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02-20-2010, 06:16 PM   #1
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Extension tubes anyone?

I just bought a set of Marumi auto extension tubes in Ka mount (no AF though). I tried them with several lenses and results with my M 50/1.7 and 135/2.5 look great. The 135 gives better working distance. Just fooling around, I tried them with my K20D built-in flash. Turns out you can get perfect exposure with some very comfortable setups. I found out if I set the 135 at f/11, ISO 100, and the lens to it's minimum focusing distance, using the complete tube set (31+21+13mm), whatever is in focus is properly exposed. You can fiddle with apertures and focus distance, but it works great. Direct flash illumination is not the prettiest for macro work, but the big plus is you can set the top sync speed (180) and with the flash you don't need shake reduction, you can shoot hanheld, perfect pictures as long as you get the focus right, no tripod.
It's probably nothing new to a lot of people, but I was pleasantly surprised.
An example:

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02-20-2010, 07:05 PM   #2
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A salted Planter's peanut through the jar.

No extension tube but same effect. Found a cheap 2x TC and took out its optics before mounting it to my smc PENTAX-M 50mm f1.4.

02-21-2010, 12:37 AM   #3
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Vivitar PKA 2X teleconverter with optics removed to use as extension tube:



Tamron 1.4X teleconverter, taken with a DA 40mm Ltd. at closest focus point:



Same Tamron teleconverter, taken with the DA 40 mm Ltd and the above-mentioned extension tube:



Above photos are down-sized from JPEG files directly from a K10D, no cropping, no additional post-processing.
02-21-2010, 03:14 AM   #4
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Pentax K20D
Auto-Takumar 55/2
M42 Extension Tubes



02-21-2010, 05:43 AM   #5
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Full set of tubes on a FA 50mm f1.7.

02-21-2010, 07:00 AM   #6
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This picture was taken with a M50F2, Fotodiox 50mm extension tubes, and a tripod. The photo is of mold growing on a wall in the Lower 9th Ward in NOLA after Katrina, and I was using my flashlight to create the shadows on the wall.



Side note: extension tubes are fun, but can allow a lot of dust inside the camera if you are not careful when removing the tube(s).
02-21-2010, 12:56 PM   #7
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Can someone help me?
I'm trying to join the extension tube club but I don't accept simple PK extension tubes costing "that" much (around $50).
Since I have the Vivitar Macro Converter which has the big advantage to be of variable length I want to use this one. Coupled with the SMC 2.5/135 the thread starter also owns and my fast 50 this would make a great pair.
However I couldn't figure out how and if you can remove the lenses from the converter without destroying both the glass and/or the converter.

Unscrewing the mount part you can remove the whole glass part which would already solve the problem but unfortunately this element also consits the aperture linkage with I don't want to lose.
So does anybody know if I can just twist the inner barrel holding the lenses till it loosens (if it is only glued - like it seems) or if there is something else holding it in place?
02-21-2010, 09:06 PM   #8
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QuoteOriginally posted by EsBee Quote
A salted Planter's peanut through the jar.

No extension tube but same effect. Found a cheap 2x TC and took out its optics before mounting it to my smc PENTAX-M 50mm f1.4.
No need to remove the optics, use as is: gives the same effective result.

02-21-2010, 09:12 PM   #9
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QuoteOriginally posted by Egg Salad Quote
Can someone help me?

However I couldn't figure out how and if you can remove the lenses from the converter without destroying both the glass and/or the converter.
...So does anybody know if I can just twist the inner barrel holding the lenses till it loosens (if it is only glued - like it seems) or if there is something else holding it in place?
Do not do anything to it, just use it as it is: The effective result is the same. Essentially, you will be multiplying the size of the image, whilst retaining the same minimal focusing distance: a bit like cropping, when using a full frame lens on a crop body.

Also, using the TC, you retain infinity focus (lost when using extension tubes), which could be handy to have when doing a walkabout.

Check out this thread:

http://www.apug.org/forums/forum206/59211-extension-rings-vs-teleconverter.html

Last edited by Banjo; 02-21-2010 at 09:26 PM.
02-27-2010, 02:53 AM   #10
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No the results are not the same. The way it is it is only useful with a 50mm lens.
Simply reversing this 50mm lens gives better sharpness than when on the TC.
But working with reversed lenses is quite uncomfortable as you can't focus and have to close the aperture yourself.

Without the glass - so as a simple extension tube I could also use the 135/2.5 as a macro lens.
What I'm not sure about but think to be true is higher light transmission without the glass part - mathematically there is still a two light stop loss (but this doesn't account for the light transmission (t-stop)).
Besides as an extension tube magnification goes far beyond 1:1.
Infinity performance is not a strength of the TC so loosing it is not a great loss.
02-27-2010, 04:35 PM   #11
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I read a dpreview post last year where someone resorted to smashing the glass in the Vivitar 2x MFTC. Removing the optics is not that easy, apparently, and harder on the KA mount ones because of the multiple contacts on sprngs. In your case, you don't seem to need the KA feature to use a 135/2.5. If your MFTC is a KA one, you should be able to sell it for more than tubes cost.
02-27-2010, 08:06 PM   #12
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Nope it is the older one without contacts. What I don't get is why extension tubes are so expensive - this converter cost me $40, a plain tube $20-30. More advanced models with A contacts are hard to find and sell for $70 and up.

Smashing the glass would be alittle bit extreme and probably decrease the resale value by a fair amount but it still seems this makes for the best extension tube around.
Before I destroy anything I'd try to twist the whole lens group out with a pipe wrench.
02-28-2010, 04:42 PM   #13
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QuoteOriginally posted by Egg Salad Quote
No the results are not the same. The way it is it is only useful with a 50mm lens.
Simply reversing this 50mm lens gives better sharpness than when on the TC.
But working with reversed lenses is quite uncomfortable as you can't focus and have to close the aperture yourself.

Without the glass - so as a simple extension tube I could also use the 135/2.5 as a macro lens....
A 2x teleconvertor will, effectively, give you some magnification (depending on the prime lens used) with ANY lens you can attach it to, without reducing the minimal focal distance, with the retention of infinity focus, and with the loss of two stops of light.

Were the same casing (the TC with glass removed) to be used as an extension tube, the magnification would depend on the length of the casing and the focal length of the prime lens used (the longer the focal length, the less magnification). There would still be loss of light (again dependent on the focal length of the prime lens) but there would also be a loss of minimal focal distance as well as the loss of infinity focusing.

Image quality would depend on the quality of the prime lens and the quality of the TC. Assuming that both are "decent", the impact on IQ for small enlargements, say up to 8"x10" would -to most observers- be insignificant

If you are a 35mm film user, interested mainly 4"x 6" prints, using a teleconverter for walkaround photography is a relatively cheap and very handy approach to close-focus photography.

This would be especially the case where the subject is difficult to approach or out of reach of combinations with a relatively short focusing distance: for example, many "Macro" or normal lens-extension tube combinations still require one to approach closer than 6" or 8", whereas, a 2x TC and a 100mm prime lens will give you a lens-subject distance of 39" for a 0.25 magnification and still more (subject distance), if a smaller effective magnification is acceptable.

Last edited by Banjo; 03-01-2010 at 05:52 PM.
03-01-2010, 01:38 PM   #14
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I've run some tests today and as it seems the TC doesn't degrade IQ visibly.
Besides as stated working distance is much better with the TC than with extension tubes. For nearly the same magnification distance was halfed with tubes (13cm with TC to 5.5cm without).
I didn't evaluate my pictures to full extent yet but for now I'm taking everything back except the statement about additional light loss. This TC is great.

Ambient light was far from consistent but with the lens on ext. tubes exposure was clealy shorter - like 1/6s vs. 1/30s.

Shots + more text coming soon...
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