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Re: Just got a Canon 100mm IS L macro. Now what?

[ Edited ]

As a side note, did the cake have lit candles on it? 

 

I have recently discovered that taking a shot that is lit only by candlelight is really hard and tricky to do.  It is a HDR problem that I've been experimenting with every so often.  Imagine a shot of someone holding a lit candle at chest height, and their face and upper body is lit up by the candle.

 

It's easy to capture either the candle, or the immediate surroundings, but not both.  Either the candle is way overexposed, or the surroundings are way underexposed to the point of being nearly invisible in the darkness.

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Re: Just got a Canon 100mm IS L macro. Now what?

Two words for you!

RAW and Photoshop.

EOS 1DX and 1D Mk IV and several lenses!
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Re: Just got a Canon 100mm IS L macro. Now what?

[ Edited ]

@Waddizzle wrote:

As a side note, did the cake have lit candles on it? 

 

I have recently discovered that taking a shot that is lit only by candlelight is really hard and tricky to do.  It is a HDR problem that I've been experimenting with every so often.  Imagine a shot of someone holding a lit candle at chest height, and their face and upper body is lit up by the candle.

 

It's easy to capture either the candle, or the immediate surroundings, but not both.  Either the candle is way overexposed, or the surroundings are way underexposed to the point of being nearly invisible in the darkness.


Here's how my wife handled it (with her 60mm macro lens) a few years ago. Some of the picture is underexposed, but I think you almost want it to be. A lot of the effect wuld be lost if it looked like ordinary room lighting.

20101127_3.JPG

Bob
Philadelphia, Pennsylvania USA
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Re: Just got a Canon 100mm IS L macro. Now what?

Nice shot, Bob.  I was thinking more along the lines of a single candle, though.  That's the tough one.

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Re: Just got a Canon 100mm IS L macro. Now what?


@ebiggs1 wrote:

Two words for you!

RAW and Photoshop.


Who?  Me? I always shoot RAW, except for in-camera HDR. 

 

I also have Photoshop Elements 10.  I've been considering upgrading, but so far haven't found the pressing need to do so.  I also have Lightroom 6, which is significantly better at panoramas than Photostitch.  LR6 can merge the sky portion of photos seamlessly, not Photostitch.  Sorry, Canon.

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Re: Just got a Canon 100mm IS L macro. Now what?

Than I have four more words for you.

 

Learn how to use ___________ (insert RAW and/or Photoshop)  Smiley Wink

 

I use and I love LR 6 but it isn't even on the same planet when compared to what it can do and what PS can.

I probably use LR6 75% of the time.  But when the rubber meets the road, PS is the way to go.

 

Another tip, Hdrsoft Photomatix Pro 5.0, is the HDR software.  And, again for stiching PS wins.  Remember Canon makes cameras.  They don't do software very well.  But at least they try. Some camera makers are worse with what they put out. Some even charge for theirs!

EOS 1DX and 1D Mk IV and several lenses!
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Re: Just got a Canon 100mm IS L macro. Now what?

This is the "inverse square" problem.  The problem is identical for any light source (and lots of other things like radio waves, etc. which all follow the same law of physics.)

 

If one subject is 2' from the candle, but something else is 4' from the candle then... 

 

2 squared = 4 and the inverse of 4 is 1/4.  4' squared is 16 and the inverse of 16 is 1/16.   Now you want to know how much brighter or dimmer one is from the other.  So if you treat 1/4 as 4/16 then you've got one subject getting an amount of light that we'll call 4/16ths and another getting 1/16th... which is exactly 1/4 as much light.  It turns out you can do this with any arbitrary distance you want (I do it with planets.)

 

But another way to think of it ...  the reason the rule works is because in geometry, there's a relationship between the square root of 2... and a circle.   The square root of 2 is roughly 1.41 (the number goes on and on and for exposure purposes only the "1.4" actually matters (you can ignore the rest of the digits because they are too insignificant to have any noticeable effect on your exposure.)    If you calculate the area of a circle... and then increase it's area by a factor equal to the square root of 2... then the NEW area of the circle will be EXACTLY DOUBLE.  

 

This is, btw, where the whole stops come from in f-stops... f/1, f/1.4 (there's that number), f/2, f/2.8, f/4, f/5.6 etc. are all even powers of the square root of 2.  

 

1 = square root of 2 raised to to the 0 power.  (f/1)

1.4 = square root of 2 raised to the 1st power.  (f/1.4)

2 = square root of 2 raised to the 2nd power.  (f/2)

2.8 = square root of 2 raised to the 3rd power.  (f/2.8)

4 = square root of 2 raised to the 4th power.  (f/4)

5.6 = square root of 2 raised to the 5th power.  (f/5.6)

8 = square root of 2 raised to the 6th power.  (f/8) 

and so on.

 

Notice how each full stop is really just the square root of 2 raised to the next even exponent (power).  This is why changing one full stop of aperture will exactly halve or double (depending on if you're increasing or decreasign the f-stop value) the amount of light collected at that aperture.

 

If the camera is set to accurately expose for some amount of light, most camera sensors can comfortably handle underexposure by at least 3 stops and can also handle over-exposure by at least 3 stops.    So let's go with that....

 

If we place a candle 10' from our subject and accurately set the exposure for that candle light at 10', then 3 stops nearer (brighter) would be 3.5'   (7' is twice as bright, 5' is twice as bright again, and 3.5' is twice as bright again).  

 

Going farther away (darker) it's 14' (half as bright), 20' (half as bright again), then 28' (half as bright again).  

 

So a candle at 10' away would allow us to expose everything from 3.5' to 28' away and it would all fit within about 6 full stops of exposure and we'd want to set the camera for a proper exposure at the 10' distance.  

 

But the "problem" is the candle is 10' away... probably not even in the same frame with out subject.   Suppose we put the candle merely 3' away (probably a more realistic distance.)  Now we get 2.5' (twice as bright), 1.75' (twice as bright again), and 1.25' (twice as bright again) to get 3 stops brighter and we also get 4.25' (half as bright), 6' (half as bright again), then 8.5' (half as bright again.)  So everything from 1.25' to 8.5' would fall within those 6 stops of dynamic range if we place the candle 3' from our subject and expose for that.

 

If you do this then you will have areas that are siginificantly brighter and significantly darker (6 stops of exposure difference is a lot -- not enough to be "clipped" but enough for one part of the shot to seem very bright while another seems very dark.)  If what you want is for most of the shot to fall within a couple of stops (so brightness differences aren't so strong) then the candle needs to be a lot farther away (or you need more than one candle placed about the room.)

 

It's a bit of math, but the point is it's possible to figure out where you should place the candle relative to your subject based on the needs of the shot.

 

Ok ok, I get it... it's a lot of math and most people would rather just do some testing and move the candle around.  But since you know the light fall-off effect will be less rapid if the light source is farther away from the subject, then you can quickly realize that moving the candle farther away from the subject will help, and moving the candle closer (though it might seem intuitive to increase light by moving the candle closer) is actually only going to make the problem worse because the light fall-off will happen even faster.  

 

Knowing the inverse-square law and how it relates to exposures (lights, light distances, and stops of aperture) is probably the most complex math in all of photography.  If you can learn how the square root of 2 relates to exposure then you can do anything.  (Wait... I just remembered the Scheimpflug principle  https://en.wikipedia.org/wiki/Scheimpflug_principle)

 

Here's a video (Adorama TV's Mark Wallace):

 

 

It's just over 12 minutes long and at the beginning he covers the rules and fundamentals... but toward the back half of the video he starts showing real examples by moving a light source closer or farther from a model (and he's marked the floor with measured distances) so you can visually see it happen and it makes it much easier to understand.

 

Tim Campbell
5D III, 5D IV, 60Da
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Re: Just got a Canon 100mm IS L macro. Now what?

[ Edited ]

Thanks, Tim.  I do math.  I speak diffy-que, well I used to be fluent in it, once upon a time.

 

Thanks, Ernie.  I looked up that package, and it seems to have an add-in for LR6.  So far, everything I've needed to do I've always been able to do with PS Elements, Paint dot Net, or my CAD software.  The CAD software uses layers in a far more sophisticated manner than what Photoshop CC will ever approach.

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Re: Just got a Canon 100mm IS L macro. Now what?


@Waddizzle wrote:

Nice shot, Bob.  I was thinking more along the lines of a single candle, though.  That's the tough one.


For the case you cited (a face lit from below by a candle), maybe a parabolic reflector held above the tripod would help.

Bob
Philadelphia, Pennsylvania USA
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Re: Just got a Canon 100mm IS L macro. Now what?

[ Edited ]

@RobertTheFat wrote:

@Waddizzle wrote:

Nice shot, Bob.  I was thinking more along the lines of a single candle, though.  That's the tough one.


For the case you cited (a face lit from below by a candle), maybe a parabolic reflector held above the tripod would help.


Aw, that takes the fun out of it, Bob.  Besides, a mirror would take a lot away from the dramatic effect of the shadows cast by the lone candlelight.  I envision a nearby wall behind, or beside, the person, and their shadow being visible on the wall.  It's a tough nut to crack.  I've come close, but my flame always looks more like a white blowtorch than a gentle flame, like what your wife captured.  Nice, once again!  Although, her flames are a little hotter than what I'm after.

 

Ernie might be onto something with that software package of his.  I've looked into it.  It would seem that it gives you the power to control and guide just how the final HDR image is constructed.  Maybe I can treat myself to another holiday present.  I just grabbed a better backpack, the Gura Gear  Kiboko 22L+.  Now I might pass along my old Case Logic to my son.

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