Light height sweep

rmpsrpms

Not sure if I have published this before, but several folks have asked me about how the height of the lights affects the coin image. I've recently seen a few posts showing the coin features "ringed" with reflected light, while the fields and flat surfaces of the features were dark. This is opposite of what we look for in coin illumination, but it's hard to describe so I made an animation to show the effect. The lighting sweeps from nearly flat to nearly vertical and back again. I usually describe it as being at an angle versus horizontal, so the sweep goes from 10-deg up to 80-deg. I did not go all the way up to 90-deg ("axial") because my setup could not do the full range while including axial. Anyway, let me know any questions, and enjoy!

PS: give it a little time to load...it's a big file

Steven59

Whoa! Thought somebody slipped me a hit of acid there for a second

lilolme

Cool. Thanks for the time involved for this.
I am not a photographer but I sometimes mess around with the snap-o'matic and lights and stuff (a couple threads). It is interesting how details from luster, color, strike, contact marks and 'lines' can change from one setup to another.

Might also be interesting to see each individual photo listed as one could maybe 'focus' on how the changes are happening.

Namvet69

Me like!

may

@Steven59 said:
Whoa! Thought somebody slipped me a hit of acid there for a second

WAYNEAS

Thanks for the food of thought.
Will try adjusting my lights to see if I can get a better pic.
Wayne

rmpsrpms

@lilolme said:>
Might also be interesting to see each individual photo listed as one could maybe 'focus' on how the changes are happening.

I did this a while back and can't seem to find the originals. Will check in another spot but they might be gone.

lilolme

@rmpsrpms said:

@lilolme said:>
Might also be interesting to see each individual photo listed as one could maybe 'focus' on how the changes are happening.

I did this a while back and can't seem to find the originals. Will check in another spot but they might be gone.

.
I down loaded the gif and the pictures came through also. I can send them to you or post a few of them showing some of the steps. But don't want to step on your thread.

With that said - Wow you did a lot more than I was thinking. 80 photos in the gif. I can see that number 1 and 41 are unique. The others are duplicates showing the steps up and then reused to go back down in the gif. So that is 41 different photos.
Since you mentioned in the OP lighting angles from 10 degrees to 80 degrees (or so), I was thinking every 10 degrees (8) or maybe 5 degrees (15 pics). But 41 light angles...

rmpsrpms

I actually didn't do that much work. As I remember, I shot from 10-80 degrees in 10-deg steps, and then when I rendered the animation, I let the software composite some transitional "smoothing" shots to make the video less choppy. Might be hard to tell which shots are transitions and which are the originals.

lilolme

@rmpsrpms said:
I actually didn't do that much work. As I remember, I shot from 10-80 degrees in 10-deg steps, and then when I rendered >the animation, I let the software composite some transitional "smoothing" shots to make the video less choppy. Might be >hard to tell which shots are transitions and which are the originals.

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Ah, that makes more sense and is close to what I was initially thinking - every 10 degrees or maybe 5. I was trying to visualize changing the lighting angle at such small increments with 41 photos from 10 to 80 degrees. I can visualize every 10 degrees as you noted.

I have not looked to see if one can tell the difference in an actual photo or a 'transitional "smoothing" shot' - would guess not. There are slight light shifts from one to another. 10 to 80 degrees would be 8 photos or 7 steps. So it does not divided into the 41 photos or 40 steps evenly. But appears the 'smoother' added 4 or 5 'smoothed' photos per step. Interesting, thanks.

Meltdown

What a great view. Impressive breakdown to show even the slightest variation determines how the coin looks from a photo.

lilolme

I looked at the gif photos and I can not tell the actual photo from the 'smoothing' photo. Starting with number 01 and going to 41, I took every 5th photo (01, 06, 11, 16, 21, 26, 31, 36 and 41) and grouped them and took a screen shot. Below is the progression.

Thanks @rmpsrpms I think this is cool and good info. Strike feature variance.
I noticed my phone has a gif on it. Not much instructions or if it has any smoothing but might test it with some snap-o'matic photos.

01 top left, 06 top right
11 bottom left, 16 bottom right
.

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21 top left, 26 top right
31 bottom left, 36 bottom right
.

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And 41
.

rmpsrpms

I just use ezgif.com to make my animations. It's an easy and free upload, and they have selections for timings, transitions, and once you finish it has many options for optimizing the size and performance. The input files can be jpgs or gifs or whatever.

As you can see, the higher you can get the lights, the better for showing details, color, etc. This medal doesn't have much/any luster, but if it did you'd see that luster is best in the middle angles. But the lower angles are bad for most everything, and look very unnatural, and this was the point I wanted to make with this animation.

Edited to add: since details and color show up best at high angles, and luster at middle angles, is there an "optimum" angle that shows luster, color, and details? I tend to prefer ~70-75deg, which gives a good compromise between these characteristics. Some folks use both "high" and "middle" lights. What you want to avoid is anything coming in too low.