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04-22-2008, 11:05 AM   #1
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Close up lenses

Hello all! I need some help

I have version 3 of the 70-210 Vivitar Series 1 lens

Vivitar 70-210 Series 1 Macro Zooms - Mark Roberts Photography

Which close up lens / diopter do I need to use to make it 1:1 ? What is the formula for this stuff. In the webpage he mentions he uses a sigma 1.6 but that is hard to find and it's not 1:1.

04-22-2008, 11:56 AM   #2
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Since the lens has a 62mm filter thread, I suggest you go for Raynox DCR-250 lens. I just got it form my Tamron 70-300 and it goes even over 1:1, depending on focal length.
Don't bother with cheap diopters, or you will be disappointed as I have been.
04-22-2008, 12:22 PM   #3
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Thanks for the info Pentagor. I've also read that the nikon's lenses are great (5t, 6t etc) do you know how they compare?
04-22-2008, 01:03 PM   #4
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Sorry, don't know them.

04-22-2008, 01:11 PM   #5
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Note, close up lenses

diopters are actually 1/focal length, therefore 1 diopter is a 1 meter focal length, 2 diopters is a 1/2 meter focal length etc.

the maximum focusing distance for a lens with a close up lens attached is the focal length of the close up lens. This is because it converts light from an object at the focal length to parallel light rays as they enter your camera,

Adding a close up lens also reduces the actual focal length of your lens, The new focal length of the combination is FL new = 1/ (1/FL old + Diopter)

You get to 1:1 when you achieve a close focusing distance of 2 times the FL new number with your close up lens attached
04-23-2008, 12:23 AM   #6
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QuoteOriginally posted by Lowell Goudge Quote
Adding a close up lens also reduces the actual focal length of your lens, The new focal length of the combination is FL new = 1/ (1/FL old + Diopter)
I think you mean: New FL = 1 / (1 / Focal Length of the lens + 1 / Focal Length of the diopter).
In the case of the Raynox DCR-250 (8 diopters), the focal length of the diopter is 125mm, which leads to a resulting focal length of 44.9mm with a 70mm lens or 78.4mm with a 210mm lens.

QuoteOriginally posted by Lowell Goudge Quote
You get to 1:1 when you achieve a close focusing distance of 2 times the FL new number with your close up lens attached
Magnification = Focal Length of the lens / Focal Length of the diopter
So, the magnification ratio with a 70mm lens would be X0.56 and X1.68 with a 210mm lens. When used with my Tamron 70-300 at 300mm, it produces a whopping X2.4 ratio, and even more when the zoom is set at its minimum focus. The best part is that the combo is fully usable handheld, thanks to its F/5.6 effective aperture (try to shoot handheld with extension tubes or bellows at X2.4 ). And since the Raynox has 3 glass elements, the aberrations are very well corrected too. Not bad for a device costing less than 50 bucks...

Cheers!

Abbazz
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