Vivitar 28mm K mount problem

rupi · 11-30-2010, 02:56 PM

Hi,
I would like some help from you folks with Vivitar k mount lenses.
Just got this 28mm f2 k mount, but it doesn't mount in my K20D. The problem is this piece in the back around the lens that is to big. I compared with other Vivitar 28mm I got, the Close Focus f2.8 (which is very good). See the pictures for the comparison.
I think it is possible to grind/cut the piece so the lens can mount. The questions are: is this f2 lens good enough to be worth the trouble to made the modification? Is that piece of metal really necessary, what is it there for?
(Sorry the bad grammar)
Thanks for any help and advice.

Lowell Goudge · 11-30-2010, 03:21 PM

there are lots of threads on cutting this down to size, or removing it.

there should be several small screws that remove this from the lens mount.

I would remove it then cut it, do not cut or file it while on th elens for risk of scratching the rear element, and also to avoid filling the lens with filings

also note that this lens is prone to sticking aperture blades, due to oil leaking out of the focusing helix grease

RolloR · 12-01-2010, 10:30 PM

I have an M42 version of this lens and even it wont fit well in my k-x + m42 adapter.

Anyway, I grinded that metal part with my Dremel.

The lens is also pretty soft and mine has a lot of oil in the aperture blades and won't stop down past f4.

rupi · 12-02-2010, 04:09 PM

Here it is after the grindind. It works now. The task wasn't so difficult after all.
There is some oil in the blades in my copy too but they still work fine. The problem now is the focus ring is so hard, but I'm afraid I don't have the skills to fix that.

I have to test the lens to see if it is really whorth it.

11-30-2010, 02:56 PM	#1
rupi Junior Member	Vivitar 28mm K mount problem Hi, I would like some help from you folks with Vivitar k mount lenses. Just got this 28mm f2 k mount, but it doesn't mount in my K20D. The problem is this piece in the back around the lens that is to big. I compared with other Vivitar 28mm I got, the Close Focus f2.8 (which is very good). See the pictures for the comparison. I think it is possible to grind/cut the piece so the lens can mount. The questions are: is this f2 lens good enough to be worth the trouble to made the modification? Is that piece of metal really necessary, what is it there for? (Sorry the bad grammar) Thanks for any help and advice.

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11-30-2010, 03:21 PM	#2
Lowell Goudge Pentaxian	there are lots of threads on cutting this down to size, or removing it. there should be several small screws that remove this from the lens mount. I would remove it then cut it, do not cut or file it while on th elens for risk of scratching the rear element, and also to avoid filling the lens with filings also note that this lens is prone to sticking aperture blades, due to oil leaking out of the focusing helix grease

12-01-2010, 10:30 PM	#3
RolloR Senior Member	I have an M42 version of this lens and even it wont fit well in my k-x + m42 adapter. Anyway, I grinded that metal part with my Dremel. The lens is also pretty soft and mine has a lot of oil in the aperture blades and won't stop down past f4.

12-02-2010, 04:09 PM	#4
rupi Junior Member	Here it is after the grindind. It works now. The task wasn't so difficult after all. There is some oil in the blades in my copy too but they still work fine. The problem now is the focus ring is so hard, but I'm afraid I don't have the skills to fix that. I have to test the lens to see if it is really whorth it.