Photography Tip: Inverse Square Law

9 years 7 months ago - 7 years 7 months ago #42797 by PhotographyTalk
The following user(s) said Thank You: KevinA65, elaine , flanagans.photography, LesFenton, savvysuz, sjit123, _Colleen_, rosh2607, KeezOfLife, gadam777 and 2 other people also said thanks.

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9 years 7 months ago #42825 by Baydream
Good information and well explained.

Shoot, learn and share. It will make you a better photographer.
fineartamerica.com/profiles/john-g-schickler.html?tab=artwork

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9 years 7 months ago #42836 by chasrich
:judge: :agree:

“Amateurs worry about equipment, professionals worry about money, masters worry about light, I just make pictures… ” ~ Vernon Trent

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9 years 5 months ago #95637 by kyclover237
Very good video!

vintagecloverphoto.com
[email protected]

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9 years 5 months ago #95655 by photobod
Superb video, so informative and very relevant, thankyou

www.dcimages.org.uk
"A good photograph is one that communicate a fact, touches the heart, leaves the viewer a changed person for having seen it. It is, in a word, effective." - Irving Penn

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9 years 3 months ago #135236 by KevinA65
:judge: Thank you very much .......

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9 years 3 months ago #135241 by mstrozewski
Wow, great advice!


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9 years 3 months ago #135334 by image-vision
:(

As far as I can say from one time viewing (on a foreign language) there’s nothing wrong what you were saying but the video is in parts very much misleading!
Also, knowing the rule before viewing this video I expected more questions to answered – may be that is something you can cover on your next videos.

Misleading:
You say , the farther a group of people (or a face lid from the side) is away from a ligjt source, the less is the light fall-off within the group (or within the face).
This is absolutely true!
BUT the photos, you shot, in the studio (face) – you are using ambient light. That is, the Octobox is not the only light source. So the photos you show in the video are not correct, since you use other lightsource(s) too, not only the Octobox!
The photos (and your words) give the impression: If you don’t want to have hard shadows in the face of a person your shooting – improve the distance between the person and the lightsource. – Which is ( I hope you know this) absolutely wrong – especially is you use such a large Octobox as you in the video.
The hardness, (harshness) don’t know the correct english word, is determined by the size of the lightsource versus the size of the object and the distance to the object. The bigger the lightsource the smoother the light, but the greater the distance between lightsource and object the harder (harsher) is the light.

(The best example is the sun – it’s millions of km or miles away. If on the early morning after sunrise, or late evening befor sunset, the sun is coming form the side you, get a huge fall-off in light – even bigger than you showed on the first picture when the girl ist just 1 feet away from the octobox – but the sun is muuuuuuuuch further away. So the way you explained it there should be no light fall-off, since the sun is really far away. You’r proven wrong!)

So it’s basically the opposite of that (what you don’t exactly say, but what you can see at the face-photography at… 8(?) feet) – actually at the end of the video you even say it – if you want to shoo a group, bring a greater distance between the group and the flash – this is (I’m sorry BULLSHIT). Please tell me who the heck would place a flash (if it’s only one flash) on the left or on the right hand side of the group (only in that case you would be right) instead of in the front of a group?)

What did I expected more and did not see in the video:
You shot this video in a photo studio, that’s the best location, to explain the correlation between (intensity of) light, aperture, ISO and shutter speed.
Let’s say, I already have the correct settings for a shot, but I want the model to move closer to me or further away (and that could be for example double, or half the distance (away from /towards to) the flash ---- How do I adjust my camera settings to have the same correct exposure? This is what I expected to see in the video.
Aperture (F-stops), ISO, shutter speed, are directly related to the inverse Square Law. (And it’s not too difficult to explain, with respect to the amount of light) Unfortunately you didn’t loose any word about that.

Please don’t get me wrong. But I see so often that people see the number (5.6. 8, 11…) of f-stops but they have no clue what it means in terms of “amount of light” and how it relates to ISO, or shutter speed. And a lot of it is explainable with the inverse square law – or “what to to if the distance between light and object changes?” – And btw. why are the Aperture numbers so odd – all explainable with this law….

Unfortunately you didn’t explain it. Hopefully in the near future?


The following user(s) said Thank You: sjit123

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9 years 3 months ago - 9 years 3 months ago #135367 by MLKstudios
Greetings image-vision,

I completely agree. I've seen too many YouTube videos by people who don't have a clue about what they are talking about (in all things, not just photography), but come across to many (the unwashed ones) as experts. This guy even has "camera store credentials" backing him up to convince them of his "expertise".

Those of us went to school and know photography well are in awe of how these so-called masters have made a name for themselves on the web. Are they just so ill-informed, they think they DO know what they are talking about, and imagine themselves as being helpful? This logic baffles me.

In my experience, it is best not to gather bad crumbs you have to unlearn later (I had to dispose of many along the way). PT members, PLEASE don't spread them around. Instead, learn photography right to begin with. It isn't that difficult. It just takes some time and dedication to our craft -- and knowing what the square root of two is.

Learning photography is much like buying a tripod. You can buy cheap ones over and over, or get a good one from the get-go.

Like so many videos available for free, this vid is worth what you paid for it.

Matthew

BTW there is lots of good FREE knowledge available out there. But in order to teach yourself, you first have to be able to separate the wheat from the chafe.

Matthew L Kees
MLK Studios Photography School
www.MLKstudios.com
[email protected]
"Every artist, was once an amateur"

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9 years 3 months ago #135368 by sjit123
:agree: I would also like to know more about these.


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9 years 3 months ago - 9 years 3 months ago #135369 by MLKstudios

sjit123 wrote: I would also like to know more about these.

Many natural things follow the Inverse Square Law. Sound is another. It drops off with distance the same as light does.

The reason is it (light or sound) is spread out in two dimensions -- both height and width.

If you were to take a card one foot square and held it one foot from a strobe (or flash), and called the light hitting it 100% of the light, then at two feet away you would need FOUR cards to catch all the light -- the light gets spread two feet wide by two feet tall.

2 feet squared, inversed = 1/4. Each card receives 1/4 (or 25%) of the light.

At three feet away it would take nine cards (3x3), so each card receives 1/9th of the total light. 4 feet = 1/16th and etc. One over the distance, squared.

This is why if you need double the light in a studio, you don't cut the light distance in half. Instead you move it a square root of two closer.

The f/stop number also uses square roots, and is why 1.4, 2.8, 5.6, 11(.2) and 22(.4) are full stops.

The ability to understand simple 8th grade math is all that is needed to understand light and the Inverse Square Law (as well as what those lens numbers really mean). But first, someone needs to tell you what a STOP is!

Bryan, are you listening?

Matthew :)

Matthew L Kees
MLK Studios Photography School
www.MLKstudios.com
[email protected]
"Every artist, was once an amateur"

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9 years 3 months ago #135397 by Henry Peach
I like to check out a photographer's portfolio to assess whether they know what they are talking about. I just visited Mark Wallace's portfolio for the first time. I don't know that it shows he's a master of photography, but I think it suggests he knows more than a little bit about photography. He has some pretty decent crumbs. :)

www.markwallacephotography.com/

MLK and image-vision, care to put your work up for examination? :) I can't even tell if you guys have "camera store credentials". Put your money where your mouth is, and show us your work! It's 2011, guys. Sorry, but there' nothing fishier than a know-it-all who's afraid to share their work.

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9 years 3 months ago - 9 years 3 months ago #135409 by MLKstudios
HP, I have plenty of work posted on threads here. Sorry you missed it. Some of it is good.

Regarding the video, it's the data that's poor. Poorly explained, and incomplete. Having taken a great picture, doesn't make one a great teacher. The "science" behind the camera is absolute. It's based on math and physics.

The art of photography is another thing. However, if you know how the camera and light works, you have more control of the results. That's where education comes in.

image-vison's point was, with the studio and equipment he was using, he could've covered much more and made it much clearer. But, instead he throws out a wiki definition of the inverse square law and makes it sound really complicated (which means he doesn't really know either).

It just isn't that difficult. It takes 8th grade math to explain it well.

Matthew :)

BTW Zach couldn't explain the inverse law on his high end videos either. For hundreds of dollars you get a gorilla shoot shot by an amateur. Available at a store near you.

Matthew L Kees
MLK Studios Photography School
www.MLKstudios.com
[email protected]
"Every artist, was once an amateur"

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9 years 3 months ago - 9 years 3 months ago #135634 by MLKstudios
An example of a Week 4 student, posted today (shot yesterday). There's a lot wrong with it, she's still learning. She's had her T2i camera but a few months.

Can anyone tell me, after watching the video above, how come the second girl isn't darker than the closer one? It's lit entirely by on camera flash she got yesterday. Not off camera flash.



These are things a shooter needs to know. She'll get better and be able to capture special moments in her life and her family's life too. Or events, or weddings, or other things that can earn her a living as a camera-person. And maybe even grow as an artist/a human being/a person.

________

"Be self-centered, self-involved,and generally entitled and always pushing -- and damned to hell for doing it."

-- Charles Traub, The Education of a Photographer

Matthew L Kees
MLK Studios Photography School
www.MLKstudios.com
[email protected]
"Every artist, was once an amateur"

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9 years 2 months ago #137859 by Towcestermark
I think that we must remember here that Mark Wallace produces marketing videos, not instructional videos. And, I mean that in the nicest possible way, the videos are made to gain revneu, sign ups, advertising, selling products that their company makes on.

They are not to teach YOU how to be a photographer. As you gain more knowledge, you begin to realise that they are 'hyped'

To a noob, they sound too technical, therefore the noob, needs or desires more information - obviously from their products or services.

Please don't get hot under the collar about them, they bring noobs into the fold, sell product and make products cheaper for those that might have a clue.

Don't be too harsh, he's gotta present this stuff...!


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