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Explain photography to a novice

bananapeanut
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Dsloan Dsloan
Oh boy, now you've done it. This is about to get mildly complicated. This is about relative distance (but possibly also about how your cell phone camera does it's thing - some have multiple lenses designed for different focal lengths). If your watch is 10" from the camera lens and the rest of your arm is 12" away, your arm is effectively 20% further away. When you take a picture of something further away, that ratio diminishes. So, the apparent size of the watch relative to your wrist diminishes. It's the same reason why people's faces appear different in proportion based on the camera's distance for the subject.

I didn't think about depth of field so the thicker the watch, the more pronounced the fisheye effect because the surface of the wrist is further away from the surface of the watch? So if I had drawn the contour of the watch on my wrist as suggested before, the depth of field would have been zero and therefore no distortion effect at all?
 
Deafboy
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@Dsloan and @Scarecrow Boat gave the correct answer.

The mirror has nothing to do with it. The closer object appears bigger. In the first picture the watch is relatively closer than in the second picture.
Edited:
 
bananapeanut
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Scarecrow Boat Scarecrow Boat
Take these two images of mine as an example. Same wrist, same watch, taken seconds apart but at different distances.

Yes, same effect without mirror.
 
140dave
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Fun house mirror? Or one of those they use at Macys to make us look thinner than we really are?

Or yeah, it could be what all the smart photo guys say…. 😗
 
dougwhiz
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Taking photos of watches with the iphone is difficult. I get a lot of reflections from the crystals and shiny cases. And and as my wife the graphic designer explained to me, the iphone camera adds too much contrast. A hairline scratch in real life really gets exaggerated in the photo.

Speaking of mirrors, I took a look at my Sinn the other day and thought someone spiked my drink. The double AR coated crystal combined with the coating on the bathroom mirror made for a freaky image.

Sinn mirror.jpg
 
SC1
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dougwhiz dougwhiz
Taking photos of watches with the iphone is difficult. I get a lot of reflections from the crystals and shiny cases. And and as my wife the graphic designer explained to me, the iphone camera adds too much contrast. A hairline scratch in real life really gets exaggerated in the photo.

Speaking of mirrors, I took a look at my Sinn the other day and thought someone spiked my drink. The double AR coated crystal combined with the coating on the bathroom mirror made for a freaky image.

Sinn mirror.jpg

Reminds me of what I see on my wrist after I hit some meth lines with a Krylon huff bag chaser.
 
dougwhiz
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SC1 SC1
Reminds me of what I see on my wrist after I hit some meth lines with a Krylon huff bag chaser.

Exactly!

beavis.gif
 
MRC
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rendo rendo
I think that has to do with the change in the focal length and the lens on your phone. To complicate things even further, the phone you are using could also be changing to a different lens between the two shots.
Both photos were taken with:
Exif.Photo.LensModel Ascii 34 iPhone 8 back camera 3.99mm f/1.8
 
Deafboy
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rendo rendo
To complicate things even further, the phone you are using could also be changing to a different lens between the two shots.

Actually, is it a myth that the camera's focal length affects image perspective (which is what is discussed in this thread). Two pictures taken at the same camera location with lenses of different focal length will yield the same perspective.
Edited:
 
Dsloan
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Deafboy Deafboy
Actually, is it a myth that the camera's focal length affects image perspective (which is what is discussed in this thread). Two pictures taken at the same camera location with lenses of different focal length will yield the same perspective.

Thanks for backing me up on this. I have this argument with photo students all the time!
 
janice&fred
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I have noticed when I stand in front of a mirror (I know it's scary) and look at a watch on my wrist it appears smaller than when I simply look directly at my wrist. I figured the 3-d appearance when I look directly at the watch had that effect? Is this at all related to anything discussed here so far?
 
Dsloan
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janice&fred janice&fred
I have noticed when I stand in front of a mirror (I know it's scary) and look at a watch on my wrist it appears smaller than when I simply look directly at my wrist. I figured the 3-d appearance when I look directly at the watch had that effect? Is this at all related to anything discussed here so far?

Yep! The closer things are to your eye (your watch), the bigger they will appear relative to nearby things (your wrist). I think seeing it on your wrist in the mirror is a closer approximation of how others will perceive the watch to wrist proportion.
 
rendo
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Deafboy Deafboy
Actually, is it a myth that the camera's focal length affects image perspective (which is what is discussed in this thread). Two pictures taken at the same camera location with lenses of different focal length will yield the same perspective.
I see, thanks for eliminating that one.
Deafboy Deafboy
@Dsloan and @Scarecrow Boat gave the correct answer.
The mirror has nothing to do with it. The closer object appears bigger. In the first picture the watch is relatively closer than in the second picture.
If we can both agree that the difference is related to distance between the watch and the camera lens, I have a hard time following how the mirror has nothing to do with that. I don't want to sound like an expert here, so I'm thinking out loud and throwing some ideas. This was my thinking of how the focal distance is longer through the mirror. Please let me know what I'm missing.
nh14r.png
 
Dsloan
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rendo rendo
I see, thanks for eliminating that one.

If we can both agree that the difference is related to distance between the watch and the camera lens, I have a hard time following how the mirror has nothing to do with that. I don't want to sound like an expert here, so I'm thinking out loud and throwing some ideas. This was my thinking of how the focal distance is longer through the mirror. Please let me know what I'm missing.
nh14r.png

If I'm understanding the question correctly, I think the error is that your comparing the distance the light travels from object to mirror to eye with the apparent 'virtual' image in the mirror. What we're really comparing here is the distance the light travels from object directly to the eye vs the distance the light travels to create that 'virtual' image in the mirror.

i.e.: if I had time, I'd take your illustration and draw another set of lines going directly vertically from the object to the eye.
 
rendo
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Dsloan Dsloan
If I'm understanding the question correctly, I think the error is that your comparing the distance the light travels from object to mirror to eye with the apparent 'virtual' image in the mirror. What we're really comparing here is the distance the light travels from object directly to the eye vs the distance the light travels to create that 'virtual' image in the mirror.

i.e.: if I had time, I'd take your illustration and draw another set of lines going directly vertically from the object to the eye.

I see the difference that you are describing. I would agree with you if the camera focused on the "mirror" instead of the "virtual image", but the image would be out of focus in that case.
 
madjestikmoose
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The best photos follow a kind of ‘rule of three segments.’ In other words, the rectangular picture is split into three roughly equal parts/sections whether that might be horizontally, vertically or otherwise. Any less than that, the picture is too empty and has no real point to it, any more than that and it becomes cluttered and unpleasant to the eye.
 
Nobel Prize
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rendo rendo
I think what you call "same distance" is double the distance in terms of photography unless you get close to the mirror in the second shot. You are not focusing on; youirror, you are focusing on the same watch through the mirror.

This is the answer here. Most lenses distort to some level, Some more than most, others (Very few) almost nothing. Wide-angle lenses (Like a phone) tend to distort more. Mid-distance lenses like 35mm still distort a little but give a more natural look. At 44, to 50 mm lenses offer the most natural undistorted look, Closest to the natural eye. 35 is the most popular range since it is close to natural but offers a wider context. 50 is next as it offers a great natural view for contextual portraits...75 to 100 is best after that for undistorted portraits etc etc.

Longer range and Zoom lenses tend to compress the image (opposite to wider angle). Meaning you often perceive the background and subject as closer together than it actually is.

The closer the object is to the lens the more these properties are displayed. So, for example, on a wide-angle lens, the objects closest to the lens will be more distorted. This can be either pinched or pulled (distortion from the center to the image's border or distortion from the border to the center. ) Or think fish eye or inverted fish eye...

When you take the image directly on your wrist, the distance from the dial to your arm is huge in terms of wide-angle lens closeup unless you use a specialized lens. When you take an image in a mirror, you are doubling the distance to the subject, hence reducing the distortion.

In non-photographic terms, the issue is a matter of geometry and how close subjects are to the lenses (no matter what lens). This is scientifically a more accurate explanation since the wide angle lenses are closer to the subject than the zoom lenses to bring the same ratio.

See here for a comparison. Just imagine the nose is your watch and the face your arm. On the mirror, you see a jump from x to 2x

Screenshot 2023-02-28 at 12.18.31 PM.png


Image above is not mine. credit to Bakerdh
Edited:
 
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