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04-16-2015, 06:45 PM   #31
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QuoteOriginally posted by Sagitta Quote
I would love to pick up a modern TC if I could justify it. The fact I have no modern lenses however kind of makes it a wishful thinking kind of thing.

Out of curiosity, if I have a modern TC attached with an old 'A' or "M' lens, would the camera be able to be stopped down? Thats the one glaring weakness with the old TCs I've used. Unless I'm using a preset lens, I'm stuck at whatever maximum aperture the lens is at.

I certainly wouldn't call the old TCs useless, just limited due to the advancement of technology over the years.
I wouldn't buy a TC for old glass without trying it first. My 70-210 with the new 1.4 has dreadful purple fringing and CA. But I would expect, that if you have FA* glass it would be OK. My A-400 stops down just fine with either the 1.4 or 1.7 TC. OF course by the time you have the TC on you don't want to stop it down much anyway.

04-17-2015, 05:57 AM   #32
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QuoteOriginally posted by pacerr Quote
Life becomes a lot easier when you stop thinking of a TC as a cheap means to acquire an expensive telephoto lens and accept it for what it is -- a relatively cheap and small way to get the results of a long FL lens of the optical era in which it was built. Life's a compromise - so 're TC's.

I carry a TC for one reasons only and use it solely with the best, longest FL lens at hand at the time of need. The reason? To achieve the PERSPECTIVE/POV of a longer lens when I can't otherwise gain position to do so.
This is an excellent way of viewing it. If you're both aware of and prepared to pay the price in f/stops and IQ, there's nothing to stop you from recognising it as a quick way to double the size and reach of your lens collection in an instant (or multiply it by the number of compatible TCs you have).

As I understand it, the ability to stop down (or not) seems to be an argument for using the manual M42s, upon which you can force stop-down at any time to give the camera the true picture (always) of how much light it is getting. Therefore it seems to make sense to put a K-mount TC on the camera, an M42-to-K-mount adapter on the TC as required, and attach the screw-mount lens to that. Yes? (If nothing else, it keeps stray stop-down pins and other potential nasties away from delicate mount contacts that weren't even imaginable when these things were first designed.)
04-17-2015, 06:51 AM   #33
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FWIW, thanks to this thread I found and ordered up a 2X Tokina TC with contacts on it just out of pure dumb curiosity. I paid about twice what I normally would for one of these things ($20) but it should be interesting to see how it fares for me.

I grabbed the Tokina simply because most of my old glass is made by them, so I can pretend theres at leasts ome sort of compatibility going on before I shelve the thing as a novelty.
04-17-2015, 06:39 PM   #34
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In a fit of boredom I went in and ripped out the guts of the 3X, leaving only the glass.

Why?

Because now I can stop down any lens I attach to the thing (basically treating any K-mount as if it were a preset). Hopefully this will kill the glaring "always shooting wide open" CA and fuzziness anything I attach to it has.

04-20-2015, 10:54 AM   #35
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Got mine today. Am concerned in that the stop-down lever moves freely. Very freely. With a Sigma 70-210 KA mount lens attached, I can push on the lever against spring pressure to open the lens up to its fullest extent, but it does not support stop-down when on my K5 in the manner that the lens alone does when using the aperture ring. There may also be issues with infinity focus, but for the time being exposures appear correct, whether indoors or out, and any fuzziness is probably due to camera shake as I don't have a tripod to hand.

Sagitta, looking at your last post, I suspect this is par for the course? I want to make sure of this before I go making a fuss to the vendor.

ETA: Pics with annotations. https://www.pentaxforums.com/forums/members/82288-pathdoc/albums/9641-experimental-things/

Last edited by pathdoc; 04-20-2015 at 11:23 AM. Reason: Add pictures.
04-20-2015, 12:27 PM   #36
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QuoteOriginally posted by pathdoc Quote
Got mine today. Am concerned in that the stop-down lever moves freely. Very freely. With a Sigma 70-210 KA mount lens attached, I can push on the lever against spring pressure to open the lens up to its fullest extent, but it does not support stop-down when on my K5 in the manner that the lens alone does when using the aperture ring. There may also be issues with infinity focus, but for the time being exposures appear correct, whether indoors or out, and any fuzziness is probably due to camera shake as I don't have a tripod to hand.

Sagitta, looking at your last post, I suspect this is par for the course? I want to make sure of this before I go making a fuss to the vendor.

ETA: Pics with annotations. pathdoc's Album: Experimental things - PentaxForums.com
I'm not 100% certain (which is why I bought a TC with the electronics in it, I'm nosy), but I know old, non 'A" TC's will not allow you to stop down with a modern camera (at the very least I have never figured out how to). Again (unless you spent a lot of cash on the thing), the solution is easy enough - gut the TC, leaving the glass. That makes it easy enough to compose and focus as you can then just use the lens like a preset by using the aperture ring on the lens. The quality of the teleconver is going to depend entirely on how well that glass inside of it was made. Since the TC is basically acting as a huge magnifier, its going to show whatever flaws are in it (or the attached lens) right off. Fringing you can live with on a normal shot is going to be amplified due to the TC.

I suspect the fuzziness you're seeing is more to do with the fact you were stuck shooting at f/4 (ie, wide open) more than anything else. I'm not seeing any fringing in your shot, which is a good sign.

I snuck out yesterday and used mine down at the local park with a certain subject in mind. I was using a tripod and remote to minimize shake, and since I'd gutted the TC I was able to stop down to f/8 or f/11 (bear in mind that thats before the 3X effect is applied from the TC). I was able to get workable results, but I could probably have done much better if there had actually been any sun out.

This was a 300mm f/5.6 stopped down a notch or two, ISO 3200, 1/200 of a second, tripod mounted with the mirror up and on a delay.

Even from about 150 feet away, the depth of field was barely larger than the bird. I also had to go in and post process out the purple and green fringing that was absolutely everywhere in this shot.

04-20-2015, 05:41 PM   #37
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Did not pay so much that I wouldn't gut it. How easy is this to do, and can it be done without upsetting the optics?

04-20-2015, 05:45 PM   #38
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QuoteOriginally posted by pathdoc Quote
Did not pay so much that I wouldn't gut it. How easy is this to do, and can it be done without upsetting the optics?
I just unscrewed the mount. The two levers were screwed to the side of the inner bits, and I just yanked them (as in, they wouldn't unscrew so I just snapped them off), then reattached the mount. It took all of about 5 minutes, if that.

I'm guessing all older TCs are similar, but your mileage may vary if you have something with extra stuff going on in there.
04-22-2015, 04:42 AM   #39
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Thanks for this little tip. May work on that some quiet evening when the kids are in bed and I've got nothing better to do (and no small fingers to help me lose screws!). My beastie is, as I've said, externally identical to yours, so what worked for you should work for me. I gather that what I end up with will be a lens which is permanently stopped down to whatever aperture I set until such time as I set it again. Fine by me.

I should admit up front that much of the blurriness you saw in those shots was probably my manual-focus skills having atrophied.
04-23-2015, 05:44 PM   #40
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The EL Tokina 2X came in. It's a bit newer than that 3X is, as it has the electronics for 'A' lenses. As such, I could use it with my (much more modern) Samyang 35mm f/1.4 today and let the TC control the aperture and whatnot. The TC was new-old-stock. It was still in the who-knows-how-old bubble wrap!

In any case, after confirming that it works, I promptly stuck it on the 3X just for giggles. I think I'm going to need the tripod for any experimenting if I'm going to insist on doing that. With the 300mm lens, thats basically shoving 1800mm (300x 3 x 2) of murky image at the camera. I haven't downloaded the shots I took out the window here yet that way, but I'm not counting on any great quality as I was shooting with the ISO maxxed on the K-3 just to even get close to hand hold-ability. What I *am* hoping for is passable enough IQ to play with some astro shots with things rigged like this.

Again, I'm not counting on great images, just interesting ones. There is a certain zen coming into play when you decide IQ doesn't really matter that much. That said, the Vivitar 3X and the Tokina both seem to have exceptional quality for what they are (both essentially being new). If I decide I'm into the whole TC thing, I may let LBA kick in and buy an actual modern TC come next tax season along with a good long modern telephoto lens and have some fun without kludging 25 year old gear together.
04-24-2015, 04:49 AM   #41
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One thing people seem to have forgotten with bodies beyond the K20 is that the TC needs to have the black finish removed to permit stopping down. For some reason, Pentax changed the programming such that the 7th pin in the mount (the data pin) needs to be grounded to let the aperture stop down. This is a problem with anodized aluminum mounts like vivitar used on TCs and extension tubes. No need to pull aperture mechanisms etc, just sand the mount
05-11-2015, 04:40 AM   #42
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Rather than disassemble or sand anything down or short any contacts, I found another solution.

I had already bought an M42 adapter; just the other day I bought my first M42 lens (something called a Samigon 135mm f/2.8). What could be easier than mounting the TC to the camera, the adapter to the TC, and screwing on the M42 lens? Just set the K5 to Aperture Priority, set the lens to M mode, and step down as desired! Voila! I have a 405mm f/8 prime (605mm EFOV for crop sensor) for really not very much money.

Of course the results in anything but bright sunlight are, as far as I can currently tell, cr*p without a tripod - but it DOES work, and it DOES appear to be metering in the right general area. (I will post about the lens separately once I have more time on it; it seems to be metering about one stop slow, and is having trouble focusing out to infinity even with an apparently genuine Pentax adapter, but it only cost me about $40 before shipping, and it's a good lens on which to gain M42 experience. For birds and squirrels in my backyard, I think it'll be the bee's knees.)

Last edited by pathdoc; 05-11-2015 at 04:47 AM.
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