Used lens, is it broken?

[dreamofgilgamesh]

Dear Group, my 1st post ever. I recently re-discoverd my old Chinon CE4 in the loft, years old (like me) Anyways, i cleaned it up and rediscovered my interest in it.

I decided to but a 2nd hand lens for an upcoming holiday. I bought a Cosina Cosinon 200mm pentax k mount lens from ebay. Heres the ebay link so you can see it,,,beware of text wrap!

http://cgi.ebay.co.uk/ws/eBayISAPI.d...=STRK:MEWNX:IT

Cosmeticaly it looks great, but i'm not sure it right, as i have very very limited knowledge.

The mount looks the same as my 50mm and 135mm lenses. It has a little tab on the mount the same as my other lenses and mounts the same.
However, on my other lenses when you move the tab the iris opens and closes, as it does when i use the depth of field preview button.
On my new (old) lens i can feel spring pressure when moving the tab but no sign of an iris! There is also no depth of field preview either.
If i mount the lens, and partly depress the shutter button i can see a LED display of the shutter speed. As i alter the aperture the speed alters.
I'm totally confused, have i bought a different non standard type of lens, or is it a dud?

Thanks very much chaps

Martin

[daft_biker]

Welcome Martin. I'm not familiar at all with the lens or mount you describe but the language in the description sets alarm bells ringing for me - described as a "fixed zoom lense" or something along those lines. The seller doesn't appear to know much about the lens so I wouldn't be surprised if it was sold broken because they don't know how it's supposed to work.

Hopefully someone that is familiar with this or similar lenses will be along shortly and can give better advice.

[Fen]

but the language in the description sets alarm bells ringing for me - described as a "fixed zoom lense" or something along those lines. The seller doesn't appear to know much about the lens so I wouldn't be surprised if it was sold broken because they don't know how it's supposed to work.

Anyone who puts an advert up for a 'lense' and can't even spell 'lens' would be best avoided in my opinion!

[dreamofgilgamesh]

Thanks Mr Biker, fair point indeed, i may have fallen into the something for nothing pit.
The lens is a standard Pentax K bayonet, and probably my terminology isn't spot on. What i was attempting to describe is a little "tang" or "lever" that protrudes from the lens mount. I believe that when mounted it must marry up to a corresponding fitting in the camera body which allows the iris to be opened (or closed). Anyways, when moving the litle lever, nothing happens.
I dare say you're right though, maybe it's broken.

Thanks

Martin

[AlexMonro]

I've just had a play with some of my K mount lenses. It sounds like the lever you're talking about is the diaphragm stop-down lever that holds the diaphragm fully open for focusing until you actually take the picture. It's spring loaded to close the diaphragm down to the pre-set f-stop, and if you push it gently sideways, the diaphragm should open all the way (unless it's already set to maximum aperture, of course! ) You should see it move as you adjust the aperture ring.

If none of this works (and it's not because it's set to max aperture), then I'm afraid it does look like your lens is broken.

[TimF]

There's one way to find out without taking it to a service guy. Stick a roll of film in the camera and take a series of pictures of an average scene with the lens using all apertures. If they all come out properly exposed it's probably OK (use slide film as what you get is what you see).