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Old Feb 7, 2007, 9:49 AM   #11
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Great shots btw... number one is cute and number two displays some stunning colors! Keep it up!

ejbrusselsprout, Thanks for the explanation of the ratios... it all makes since now!
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Old Feb 7, 2007, 1:13 PM   #12
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ejbrusselsprout wrote:
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inneyeseakay wrote:
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How do determine what 1:1 is? How can I figure out what ratio I am getting with a certain lens and an extention tube?
pretty easy really. your sensor is about 23.5 mm across so if you can fill it with a subject that size you've got it. the old rule of thumb (which i'm not sure is totally accurate but at least is pretty close) was for any given focal length you need that amount of extension to reach 1:1. of course the normal focussing ofthe lens extends it so you don't need a 50mm tube to reach 1:1 with a 50mm lens.

the easiest way to tell what you're getting is just take a close up of a ruler. if the picture covers 23.5mm you're getting 1:1, if it only covers 47mm you've got 1:2 etc.

if you were shooting film or a full frame sensor camera the numbers would change but the idea's the same.

all the best, eric
Eric ,

Thanks for the info.

Fred
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Old Feb 7, 2007, 6:13 PM   #13
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inneyeseakay wrote:
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Fred2726 wrote:
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...trying to get a 1:1 shot forget about it.

Fred
How do determine what 1:1 is? How can I figure out what ratio I am getting with a certain lens and an extention tube?
macro ratio 101.
get yourself a ruler in MMs.(download and print) focus on it, how manyMM do you see?? 1:1 will be just under 24mm which is the width of the sensor. if you see 47mm then you are at 1:2, half lifesize. if you only see 12mm then you are at 2:1 , twice lifesize.
1:1 means life size on the sensor if it's a half inch in real life then it will project an image onto the sensor that's 1/2''long.

roy
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Old Feb 7, 2007, 6:14 PM   #14
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fred, don't you love that lens?????

roy
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Old Feb 7, 2007, 6:48 PM   #15
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robar wrote:
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fred, don't you love that lens?????

roy
Roy,

Yes! Thanks for the recommendation!

Just you wait and see. I'm working on something right now. Should have it done in the next day or too.

I can't take this lens off! I only switch it to use the 50mm A 1.7, when light is really scarce.

Fred
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