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05-31-2009, 03:11 PM   #16
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How many miles away was that pigeon?

05-31-2009, 05:19 PM   #17
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QuoteOriginally posted by Quicksand Quote
How many miles away was that pigeon?
Not that far actually--maybe 200 feet(?) As I mentioned, the TC shortens min & max focusing distances so you sacrifice reach for magnification.
06-01-2009, 07:02 AM   #18
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CORRECTION! I tested again this morning and discovered I was flat-out wrong about the shortening of focus distance. I don't know why I couldn't get it to focus at longer distances (even manually) yesterday but I had no problem this morning.
06-01-2009, 11:38 AM   #19
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you need to keep in mind that the SMC-F 1.7x AF TC is a unique beast, where the elements inside the TC move to make the lens "auto focus"

If the TC is sitting at the minimum focus distance (for the TC) the lens attached will not focus to infinity.

With this TC, depending on where it starts, it may cycle fully to one extreme and back to the other, and as a result go right back to the position of being focused at minimim.

Remember this will not focus on the 1000 F8, I have never successfully have it focus on an F5.6 lens. The combined effective aperture is just too small to permit AF to work.

06-01-2009, 11:57 AM   #20
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QuoteOriginally posted by dadipentak Quote
CORRECTION! I tested again this morning and discovered I was flat-out wrong about the shortening of focus distance. I don't know why I couldn't get it to focus at longer distances (even manually) yesterday but I had no problem this morning.
As Lowell already pointed out: The AF-adapter has a very limited focus range. It will not AF from the minimum focusing distance of any lens right through to infinity. You need to roughly pre-set the distance with the manual focusing ring on the lens and just let the AF-adapter do the fine focusing. This way, you will be able to use the full focusing range of the lens and a bit more, as the AF adapter would focus a bit nearer, than the lens on its minimum setting.

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06-01-2009, 11:59 AM   #21
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QuoteOriginally posted by dadipentak Quote
Well, I tried it this morning on AF.C and the focus worked fine. The light was pretty good but not great so I got a fair amount of noise (which Neat Image refused to treat for some reason.) I'm quite pleased with the resolution.
How much CAs and purple finging did you remove in post-processing? Would be interesting to know, as the 500/4.5 has horrible CAs, when combined with the AF-adapter.

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06-01-2009, 12:14 PM   #22
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QuoteOriginally posted by Ben_Edict Quote
How much CAs and purple finging did you remove in post-processing? Would be interesting to know, as the 500/4.5 has horrible CAs, when combined with the AF-adapter.

Ben
It is probably no worse than on my 300mm F4 perhaps worse is not the right word, I am sure it is worse, due to the lens design, but if you are not careful, the 300 F4 can also produce some "great" fringing. I avoid shooting white egrets with this combo
06-01-2009, 03:15 PM   #23
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It is a unique and quirky beast, Lowell. I swear, though, it does seem to AF when the K20D is set to AF.C. I do get some green & magenta highlights which are usually easily removed (but not when there's foliage in the shot). So far, that hasn't been as severe a problem as with the 500mm f4.5

I did some testing this morning trying to assess whether I'm better off with the TC or shooting with the lens alone and cropping. Here are some samples, resized and converted to jpeg with no other processing The first is with the TC; the second, without. What do you think?

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06-01-2009, 03:20 PM   #24
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QuoteOriginally posted by dadipentak Quote
Here are some samples, resized and converted to jpeg with no other processing The first is with the TC; the second, without. What do you think?
You would have to crop the bottom one 1.7x in order to compare properly.
06-01-2009, 06:58 PM   #25
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QuoteOriginally posted by Miserere Quote
You would have to crop the bottom one 1.7x in order to compare properly.
It is done.
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06-01-2009, 07:53 PM   #26
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QuoteOriginally posted by Ben_Edict Quote
How much CAs and purple finging did you remove in post-processing? Would be interesting to know, as the 500/4.5 has horrible CAs, when combined with the AF-adapter.

Ben
I have the Sigma 500 F/4.5 and have never seen any PF and I have used it with the Sigma 1.4 TC. I have not used it with the Pentax version 1.7 though.
06-02-2009, 02:59 AM   #27
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QuoteOriginally posted by jgredline Quote
I have the Sigma 500 F/4.5 and have never seen any PF and I have used it with the Sigma 1.4 TC. I have not used it with the Pentax version 1.7 though.
Javier, sorry for the confusion, I was asking about the old Pentax K 500/4.5, which has in many situations acceptable CAs, but goes overboard with the 1,7x AF-adapter.

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06-02-2009, 07:02 AM   #28
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Interesting: the PF in these shots isn't nearly as apparent on my calibrated monitor at home as it is on my laptop here at work.
06-02-2009, 07:28 AM   #29
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Dave, I think the cropped image looks sharper than the TC one. You could start a poll
06-02-2009, 09:32 AM   #30
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Thanks, Mis! A poll, huh--that could be interesting...
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