'MACRO' pound coins

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michaelho

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Had another play with my extension tubes. What do you think?

coinsw0.jpg



Michael
 
michaelho said:
for anyone who hasn't noticed, read the word down the middle of the stack :p
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Now that is clever!!
meant to comment on this earlier, its really good! what lens did u use with the extension tubes?
 
mmmn very clever but is the "r" one a £2 coin by any chance?

Dont think theres any "r"s on a pond coin edging?
 
good shot - but make the file size smaller - half a meg for this is far too big - 100k would not look worse on screen and dl a lot faster!
 
Great Shot...Have been playing with my extension tubes on a 5D with 100mm macro ....awesome magnification and detail.
 
wish I could afford to do that shot, I had to use a 1p for mine :(

loving the macro thing hehe
 
Great that you have got them working well. What make are they? Do they transfer focus info etc from the lens or do they make it all manual (like mine do). My macro tubes cost £26 for TWO sets inc delivery!!

After your first post I got my macro tubes out having bought them when I bought all my kit a few months ago and not yet used them. They didn't come with instructions and I haven't seen any instructions for their use so I didn't realise just how much light you loose! When I tried to use them at first I didn't get anything but when I switched to manual I have actually got some shots. Nothing worth sending in yet as I have blown both the bulbs in my spots so had to guess the focus and shoot off my flash five times during the exposure! I will submit some when I get some new bulbs!

Oh if anyone wants the address for a UK supplier who sells macro tubes at about £15 per set inc postage let me know and i'll try and dig it back out. They are not brilliant quality as you can imagine but as there is no glass in a macro tube they do the job and its not a lot to pay for something to have a play with!
 
Thanks for all your comments. Yes that is a two 'pound coin' added in there as I needed the 'R' to spell out 'MACRO' :p Also added little borders on the top and bottom with pound coins that have a pattern around the edge haha.

I am using the Jessop branded extension tube kit (13, 21 and 31mm) which can be had for a bargain price of £22.49!

For this shot I used my Tokina 100mm f2.8 Macro lens with either the 21mm or the 31mm tube attached. Also used a tripod, remote release and 580Ex flash with lightsphere diffuser attached to it.

cowasaki: there's not much else involved in using extension tubes, I have found that I first start off with just the macro lens attached to the camera to see how close it gets on it's own, then I add on the extension tube depending on how much closer I want to get. Position the camera in the right position and focus the subject. These tubes work with Canon's AF system but I tend to use manual for my macro shots anyway so I get exactly what I want in focus.
 
foodpoison said:
I'm assuming its a crop
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I have only cropped a little bit from the top and a little bit from the bottom, that's it. The extension tubes on a macro lens can really get you in close.


AWP: I usually save my jpegs with max. quality setting, would middle quality setting be sufficient?
 
yeah I agree Ally. This shot would have definitely benefited from off camera lighting, but I don't have a wireless transmitter or a hot shoe cord. With the extension tube attached the camera was very close to the stack of coins therefore the mounted flash provided light from an acute angle very close to the coins. If I could I would have moved the light more central and further away from the coins to give a more even lighting.
 
Great shot! - Might have a go at reproducing it. What sort of lighting setup did you have for the shot? - I know you said you had a difuser, but did you have it in a light box or anything like that?
 
lol 'ate em', is 'MACRO' not very obvious? I tried to hint by highlighting 'MACRO' in the topic title :p

Thanks again for your comments.

DaveHope: No lightbox involved, stacked the coins on a piece of A4 paper, set up the camera on a tripod, mounted my flash on the camera and put a lightsphere diffuser on the flash then just shot away using remote shutter.
 
EdinburghGary said:
Cooooooooool photo. How do extension tubes work?
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They are a collection of empty tubes which move the lens further away from the sensor so that only part of the light hits it. Each tube is a different length allowing lots of different magnifications. At its maximum magnification maybe only the central 10% of light that hits the lens gets the the sensor so this is spread out over the same area and is effectively magnified optically which is much better than say cropping out the central 10% of your picture and then resizing it. Because they are just basically empty tubes with a mount at each end they are quite cheap. Some pass the electronics between lens and camera and are more expensive some do not and can be as cheap as £10-15.

Because they spread this light out over a wider area tubes are much darker than a proper macro lens and as such it is like stopping down a long way. My bulbs all blew on my macro lamps so to get a picture with all the tubes attached I needed a 30 second exposure with 5 flash gun flashes during it! I am looking forward to messing with them when I get some more bulbs!
 
The light loss has nothing to do with the magnification letting less light in, it's because the light has to travel further and the inverse square rule starts to have an effect.
 
pxl8 said:
The light loss has nothing to do with the magnification letting less light in, it's because the light has to travel further and the inverse square rule starts to have an effect.
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If you let x amount of light through the end of a tube then the length of the tube dictates how much light comes out of the other end (unless it is a beam) as you say but this is because only a small amount of the light that enters hits the object, which is what I was saying. Ie if the picture is 10% of the size then the light hits that hits the sensor will be (.1x.1 = .01th) as much or 1% as bright. It has nothing to do with just how far the light travels. Its the same principle as looking at a star hundreds of light years away. It looks dim because effectively you are only looking at a minute percentage of the light in much the same way as a macro tube. Light does not just dim over a distance* or your 500mm 40cm long lenses would be rubbish. They have a bigger front glass to let more light it so allowing a bigger percentage of that light to hit the sensor.

I might not know much about photography but I know about Physics! :)

* this is the conservation of energy principle. Light may dim by a tiny amount as it hits dust etc but over 8cm there would be no measurable loss.
 
I'll add, as it might help, that it's important to remember that a camera records the amount of light arriving at the sensor/film plane and not how much light is at the point in space it is pointing at.
 
If you look at your link to wikipedia it nicely explains exactly what I am saying!!

I am just going back to simple principals the amount of light that hits the sensor is less because only a small percentage of the light entering it gets to the sensor like I explained. If you think about it we are saying the same thing. I was just explaining why. Saying that it is because of the distance is simplifying it too much. The light itself does not dim over distance it is spread out so less is hitting just like your diagram explains. If you still don't get it I will do another diagram showing a camera lens with and without the tubes
 
Pixl8, we really are saying the same thing! Here, I have done a diagram with photoshop (yes I know its a bit rubbish but it does explain how a macro tube works and the loss of light!)

macro-tube.jpg


Basically with the lens fitted normally the sensor would be at pos A.

With a small tube the sensor is effectively at pos B. Just like you said the inverse-square law applies BUT all that is saying is what I was saying it was just that I was explaining it in laymans terms. Less of the light coming from the lens hits the sensor making the picture darker. (and this percentage is related to the magnification)

With a longer tube the sensor is effectively at pos C again the picture is magnified further but less of the light is hitting the sensor so it is darker still.

Just take a look at the diagram we really are saying the same thing I am just trying to explain it using simple principals :)
 
cowasaki said:
With a small tube the sensor is effectively at pos B. Just like you said the inverse-square law applies BUT all that is saying is what I was saying it was just that I was explaining it in laymans terms. Less of the light coming from the lens hits the sensor making the picture darker. (and this percentage is related to the magnification)
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You're still hung up on the magnification but it's got nothing to do with the reduction of light.

If you put a 25mm tube on a 50mm lens the magnification is greater than putting the tube on a 100mm lens. But the light loss is the same for both. The light loss has NOTHING to do with the magnification only the distance the light travels - the further it travels the more it will spread (and that's got nothing to do with the magnification).
 
pxl8 said:
You're still hung up on the magnification but it's got nothing to do with the reduction of light.

If you put a 25mm tube on a 50mm lens the magnification is greater than putting the tube on a 100mm lens. But the light loss is the same for both. The light loss has NOTHING to do with the magnification only the distance the light travels - the further it travels the more it will spread (and that's got nothing to do with the magnification).
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The light spreading out is what CAUSES the magnification the reduction in amount of light is caused by this spread (not caused by the distance) but it is completely linked to the amount of magnification. I am not hung up on the magnification that is just how it is, we both clearly understand how it works we are just explaining it from alternative directions! If you look at my diagram and the one you found on wikipedia they really are the same thing!
 
I think you both are talking about the same thing, it's just that cowasaki is refering to magnification regarding the use of one specific lens. E.g. if you use a 31mm tube it's more highly magnified compared to using a 21mm tube with the same lens, and this extra magnification is a confounding factor to the extra distance of the 31mm tube which reduces the light hitting the sensor.
Pxl8 is just saying that magnification is just a confounding factor and actually does not affect the amount of light, it's actually the extra distance the tube moves the lens away from the sensor that is the real determinant of how much light hits the sensor.

Sounds right?
 
michaelho said:
nice diagram btw cowasaki :p
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Thanks, I think it explains how it works! This kind of arguement happens a lot on forums. Two people basically saying the same thing. Pixl8 obviously understands it just like I do but we have looked at explaining it in a different ways!
 
not just forums, I find myself arguing the same arguments with my girlfriends. She just has to win.....but then again so do I lol.
 
cowasaki said:
The light spreading out is what CAUSES the magnification the reduction in amount of light is caused by this spread (not caused by the distance) but it is completely linked to the amount of magnification.
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If I understand the above you're saying that because the image being resolved is spread further out (magnified) less light reaches the sensor?

Yes?
 
pxl8 said:
If I understand the above you're saying that because the image being resolved is spread further out (magnified) less light reaches the sensor?

Yes?
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Yes I am, I was just trying to explain that the greater the magnification the less light. The distance and magnification are inextricably linked so if either increase so does the other (for any given camera/lens). So yes we are completely saying the same thing I was just trying to explain it without getting too scientific! ;)
 
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