Tamron SP 70-210mm F/3.5 19AH: won't focus at infinity
TJ
I have a Tamron SP 70-210mm F/3.5 Model 19AH: with the Adaptall 2 for
Canon EOS on a 450D body.
It is wonderfully sharp - but won't focus sharply on infinity - like
the moon.
What to do?
Thanks
TJ
No One
"TJ" <ra...@hotmail.com> wrote in message
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"TJ" <ra...@hotmail.com> wrote in message
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mount. That's why Tamron dropped them fairly early on.They often wouldn't
allow infinity focus, Canon had the same issue with their own FD-EOS
adapter.
Handy Andy
If you don't have access to a precision machine-shop to refigure the faces
of the adapter by making it a couple millimeters thinner, you can also
replace the negative achromat in it with something of slightly higher
negative power. A couple extra negative-mm's focal-length would do it. Or
you could instead add a similar very-low power negative achromat to the
front of any lenses you put on the adapter, effectively achieving the same
effect. The cost of putting the fix on the front of the lens, as opposed to
replacing the achromat in the adapter, would be rather high. Well figured
achromats jump in price astronomically as diameter is increased. Especially
negative achromats of the size needed to put in front of a lens because
that size would most certainly be a specialty low-production-run item.
If it was me? I'd probably disassemble the adapter and see which
internal-facing flanges or collars could be ground thinner, then probably
do this by hand on a flat surface with grinding compounds. A couple
millimeters wouldn't take too long to remove and be the simpler and less
costly solution. Though, I would first dig in all my optics "parts boxes"
to see if I had a negative achromat of just the right diameter and
focal-length to replace the lens element first. It would be extreme pure
luck if I had one just the right specs but stranger things have happened
from my optics "parts boxes".
On second thought, you *might* get away with inserting a very low-power
crown or flint (inexpensive) negative single-element lens (not achromat)
just in front of or behind the internal achromat lens element. Whichever
side has the most available working space. There might be enough
refraction-match where you could get away with this and not impart
excessive CA or softness. I had this happen once on a fish-eye lens that
wasn't quite matching my camera's FOV with a full-frame circle, top and
bottom of the circle ever-so-slightly truncated. By inserting a low-power
negative flint element behind this lens I not only obtained a full-circle
FOV, but it also surprisingly cleaned up a very slight bit of CA that was
inherent in the original design. Win-win just by experimenting with some
"junk lenses" that I had laying around in my surplus parts boxes.
TJ
access to a precision machine shop! so will investigate
possibilities.
Alternatively, I'm waiting for another Adaptall 2 for EOS to come from
Hong Kong, to fit a Tamron lens I bought a friend. I will try that
adapter on my 19AH lens and see if the non-factory takeoff 'corrects'
the no-infinity focus defect. If it does, I'll buy another. If not,
I'll try grinding a few mm off.
TJ
Darrell A. Larose
surfaces (what engine tuners call blueprinting). I think it may be easier to
adjust the infinity stop of the lens. I don't recall if there was an
adjustment screw undre the rubber hand grip on the zoom-focus ring or a cam
in the mechanism, but almost all manual focus lenses had some method to
adjust infinity.
Bill Graham
Someone should make a minus diopter filter, just like my eyeglasses.....I am
slightly nearsighted.....My eyes won't focus on the moon either. (infinity)
so my glasses are reducing lenses. If you can find a filter which is a
reducing (concave) lens, then it would fix your problem.....It would
probably only need to be like -.5 diopters or less.......
TJ
> It probably doesn't need a "few mm" it may only need a polish on all
> surfaces (what engine tuners call blueprinting). I think it may be easier to
> adjust the infinity stop of the lens. I don't recall if there was an
> adjustment screw undre the rubber hand grip on the zoom-focus ring or a cam
> in the mechanism, but almost all manual focus lenses had some method to
> adjust infinity.
Thanks for your advice, Darrell.
'Polishing' sounds like a prudent way to start.
If that fails there probably is an infinity adjust screw somewhere.
But unless I can find photos of the insides, or a plan, so I know
exactly where it is, I really hesitate to open the lens and tinker
around. The lens is a cracker. Would be stupid to ruin it. The moon I
can live without.
In fact, come to think of it. How many times have you ever used a tele
lens (longer than a portrait) lens on subjects at infinity? For long
'scenery' shots there's usually just too much heat haze/pollution to
get a sharp image anyway.
TJ
Darrell A. Larose
lens
http://forum.manualfocus.org/viewtopic.php?id=12559
his website is;
http://www.snaar.co.uk/lenses
He may have some tips.
Darrell Larose
Ottawa
TJ
> I saw that this fellow rebuilt and adjusted the infinity stop on the same
> lens
>
> http://forum.manualfocus.org/viewtopic.php?id=12559
>
> his website is;http://www.snaar.co.uk/lenses
>
> He may have some tips.
I'm sure he has. But are my hands steady enough and my eyes sharp
enough to take advantage of it ??? !! That is the question. I'll try
the polishing first, I think.
His pix are inspirational, however, in so much that they prove that
great optics, are still great optics, even if they are old, and manual
focus. I use a series of Leica/Elmarit R lenses via an adapter on the
Canon 450D body. I bought an (virtually unused) 3000 EOS 35mm body for
beer money, just to have a the option of shooting film on a
lightweight back as the lenses weigh a ton.
TJ
David Nebenzahl
>> I saw that this fellow rebuilt and adjusted the infinity stop on the same
>> lens
>>
>> http://forum.manualfocus.org/viewtopic.php?id=12559
>>
>> his website is;http://www.snaar.co.uk/lenses
>>
>> He may have some tips.
>
> I'm sure he has. But are my hands steady enough and my eyes sharp
> enough to take advantage of it ??? !! That is the question. I'll try
> the polishing first, I think.
I wouldn't do that. After all, why take a chance on physically altering
your lens, possibly damaging it, when a simple adjustment might solve
your problem?
Another source of information is Rick Oleson
(http://members.tripod.com/rick_oleson/index-18.html). I don't think he
has specific information on working on your lens (I haven't searched the
site recently, so it's possible he does), but I've contacted him in the
past with repair questions and he's been happy to help. He's quite
knowledgable and can be trusted to give reliable information.
--
Found--the gene that causes belief in genetic determinism
TJ
> > I'm sure he has. But are my hands steady enough and my eyes sharp
> > enough to take advantage of it ??? !! That is the question. I'll try
> > the polishing first, I think.
>
> I wouldn't do that. After all, why take a chance on physically altering
> your lens, possibly damaging it, when a simple adjustment might solve
> your problem?
No need for alarm, David. It's not the lens I would 'polish' , only
the Adaptall 2 ring. So the optics are moved slightly closer to the
film plane. The ring costs about $15 or less in Hong Kong.
TJ
Wolfgang Weisselberg
> I know a few people had issues with the Maxxum and the EOS Tamron Adaptall 2
> mount. That's why Tamron dropped them fairly early on.They often wouldn't
> allow infinity focus, Canon had the same issue with their own FD-EOS
> adapter.
Canon's FD-EOS adapter had no infinity focus problems. After all,
it was designed as a 1.25x (IIRC) teleconverter (extender) to
circumvent the problem (and it only worked with the long lenses).
Cheap FD-EOS converters (without optics) have infinity problems,
and cheap ones with optics have quality problems.
-Wolfgang
nospam
Weisselberg <ozcv...@sneakemail.com> wrote:
canon offered two adapters, one that was a weak teleconverter (and with
limited availability) and one that had no optics and was much cheaper,
and that one *did* result in no infinity focus.
Robert Coe
:
: > It probably doesn't need a "few mm" it may only need a polish on all
Funny you should ask. Earlier this week my wife and I both used telephoto
lenses to photograph the surf at the New Jersey shore. It was a cool day, and
the wind was blowing fairly hard, so haze was not a factor. The pictures came
out fine.
Bob
TJ
> : In fact, come to think of it. How many times have you ever used a tele
> : lens (longer than a portrait) lens on subjects at infinity? For long
> : 'scenery' shots there's usually just too much heat haze/pollution to
> : get a sharp image anyway.
>
> Funny you should ask. Earlier this week my wife and I both used telephoto
> lenses to photograph the surf at the New Jersey shore. It was a cool day, and
> the wind was blowing fairly hard, so haze was not a factor. The pictures came
> out fine.
>
> Bob
Bob, I have a feeling that depending on what tele lens you're using
(and the internal screw setting) , FAILURE to focus on 'infinity' can
be a long way off !! Landscape territory. Or inner space like the
moon.
The Tamron is sharp to a mile, and maybe, given optimum environmental
conditions, to a few more: which again is landscape photography.
What I realise I need, is to change the screen on the 450D - to a
split screen for easier focusing with manual lenses. That will make it
easier to see when it fails to focus.
TJ
Robert Coe
:
: > : In fact, come to think of it. How many times have you ever used a tele
: > : lens (longer than a portrait) lens on subjects at infinity? �For long
: > : 'scenery' shots there's usually just too much heat haze/pollution to
: > : get a sharp image anyway.
: >
: > Funny you should ask. Earlier this week my wife and I both used telephoto
: > lenses to photograph the surf at the New Jersey shore. It was a cool day,
: > and the wind was blowing fairly hard, so haze was not a factor. The
: > pictures came out fine.
: >
: > Bob
:
: Bob, I have a feeling that depending on what tele lens you're using
: (and the internal screw setting) , FAILURE to focus on 'infinity' can
: be a long way off !! Landscape territory. Or inner space like the
: moon.
Modern AF lenses don't appear to have an infinity stop, presumably so that the
high-speed focus mechanism won't bang up against it. So you're probably facing
an issue that will become increasingly rare with time.
: The Tamron is sharp to a mile, and maybe, given optimum environmental
: conditions, to a few more: which again is landscape photography.
We were on the beach at Ocean City, and some of our shots included the skyline
of Atlantic City, which is ten or fifteen miles away. That's infinity for any
lens this side of Mt Wilson.
: What I realise I need, is to change the screen on the 450D - to a
: split screen for easier focusing with manual lenses. That will make it
: easier to see when it fails to focus.
Good luck with that. I don't think Canon makes a split image for a 450D.
KatzEye does, I think; but if the 450D uses the same viewfinder as the 400D
(and again I think it does), you won't be able to see the focus points in the
viewfinder. Rachael Katz told me they've tried countless workarounds for that
problem, but without success. I bought a KatzEye screen for my 400D anyway;
but since I also have a 50D, I'm willing to pretty much treat the 400D as a
manual-focus camera.
Incidentally, the greatest value in an aftermarket screen is that you can have
grid lines etched on it. (KatzEye offers about a dozen variations.) For
architecture and seascapes, I couldn't function without a grid.
Bob
TJ
skyline
of Atlantic City, which is ten or fifteen miles away. That's infinity
for any
lens this side of Mt Wilson.
> Bob
Ah so! That is a sharp lens.
But you could not see the 'snake eyes' on the dice in AC, no !!!
I found a screen in HK for $20 delivered.
TJ
Paul Furman
I have had to do a little grinding on an adapter like that. I went too
far, which isn't a big problem: some tele lenses are built that way
intentionally to allow for heat/cold changes, it just requires more care
focusing.
--
Paul Furman
www.edgehill.net
www.baynatives.com
all google groups messages filtered due to spam
Robert Coe
: We were on the beach at Ocean City, and some of our shots included the
: skyline of Atlantic City, which is ten or fifteen miles away. That's
: infinity for any lens this side of Mt Wilson.
:
: > Bob
:
: Ah so! That is a sharp lens.
I was using a Sigma 50-150mm constant-aperture f/2.8; my wife was using a
Canon 28-135mm f/3.5-5.6 IS. Both are pretty good lenses.
: But you could not see the 'snake eyes' on the dice in AC, no !!!
No, but we could see the windows in the buildings. ;^)
: I found a screen in HK for $20 delivered.
Not bad. Let us know how you make out installing it and whether you can still
see the focus points.
Bob
TJ
still
see the focus points. "
Bob
THAT'S what I'm worried about !!! Don't hold your breath. I may just
chicken out and drop the whole idea: If it ain't broke, don't fix it.
TJ
PS RE: resolving power.
This was on 100ASA film, mind you, with a Leica/Elmarit 90mm F2.8
lens. You could clearly see 1" diameter guy wires, 3 miles away. Good
optics is a truly wonderful thing. Imagine what they have in spy
satellites.