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Tiny flowers with FA 100/2.8+ext tube
Posted By: Ash, 10-20-2009, 04:37 PM

Courtesy of pcarfan (thanks mate), these puny flowers were captured with an extension tube (converted from an A-capable TC) and my FA 100/2.8 macro.









Interestingly, the 'extension tube' being about 25mm long provides minimal further magnification to the macro lens alone. I found this by testing the lens with and without the ext. tube fitted on a tripod shooting the same subject. How much magnification would one expect with a 25mm ext. tube? What FL equivalent does a 100mm lens become with the ext. tube?
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10-20-2009, 06:51 PM   #2
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if a 100mm macro gives 1:1 then you would need 100mm of extension to give 2:1
if a 50mm macro gives 1:1then you would need 50mm of extension to get 2:1
Do you get the idea?
10-20-2009, 07:35 PM   #3
Ash
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Yes Taff. Thanks.
Now where's my FE lens so I can get 5:1 macro?!?
10-20-2009, 11:13 PM   #4
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i didnt realise it was you posting Ash, there is a question mark ya know lol

10-21-2009, 02:46 AM   #5
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QuoteOriginally posted by Taff Quote
if a 100mm macro gives 1:1 then you would need 100mm of extension to give 2:1
if a 50mm macro gives 1:1then you would need 50mm of extension to get 2:1
Do you get the idea?
Well, this applies for an ordinary 100mm and 50mm lens. But does it apply if they are already capable of 1:1 or 1:2 from the start?

Tamron adaptall 2 SP 90mm f2.5 macro 1:2 certainly don't need a 90 mm tube to get to 1:1. The dedicated adaptall 2 tube is only about 4 cm.
When I've been playing around with my SMC Pentax-DFA 100mm f2.8 macro 1:1 with tube and maximal close up (set to 1:1) it appears that I get 2:1 already with a tube of about 4cm length, not 100mm (I've been measuring actual size of subject and it's size on the picture knowing the sensor size and calculated the macro dimension).

So I think this problem is more complex for macro lenses.
10-21-2009, 04:28 AM   #6
Ash
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I pondered this but found it hard to quantitate.
Certainly a 25mm tube on a 100mm macro lens doesn't get much further away from 1:1...
10-21-2009, 07:30 AM   #7
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3rd and 4th are nice images. I have no clue on the magnifications, but I know it does well with even the F135/2.8 and with the 77/1.8 (which I don't use with the ext.tube).

10-21-2009, 07:41 PM   #8
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Thanks S,
It doesn't matter too much to me - just curious.
10-21-2009, 09:12 PM   #9
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Love the first one Ash though I may have cropped the top a bit. JIM
10-21-2009, 09:13 PM   #10
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Thanks Jim,
I cropped a little but agree, a little more from the top would suit well.
Cheers.
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