Canon 24mm f2 ghost image
dte...@freenet.vcu.edu
This problem may have already been discussed, but I couldn't find
anything about it by searching Dejanews, etc.
I just bought a used FD 24mm f2 lens that seemed to be in really
good shape. When I started using it I noticed an objectionable
ghost image whenever I pointed the lens at a bright object.
(such as lightbulb). The image is very distinct and moves w/the
direction of panning.
Stopping down doesn't seem to help. Do all wide angles do this, or
is it an artifact created by the camera's pentaprism?
The front and back coatings look like they are in good shape
(the purple, blue, green and pink colors all visible, etc.).
Should I return this lens???
thanks
Dave
Bob Neuman
In article <4n6hj5$2...@doc.zippo.com>, dte...@freenet.vcu.edu says...
>I just bought a used FD 24mm f2 lens that seemed to be in really
>good shape. When I started using it I noticed an objectionable
>ghost image whenever I pointed the lens at a bright object.
>(such as lightbulb). The image is very distinct and moves w/the
>direction of panning.
>Stopping down doesn't seem to help. Do all wide angles do this, or
>is it an artifact created by the camera's pentaprism?
>The front and back coatings look like they are in good shape
>(the purple, blue, green and pink colors all visible, etc.).
>Should I return this lens???
This is a tough test for any lens, and most lenses will show
spots, ghosts, aperture reflections, etc. when aimed at a bare
lightbulb, particularly if the background is dark. To see if
an effect is caused by the lens or the viewing system, hold
the camera/lens still while moving your eye relative to the
eyepiece - VF effects will move, but lens effects will not,
if the VF optics are the cause. I would try the lens in normal
picture-taking situations (including some difficult ones, like
interior photos with windows included [or just outside] the
angle-of-view) to see if the lens is suitable for your use
before returning it. All lenses are optical compromises,
and it is easy to find tests that would make any lens look
bad. It is useful to know the faults of your lenses so that
you can work around them (or return the lens, if the fault[s]
makes the lens often difficult to work with), but it is not
useful to avoid lenses that have relatively minor faults, or
faults that show up only under unusual conditions - otherwise,
you would have no lenses to shoot with! ;-(
(Note that the above advice is given by an
unrepentant perfectionist "lensaholic"........;-)
Hope This Helps
Lee Choong Hsen
dte...@freenet.vcu.edu wrote:
: I just bought a used FD 24mm f2 lens that seemed to be in really
: good shape. When I started using it I noticed an objectionable
: ghost image whenever I pointed the lens at a bright object.
: (such as lightbulb). The image is very distinct and moves w/the
: direction of panning.
This lens has quite a bit of glass. Have you tried either:
1. throwing away that cheap filter on the front or
replacing it with a good HMC filter
2. using an appropriate lenshood.
From what you describe, it appears to be a flare problem.
Doug Alspaugh
>> When I started using it I noticed an objectionable
ghost image whenever I pointed the lens at a bright object. <<
I believe you are seeing what is known as flare. It is not uncommon and
is more predominant with a wide angle lens. You will usually see
reflections of this kind if you point a lens directly at a bright light.
If the light is entering from an angle you can use your hand to shade
the front element and prevent the flaring. It is wise to get the lens
hood if you can find one for it. This will take the place of your hand
for shade.
Doug
David Jacobson
In article <4n6hj5$2...@doc.zippo.com>, <dte...@freenet.vcu.edu> wrote:
>This problem may have already been discussed, but I couldn't find
>anything about it by searching Dejanews, etc.
>
>ghost image whenever I pointed the lens at a bright object.
>direction of panning.
>is it an artifact created by the camera's pentaprism?
>The front and back coatings look like they are in good shape
>(the purple, blue, green and pink colors all visible, etc.).
>Should I return this lens???
>
>Dave
The problem might be from a filter on the lens rather than the lens
itself. Here is the test. Unscrew the filter at tad and wobble it
while looking through the viewfinder. If the ghosts move the filter
is at fault. Replace it with a good multicoated filter.
You'd be amazed how many ghosts are tracable to filters.
However the problem is usually restricted to the center part when you
stop down. This tends to disprove my hypothesis, because you say
stopping down does not help. By the way, when you say that stopping
down does not help, exactly what do you mean? Please tell us exactly
the experiment you did.
-- David Jacobson
Miratel
>This problem may have already been discussed, but I couldn't find
>anything about it by searching Dejanews, etc.
>
>I just bought a used FD 24mm f2 lens that seemed to be in really
>good shape. When I started using it I noticed an objectionable
>ghost image whenever I pointed the lens at a bright object.
>(such as lightbulb). The image is very distinct and moves w/the
>direction of panning.
>Stopping down doesn't seem to help. Do all wide angles do this, or
>is it an artifact created by the camera's pentaprism?
>The front and back coatings look like they are in good shape
>(the purple, blue, green and pink colors all visible, etc.).
>Should I return this lens???
The wider the angle of the lens, the more it is susceptible to lens
flare when you point the lens towards a bright light source whether
the lens is coated or not.
What you are experiencing is a classic symptom of a direct bright light
source striking a glass surface, a small fraction of it is reflected
and scattered and causes lens flare. This flaring is similar to the glare
you experience when you try to look at the object with a bright light
shining in your eyes. Although most current lens of some brand names are
coated with inorganic salts and rare earth elements to reduce the flaring,
other old lens are not.
I believe some Canon FD lenses are not coated but some are.
However, you said that you pointed the lens to a bright object like
a light bulb. If that is so, you're going to get lens flare no matter
how good the coating you've got on your lens or whatever multi-coated
filters that you try to put on like others have suggested. Coating can't
eliminate flaring when you point the lens towards the sun or light bulb.
You can reduce lens flare while shooting towards the sun or light bulb by
putting on a lens shade (or lens hood).
A lens shade MUST BE DESIGNED for your Canon 24mm lens. Don't put any lens
hood that you wish. A lens hood designed for a 50mm lens when mounted
on your 24mm lens will definitely produce vignetting (black round corners)
on your pictures.
You must get a lens hood specifically designed for your lens. Keep the
lens hood on at all times and you can keep or eliminate flaring all
together.
Hope this helps..
Bryan Putnam
fba4...@leonis.nus.sg (Lee Choong Hsen) writes:
>dte...@freenet.vcu.edu wrote:
>: I just bought a used FD 24mm f2 lens that seemed to be in really
>: good shape. When I started using it I noticed an objectionable
>: ghost image whenever I pointed the lens at a bright object.
>: (such as lightbulb). The image is very distinct and moves w/the
>: direction of panning.
>This lens has quite a bit of glass. Have you tried either:
>1. throwing away that cheap filter on the front or
> replacing it with a good HMC filter
>2. using an appropriate lenshood.
> From what you describe, it appears to be a flare problem.
I've noticed that if I aim my "AF Nikkor 35-80mm f4-5.6 D" at a
streetlamp (at night) I get a ghost image such that the midpoint
of the line connecting the lamp and the ghost image is at the
center of the viewfinder. Removing the UV filter (Tiffen Haze 1)
almost eliminates the problem, but I can still detect it.
It appears that it might be a good idea to remove filters when
doing night photography of a bright object against a dark
background, as other posters have already noted.
Bryan
Miratel
>This problem may have already been discussed, but I couldn't find
>anything about it by searching Dejanews, etc.
>
>I just bought a used FD 24mm f2 lens that seemed to be in really
>good shape. When I started using it I noticed an objectionable
>ghost image whenever I pointed the lens at a bright object.
>(such as lightbulb). The image is very distinct and moves w/the
>direction of panning.
lens hood on at all times and you can reduce or eliminate flaring all
together.
Hope this helps..
Magnus Ostvall
Well I'd say you do'n have to get the right shade -
I made a 28mm lens shade out of a 85 simply by sawing off most of the
front part. Sure - I don't have cutouts at the corners, but it's
better than to get a new one.
--
Magnus Östvall qpk...@ryepk.ericsson.se
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
http://www.pt.hk-r.se/~mpt95mos/photo (public access)
Vaughan Bromfield
In article <4n7l6u$l...@nuscc.nus.sg> Lee Choong Hsen,
fba4...@leonis.nus.sg writes:
>dte...@freenet.vcu.edu wrote:
>
>: I just bought a used FD 24mm f2 lens that seemed to be in really
>: good shape. When I started using it I noticed an objectionable
>: ghost image whenever I pointed the lens at a bright object.
>: (such as lightbulb). The image is very distinct and moves w/the
>: direction of panning.
>
As you are looking through the viewfinder, perhaps the problem is flare
in the pentaprism rather than a problem with the lens.
My OM1 displays a bit of distortion in the viewfinder, but produces
lovely, straight lines on the negs! Perhaps your camera is similar...
Vaughan