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Old Nov 8, 2006, 1:35 AM   #1
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The lens I have been using for birding is a Sigma f400 1:5.6, fully manual. If things are going well I can get closer to the birds than the minimum focus distance for the lens so the thought strikes me, "How about putting an extension tube or two behind the lens?"

I have not been out yet but playing around indoors with about 30mm (say, 1.25") of extension tubes allows me to focus down to about four feet whereas 15 feet or so is the minimum without the tubes.

Naturally I will loose infinity but who cares when trying to photograph something the size of a sparrow? As far as I can tell I still have a maximum of about 20 feet in focus. I guess using a shorter extension give different max and minimum focus points.

I will not be the first to try this so I am wondering if there are any opinions out there?

Isnt digital grand that we can experiment like this without expense or delay?:-)




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Old Nov 8, 2006, 8:39 PM   #2
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Pouring with rain and cold winds. No chance to go out and try the configuration in the field.:sad:

Sigh! I hope my new friends the tui and his mate have a nice warm tree to sit it out!:roll:


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Old Nov 13, 2006, 12:48 AM   #3
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I found this little waxeye on a New Zealand flax plant, the wind was quite blustery and I am suprised he was not motion blurred terribly.

*istDS 400mm Sigma f 1:5.6 with 10mm of macro tube used with the intention of reducing the minimum focus distance somewhat. 1/125 second 0.5 bias. Handheld.

Sharpened a little in Paint Shop but no other changes.



Although I have been trying for interestin bird pictures every lunch time for the last month or so I believe this is my first even moderately decent result.



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Old Nov 13, 2006, 7:07 PM   #4
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That is an interesting idea, one I would never have thought of, thanks for sharing the results.

Tim
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Old Nov 13, 2006, 7:53 PM   #5
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john,
great image and idea. i may try it on the 300 & 500. who knows.
definately needs noise reduction and a 1.5meg d/l is tough for dialup. ran it thru noise ninja.

roy
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Old Nov 13, 2006, 7:56 PM   #6
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looks like saving at 115K introduced as much noise as i got rid of.
oh well.

roy
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Old Nov 13, 2006, 9:43 PM   #7
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No disputing that the picture is bit of a sow's ear but it is the best I have managed in several weeks of trying!

I did find when I was trying to capture the tui(i.e.parson birds) (since gone to new feeding grounds :sad that I was managing to get inside the minimum focus distance.

Presumably the principle does give a bigger image but the real aim was to get physically closer albeit at the cost of loss of infinity.





BTW, do we have a size etcconvention for displaying pics on the forum?
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Old Nov 14, 2006, 2:13 AM   #8
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Looks like there's wuite some purple fringing in the eye...might want to desaturate that part in PS.

Other than that, looks fine to me. I like the bokeh. Roy's edited version does make the image better.
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