[pure-silver] Re: old rollei over exposing
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Fri, 18 Feb 2005 12:51:41 -0800
----- Original Message -----
From: "Shannon Stoney" <sstoney@xxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, February 18, 2005 8:23 AM
Subject: [pure-silver] Re: old rollei over exposing
> >I agree with Mr. Knoppow,
>>
>>Though both of the failed mainsprings I've actually seen
>>were broken as a
>>result of a crack started from a spot of surface
>>corrosion.
>>
>>I have seen several synchro-compurs on old Rolleiflex MX's
>>that were just
>>plain worn out. The first symptom is usually a failure to
>>cock the shutter
>>when the board is extended outward. The wear on all the
>>cocking mechanism
>>parts stacks up to the point where there isn't enough
>>travel left to quite
>>cock the shutter. Generally the shutter would still
>>function if you could
>>cock it manually, but even then it feels pretty rough
>>while the shutter is
>>being cocked. Theres a steel toothed ring that bears on
>>the aluminum
>>housing, and that's one of the main wear points. These
>>shutters are on
>>either heavily used cameras, or have a lot of dirt in
>>them.
>
>
> thanks for all the advice about this. I called the guy who
> repaired
> my rollei, and he said that he had checked it after
> adjustment and
> the shutter was working fine. I am beginning to believe
> that the
> reason I think the film is overexposed is that Ilford's
> HP5+ roll
> film is actually a very fast film, and shadow densities
> fall in the
> 0.7 range by design (by Ilford). I THINK my exposures are
> too dense,
> by inspection and by densitometer measurement, but Ilford
> wants them
> that way, so fine. Printing times will just be longer.
>
> By the way, you might find it amusing that Eudora thought
> that your
> message, quoted above, contained language that some might
> find
> offensive. ;-) Can't think what it might be:
> "corrosion"?
> "crack"? "rough"? In any event, there were two hot
> peppers next to
> it.
>
> --shannon
>
Well, checking with the guy is not going to tell you if
the shutter is accurate, you must measure it in some way.
Ilford claims they do not use the ISO method of measuring
speed. The ISO method effectively specifies a contrast
index. This value of CI is fairly high, suitable for contact
printing and diffusion enlarging, perhaps even a bit high
for that. Ilford rates the film when it is developed for a
contrast index midway between that required for diffusion
enlargers and that for condenser enlargers. The results you
get should still be full range negatives. If measured by the
ISO method the film will probably be a little faster than
the Ilford numbers but probably by no more than half a stop.
If the negatives are over exposed (dense but of normal
contrast) the most likely culprit is the shutter unless the
stop linkage is somehow not working right. This last can be
checked easily by seeing if the iris is fully oped when the
indicator is at the maximum stop and not some other point.
This can happen if the camera is butched badly in repair. My
vote is the shutter.
See if someone in your area has a shutter tester and will
check the shutter. The Calumet tester I mentioned is nice to
have but is too expensive for a single test.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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