consistent with what you would expect, using techniques required to capture such images?
Bonus: How would shutter speed affect recording two objects, moving independently, around multiple axises, from a distance?

Thanks for your insight /p/

Anonymous

Anonymous Thu 28 Sep 2017 03:53:44 No.3159237 Report

Quoted By:

>>3159234
That's what I've heard..
The other half says it's camera tricks. What better place to ask about the tricks than here on /p/.

Anonymous

Anonymous Thu 28 Sep 2017 03:57:15 No.3159238 Report

Quoted By: >>3159250

Okay!

At a very basic level, the focal length of a lens determines how magnified the picture is going to be. So if you have a short focal length, it's gonna be a wide-angle lens and you'll get a lot in frame. If you have a long focal length, it's gonna be a telephoto and you'll only get a little bit (and generally a little bit that's far away) in the frame. If you're familiar with the concept of a zoom lens, the long end of the zoom is a large focal length, and the wide end is a small focal length.

So the other thing that focal length gets you is a change in perspective. What "perspective" means in this context is how close objects look to each other, front to back. Next time you're driving down a road, look at the dashed lines between the lanes. Each of those lines (and the spaces between those lines) is the same distance, by law. But if you look at the far away dashes, they look like they're closer together than the ones right in front of you. When you use a lens with a long focal length, you're basically just looking at a small far-away chunk of the world, and when things are far away, they appear closer together.

So that's why "focal length" is the answer to why the spatial relationships between the Earth and the Moon sometimes look different from one photo to the next. If they're using a longer focal length, it's gonna make the earth look closer. If they're using a shorter length, it'll look farther away.

Lemme know if any of that didn't make sense to you and I can try to clarify.

fucking cuck !!L1lx81epp6B

View Same Google ImgOps iqdb SauceNAO IMG_7363.gif, 1004KiB, 402x301

fucking cuck !!L1lx81epp6B Thu 28 Sep 2017 03:58:54 No.3159239 Report

Quoted By: >>3159250

Here's everything you need to know about focal length in gif form.

The wider the angle of lens you're using, the smaller background details (like the earth) appear in comparison to foreground details. The inverse is obviously also true. Why? Spatial perspective is the real culprit here. All that focal length changes is the size of the frame. Longer focal length, smaller frame. Everything within that frame gets magnified, and due to perspective, background elements appear larger in comparison to your subject.

Anonymous

Anonymous Thu 28 Sep 2017 04:07:57 No.3159240 Report

Quoted By: >>3159256

>>3159236
>On the basis of focal length, are the OP images legitimate?
The right two images certainly are. The left two might be photoshopped--they look a little too perfect, like a render rather than a photograph.
>Is it possible to recreate similar images from ground level, or other vantage point?
Yes, although it'll be harder to see the difference since the moon is so much smaller than the Earth. I.e., if you took a picture of someone with a really long focal length with the moon behind them, the moon would look a lot bigger than if you took a picture of someone with a small focal length.
>Is the quality of the images presented in OP consistent with what you would expect, using techniques required to capture such images?
Yes. At least, again, the right two images. Left two do not appear to be photographs.
>Bonus: How would shutter speed affect recording two objects, moving independently, around multiple axises, from a distance?
In the context of the Earth and the Moon, very little for normal shutter durations. The moon is circling the Earth at a pretty fast clip, but it's far enough away that the movement isn't that big a deal. If you're doing like a multi-second exposure, sure, it'll be blurred. But if you're doing a fractional-second exposure, it's fine.

It's like when you're looking out the side window while riding in a car going 60mph. Shit right next to you looks like it's zooming by at 60mph (because it is). Shit off in the distance is also moving at 60mph, but it looks like it's moving a heck of a lot more slowly. The moon is around 238,900 miles away, so it looks like it's moving a lot more slowly than it actually is.

Also, the moon is tidally locked with Earth, so while it's technically turning on its axis, it's turning so it's always pointing the same face towards us.

Anonymous

Anonymous Thu 28 Sep 2017 04:23:21 No.3159250 Report

Quoted By: >>3159253 >>3159255

>>3159238
I think I get it, at least how it works generally. Makes me think of a shotgun: shorter the barrel, bigger the spread; longer the barrel, tighter the spread.

It's weird how it keeps the foreground stationary like >>3159239 shows.
Everything moves, including the ground before the cement block, but not the block itself.
Is it difficult to keep an object stationary like that?

>Everything within that frame gets magnified
Man that's weird as fuck.. It's like the camera is squinting it's eye x 1,000.
How the fuck does that even work?

Anonymous

Anonymous Thu 28 Sep 2017 04:27:41 No.3159253 Report

Quoted By: >>3159263

>>3159250
What's happening in that gif is that they took a picture then zoomed in a little bit and walked backwards a little bit to keep the concrete block at about the same size in the frame. Lather, rinse, repeat, then combine all of the photos you took into one GIF to illustrate the concept of perspective.

fucking cuck !!L1lx81epp6B

fucking cuck !!L1lx81epp6B Thu 28 Sep 2017 04:28:18 No.3159255 Report

Quoted By: >>3159263

>>3159250

It's kind of difficult, but it's also just math. If you have a lens that makes an object look that big at 50mm (common focal length), you will need to move twice as far away if you use a 100mm lens.

Anonymous

Anonymous Thu 28 Sep 2017 04:30:26 No.3159256 Report

Quoted By: >>3159267

>>3159240
All of those images are from NASA

Are any of the distances between objects interesting in any way?
What I mean is.. would it be a challenge to stand 250' away from an 8' wide object and create the right and bottom images?

Anonymous

View Same Google ImgOps iqdb SauceNAO 20161114-5D3_7838.jpg, 408KiB, 667x1000

Anonymous Thu 28 Sep 2017 04:31:20 No.3159257 Report

Quoted By: >>3159259 >>3159279

Managed to dig up a relevant example from my own catalog. Pardon the model's expression--these were taken when I was testing/setting up the technical bits of the shoot, so she wasn't actually posing yet.

This was shot with my lens at 170mm.

Anonymous

View Same Google ImgOps iqdb SauceNAO 20161114-5D3_7837.jpg, 285KiB, 667x1000

Anonymous Thu 28 Sep 2017 04:33:56 No.3159259 Report

Quoted By: >>3159265 >>3159279

>>3159257
And here it is at 200mm with roughly the same subject size. See how the moon looks noticeably bigger?

(Again, this wasn't a controlled test for showing off this feature of optics, so this is also being affected a bit by sloppiness with camera distance and aperture, but it's close enough to illustrate the point)

Anonymous

Anonymous Thu 28 Sep 2017 04:44:00 No.3159263 Report

Quoted By:

>>3159253
>>3159255
Wow, I was always puzzled how you could zoom everything but the object you were focused on.
That shit was like magic..

how far away do you have to move? Is there some kind of ratio?
Like, you can get a clear/decent picture of the BG if you're within 1/3 the distance of the subject and BG?

Anonymous

View Same Google ImgOps iqdb SauceNAO 1506573236625.jpg, 75KiB, 667x1000

Anonymous Thu 28 Sep 2017 04:47:30 No.3159265 Report

Quoted By: >>3159272 >>3161322

>>3159259
and here it is at 10000mm. The subject size changed a lot because of the gravitational pull from my giant lens. See how the moon looks noticeably bigger?

(again, this wasn't a controlled test for showing off this feature of optics, so this is also being affected a bit by sloppiness with camera distance and aperture, but it's close enough to illustrate how much a faggot I am)

Anonymous

Anonymous Thu 28 Sep 2017 04:48:56 No.3159267 Report

Quoted By: >>3159288

>>3159256
>Are any of the distances between objects interesting in any way?
I'm not sure I understand the question. It's pretty interesting if you're into astrophysics and astronomy...?

> would it be a challenge to stand 250' away from an 8' wide object and create the right and bottom images?
Here's what's happening in the four images, starting with upper left and moving clockwise to lower left.

1. Camera positioned 1 million miles away, with a ridiculously long focal length. Source https://www.nasa.gov/feature/goddard/from-a-million-miles-away-nasa-camera-shows-moon-crossing-face-of-earth
2. Photographer standing on the surface of the moon with a reasonably long lens, which makes the (distant) Earth look bigger in relation to the surface of the moon he's standing on. Source: https://www.nasa.gov/multimedia/imagegallery/image_feature_1249.html
3. Relatively short focal length. Probably a normal (i.e., not wide nor telephoto) lens, but might be slightly wide. Couldn't find the source image on this one.
4. Composite image from the Lunar Reconnaissance Orbiter, about 83 miles above the surface of the moon, with a long focal length lens. Also with a wide angle lens. It's a composite image, so they actually took a bunch of different pictures with the telephoto (in black and white) and the wide (in color) and did some processing to make the image look like it's in color, which is why this one looks rendered--it kind of is. Source: https://www.nasa.gov/image-feature/goddard/lro-earthrise-2015

Anonymous

Anonymous Thu 28 Sep 2017 04:56:30 No.3159272 Report

Quoted By:

>>3159265
This was really amazingly funny.

Anonymous

Anonymous Thu 28 Sep 2017 05:02:37 No.3159279 Report

Quoted By: >>3159294

>>3159257
>>3159259
Reminds me of Jennifer Morrison

The Earth is about 4x as big as the moon, so top photo is about the same size as OP's bottom right, but at least 4x smaller than Earth in OP's bottom left.

I definitely understand the concept, but I've never seen anything that closely replicates what we see from NASA photos.

What are the min/max limits of focal length? Is there any kind of chart that details what kind of distortion you'd expect from a particular focal length at a specific distance?

I know I'm asking stupid questions.. Basically it comes down to recreating the images from OP. from those distances.
Is it possible to make those images if your subject is an 8' wide thing and you are 250' away?
Can any smart fucker do the math on that?

Anonymous

Anonymous Thu 28 Sep 2017 05:13:27 No.3159288 Report

Quoted By: >>3159311

>>3159267
>ridiculously long focal length
What does that mean? The article you linked doesn't contain any information on the cameras used.
How long is ridiculously long? What's the longest civilians have available? Is that enough to create that image?

>reasonably long
>relatively short

That doesn't mean anything.. Is it possible to get those kinds of shots?
Not with relatively ridiculously reasonable technology, but with what we have today?

Anonymous

Anonymous Thu 28 Sep 2017 05:27:13 No.3159294 Report

Quoted By: >>3161359

>>3159279
>I definitely understand the concept, but I've never seen anything that closely replicates what we see from NASA photos.

Well, I mean, they put people on the moon. It's hard to get a good shot of the moon with the Earth in the distant background if you're standing on the Earth. Getting an equivalent shot from Earth with the moon in the background would require a longer lens (since the moon is smaller), plus it won't be as sharp because the earth has an atmosphere, plus the surface of the Earth usually has a lot more shit on it blocking your path. There are a bunch of images out there where the moon looks super huge while down at the horizon, but they're hard to find among all of the shots that people made by photoshopping a supertelephoto picture of the moon into a landscape instead of doing it with a long lens.

> What are the min/max limits of focal length?
That's harder to answer than you might think.

Well, max is easy to answer--the limit of that is basically how much you or your government is willing to pay. Also note that "focal length" per se doesn't tell you the field of view by itself--you also need to include the size of the imaging surface it's projecting on. A 50mm focal length is a wide-angle lens on a Hasselblad, an ultrawide on a large format view camera, a normal on 35mm film, a short telephoto on crop digital, and a ridiculously long tele if it's in front of a cameraphone sensor. Where the lens is a telephoto, it'll give you telephoto compression perspective. Where it's wide, it'll give you wide angle stretched perspective.

>Is it possible to make those images if your subject is an 8' wide thing and you are 250' away?
I'm still confused by this question, since the earth is 7,917 miles wide. and is 238,900 miles from the moon.

Anonymous

Anonymous Thu 28 Sep 2017 05:48:17 No.3159311 Report

Quoted By: >>3159316

>>3159288
> What does that mean?
It means it was shot with, basically, a telescope. I can't give you the exact focal length, but something long (relative to the size of the imaging sensor in the satellite).

> What's the longest civilians have available?
Again, kind of hard to answer. If you mean just the longest lens you can buy off the shelf, then Nikon and Canon both have 800mm lenses and they both sell 2x teleconverters that'll get you up to 1600mm. But you can also buy telescopes that attach to your camera that get you even longer than that (although with comparatively shitty image quality).

The optics in the two satellite shots are most likely going to be in the "Telescope" range (i.e., over a meter). The optics in the two shots that were taken by actual humans on the moon are a lot shorter.

I just found some more info on the upper right shot, and it was actually taken from orbit around the moon on the Apollo 8 mission, and it's with a 250mm lens on a Hasselblad (which would be equivalent to roughly 137mm on full frame digital or 135 film, if you ignore the vastly different aspect ratios). So, just a moderate telephoto lens. It's unclear if it's cropped at all, which would also make the moon look bigger.

> That doesn't mean anything
Yeah they do. The actual numbers are 250mm for the "reasonably long" lens and 80mm for the "relatively short" lens. A short telephoto lens and a normal lens on Hasselblad 6x6 film.

> Is it possible to get those kinds of shots?
Of course it is. Those kinds of shots were got. You posted them yourself.

>Not with relatively ridiculously reasonable technology, but with what we have today?

Yeah, and easily with what we had in the 1960s, too.

Anonymous

Anonymous Thu 28 Sep 2017 05:58:48 No.3159316 Report

Quoted By: >>3159319

>>3159311
>I can't give you the exact focal length
Oh! Wait! It's NASA, so a lot of this shit is public information.

https://epic.gsfc.nasa.gov/epic

The EPIC camera on the DSCOVR satellite has a field of view of 0.62 degrees. Plugging that into this handy calculator: https://www.pointsinfocus.com/tools/depth-of-field-and-equivalent-lens-calculator/

tells us that the camera the moon-transiting-Earth picture was taken with had the equivalent of a 4000mm lens (in 35mm-equivalent terms).

Anonymous

Anonymous Thu 28 Sep 2017 06:02:53 No.3159319 Report

Quoted By:

>>3159316
Oh, and reading a little further, it's a 30.72x30.72mm sensor, which means it's probably ACTUALLY a 4000mm lens, give or take, too. Except not really a lens per se since it's using mirror optics instead of lenses to take pictures.

Anonymous

Anonymous Sun 01 Oct 2017 09:49:00 No.3161295 Report

Quoted By:

>>3159232
It has nothing to do with focal length."telephoto compression" is simply just an effect of perspective/geometry caused by distance and only distance. Focal length/zoom only gives you more resolution, or different dof.

Things appear to stack up and compress the further you get away from them because their distance from each other slowly becomes insignificant compared to how far you are from both of them.

Anonymous

View Same Google ImgOps iqdb SauceNAO 1494703622772.png, 574KiB, 557x719

Anonymous Sun 01 Oct 2017 10:49:44 No.3161306 Report

Quoted By: >>3161360

>The Earth's diameter is 7,917m (8,000m)
>The Moon is between 225,623m - 252,088m away from Earth (250,000m)
>The Moon's radius is 1,079.6m (1,000m)

Americans and the metric system, not even once

Anonymous

Anonymous Sun 01 Oct 2017 11:56:00 No.3161322 Report

Quoted By:

>>3159265
I thought this was real from the thumbnail and I was about to reply 'what are the specs on that lens'

Anonymous

Anonymous Sun 01 Oct 2017 13:57:41 No.3161359 Report

Quoted By:

>>3159294
>plus it won't be as sharp because the earth has an atmosphere
Whether doing a shot of the moon from earth, or a shot of earth from the moon. You are going to have to go through Earth's atmosphere in both cases.

Anonymous

Anonymous Sun 01 Oct 2017 14:00:17 No.3161360 Report

Quoted By:

>>3161306
Pretty sure that's just some idiot that typed m instead of mi.

Capcode	All Only User Posts Only Verified Posts Only Moderator Posts Only Manager Posts Only Admin Posts Only Developer Posts Only Founder Posts
Show Posts	All Only With Images Only Without Images Only Spoiler Images Only Non-Spoiler Images
Deleted Posts	All Only Deleted Posts Only Non-Deleted Posts
Ghost Posts	All Only Ghost Posts Only Non-Ghost Posts
Post Type	All Only Sticky Threads Only Opening Posts Only Reply Posts
Results	All Grouped By Threads
Order	Latest Posts First Oldest Posts First

On these archives

Your latest searches