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Old Oct 13, 2007, 4:12 AM   #1
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Hi Pentax friends (for some reason, every time i come back to this forum, I feel like im coming "home":love

I took a trip back to Canada recently and got my old SLR and equipment out of storage, so I'm now ready to see what i can and can't use on my Pentax K100D.

So here is what I'm looking at specifically - I'd like to attach my Sigma 70-210mm zoom/telephoto lens. So what i figure is that i need a M42 screw lens to K-mount adaptor.

I found this online: M42 screw lens adaptor

but the wording on the add has me second-guessing - it says its to use a new lens with an old camera, whereas I want to use an old lens with a new camera. Stupid question - is the adaptor reversible? Is that what i want shown there in that ad?

2nd question: the lens looks to be in great shape, having been stored in its cushy case all these years. I put it on the old praktika and looks good. The only thing is, it sounds like theres something loose inside - as if theres sand in side - when i move it, theres a sound like there's sand inside. What is this?

Ok, 3rd question - is my external flash from my old SLR of any good use? What situations would you use an external top mounted flash, vs the one thats built into the pentax?

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Old Oct 13, 2007, 5:19 AM   #2
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Hi Michelle!

The adaptor is for use with screw mount lenses and K mount bodies - so far it's OK for your needs. But! - it looks like one of those adaptors that adds a small distance between the lens and the body. Therefore the lens will not be possible to focus at infinity. The original Pentax adaptors and some off brand ones don't have the flange between the body and lens, and let you use the lens at its full capacity. I wouldn't buy this one, I'd look for an original Pentax or similar adaptor instead. I think they still can be bought new from Pentax (at a bit higher price than 5 EUR though).

I also have a lens that sounds like there is sand inside it when I turn the focus ring. Thats because there's sand inside it.:-)

The advantage of a top mounted flash is that it is more powerful and can be used at longer distances. Probably your flash is fully manual, you'll have to experiment a bit to get the best setting of time and aperture to get good results. Another advantage is that the flash works at a bigger distance from the lens axis, thus avoiding that the lens itself shadows the lower part of the picture. Maybe your flash even has a swivel head, so it can be bounced against the ceiling or a wall to obtain softer shadows in the picture.

If it's not an original Pentax flash, wait for someone more knowledgeable to answer. There is some issue with voltage that might fry your camera if you use the wrong flash.

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Old Oct 13, 2007, 7:01 AM   #3
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Regarding your flash question; go to this link:


and scroll down to find the make and model of your flash. The table will show if the flash is safe to use with a Canon EOS camera with a simple yes or no. The next column over shows the "trigger voltage". Rule of thumb has been not to use a flash with trigger voltage over 6v. That may or may not be true for the Pentax DSLR cameras. I've never seen any conclusive facts on the max trigger voltage for the Pentax cameras. Some of the older flashes had trigger voltages of over 100v. You don't want to use that on your DSLR. I'm not making any recommendation at all here, just be careful of using an old flash on your DSLR. I made the mistake of using on old Vivitar 2600 flash on my Kodak DC4800 through the flash sync port. It worked for about a dozen flashes and then fried the flash sync port circuitry on my camera. The camera still worked, but not with a flash attached to the sync port. I was lucky I didn't ruin the camera.

You should try to find out what the max trigger voltage allowance is for your Pentax DSLR before attempting to use anything except the Pentax recommendedflashes in your user manual. If you can't find your flash listed on the table above, I wouldn't even try it. You won't hurt the flash, it's the camera at risk.

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Old Oct 13, 2007, 7:46 AM   #4
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THIS will work for the adapter. notice, it has the same diameter bottom and top ring. if they differ then usually you will loose infinity focus.

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