Moonrise Illusion

[Tom OD]

Hi All,

Well I had this idea in my head to try and show the size our mind sees the moon at when its low on the horizon. I found that when keeping both eyes open, with one looking through the viewfinder, and the other watching the size of the moon, about 70mm gives an approximate scale.

In this image I started with a 200mm zoom. I took a picture every 20s until the clouds came in. I changed the zoom a tiny bit on each image, and then blended it onto a foreground image.

The image without the foreground blend looks better, but this was done just to give it some scale.

I'm not sure about this, I don't think it looks right, what do you think?

Tom

[wxsatuser]

This may help, scroll to figure 6, just over halfway down.

http://facstaff.uww.edu/mccreadd/sectionI.html

[Tom OD]

This may help, scroll to figure 6, just over halfway down.

http://facstaff.uww.edu/mccreadd/sectionI.html

Thanks for that. I need to get the calculator out to see if you can get the exact focal length to represent the size a ta given angle. That really complicates the idea. Here is a better version with every second image removed from the layers, and not looking quite as rude as the first one.

Tom

[Knight of Clear Skies]

I think the second version is an improvement, in the first it looks like the yachts are being menaced by a giant tongue depressor. It might look better as a line of separated Moon images with black space between them perhaps. I like the foreground and the way it illustrates the reddening caused by looking through more atmosphere.

Don't know what your plans for it are but titling it 'Moon Illusion' or something might be a good idea, someone is likely to get the wrong end of the stick (or tongue depressor) otherwise.

[acey]

To my eye it looks like the moon is getting smaller as it rises higher, but I know that must be an optical illusion too. The image ought to include parallel lines showing that the width of the moon band is not changing.

[LukeSkywatcher]

The most famous Lunar optical illusion captured brilliantly on camera. Never seen it before in an image.

[Tom OD]

I think the second version is an improvement, in the first it looks like the yachts are being menaced by a giant tongue depressor. It might look better as a line of separated Moon images with black space between them perhaps. I like the foreground and the way it illustrates the reddening caused by looking through more atmosphere.

Don't know what your plans for it are but titling it 'Moon Illusion' or something might be a good idea, someone is likely to get the wrong end of the stick (or tongue depressor) otherwise.

Thanks Knight. I did call the thread Moon Illusion, so the image will go with that tag too. The battery on the laptop was about to die to I did not put enough text in the initial description. The difference in size was the idea behind the image, but of course to show the changes in colour was important, and an added bonus when you take a rising moon, I forgot to mention that bit originally. I'll space out the moons with some back background and see how it goes. Thanks for that advice.

To my eye it looks like the moon is getting smaller as it rises higher, but I know that must be an optical illusion too. The image ought to include parallel lines showing that the width of the moon band is not changing.

Yes the idea behind the shot was to show it as we see it, not as the camera sees it. So that's why I started at the highest zoom on the lens the 200mm mark. By stepping it down just a little each time, I got to show a smaller moon with each image. I wanted to get back to 70mm which I think is about how big the moon looks to our eye. Problem was the clouds came in as I got back to 100mm zoom. I had thought about that parallel run of moons as the camera sees it. Correctly really, with the moon as the same size. I did take some moon shoots 1 month earlier from close to the same spot as this image. They were more spaced out, but taken at 55mm. I could probably add it in to this picture. I had thought I might be able to take a zoom shot, then a 70mm shot, then a less zoomed shot then a 70mm shot for each run. This way I could have ran the two parallel lines. However I had no way of going from the 70mm shot back accurately enough to the lessened zoom value for the next shot. There are only the 70, 100, 135 and 200 mm markings on the lens. I think this could be done again, but a second camera set to 70mm might work. Shame I don't have a second camera

The most famous Lunar optical illusion captured brilliantly on camera. Never seen it before in an image.

   Thanks Luke, I did not want to get disheartened with the project by looking up to see if others have done this previously. I'm sure someone probably has, but I don't remember seeing it done either. It was good fun, and I think it can be improved.

Tom

[laser_jock99]

Alternatively use the foreground in your moonrise shot to freak out the viewer!

[Joe_L]

This may help, scroll to figure 6, just over halfway down.

http://facstaff.uww.edu/mccreadd/sectionI.html

Interesting article but seems to miss out on discussing refraction. Excellent picture Tom thaqt nicely illustrates the genuine optical effect of diffraction. The human perception of size of course accentuates our experience of it.

Joe

[Ptarmigan]

 someone is likely to get the wrong end of the stick (or tongue depressor) otherwise.

Prophetic !

I think some already have ?!

[wxsatuser]

Interesting article but seems to miss out on discussing refraction. Excellent picture Tom thaqt nicely illustrates the genuine optical effect of diffraction. The human perception of size of course accentuates our experience of it.

Joe

Refraction does'nt really have an effect on our perception of the moon size.

Refraction causes the moon's apparent horizontal angular diameter, near the horizon, to be about 1.7% smaller.

The vertical angular diameter at the horizon is even smaller, this causes the moon to appear flattened.

The Moon is also 2% smaller due to it being an Earth's radius further away, at the horizon.