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02-06-2010, 08:52 AM   #1
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A few questions about Vivitar 105mm F2.5

Hey guys,

I recently purchased a Vivitar 105mm F2.5 from Ebay for my K7 and it just arrived. I was testing the lens out and I noticed when the lens is not mounted and i moved around there is a light noise coming from the inside (as if something is loose). This made me wonder what could be causing it. So i compared it to my Pentax M 50mm F2 and it seems like the diaphragm (i dont know if i am calling it right - the notch responsible for the aperture) behaves differently with the Pentax than with the Vivitar. When I change the aperture on the Pentax the diaphragm moves as well while with the Vivitar it does not. Could this be because the mechanism is slightly different (on the Vivitar if you look closely enough you can actually see a spring attached to the diaphragm which is not visible on the Pentax). The aperture ring on the lens feels right works fine as you can see the blades closing down.

Another thing that I observed was that neither the Pentax nor the Vivitar could meter properly when I close the aperture significantly. For example past F16 when I meter using the green button the shutter no longer slows beyond 1.6seconds. Is there a way to change this?

Also when I use the green button with both of the manual lens it seems like there is more noise generated compared to say my kit lens that came with my camera. Is that normal or not? Is there a better way to meter with manual lens? (

Also it seems when i turn on the camera the dust removal is also louder with both lens compared to the kit lens. Is this normal?

Should I be concerned about any of these things or am I just being paranoid? I am pretty new to the digital SLR experience so any comments would be extremely helpful! Thanks in advance!

02-06-2010, 08:59 AM   #2
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A couple of things. First of all, I didn't understand any of your analysis of the "loose" noise you are hearing, but that is just a part of this lens. I was worried when mine arrived from ebay also, but upon reading some posts here, I learned it was normal. It sounds like a little ball floating around. So don't worry about that.

Now, as to the green button questions, you will be pleased to learn that you do not need to use the green button metering with this lens. This is an "A" lens, which means that you should set the aperture on the lens to the "A" position, and you can now use all metering modes on your K7, such as AV, TV, etc. Flash will work properly. It will work just like all of the modern lenses, just without AF.

So be happy you got this wonderful lens, get it set up properly, and enjoy. Let us know if you have any other questions.

Last edited by jeffrey r; 02-07-2010 at 06:41 AM.
02-06-2010, 08:05 PM   #3
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thanks for the reply. looked it up and it appears that a lot of ppl that noticed that particular noise. also thanks for letting me know about the A setting, i had no idea the lens would allow me to do that!
02-06-2010, 09:42 PM   #4
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The extra noise has two causes. Third-party lenses often have a two-part action to move the aperture blades, because the action has to be adaptable to other camera mounts. A Pentax lens doesn't have to be as flexible so the design can be simpler. In a Vivitar, there's more stuff to rattle around.

Also, this is a telephoto macro lens, so the aperture blades are pretty deep into the lens. If you're focusing really close and the lens is fully extended, those blades are about 2" deeper than with your 50mm prime. These long metal arms are what moves the blades:



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