This is a practical test more so than a scientific one. The original photos were taken 4 times and the best for each option was chosen for the comparison.. Distances are approximate,
4 photos were taken 4 times each.
Focus was Auto single point at the intersection of a black piece of tape providing decent contrast.
Sigma 105 without the TC, at 9 feet 4 times each.
Sigma 105 with the TC, at 12 feet 4 times each
These two had the tripod setup moved so the image size was the same regardless of the TC present or not.
Sigma 105 at < 1 foot (macro) without the TC, 4 times each
Sigma 105 with the TC Still Macro with the TC, at just over 1 foot 4 times each
These two also had the tripod setup moved so the image size was the same regardless of the TC present or not.
I evaluated each set of 4 against others of the same set, distance, and focus by viewing both the brick and mortor and the fine sand present.. Then selecting the best by how sharp it looked compared to the others in the same group. I never saw or was able to distinguish any 1 best one within a set. . Then I enlarged the best 2, one with and one without the TC on the screen so that both were the same size as displayed. Then evaluated them.
The tfw is on each photo.
This first pair is the 12 and 9 foot shots with the 105mm on the left and the 105+TC on the right.
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the 2nd pair is the Macro shots with the 105mm on the left and the 105+TC on the right.
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I found it difficult to pick any one of the pair. What I did notice that what difference was present was not enough to warrant loosing a full stop of light. As long as you had adequate number of pixels to enlarge the non TC shot to the same image size as the TC shot then I saw no advantage to using the TC, EXCEPT...
The TC has a trait which is desirable for shooting butterflies and that is, when adding the TC the minimum focus distance does not change in essence seeming as though you are closer but yet not scaring the bug!
I also found not using the TC to be an advantage or disadvantage. I will keep mine solely on the basis of making my minimum focus distance greater.
4 photos were taken 4 times each.
Focus was Auto single point at the intersection of a black piece of tape providing decent contrast.
Sigma 105 without the TC, at 9 feet 4 times each.
Sigma 105 with the TC, at 12 feet 4 times each
These two had the tripod setup moved so the image size was the same regardless of the TC present or not.
Sigma 105 at < 1 foot (macro) without the TC, 4 times each
Sigma 105 with the TC Still Macro with the TC, at just over 1 foot 4 times each
These two also had the tripod setup moved so the image size was the same regardless of the TC present or not.
I evaluated each set of 4 against others of the same set, distance, and focus by viewing both the brick and mortor and the fine sand present.. Then selecting the best by how sharp it looked compared to the others in the same group. I never saw or was able to distinguish any 1 best one within a set. . Then I enlarged the best 2, one with and one without the TC on the screen so that both were the same size as displayed. Then evaluated them.
The tfw is on each photo.
This first pair is the 12 and 9 foot shots with the 105mm on the left and the 105+TC on the right.
---
the 2nd pair is the Macro shots with the 105mm on the left and the 105+TC on the right.
---
I found it difficult to pick any one of the pair. What I did notice that what difference was present was not enough to warrant loosing a full stop of light. As long as you had adequate number of pixels to enlarge the non TC shot to the same image size as the TC shot then I saw no advantage to using the TC, EXCEPT...
The TC has a trait which is desirable for shooting butterflies and that is, when adding the TC the minimum focus distance does not change in essence seeming as though you are closer but yet not scaring the bug!
I also found not using the TC to be an advantage or disadvantage. I will keep mine solely on the basis of making my minimum focus distance greater.