Help with Apo Sironar S washers

[hfsilva]

Hello all. New member and absolute rookie. Just got my ..y-bought 150 5,6 Apo Sironar S. Mint as advertised, but with the lens cells in reversed positions (front in the back and vice versa). While correcting the situation, two very fine metal washers fell from the lens. Where do these go exactly?
Best regards
hfs

[Bob Salomon]

Ether back to the factory in Germany to be put back on the optical bench or back to the seller for a refund.

[Steve Goldstein]

On any Apo-Sironar-S I've ever seen (135mm, 150mm, 180mm, 210mm) the washers have gone between the front cell and the lens. Same for several different focal lengths of Nikkor-SW. Why not put them there and test the lens to see if it meets your performance expectations?

I suspect the manufacturers would want to avoid washers on the rear cell because removing the cell for lensboard mounting increases chance of loss.

[Jim Noel]

On any Apo-Sironar-S I've ever seen (135mm, 150mm, 180mm, 210mm) the washers have gone between the front cell and the lens. Same for several different focal lengths of Nikkor-SW. Why not put them there and test the lens to see if it meets your performance expectations?

I suspect the manufacturers would want to avoid washers on the rear cell because removing the cell for lensboard mounting increases chance of loss.

Don't you mean between the front cell and the shutter?

[karl french]

That's been my experience as well. I've moved two Sinaron (aka Sironar) lenses out of Sinar DB shutters. In both cases the washers were between the front cell and the shutter.

[Steve Goldstein]

Don't you mean between the front cell and the shutter?

Umm, yeah. My fingers are definitely faster than my brain.

[DennisD]

Apo-Sironar -s, 150 mm .
I 've owned 2 lenses of this type both 150mm.

One had 2 shims between the front element and the shutter housing. The other had no shims at all and was fine.

I often wondered whether the 2nd should have had shims as I bought it used. Who knows what the last guy did ! A shim can fall off easily when the lens is dismounted from the shutter body. A careless person might never be the wiser until, one day, he finds a skinny round "washer" lying on the floor. By then, he'd be scratching his head in wonder.

However, I believe Bob Salomon said that the need for shims is determined by the factory after the lenses and shutter are mated. It's a matter of factory testing and "fine tuning". Some lenses may have no shims, while others might have a few.

Bob, please correct me if I mis-stated anything.

[dave_whatever]

I have a sinaron-se which I bought in its original DB shutter, it didn't have any shims. Performs great.

[Bob Salomon]

Apo-Sironar -s, 150 mm .
I 've owned 2 lenses of this type both 150mm.

One had 2 shims between the front element and the shutter housing. The other had no shims at all and was fine.

I often wondered whether the 2nd should have had shims as I bought it used. Who knows what the last guy did ! A shim can fall off easily when the lens is dismounted from the shutter body. A careless person might never be the wiser until, one day, he finds a skinny round "washer" lying on the floor. By then, he'd be scratching his head in wonder.

However, I believe Bob Salomon said that the need for shims is determined by the factory after the lenses and shutter are mated. It's a matter of factory testing and "fine tuning". Some lenses may have no shims, while others might have a few.

Bob, please correct me if I mis-stated anything.

That is correct

[Leigh]

The shims compensate for slight variation in the actual dimensions of the parts, particularly the shutter thickness (front to back).

All manufactured items have tolerances for all dimensions.
As those tolerances get tighter (more precise dimensions), the cost of making the part goes up substantially.

It's cheaper to make a part with tight but not excessively tight dimensional tolerances, then use washers to accommodate the variations during assembly.

- Leigh