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Old Sep 9, 2010, 11:06 PM   #1
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Default Gettin a lil closer...

Alright, I took Mntgal's advice on the DIY extension tube and finally decimated that POS Vivitar 3X auto Teleconverter and made a real nice extension tube (approximately 50mm ext.) that allows electrical contacts to camera to keep the lens auto functionality.

Im sure youve seen pics of mine with my vivitar 90-230 close focus lens, and with this added ext. tube, the versatility of this consumer lens just sky rocketed.

In case you want to see this lens in on some telephoto action, you can check out an older post of mine of mainly birds. http://forums.steves-digicams.com/pe...ome-birds.html


While its not the sharpest lens I own, it is great as the close focusing allows it to enter macro mode from 90mm -230, which I have yet to figure out the mathematical forumula of the actual magnification, but unlike other macro /telephoto lenses ive used, there is no line or barrier between macro mode and telephoto mode, meaning you can set it between macro and telephoto to get seamless focusing distance from about 6 inches all the way to infinity.

Well now with the tube added, the magnification increases and at max macro mode, the focus distance is pressed up on the glass, which can be handy for ultra macro of the non living, but you can still pull it back to give insects some room and acheive even greater magnification than before.

Im not sure if its quite 1:1 with this, I tried crunching some numbers and gave up, but bottom line is its allowing me to get extremely close and still take macros from a rocks throw all the way up to the glass and Im loving it.

I attatched some photos here,

NOTE: these are handheld so dont judge these by sharpness. Again because of the ext tube, this already kinda slow 4.5 lens is now even slower, but if i can manage these handheld in my living room, I am thinking itll produce some pretty good shots outdoors during day, I will have to test that of course tomorrow.

Heres what I have for now



uncropped dime:






cropped of the same shot:

(not 100%, )



100% crop, again hand held so im pretty impressed so far..




now for some potato "stink" bugs


This actually wasnt zoomed in all the way, I didnt want to harass the little bugger, so I kept a distance of about 6 inches for this shot.

Uncropped







a little closer, same shot











this one here is only 33% crop, not even 100%.. due to handheld, the 100% crop looked a little iffy, so im going to have to try tomorrow outdoors to get something a little better for comparison. Still, not too shaby IMO






Now the down side, the lens itself is pretty light for being an old metal zoom lens (90-230s usually are on heavy and long side) but the lens normally balances well with K20d.. The added 50mm between lens and camera throws balance off quite a bit so it feels a little akward in my hand, but the real test will be tomorrow in daylight



sorry for writing a book here, just thought this was cool, the lens now can go from micro to telephoto in the flick of the wrist

thanks for idea mntgal!
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Old Sep 10, 2010, 4:37 AM   #2
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you can still focus to infinity even with the extension tube attached?
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Old Sep 10, 2010, 5:44 AM   #3
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Looks like a nice sharp combination!
You will probably find tripod or monopod a big help with the balance...
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Old Sep 10, 2010, 8:20 AM   #4
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Quote:
Originally Posted by John.Pattullo View Post
you can still focus to infinity even with the extension tube attached?


actually no, i dont believe so, but the test shots i did in my house let me focus to everything inside, obviously. I did forget about that hinderance with ext. tubes, so Ill have to see what the maximum focusing distance is, I do know its atleast fifty feet or so, because I was able to focus on things just fine in my kitchen from my living room.

sorry for my mistake, and thanks for remindin me, another thing to test
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Old Sep 11, 2010, 9:12 PM   #5
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Not bad at all. I find it is A ton of fun to play with different lens and adapter combination's.
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Old Sep 11, 2010, 9:33 PM   #6
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Im trying to rig up an extending extension tube out of an old push/pull zoom lens that I broke glass out of, trying to figure out a way to attach a female k mount or an m42 thread on the other end. I havent quite figured it out yet, but when I do it should be pretty sweet to be able to push/pull the lens out and acheive different magnification.

Wish me luck on this project
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Old Sep 12, 2010, 1:35 PM   #7
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Cool project, I've thought of trying the same thing but decided against it. It seems easier to just have a couple of tubes, a really sharp lens and a reversing ring for when I want more power. I can cover up to about 2x that way and anything longer than that it's better to just stack.

John
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Old Sep 12, 2010, 3:42 PM   #8
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I'd never thought about doing something like that. What about getting a reversing ring, the one that has threads on one end and the K-mount on the other. Then reverse it - have the threads on the glass-less push/pull extension tube and the K-Mount on the lens. Or another option might be to take a rear lens cap and glue a filter without glass in it to create your own. I'm horrible at such things so the glue wouldn't hold if I tried it, but it's an idea.
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Old Sep 12, 2010, 8:28 PM   #9
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i actually have a 2x teleconverter that is K mount on one side and m42 threads on the other I was thinking about ways to incorporate it in, but decided I may just make a double ended M42 push/pull adapter.

I do like your idea of the lens cap tho, brilliant! I was thinking of ways to block out the light and some reason the simplicity of that escaped me. Definitely seems like the way to go, now that you mentioned thanks much!

although I admit:

I read your first idea a few times over and I still am not getting what you mean?
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Old Sep 13, 2010, 12:55 AM   #10
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All you really need to do is get a female K-mount on the end of the lens right? Just buy a cheap 2x TC and unscrew and remove the one side, then epoxy it to the end of the lens and you're done. I think on my Albinar TC that I removed the glass from the female side came w/o the glass.

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