> While cleaning the final lens on my Tl-120,Do you mean "the last of the three lenses", or "the last
> the lens, theDo you mean the objective (the outer-most lens element), or
> ocular, slipped out of place.
> optic and its sealing o-ring held in place by the "final"This sounds like the outer retaining ring.
> metal portion.
> Any advice as to how to effect a repair?First, don't do anything until you have an action plan. If
On Aug 31, 2012, at 12:17 PM, John Thurston <juneau3d@thurstons.us> wrote:
On 8/31/2012 1:07 AM, David Richardson wrote:
> While cleaning the final lens on my Tl-120,
Do you mean "the last of the three lenses", or "the last
glass element in one of the lenses"?
If the former, is it the viewing lens or one of the taking
lenses?
> the lens, the
> ocular, slipped out of place.
Do you mean the objective (the outer-most lens element), or
one of the inner elements?
? One can see the wayward
> optic and its sealing o-ring held in place by the "final"
> metal portion.
This sounds like the outer retaining ring.
Can you either post a picture of the problem lens, or shoot
me a couple of pictures off-list?
> Any advice as to how to effect a repair?
First, don't do anything until you have an action plan. If
you start taking things apart, you may end up creating more
problems than you have right now. Try specifically to avoid
rotating anything. If the outer element is the one which is
loose, try to make indicator marks so you can maintain its
orientation with the other elements in the lens.
Second, better identify for us the problem lens and location
of the problem. The more information you can share, the
better we can help.
Third, I have spare lenses for the TL120-1. Depending on
what the problem is, it may be better to replace than
repair. If the problem is in a taking lens, you may need to
pay a professional to recement or realign the lens after you
get it apart/together. If the problem is in the viewing
lens, alignment of the elements is probably not as critical.
It may make sens to replace a lens than try to repair it.
Fourth, if it is the taking lens and the damage is severe,
and you are willing to live without the internal meter and
ground-glass finder, you could just take the lens off and
rig a bright-line finder for the camera.
Fifth, depending on the extent of the damage, it may be best
to replace the whole lens cluster. Like I say, I have a full
set of spare lenses. You could also take the opportunity to
turn your TL120-1 into a TL120-55 :) Take off the focusing
75mm lenses and install fixed-focus 55mm lenses.
I'm happy to help. Post more information here, or send it
off-list to me.
--
John Thurston
Juneau, Alaska
> 55mm lenses sound [interesting?] is this a mod that can be done relatively easily assuming there is a source for the lenses!It isn't a _complicated_ mod, but it isn't something you
> The spreadsheet shows that at f/22, with the camera focused at 3.4Look in the archives:
> meters (11.2 feet), the resulting circles of confusion can support a
> goal of 5.71 lp/mm for subject spaces that fit these distance ranges:
>
> f/22.6 --- 6 feet to Infinity
> f/19.0 --- 7 feet to 68 feet
> f/16.0 --- 7 feet to 38 feet
> f/13.5 --- 7 feet to 24 feet
> f/11.3 --- 8 feet to 22 feet
> f/9.5 --- 8 feet to 18 feet
> f/8.0 --- 9 feet to 17.5 feet
>
> Remember that each of these distance ranges can be expanded by
> lowering the resolution goal, but if John shoots only subjects that
> fit these distance ranges for the apertures shown, I'm certain he cab
> bring home some razor sharp wide angle stereo views.
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