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10-18-2009, 08:11 AM   #1
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Macro lens and TC

I would like to buy a dedicated macro lens (Tamron 90mm macro) and I am wondering if it can be used with the Pantax AF 1.7X? Anyone ever tryed this combination or, more generally, a macro lens with a TC? Does the focus distance and magnification ratio stay the same when used with a TC?

10-18-2009, 09:48 AM   #2
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I use the SMC-F 1.7x AFTC with my SMC-M 100F4 all the time.

As long as you are using a macro prime aF4 and faster it should be OK, note you loose stops as you close focus
10-18-2009, 11:26 AM   #3
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Lowell I'm glad you replied here. I have kind of question related:
If I attach TC (say Kenko 1.5x) to dedicated Macro (say Sigma 105/2.8). Would I get:
a) 160(ish)/4 1:1 macro
b) 160(ish)/4 x:1 macro (where x>1)
???
In layman English. Would TC+macro lens combo let me take bigger than life size magnifications? or would it move the minimal focusing distance further apart thus keeping 1:1 ratio??

sorry for hijack

BR
Peter
10-18-2009, 11:54 AM   #4
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A TC increases your focal length, without changing minimum focus distance, but I am not sure, when focused in close the exact relationships for magnification ratio.

Taken on face value, a 2X TC would double your image size, therefore my 100mmF4 which gives 1:2 at close focus would become a 1:1. I would want to test this though to make sure, and this might not hold for internal focusing macros that seem to have a reduction in focal length as they focus in close.

10-18-2009, 03:18 PM   #5
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QuoteOriginally posted by Lowell Goudge Quote
A TC increases your focal length, without changing minimum focus distance, but I am not sure, when focused in close the exact relationships for magnification ratio.

Taken on face value, a 2X TC would double your image size, therefore my 100mmF4 which gives 1:2 at close focus would become a 1:1. I would want to test this though to make sure, and this might not hold for internal focusing macros that seem to have a reduction in focal length as they focus in close.
does this mean that for dedicated 1:1 macros with normal focusing and 2xTC would (should in theory) make it 2:1??
10-19-2009, 07:55 AM   #6
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QuoteOriginally posted by axl Quote
does this mean that for dedicated 1:1 macros with normal focusing and 2xTC would (should in theory) make it 2:1??
Saw some work on another forum by a fellow who used a Vivitar 2X macro converter with with a 100mm macro lens for larger than life size images. Caused me to go on flea bay and pick up one of those. However, he used macro flash with his shots and from my little experience with that combo I think you really need to use the flash set up to get small enough apertures to get things in focus, which is fiddly any way ...perhaps a macro focusing rail might help.
10-19-2009, 10:18 AM   #7
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QuoteOriginally posted by axl Quote
does this mean that for dedicated 1:1 macros with normal focusing and 2xTC would (should in theory) make it 2:1??
Yes.

I just tried it with a kenko 1.5X on a Tamron sp 90. No change in working distance , 1.5X change in magnification.

Dave in Iowa
10-19-2009, 10:48 AM   #8
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I use extension tubes to get a greater than 1:1 ratio, but I use my 28mm for most of my macro work.

10-19-2009, 06:34 PM   #9
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Thus, if I understand the previous posts, teleconverters do not affect minimum focusing distance, but they do have an effect on field of view. Therefore, using an AF 1.7X adapter with a Tamron 90mm macro would give me the same minimum focus distance, but the FOV would be equivalent to a 150mm.
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