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Old Sep 6, 2010, 10:13 PM   #1
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Default help me with TC's Please

Ok, so I talked myself out of buyin the Pentax Da*300 again, cuz it'd leave me eating ramen for probably a month till I catch back up! :-D

I definitely want more range tho, Im lookin at a TC, but geeze there seems to be so many options. Aside that, I actually tried to do my research by rehashing on old forum posts here but it seems most of the ones people talk about are simply not able to be had, even on ebay and craigs list


I think I ultimately want the pentax AF 1.7X T.C. im a little confused, does this actually allow camera to AF with old manual lenses? Ive heard something of the sort, but cant get my finger on a definite answer.

I just missed one for 300 BIN on some second rate forum, and ebay, people are listing and selling them for over 5-600.00 USD.

It tempted me, but if im gonna step there I might as well buy the dang lens. (although I really want both)

So I want my Zeiss Sonnor electric 200mm 2.8 to get a little more range, but I cant find any good comparable TC's that are good IQ. Im ok with dropping a few hundred, and heck I may end up gettin the pentax AF 1.7X anyways, but I thought Id ask your opinions.

I did see one of these on ebay for 150.00:

Kenko 1.5X Pz-AF Teleplus SHQ


any tips/ideas? I am going for IQ overall, this lens is very sharp so itll have a little headroom but I tried it with a 3X vivitar 7 element and it was a complete and utter joke!



im running circles here around the same info/lenses to pick from

any insight would be appreciated as I dont have tons of cash to throw around so I need to make sure my investments are solid and wise decisions, though Id rather spend to get a keeper than juggle with upgrades and having to resell



thanks again!








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Old Sep 6, 2010, 10:34 PM   #2
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Yes the AFA allows old glass to AF with in limits. I believe Scott has discussed this elsewhere but for any lens longer than 50mm you have to rough adjust the focus and then let the AFA do it's thing.

I have a Kenko 1.5 and find it to be fine. It's the older model and from what I've heard some think it's not as good but it's fine for my purposes.

3x is always a joke w/digital. You could get away with it on film but not with digital. Even 2x is questionable unless you're buying a high end model. I have a Tokina 2x 7 element and while it works I wouldn't want to use it all the time, requires a fair amount of PP to get the sharpness back.

Ultimately your always better off with a longer lens than a shorter one with a TC (within limits, over 400mm the longer glass may not be an option).

John
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Old Sep 7, 2010, 12:50 AM   #3
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Thanks for the info, jelow1966.

Looks like its either going to be the AFA or Kenko for IQ, if i can find the AFA cheap enough (300ish like I saw one last week) I may get it, otherwise for IQ the Kenko seems to be the next best thing


yeah ive been running circles over which 300-400 lens to get and i really prefer primes, which theres far less options for.

Ive tried a few zooms and the sharpness, coloring, and bokeh of my 200 2.8 is so far unmatched,

also deterring me from the da star 300 is the fact that with a 1.5 TC i can get 300 f4, for the price (and near sharpness depending on IQ degradation ) and with the AFA I could have near af from what ur saying, (though im not sure how the afa is going to turn such a heavy lens, ) for about a thousand dollars less than buyin the da star 300.

Ive looked at some other lens options 200-400, bigma, tamron 135-400, I really dont know what I want cuz I want it all! :-) Im just not sure what to settle on, i think for me right now the best thing would be the TC so I can get an idea of what a nice one does to the lens and then try to pick up longer glass in the future. Seeing very few lenses at 400 faster than 5.6 for pentax is unfortunate and theyre all more money than my car cost, (you can see where my priorities are)

I know theres no such lens out there that fits my needs as itd be free :-D but perhaps a TC will keep me happy till Ive got that kinda money layin around.


Anyone need a kidney?
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Old Sep 7, 2010, 11:21 AM   #4
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Important information about the Pentax SMC-F 1.7X AF Adapter is that it according to the Pentax manual only works with lenses with largest f-stop 2.8 or larger. But Scott and others use it successfully with f4 (like the DA*300mm) and f4.5 (like FA* 300mm) lenses. Especially the K7 autofocuses well also with those smaller apertures. I have tried it with K20D and my 600mm f5.6 lens but it didn't work (as a TC yes, but no AF).
If you find one at or below 300USD it's well worth it's price.

Kjell
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Old Sep 7, 2010, 2:06 PM   #5
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Quote:
Originally Posted by NMRecording View Post
Thanks for the info, jelow1966.

Looks like its either going to be the AFA or Kenko for IQ, if i can find the AFA cheap enough (300ish like I saw one last week) I may get it, otherwise for IQ the Kenko seems to be the next best thing


yeah ive been running circles over which 300-400 lens to get and i really prefer primes, which theres far less options for.

Ive tried a few zooms and the sharpness, coloring, and bokeh of my 200 2.8 is so far unmatched,

also deterring me from the da star 300 is the fact that with a 1.5 TC i can get 300 f4, for the price (and near sharpness depending on IQ degradation ) and with the AFA I could have near af from what ur saying, (though im not sure how the afa is going to turn such a heavy lens, ) for about a thousand dollars less than buyin the da star 300.

Ive looked at some other lens options 200-400, bigma, tamron 135-400, I really dont know what I want cuz I want it all! :-) Im just not sure what to settle on, i think for me right now the best thing would be the TC so I can get an idea of what a nice one does to the lens and then try to pick up longer glass in the future. Seeing very few lenses at 400 faster than 5.6 for pentax is unfortunate and theyre all more money than my car cost, (you can see where my priorities are)

I know theres no such lens out there that fits my needs as itd be free :-D but perhaps a TC will keep me happy till Ive got that kinda money layin around.


Anyone need a kidney?
Hi NMR,

The 1.7x AFA is indeed a confusing item, as it is relatively unique, so there's nothing for most people to compare it to in their experience. It has no trouble focusing heavy lenses since the AF is done within the AFA. This is unlike any other AF TC which just passes through the AF drive and information to the lens's AF mechanism.

This is why the focusing range is limited for tele lenses, and manual prefocusing is necessary at the lens to get within the range of the AFA. With most tele lenses, the AFA will focus from about 50' to infinity when the lens is focused to infinity. At closer ranges, the focusing range decreases in proportion to the focusing distance -- the closer you get, the distance range that the AFA will focus gets smaller, and at 1:1 macro distances, the range actually shrinks to only a few mm.

I'd be willing to bet (a modest amount, of course) that the AFA would mate well with your Zeiss 200/2.8, and as Kjell stated, it works well with high quality lenses with f4-4.5 max apertures, despite the f2.8 limitation stated by the factory. With the K-7's improved AF sensitivity, I've even been able to AF with my FA*300/4.5 + a 1.4x TC + the AFA, so it's conceivable that it'll allow AF with an f5.6 max aperture lens with this body. The f4.5 lens +1.4x TC is equivalent to an f6.3 max aperture lens, but the AFA will not AF with my DA 18-250 f3.5-6.3 at 250mm on the K-7, so stated max aperture is not the only factor in this. My guess is that resolution and contrast play a role. . . and though the 18-250 is sharp, it's not really close to the FA*300, both lenses wide open.

The Kenko 1.5x SHQ has historically been assumed to be the same TC as the Tamron F 1.4x MC4, with one being a rebadge of the other. I have a Tamron F 1.4x PZ MC4, and it's a very good TC. FYI, this item had a common street price of @ $69 USD for quite a few years before it was discontinued by both Kenko and Tamron a few years ago. In my estimation, the Tamron is a bit better optically than the considerably more expensive Sigma 1.4x APO, but they're so close, I use the Sigma more often because of the difference in build quality.

Since you mentioned the DA*300, I'll mention this: Both the Tamron and Kenko TCs have been available in a "PZ" (Power Zoom) versions. These have the additional electrical contacts that match those used by SDM lenses, but though they allow the functioning of SDM motors, actual compatibility with the SDM focusing system is a bit up in the air, IMO. These TCs were designed before the SDM focusing was introduced by Pentax, and while there's no question that they will supply power to the in-lens motor, my experience with my only SDM lens (DA*50-135) is less than acceptable. The lens hunts lock to lock 3 times then quits, does this again with a reactivation of the AF, then will usually lock on the 3rd try, once the lens is pretty close to focus. This happens under any lighting conditions.

I actually got into a dispute with a member on another forum, where he stated that the DA*300 was absolutely compatible with his Tamron 1.4x, and he questioned my reporting of the performance of my DA*/Tamron combo. In another post on a different thread a month later, he stated that his DA* with the Tamron TC hunted some, but worked well when the focus was close. . . which sounds pretty close to what I said I considered unacceptable. . .

I might as well also mention that all Sigma TCs have a protruding front element to the TC which prevents it from physically fitting any lens that doesn't have a recessed rear lens element. . .

As you might guess from all this, the question of TCs and Pentax is a pretty convoluted matter at this point.

Scott
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Old Sep 7, 2010, 7:22 PM   #6
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thanks for all the great info. Ive been trying to stay away from the sigma TC's, as I really only have one lens that it'd be compatible with. Also, they seem pretty pricey, esp. considering the IQ isnt the best out there.

I think im gonna pick up the pentax AFA,

it blows my mind how that little T.C. can focus a lens with no internal AF mechanism, I guess my knowledge of how lenses are built is pretty slim, Do you pretty much have to hold the outside focus ring still so that it can rotate the lens at the mount, or is there something inside that it catches to obtain this?



thanks again

Last edited by NMRecording; Sep 7, 2010 at 7:33 PM.
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Old Sep 8, 2010, 1:08 AM   #7
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Originally Posted by NMRecording View Post
thanks for all the great info. Ive been trying to stay away from the sigma TC's, as I really only have one lens that it'd be compatible with. Also, they seem pretty pricey, esp. considering the IQ isnt the best out there.

I think im gonna pick up the pentax AFA,

it blows my mind how that little T.C. can focus a lens with no internal AF mechanism, I guess my knowledge of how lenses are built is pretty slim, Do you pretty much have to hold the outside focus ring still so that it can rotate the lens at the mount, or is there something inside that it catches to obtain this?



thanks again
The AFA has glass elements that focus internally, the focus in the lens you use with it stays where you leave it. That's why with anything longer than 50mm you have to get the focus close, there is only so much room for the lenses to travel in the AFA.

John
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Old Sep 8, 2010, 1:10 AM   #8
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Originally Posted by NMRecording View Post
Thanks for the info, jelow1966.

Looks like its either going to be the AFA or Kenko for IQ, if i can find the AFA cheap enough (300ish like I saw one last week) I may get it, otherwise for IQ the Kenko seems to be the next best thing


yeah ive been running circles over which 300-400 lens to get and i really prefer primes, which theres far less options for.

Ive tried a few zooms and the sharpness, coloring, and bokeh of my 200 2.8 is so far unmatched,

also deterring me from the da star 300 is the fact that with a 1.5 TC i can get 300 f4, for the price (and near sharpness depending on IQ degradation ) and with the AFA I could have near af from what ur saying, (though im not sure how the afa is going to turn such a heavy lens, ) for about a thousand dollars less than buyin the da star 300.

Ive looked at some other lens options 200-400, bigma, tamron 135-400, I really dont know what I want cuz I want it all! :-) Im just not sure what to settle on, i think for me right now the best thing would be the TC so I can get an idea of what a nice one does to the lens and then try to pick up longer glass in the future. Seeing very few lenses at 400 faster than 5.6 for pentax is unfortunate and theyre all more money than my car cost, (you can see where my priorities are)

I know theres no such lens out there that fits my needs as itd be free :-D but perhaps a TC will keep me happy till Ive got that kinda money layin around.


Anyone need a kidney?
What length are you after and what is your price range? There are several options in the 300 and 400mm range as well as zooms such as the Sigma 135-400 though having one I can't say I'd recommend it unless you camera has the ability to tweak the focus point as mine front focuses pretty badly.

John
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Old Sep 8, 2010, 11:48 PM   #9
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the price range is hard to say, I tend to buy things when its really a steal.

my 200mm 2.8 zeiss sonnor electric was 21 dollars, which is pretty amazing. I REALLY want the da star 300 because of the IQ, which ill take over length. 400mm would be nice but I havent seen many great options that have equal IQ and are fast as well for under 2 grand. (Im even a tad skepticle of the F/4 maximum on the da* but pics prove to me aperture its still fast enough for BIF) Im not keen on a zoom because Im going to have it pushed to the end the whole time, this is pretty much a birding lens for me. TO me the zoom is just going to degrade the IQ and slow the lens down, add heft etc. and be a waste when I am not going to be using anything under 300mm if its available.

i would definitely buy a decent lens if the price is right but from what I can tell theyre all an arm and a leg so I might as well just get the one I have my eye on, unless theres one out there I missed.
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Old Sep 9, 2010, 1:13 AM   #10
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If i were you I 'd look into the Tamron SP 300/2.8 coupled with the AFA. Would give you a total length or 510mm and a lens that will autofocus. Not sure it would be fast enough for BIF and I don't know enough about the focus system on Pentax DSLRs to know how well they work (Olympus is not good for that so I can get just as good of results with manual focus). You could put together that setup for under a grand but it would be heavy. Personally i think 300mm is too short for serious birding but that's just me. 400-800mm is what I prefer. Then again I don't do much BIF so the extra length is more important to me than the slower speeds, I could see how in your case the speed would be an issue and you're right, there is little in the way of choice in fast 400mm that won't cost as much as a car.

John
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