Rodenstock is it a 90 6.8 or 5.6

[ross_schuler2]

I just purchased a Rodenstock 90mm 6.8 Grandagon. Can anyone tell me why the f stop on the lense starts at 5.6. Is it a 5.6 or a 6.8. If I meter a landscape at f22 do I use f22 on the lense. As you can tell I am new to LF. Ross

[dhananjay_n]

The lens might have been adapted into another shutter but they

ommitted to change the iris scale. The quickest check would be to

measure the diameter of the iris wide-open and divide focal length by

this number and see if you get 5.6 or 6.8. You should get reasonably

close - f/5.6 is more than 16mm while f/6.8 is about 13 mm. A

difference of almost 3mm should be possible to measure with a scale

or preferably a pair of calipers. Cheers, DJ.

[jim_galli4]

If it says on the lens that it's f6.8, that is what it is regardless

of the scale on the shutter. Look into the glass and when you start

to close down the iris when do you see the blades for the first time?

Between "5.6" and 8? If so it's probably fine. I think the

Rodenstock Grandagon's came in either 4.5 or 6.8, but not f5.6.

[bob_salomon2]

If you bought a remounted shutter the cells may also be out of

position to each other. Rodenstock original shutters frequently

have a small Rodenstock decal on the side of the shutter. If in

doubt Rodenstock service in the US is 973 808-9626. They will

reopen Wed.

[jennifer_waak]

The original poster wrote to me off board b/c I have to same lens. He

said that the shutter says Sinar on it and goes from 5.6 to 64. Since

Sinar has lenses with shutters that are Copal 0 (as the Rodenstock is)

and f5.6 to f64 I'm just assuming that it had been re-shuttered in a

previous life.

 

<p>

 

So, assuming the poster has no recourse back to the seller or finds it

to be more trouble that it is worth, what is the best bet? Send it to

SK Grimes for a new iris to be engraved? I don't know if the buyer has

recourse or not, so I'm throwing this last part out as a hypothetical.

[s.k. grimes inc]

The iris scale on the shutter does not match the lens. The shutter

may have been replaced/exchanged for a different one and the original

scales may not have been compatible with the replacement shutter.

New shutters are supplied without iris scales. It's expected that

the user will take the original scales from the old shutter (along

with any spacers associated with the lens) and install them to the

new shutter. There are variations between old/new models of the

shutters. The shutters are all accurately made and, as a practical

matter can be interchanged. Its expected that attention be paid to

keep with the lens elements any spacers (they look like thin washers)

which may have been installed at the factory.

 

<p>

 

See: <a href="http://www.skgrimes.com/iris/index.htm"> my page about

engraving iris scales </a> for more about replacement iris scales.

As a practical matter <i>f</>-6.8 is not drastically different from

<i>f</i>-5.6 and the lens/shutter may be useable as is, although you

may notice some inaccuracy in the exposure similar to the innacuracy

from errors in shutter speed.

[ross_schuler2]

Problem resolved The person I purchased the lense from put on the

wrong shutter. Correct shutter is on the way Thanks for all the

information Regards Ross

[bob_salomon2]

"Problem resolved "

 

<p>

 

Probably not. This lens needs to be checked for proper spacing

in the shutter by a qualified and experienced technician.

You can't simply swap shutters on wa lenses so casually and

expect to have factory spec performance.

[bob_salomon2]

"Problem resolved "

 

<p>

 

Probably not. This lens needs to be checked for proper spacing

in the shutter by a qualified and experienced technician.

You can't simply swap shutters on wa lenses so casually and

expect to have factory spec performance.

[jennifer_waak1]

</I>Fixing the HTML.