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Old Feb 7, 2006, 2:56 PM   #1
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hi, does anyone have experience with using older K mount tubes with the pentax kit lens (18-55) on the ist dl/ds/etc.?? i'm guessing they would work fine with older lenses (limited to manual focus) but not sure about the newer ones.

i was at one time friendly with a K-1000 and some nice Pentax prime lenses and used extension tubes a lot but soldeverythingon e-bay to finance a Fuji s602z. the 602's been great but with the drop in dslr prices it's going to be hard not to go back to a "real" camera. thanks for any help on this. eric
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Old Feb 7, 2006, 3:31 PM   #2
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I was wondering about something similar, as I was playing with some old K mount lenses and accessories. One of the items is a teleconverter thatfits between the lens and the camera. Is that the same sort of thing that you mean when you say "extension tubes"?

I figure there is no way I could use it with the kit lens because there's no way to set the aperture (since the kit lens doesn't have an aperture ring like my old manual lenses do), and there's no electronic contact on the teleconverter to get the camera to communicate with the lens.

I triedthis old teleconverterjust a bit with one of my manual lenses, and found it was really soft - itdidn'tquite focus. Is that because of: a) back teleconverters don't quite work right with the digital cameras even using a manual lens; b) this particular one might be messed up (considering it is around 25 years old and has been in a closet for 10 of them); or c) "operator head-space and timing" (in other words, I didn't get it focused right).

Thanks for any help!
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Old Feb 7, 2006, 5:22 PM   #3
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no, what i'm talking about are empty tubes that physically move the lens away from the film or sensor plane. the ones i had were "auto" tubes, meaning the lens stayed wide open to focus and compose, only stopping down to the chosen aperture when the shutter was pressed. what you have (i think) has glass in it and multiplies the length of your lens (by 1.4x or 2x etc.) they can work for macro because the lens still focusses at the same min. distance but the image is larger. i had one of those also and used it some but it tended to lower image quality as well as losing an appreciable amount of light. the extension tubes really were my favorite option for close ups (although you lose light with them also).

however you've identified more clearly what i'm concerned about; older pentax lenses will work with the istd's with some possible restrictions like manual focus and maybe manual exposure, but what happens when you place old accessories like ext. tubes or teleconverters between a moderndigital lens and the camera body?

as far as focussing with a teleconverter,if you can take sharp pictures without it you probably don't need to worry about your "operator headspace andtiming":-)!remember though that it magnifies your image and increases the need for a tripod.
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Old Feb 7, 2006, 10:42 PM   #4
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My guess would it would turn your new lens into an old lens

you would loose the electrical connections

and have to use it like an old manual lens

one thing i found with a 2x converter i have,

it fits the K1000 but doesnt seem to want to fit the ds

i am not sure why and i am not going to force it

you maybe able to answer a question i was wondering about though

if i take the glass out of a converter does that make it an extension tube





my place - http://www.johndolphin.net/photos
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Old Feb 7, 2006, 11:33 PM   #5
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Thanks for the clarification - while I used to own an ME, I'd only just scratched the surface of photography and hadn't discovered extension tubes before.

I do have a 2x teleconverter, and I have no problem with using it on the DS, other than I thought the focus wasn't right. Guess I'll have to try it again on a different subject (the one I chose was a flower that seems to come out sort-of fuzzy no matter which lens you use on it) and see if I can get it to work better- I'm starting to get more reliable with manual focusing again. It's not like I really need it, I've been finding the 80-200 plenty for what I've been taking recently.

Since the tube would make the lens a manual lens, and since it doesn't have any way of setting a different aperture, I would assume that you would be always shooting with a wide open aperture?
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Old Feb 8, 2006, 8:02 AM   #6
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Was wondering about the extension tubes with my DS kit lens. Couldn't get it to work with Sigma 18-50 AF kit lens, but the old Pentax SMC manual lens works fine in aperture priority mode. I'll post a close up later.
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Old Feb 8, 2006, 8:52 AM   #7
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Regarding 2x teleconverters (slightly off-topic from extension tubes) I have an old Sakar 2x in K mount, and it functions o.k. with my manual M-series lenses on my DS2...but photos are very soft and flarey. Almost like a fog filter. I got one nice shot of my son with it, taking advantage of the soft-focus effect with my SMCP-M 50mm f1.4. Other than that, though, it's pretty useless.

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Old Feb 9, 2006, 10:44 AM   #8
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gumnut, i'd guess you could make an ext. tube that way but then your converter would be "down the tube(s)" P>}

beachboy2, your scenario with the sigma is what i'm wondering about. i'm thinking about getting a dl w/kit lens and a sigma 70-300 and don't want to have to buy (and carry) another lens if i ever decide to get some ext. tubes. maybe the 70-300 will have all the macro i need..........? i'd be happy with manual focus and exposure for close-ups but if the new lenses don't work at all that's another thing altogether!

thanks all, eric
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Old Feb 9, 2006, 11:21 AM   #9
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So I tried, and this is what I found. Maybe not surprising, but still good newsI guess.

The stuff I tried in a couple of combinations:
  • Pentax DA 16-45 lens, [/*]
  • Vivitar Auto Extension Tube. "Auto" meansthat information about the aperture setting you have made with the aperture ring is mechanically transfered from lens to body for exposure metering, and from body to lens at exposure so that the aperture is "automatically" stopped down to the chosen f-stop. There are no electrical contacts that allows electronic communication between lens and body. You can use extension tubes of various lengths to shorten the nearest focussingdistance for your lens, allowing you to take extreme close-ups. There is no glass in an extension tube, its just ametal barrel with bayonet fits in both ends. [/*]
  • Pentax A 2X Rear Converter S, doubling the focal lenth of your lens. It has the same electrical contacts as the A-series manual Pentax lenses. And of course some glass.[/*]
Well, what happened?

The DA lens does work with the extension tube! But – there is no way to stop down,there is only full aperture (4,0) and no f-stop information in theviewfinder.But there is information on over/underexposure! And you can changeshutter speed the normal way in manual mode.This means that you actually can use a DA lens with old extension tubes, as long as you are not concerned about depth-of-field. (You get very little of that at full aperture)

With the tele-converter the DA lens worked just like any manual "A"-lens, the only thing that didn't work was auto-focus!

I guess this gives us something to boast about, when we compare backwards compatibility with our N/C friends!

By the way, are there any extension tubes available that have the electrical contacts? And have anyone tried the Pentax 1,7X AF Converter? It's a lot cheaper than the non-AF converters in the Pentax line, even though it gives you AF also with non-AF lenses! Optical quality? (All of the Pentax converters can still be bought new, and the cheapest "A" (manual) costs about 2,5 times as much as the AF here in Sweden)

Kjell


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