In article , PeterN
wrote:


what filter did they put in the camera, if any?

none. The IR blocking filter was removed. (I think)

and you didn't use a blocking filter on the lens??

Nope. AFAIK they left in the AA filter.
The camera is an old Coolpix. They told me they were just removing the
IR filter. I thnk they must have adjusted the focus.
A local guy did it. They charged me $70, which is a lot less than the
Internet guys charge. I have red that some use a filter in addition to
the conversion, but then you are talking about long exposure.

that's not how it works.

You could be right. All I know is that I went to the repair guy and told
him what I wanted. He gave me what I wanted.

that's nice but it doesn't sound like you understand what is actually
needed.

removing the infrared cut filter turns it into a full spectrum camera,
which covers visible light *and* infrared. you now need an infrared
pass filter on the lens to cut visible light if you want infrared. what
you're getting now is a normal response that has infrared added to it.

Interesting, but immaterial to me.

it's very material because it affects the results.

I'm simply trying to get a certain look. If I had to get a filter made
from nail polish, it wouldn't matter.
This was one of the first I did.

unless you know what look you would get from 'a filter made from nail
polish', how would you know if it's going to advance you toward your
goal or not?

you will only get long exposures if you leave the infrared cut filter
in place *and* use a visible light cut filter on the lens, which is
basically removing everything. a little infrared leaks through, thus
the long exposures.


I've read that.

but apparently you have not processed that information, because what
you say indicates you didn't understand a word of what you read.

however, you had it modified so there is no long exposure.

what cutoff to use depends on what effect you want.

yup!

but that's not what you say elsewhere.

if it's in the
visible light range, you get quasi-normal photos with surrealistic
colours. if it's in the infrared range, you get pure infrared, which
can be b/w if it's high enough.

the advantage of a full spectrum camera is that you can decide later
what cutoff to use. the drawback is that you have a filter on the lens.


a p&s is ideal for infrared because of live view. with an slr, putting
an infrared pass filter on the lens (cutting visible light) means you
can't see anything through the lens unless you activate live view.

Yup.
Also the focus needs to be adjusted to use autofocus.

not necessarily.

that depends on the camera and its autofocus system.

for an slr, where the focusing is a separate module, it does need to be
adjusted because there are two independent optical paths and changing
one *requires* the other to changed accordingly.

for a p&s where the focusing is done on the sensor, it does not
necessarily need to be adjusted because the focusing is done on the
sensor and the lens will focus it either way.

however, in some p&s cameras, removal of the infrared cut filter can
affect the optical path such that the lens can't obtain focus at all
distances, in which case it either needs to be adjusted or a
replacement filter (clear or specific cutoff) is installed.

Try the
RAW IR I left on the sight. It gives the results I like.

you may like it, but it's not really infrared.

I don't care if the look is called fitymigick.
I know it's not pure infrared. That's why I labeled the thread: "near IR."

you're missing the point and all digital infrared is near infrared.
that's all the sensors can do.

a camera with the infrared filter removed is a normal camera that
*also* can see infrared. what you will get is mostly normal photos with
screwy colours due to the infrared contamination. these cameras are
usually called full spectrum cameras.

to get infrared, you need to *cut* the visible light and how much to
cut depends what effect you want. a cutoff around 850nm is going to
give the most dramatic effects since it's *only* seeing infrared. a
cutoff around 590nm will give surrealistic colours since it's picking
up visible red as well as infrared. a cutoff around 720nm is a good
compromise for most situations.

you can also use a hot mirror to cut infrared and pass visible light,
which make it respond as it did before it was modified. in other words,
it's back to being a normal camera.

To me the important part is that it gives the look I wanted, plus the
ability to add faux color. For other effects I can put a lens filter on
that camera, or on one of my others.

if it gives you what you want that's fine, but based on what you wrote
about infrared photography, you don't really know how to get what you
want and are mostly going with whatever you get.