[pcarfan]

Sorry for doubting you. On some forum here, someone asks whether the SMC Pentax-M 50mm 1:2 has 1:2 magnification....

With a 1:2 macro lens, the extension tube is still useful. Many macro lenses can go 1:2, and come with an extension tube to get to 1:1.

Hey, no problem...it was nice of you to pose that question in a kind manner.

I know some can take things the wrong way, and for the life of me I could never understand what those kinds are thinking. If anyone is bothering to type to get things cleared for me, even if it means to make sure I got the basics right, I know they are doing it for my own good.

I have gotten in to trouble before in trying to help others in a forum, so I know where you are coming from...but, FYI, I am not one of those @$$ h@les

[pcarfan]

A link to the thread with the image of my SD card to show the lens alone, lens and the 1.7 AFA, and now the lens with the 25mm frankenstein ext. tube.

https://www.pentaxforums.com/forums/general-pentax-photography/52718-pentax-1...r-why-not.html

[les9596]

I may be able to offer something here. I got the idea to do the same thing with the exact same TC. I got the idea from a thread on the DPReview Pentax SLR board. I bought the TC off eBay for cheap and took it to my local camera repair place (I'm fortunate to live close to Seattle, which has CameraTechs, an actual camera & lens repair business and they're very friendly and knowledgable.)

The tech took one look at it, walked over to his workbench and about 30 seconds later handed the TC and the now seperate guts back to me. So it can be done and done easily (at least by a pro.) He didn't even charge me for it (did I say they were a good bunch down there?)

BTW, the guts came out as a single assembly, threaded on one end, which was apparently held into the TC with a locking nut. There may be more to it than that, but whatever it is, it isn't a big deal.

Good luck. And hey, for as cheap as these things are, what's the worst that can happen? Crummy TC to great extension tube in one easy step!

[pcarfan]

I may be able to offer something here. I got the idea to do the same thing with the exact same TC. I got the idea from a thread on the DPReview Pentax SLR board. I bought the TC off eBay for cheap and took it to my local camera repair place (I'm fortunate to live close to Seattle, which has CameraTechs, an actual camera & lens repair business and they're very friendly and knowledgable.)

The tech took one look at it, walked over to his workbench and about 30 seconds later handed the TC and the now seperate guts back to me. So it can be done and done easily (at least by a pro.) He didn't even charge me for it (did I say they were a good bunch down there?)

BTW, the guts came out as a single assembly, threaded on one end, which was apparently held into the TC with a locking nut. There may be more to it than that, but whatever it is, it isn't a big deal.

Good luck. And hey, for as cheap as these things are, what's the worst that can happen? Crummy TC to great extension tube in one easy step!

Is your inner hole the same size as these ?





I purposely broke the aperture lever, as the last thing I wanted was for this to get stuck in my camera and not come out. So, I crushed that off.

The inner lens element did unscrew. There was no screws holding it in, but rather something like an O-ring with with a gap (so like a C ), that had to be removed prior to unscrewing the lens element. So, I guess there is really no reason to remove the 4 small screws you see on either end.

But, I did not know of any of this. So, I unscrewed the 4 screws on both ends and all 6 electrical contacts and the springs fell out, the lens mount, the rod and it's spring fell out and lastly the spring with the aperture lever sort of was hanging out. Then I had no idea the inner lens element was actually screwed in. After several use of various sharp instruments chisels and hammers, the lens started to rotate which reveled the threads for me to even know it unscrews.

Anyhow, was the final hole that you have the same size as the above. As I think a regular extension tube is totally hollow allowing for more light.

Thanks.

[pcarfan]

Some images with the Volna-9 (M42 Lens, 50mm f2.8 1:2 macro), 25mm Extension tube (gutted TC), and the Pentax 1.7X AFA with aluminum foil shorting.

So, the image was auto focused, and flash in P-TTL (nice for an M42 lens)...I am doing something wrong with wireless P-TTL, will sort it out soon.

F16 (max)


F2.8


F24

[Changa]

This was a very useful thread. Thanks to the explanations above, I was able to get the optics out of my Takumar-A TC quickly and with out any problems.

I took some pictures to help explain the very simple process.

First, this is what the optics assembly looks like. The optics screw into the TC. The ring to the left screws on to the optics assembly, using the same threads, and locks the assembly down to the teleconverter.



Sliding the assembly out.



You can see the notch where the scratch is. I used that to unscrew the optics assembly with a small screwdriver. I did not need to loosen the ring first, but the ring does have two small notches in case you would.



After removing the optics, the only defect I could see in the new extension tube was the spring that is attached to the stop-down indicator lever, no longer constrained by the optics assembly, will move out into the image path if the lens is set at anything other than A or its smallest aperture setting.

I did, however take one picture with my 50mm A lens set at 1.7 instead of A and I could not see any indication of the spring in the photo.

The optics below the spring are the optics of the 50mm lens.



Takumar-A "extension tube" with 50mm A f1.7 lens attached @ f16 (shot in Av with lens set to "A").



To compare, this is the same 50mm A f1.7 lens attached to a Vivitar 2X macro teleconverter at 1:1 focus (@ f16)



Just for fun, Takumar-A "extension tube" with DA* 50-135mm lens attached (@ f16).



The extension tube seems to work well and is significantly less cumbersome than the Vivitar macro TC. It seems "less is more" holds true for this teleconverter.