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Digital IR photography -- what camera???

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Anonymous
December 10, 2004 12:26:34 AM

Archived from groups: rec.photo.digital, rec.photo.misc (More info?)

Greetings:

I just read an article concerning digital IR photography. It said that
"most" digital cameras are not sensitive in the IR range...but the
Minolta Dimage 7 was. I own the newer Dimage 7Hi. Anyone know if this
version is suitable for IR photography?

Thanks!
Anonymous
December 10, 2004 12:57:35 AM

Archived from groups: rec.photo.digital (More info?)

I'd be careful. I had seen some images from the DImage 7 and I bought
the 7i. Spent the money for the filter then found out that they had
placed a filter in the middle of the frame - I had a large circle that
was differently exposed in every picture.

Best of luck,
Leith


On 9 Dec 2004 21:26:34 -0800, voice_of_reason@australia.edu wrote:

>Greetings:
>
>I just read an article concerning digital IR photography. It said that
>"most" digital cameras are not sensitive in the IR range...but the
>Minolta Dimage 7 was. I own the newer Dimage 7Hi. Anyone know if this
>version is suitable for IR photography?
>
>Thanks!

--------------------------------
December 10, 2004 4:10:23 AM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

Easy test, take the digital camera and turn on your preview window. Point
your TV remote at the lens, fire teh TV remote, if you see the diode of the
remote blinking on the preview screen then that camera can do IR work. I
have done IR with my Pentax * ist D and with several Olympus cameras like
the C-2000Z and the C-4000. I have seen good IR with the Nikon D70 and D100


<voice_of_reason@australia.edu> wrote in message
news:1102656394.820059.293200@z14g2000cwz.googlegroups.com...
> Greetings:
>
> I just read an article concerning digital IR photography. It said that
> "most" digital cameras are not sensitive in the IR range...but the
> Minolta Dimage 7 was. I own the newer Dimage 7Hi. Anyone know if this
> version is suitable for IR photography?
>
> Thanks!
>
Related resources
Anonymous
December 10, 2004 8:30:37 AM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

voice_of_reason@australia.edu wrote in news:1102656394.820059.293200
@z14g2000cwz.googlegroups.com:

> Greetings:
>
> I just read an article concerning digital IR photography. It said that
> "most" digital cameras are not sensitive in the IR range...but the
> Minolta Dimage 7 was. I own the newer Dimage 7Hi. Anyone know if this
> version is suitable for IR photography?

You should be able to find out by looking in your manual.
Or at the very least, checking the web-page.


--
http://www.neopets.com/refer.phtml?username=moosespet
Anonymous
December 10, 2004 11:37:23 AM

Archived from groups: rec.photo.digital, rec.photo.misc (More info?)

Hi and thanks for your response.

In fact, I did check the manual before I decied to post. I saw nothing
that referenced the wavelength sensitivity of the CCD.
Thanks for the suggestion, though.
December 10, 2004 6:38:48 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

voice_of_reason@australia.edu wrote:
> Greetings:
>
> I just read an article concerning digital IR photography. It said that
> "most" digital cameras are not sensitive in the IR range...but the
> Minolta Dimage 7 was. I own the newer Dimage 7Hi. Anyone know if this
> version is suitable for IR photography?
>
> Thanks!
>

The 7Hi is no good for IR photography. I have it and have tried it with
Wratten 87, 87C, and 89B filters. The 7Hi has a big non-IR spot in the
middle of each image. There is no way around it.

Clyde
Anonymous
December 12, 2004 3:59:08 PM

Archived from groups: rec.photo.digital, rec.photo.misc (More info?)

Gisle Hannemyr wrote:

> That's wrong. /All/ digital images are to some extent IR-sensitive,
> but some much more than others.
>

Ahhh, then that explains the results I got when trying the experiment
outline in a previous message. I tested my two digital cameras against
the TV remote as suggested.....and discovered that they BOTH were able
to register the flashing of IR diode....even though one (the Cannon
powershot) wasn't listed as being at all "IR-capable". I was confused
(I tried to post a response asking for more advice....but google was
down. Hope this one makes it!!)

So now I'm left to wonder "how much" my Dimage 7Hi is sensitive to IR.

If I get any useful data, I'll try to pass it along for you.
Thanks for your response!
Anonymous
December 12, 2004 4:46:00 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

voice_of_reason@australia.edu wrote: in news:1102656394.820059.293200
> I just read an article concerning digital IR photography. It said
> that "most" digital cameras are not sensitive in the IR range..

That's wrong. /All/ digital images are to some extent IR-sensitive,
but some much more than others.

> but the Minolta Dimage 7 was. I own the newer Dimage 7Hi. Anyone
> know if this version is suitable for IR photography?

I've maintain a page where I try to log ir-sensitivity data for as
many digital cameras as possible. You'll find it on:

http://heim.ifi.uio.no/~gisle/photo/ir.html

It confirms that the older Minolta Dimage 7 was quite IR-sensitive.

I don't have any data (yet) for the newer 7i and 7Hi - but from what
I've heard, they are much less sensitive for IR than the original
Dimage 7.

(Also: All you IR.shooters - please help build the IR-sensitivity
database. All I need is a pointer to an image with full EXIF and
the name of the filter used. You can follow-up here, email me, or
use the report form that is part of my IR-subsite.)
--
- gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
========================================================================
When you say you live in the real world, which one are you referring to?
Anonymous
December 12, 2004 5:03:34 PM

Archived from groups: rec.photo.digital (More info?)

Leith Cassone <LCassone@usa.net> writes:
> I'd be careful. I had seen some images from the DImage 7 and I
> bought the 7i. Spent the money for the filter then found out that
> they had placed a filter in the middle of the frame - I had a large
> circle that was differently exposed in every picture.

That is know as a "hot spot" and is fairly common in IR-photography.
It is caused by the way lens coatings respond to near-IR light.

If you use a dSLR, you'll discover that you get a got spot with
some lenses, but can avoid it with others. I maintain a list of
"good" and "bad" lenses for IR here:

http://heim.ifi.uio.no/~gisle/photo/ir.html#lenses

New additions are welcome.
--
- gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
========================================================================
When you say you live in the real world, which one are you referring to?
Anonymous
December 12, 2004 5:11:27 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

Gisle Hannemyr wrote:
[]
> It confirms that the older Minolta Dimage 7 was quite IR-sensitive.

By "IR" here, you are referring to the range of the spectrum just outside
red. (I mention this because there is also near-IR at about 1.6um, mid-IR
at about 4um, and far-IR at 10um).

Is there any indication that such cameras are slightly sensitive to the
higher reflectivity caused in vegetation by the presence of chlorophyll?
I.e. would vegetation look a little redder with these cameras than it
should?

David
Anonymous
December 12, 2004 7:03:11 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

"David J Taylor" <david-taylor@invalid.com> writes:
> Gisle Hannemyr wrote:

>> It confirms that the older Minolta Dimage 7 was quite IR-sensitive.

> By "IR" here, you are referring to the range of the spectrum just
> outside red. (I mention this because there is also near-IR at about
> 1.6um, mid-IR at about 4um, and far-IR at 10um).

Yes (all this is spelled out on my webpage). Just to make it clear:
I am talking about the spectrum between 720 nm and 950 nm (or 0.72 um
and 0.95 um to use your units). That's the spectrum people capture
when they stick a visible light blocking filter (usually called an
«IR-filter») such as Hoya R72 or Wratten 89B on their camera.


> Is there any indication that such cameras are slightly sensitive to
> the higher reflectivity caused in vegetation by the presence of
> chlorophyll? I.e. would vegetation look a little redder with these
> cameras than it should?

Not that I know about. I myself use two of the cameras that are
most sensitive in this particular spectrum for both regular and
IR photography - the Oly 2020Z and Kodak DCS 460 - and I've
never noticed any colour cast on vegetation during normal
shooting. I use a hot mirror (i.e. an IR-blocking filter) when
not trying to capture IR on the Kodak, but that is to keep noise
in the /blue/ channel down (don't ask why - I've just established
through experience that it helps). The Oly seems to do fine without
a hot mirror.
--
- gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
========================================================================
When you say you live in the real world, which one are you referring to?
Anonymous
December 12, 2004 7:03:12 PM

Archived from groups: rec.photo.digital (More info?)

Gisle Hannemyr wrote:
> "David J Taylor" <david-taylor@invalid.com> writes:
>> Gisle Hannemyr wrote:
>
>>> It confirms that the older Minolta Dimage 7 was quite IR-sensitive.
>
>> By "IR" here, you are referring to the range of the spectrum just
>> outside red. (I mention this because there is also near-IR at about
>> 1.6um, mid-IR at about 4um, and far-IR at 10um).
>
> Yes (all this is spelled out on my webpage). Just to make it clear:
> I am talking about the spectrum between 720 nm and 950 nm (or 0.72 um
> and 0.95 um to use your units). That's the spectrum people capture
> when they stick a visible light blocking filter (usually called an
> «IR-filter») such as Hoya R72 or Wratten 89B on their camera.

I use um just because I also work a lot in the mid and far-IR. We tend to
call anything less than 2 um "visible" and greater than 3.5 um "thermal"
really distinguishing as to whether a cooled detector is required....

>> Is there any indication that such cameras are slightly sensitive to
>> the higher reflectivity caused in vegetation by the presence of
>> chlorophyll? I.e. would vegetation look a little redder with these
>> cameras than it should?
>
> Not that I know about. I myself use two of the cameras that are
> most sensitive in this particular spectrum for both regular and
> IR photography - the Oly 2020Z and Kodak DCS 460 - and I've
> never noticed any colour cast on vegetation during normal
> shooting. I use a hot mirror (i.e. an IR-blocking filter) when
> not trying to capture IR on the Kodak, but that is to keep noise
> in the /blue/ channel down (don't ask why - I've just established
> through experience that it helps). The Oly seems to do fine without
> a hot mirror.

Thanks for that. I mentioned earlier that UV could cause problems with
correct colour rendering on some cameras - I hadn't heard of IR causing
the same problems, but neither had I asked an "IR sensitive" person!

Cheers,
David
December 12, 2004 11:28:22 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

"Gisle Hannemyr" <gisle+njus@ifi.uio.no> wrote
>
> I use a hot mirror (i.e. an IR-blocking filter) when
> not trying to capture IR on the Kodak, but that is to keep noise
> in the /blue/ channel down (don't ask why - I've just established
> through experience that it helps). The Oly seems to do fine without
> a hot mirror.

Remember that all the light sensors on a digital camera are the same. It's
the Bayer filter that screens for the red/blue/green colors. Those color
filters work great for visible light, but they are sometimes transparent to
infrared light. Depending on the filter, you could end up with any of the
red/blue/green filters passing more or less infrared. It is quite normal for
the "blue" filter to be quite poor at filtering infrared (even though it's
great at filtering visible red).

That's why you may end up with a blue cast in your infrared pictures. Or if
the internal IR blocking filter isn't much good, you could end up with too
much blue in your regular images. It's the Bayer filter that isn't filtering
the infrared evenly. This is quite normal. The solution when shooting IR is
to convert to black & white. I guess the internal IR blocking filter isn't
much good on the Kodak, which explains why it's regular pictures may be
affected by infrared. In most digital camera, the blocking filter removes at
least 7 stops of light, which effectively removes all the IR from the
exposure latitude.
Anonymous
December 13, 2004 12:05:37 PM

Archived from groups: rec.photo.digital, rec.photo.misc (More info?)

Clyde wrote:

> The 7Hi is IR sensitive in a donut shape around the outside. It is IR

> filtered in a circle in the middle. Therefore, it is useless for IR
> photography - as I was trying to say before.
>
> The Minolta Dimage 7Hi has a hot filter in the middle that leaves
that
> circle. You will get nice IR around that circle, but nothing usable
or
> recognizable inside the circle. Therefore, don't even bother to buy
> filters for it.

Yes, I saw your original post. That is another reason why I was
perplexed when I was able to see the IR diode flashing on my TV remote.

I thought I might have just happened to have the TV remote flashing
from an angle that by-passed the filtered region. So, I went back and
repeated the experiement checking all the quadrants and dead center. I
see the IR diode just fine. Then I thought maybe there might be some
difference between viewing thru the viewfinder and what actually gets
recorded, so I put the 7Hi in movie mode and made a video as I passed
the TV remote back and forth across the field of view. I figured that
as it passed thru the center, it would stop showing the diode flash (as
you had said). But nope, even on playback, I see the flashing
consistently. (I tried to do the same experiement taking an actual
picture, but I couldn't get a convient set-up to allow me to get a
photo of the remote.)

So now the question becomes: Why can I see the IR diode in my TV remote
when the 7Hi supposedly is not sensitive to IR across the center of the
filed of view?

Is it possible that the freq of the IR diode is within a range the CCD
can see, but more "natural" IR that one sees outside is filtered out?
Anybody have any ideas?
Anonymous
December 13, 2004 1:01:54 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

"Bones" <drbonesUnderscore@hotmail.com> writes:
> "Gisle Hannemyr" <gisle+njus@ifi.uio.no> wrote

>> I use a hot mirror (i.e. an IR-blocking filter) when not trying to
>> capture IR on the Kodak, but that is to keep noise in the /blue/
>> channel down (don't ask why - I've just established through
>> experience that it helps).

> Remember that all the light sensors on a digital camera are the
> same. It's the Bayer filter that screens for the red/blue/green
> colors. Those color filters work great for visible light, but they
> are sometimes transparent to infrared light. Depending on the
> filter, you could end up with any of the red/blue/green filters
> passing more or less infrared. It is quite normal for the "blue"
> filter to be quite poor at filtering infrared (even though it's
> great at filtering visible red).
>
> That's why you may end up with a blue cast in your infrared
> pictures. Or if the internal IR blocking filter isn't much good, you
> could end up with too much blue in your regular images. It's the
> Bayer filter that isn't filtering the infrared evenly. This is quite
> normal. The solution when shooting IR is to convert to black &
> white. I guess the internal IR blocking filter isn't much good on
> the Kodak, which explains why it's regular pictures may be affected
> by infrared. In most digital camera, the blocking filter removes at
> least 7 stops of light, which effectively removes all the IR from
> the exposure latitude.

There is no internal IR-blocking filter in the Kodak DCS 460.

Thanks for the explanation of why the blue channel is affected
by IR without the hot mirror - that makes sense.
--
- gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
========================================================================
When you say you live in the real world, which one are you referring to?
December 13, 2004 7:02:58 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

voice_of_reason@australia.edu wrote:
> Gisle Hannemyr wrote:
>
>
>>That's wrong. /All/ digital images are to some extent IR-sensitive,
>>but some much more than others.
>>
>
>
> Ahhh, then that explains the results I got when trying the experiment
> outline in a previous message. I tested my two digital cameras against
> the TV remote as suggested.....and discovered that they BOTH were able
> to register the flashing of IR diode....even though one (the Cannon
> powershot) wasn't listed as being at all "IR-capable". I was confused
> (I tried to post a response asking for more advice....but google was
> down. Hope this one makes it!!)
>
> So now I'm left to wonder "how much" my Dimage 7Hi is sensitive to IR.
>
> If I get any useful data, I'll try to pass it along for you.
> Thanks for your response!
>

The 7Hi is IR sensitive in a donut shape around the outside. It is IR
filtered in a circle in the middle. Therefore, it is useless for IR
photography - as I was trying to say before.

I have tried mine with Kodak Wratten filters 87, 87C, and 89B. Those are
as good of IR filters as you can get. They pretty much cover the
spectrum for IR photography.

The Minolta Dimage 7Hi has a hot filter in the middle that leaves that
circle. You will get nice IR around that circle, but nothing usable or
recognizable inside the circle. Therefore, don't even bother to buy
filters for it.

My old Canon A50 does IR very well. My newer Canon SD10 gets nothing
with the 87 and 87C filters. It will record a very faint image with the
89B filter. Even screwed up tight in Photoshop, it really isn't
workable. So, basically the SD10 is not IR capable.

Clyde
Anonymous
December 14, 2004 8:41:17 AM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

Clyde <lughclyde@attbi.comedy> writes:

> The 7Hi is IR sensitive in a donut shape around the outside. It is
> IR filtered in a circle in the middle. Therefore, it is useless for
> IR photography - as I was trying to say before.

I don't know why you experienced this, but this person has a gallery
of infrared photos taken with the Minolta Dimage 7Hi:

http://www.primaveraphoto.com/infrared/cemetery.php

They all have a very obvious hot spot, but nothing that can't be
fixed with Photoshop or PSP.

(Btw. nothing that is posted through Googlegroups makes it to the
news server I use - so I only see stuff posted through Google if
someone quotes it in a follow-up.)
--
- gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
========================================================================
When you say you live in the real world, which one are you referring to?
Anonymous
December 14, 2004 12:36:13 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

THis was done with the D70

http://www.dpchallenge.com/image.php?IMAGE_ID=126114


--
Michael Brown
Melbourne Australia
www.photo.net/photos/mlbrown

"Gisle Hannemyr" <gisle+njus@ifi.uio.no> wrote in message
news:q5brcxcx02.fsf@kaksi.ifi.uio.no...
> Clyde <lughclyde@attbi.comedy> writes:
>
> > The 7Hi is IR sensitive in a donut shape around the outside. It is
> > IR filtered in a circle in the middle. Therefore, it is useless for
> > IR photography - as I was trying to say before.
>
> I don't know why you experienced this, but this person has a gallery
> of infrared photos taken with the Minolta Dimage 7Hi:
>
> http://www.primaveraphoto.com/infrared/cemetery.php
>
> They all have a very obvious hot spot, but nothing that can't be
> fixed with Photoshop or PSP.
>
> (Btw. nothing that is posted through Googlegroups makes it to the
> news server I use - so I only see stuff posted through Google if
> someone quotes it in a follow-up.)
> --
> - gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
> ========================================================================
> When you say you live in the real world, which one are you referring to?
Anonymous
December 14, 2004 1:06:48 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

Bones <drbonesUnderscore@hotmail.com> wrote:

>I guess the internal IR blocking filter isn't
>much good on the Kodak, which explains why it's regular pictures may be
>affected by infrared. In most digital camera, the blocking filter removes at
>least 7 stops of light, which effectively removes all the IR from the
>exposure latitude.

I recall a website a while back on using video cameras for IR
(specifically, in the way of those 'X-RAY SPECS' everyone
fantasized about in comic books as kids). They supplied the
appropriate visual-spectrum blocking filters and gave details
on how to remove the IR-blocking in camera.

--
Ken Tough
December 14, 2004 7:10:39 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

Gisle Hannemyr wrote:
> Clyde <lughclyde@attbi.comedy> writes:
>
>
>>The 7Hi is IR sensitive in a donut shape around the outside. It is
>>IR filtered in a circle in the middle. Therefore, it is useless for
>>IR photography - as I was trying to say before.
>
>
> I don't know why you experienced this, but this person has a gallery
> of infrared photos taken with the Minolta Dimage 7Hi:
>
> http://www.primaveraphoto.com/infrared/cemetery.php
>
> They all have a very obvious hot spot, but nothing that can't be
> fixed with Photoshop or PSP.
>
> (Btw. nothing that is posted through Googlegroups makes it to the
> news server I use - so I only see stuff posted through Google if
> someone quotes it in a follow-up.)

Wow. That's isn't anything like what I get. My center circle is
basically a fuzzy gray spot in the middle of my picture. There is no
detail recoverable in it.

One possibility is that Minolta changed the specs of the filter during
the productions of the 7Hi. However, that is less likely than...

I'm beginning to wonder if the 7Hi is IR sensitive through the center
filter at the very nearest IR frequencies. The Wratten 87, 87C, and 89B
are completely opaque to visible light. i.e. They only let IR through.

The pictures on this web site don't seem to be full IR. The sky isn't
completely black and the grass isn't fully white. I've also seen fuzzier
white trees. (Mostly with my filters and Kodak HIE film.) Without
knowing what filter was used, it looks like it was letting in some
visible light. Therefore, it may have been letting in IR waves that were
closer to visible light than my Wratten filters were.

Therefore, the 7Hi may be workable with the right filter for very near
IR. I would like to know what filter that is. I am also retracting my
statement on the IR abilities of the 7Hi, based on new evidence.

All this would fit with voice_of_reason's findings on the TV remote
showing in the 7Hi. Some IR is getting through that center filter. Now
we need to find out what IR filter is letting that happen.

Clyde
Anonymous
December 14, 2004 9:42:28 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

Gisle Hannemyr wrote:
> Clyde <lughclyde@attbi.comedy> writes:
>
>
>>The 7Hi is IR sensitive in a donut shape around the outside. It is
>>IR filtered in a circle in the middle. Therefore, it is useless for
>>IR photography - as I was trying to say before.
>
>
> I don't know why you experienced this, but this person has a gallery
> of infrared photos taken with the Minolta Dimage 7Hi:
>
> http://www.primaveraphoto.com/infrared/cemetery.php
>
> They all have a very obvious hot spot, but nothing that can't be
> fixed with Photoshop or PSP.
>
<snip>

It looks more like it over-exposes in the middle, or doesn't focus
properly and produces a fuzzier lighter patch in the middle of the image.

I have a Dimage 7i and have made IR photos that have a light fuzzy patch
in the middle of the shot similar to the ones in the gallery.

Perhaps the lens can't focus IR properly across the whole frame?
Anonymous
December 15, 2004 9:22:46 AM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

dj_nme <dj_nme@hotmail.com> writes:
> Gisle Hannemyr wrote:

>> this person has a gallery
>> of infrared photos taken with the Minolta Dimage 7Hi:
>> http://www.primaveraphoto.com/infrared/cemetery.php
>> They all have a very obvious hot spot, but nothing that can't be
>> fixed with Photoshop or PSP.

> It looks more like it over-exposes in the middle,

Believe me, it is a classic infrared hot-spot and is caused by the
lens' coatings. It is not overexposure, but a very characteristic
fuzzy lightening effect caused by out-of-focus reflections inside
the lens.

> Perhaps the lens can't focus IR properly across the whole frame?

I would suggest you read up on IR photography.

There is also a focus shift with IR (you need to short focus for
things to be in-focus), but that affcts the whole frame.
In some of his examples, he fails to compensate for this, but the
most pronounced effect in this gallery is the hot-spots, which are
circular and affects only the center.
--
- gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
========================================================================
When you say you live in the real world, which one are you referring to?
Anonymous
December 15, 2004 9:37:32 AM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

Clyde <lughclyde@attbi.comedy> writes:
> Gisle Hannemyr wrote:
>> Clyde <lughclyde@attbi.comedy> writes:

>>> The 7Hi is IR sensitive in a donut shape around the outside. It is
>>> IR filtered in a circle in the middle. Therefore, it is useless
>>> for IR photography - as I was trying to say before.

>> I don't know why you experienced this, but this person has a
>> gallery of infrared photos taken with the Minolta Dimage 7Hi:
>> http://www.primaveraphoto.com/infrared/cemetery.php
>> They all have a very obvious hot spot, but nothing that can't be
>> fixed with Photoshop or PSP.

> Wow. That's isn't anything like what I get. My center circle is
> basically a fuzzy gray spot in the middle of my picture. There is no
> detail recoverable in it.
>
> One possibility is that Minolta changed the specs of the filter
> during the productions of the 7Hi. However, that is less likely
> than...
>
> I'm beginning to wonder if the 7Hi is IR sensitive through the
> center filter at the very nearest IR frequencies. The Wratten 87,
> 87C, and 89B are completely opaque to visible light. i.e. They
> only let IR through.

These are very high up in the spectrum - the lightest of them, the
Wratten 87, has a cut-off point of 795 nm, and the Wratten 87B is at
930 nm. These are filters that will only work with with the most
infrared sensitive cameras.

I suggest you get a Wratten 89B or Hoya R72 (both 720 nm) and give
the 7Hi a new chance. The Heliopan RG715 may also work well.

> The pictures on this web site don't seem to be full IR. The sky
> isn't completely black and the grass isn't fully white. I've also
> seen fuzzier white trees. (Mostly with my filters and Kodak HIE
> film.) Without knowing what filter was used, it looks like it was
> letting in some visible light.

He doesn't tell us what he has been using - but my guess, based upon
the look of the sky and grass you mention, is that these are Hoya R72
shots that has not been processed beyond desaturation. If he'd used
the gradient tool to fix the hot spot, and tweaked the curves, they
would have much more of the radiant foliage most people associate
with infrared.
--
- gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
========================================================================
When you say you live in the real world, which one are you referring to?
Anonymous
December 15, 2004 10:31:01 AM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

Clyde <lughclyde@attbi.comedy> writes:
> Wow. That's isn't anything like what I get. My center circle is
> basically a fuzzy gray spot in the middle of my picture. There is no
> detail recoverable in it.

You could not be so kind and mail me one of these shots, and give me
the permission to publish on my "about infrared" web page? I want to
illustrate the "hot spot" phenomenon - and this sounds like a good
candidate.
--
- gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
========================================================================
When you say you live in the real world, which one are you referring to?
December 15, 2004 6:03:16 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

Gisle Hannemyr wrote:
> Clyde <lughclyde@attbi.comedy> writes:
>
>>Gisle Hannemyr wrote:
>>
>>>Clyde <lughclyde@attbi.comedy> writes:
>
>
>>>>The 7Hi is IR sensitive in a donut shape around the outside. It is
>>>>IR filtered in a circle in the middle. Therefore, it is useless
>>>>for IR photography - as I was trying to say before.
>
>
>>>I don't know why you experienced this, but this person has a
>>>gallery of infrared photos taken with the Minolta Dimage 7Hi:
>>> http://www.primaveraphoto.com/infrared/cemetery.php
>>>They all have a very obvious hot spot, but nothing that can't be
>>>fixed with Photoshop or PSP.
>
>
>>Wow. That's isn't anything like what I get. My center circle is
>>basically a fuzzy gray spot in the middle of my picture. There is no
>>detail recoverable in it.
>>
>>One possibility is that Minolta changed the specs of the filter
>>during the productions of the 7Hi. However, that is less likely
>>than...
>>
>>I'm beginning to wonder if the 7Hi is IR sensitive through the
>>center filter at the very nearest IR frequencies. The Wratten 87,
>>87C, and 89B are completely opaque to visible light. i.e. They
>>only let IR through.
>
>
> These are very high up in the spectrum - the lightest of them, the
> Wratten 87, has a cut-off point of 795 nm, and the Wratten 87B is at
> 930 nm. These are filters that will only work with with the most
> infrared sensitive cameras.
>
> I suggest you get a Wratten 89B or Hoya R72 (both 720 nm) and give
> the 7Hi a new chance. The Heliopan RG715 may also work well.
>
>

Uh, read it a little closer. I have tried an 89B. It didn't work either.

Clyde
Anonymous
December 15, 2004 8:05:07 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

Clyde <lughclyde@attbi.comedy> writes:
> Gisle Hannemyr wrote:
>> Clyde <lughclyde@attbi.comedy> writes:

>>> I'm beginning to wonder if the 7Hi is IR sensitive through the
>>> center filter at the very nearest IR frequencies. The Wratten 87,
>>> 87C, and 89B are completely opaque to visible light. i.e. They
>>> only let IR through.

>> These are very high up in the spectrum - the lightest of them, the
>> Wratten 87, has a cut-off point of 795 nm, and the Wratten 87B is at
>> 930 nm. These are filters that will only work with with the most
>> infrared sensitive cameras.
>>
>> I suggest you get a Wratten 89B or Hoya R72 (both 720 nm) and give
>> the 7Hi a new chance. The Heliopan RG715 may also work well.

> Uh, read it a little closer. I have tried an 89B. It didn't work
> either.

Sorry, my bad. I misread it as 87B.

The Wratten 89B actually let through some visible light, so I am
surprised that it gives you such poor results.
--
- gisle hannemyr [ gisle{at}hannemyr.no - http://folk.uio.no/gisle/ ]
========================================================================
When you say you live in the real world, which one are you referring to?
December 15, 2004 8:06:55 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

Gisle Hannemyr wrote:
> Clyde <lughclyde@attbi.comedy> writes:
>
>>Gisle Hannemyr wrote:
>>
>>>Clyde <lughclyde@attbi.comedy> writes:
>
>
>>>>I'm beginning to wonder if the 7Hi is IR sensitive through the
>>>>center filter at the very nearest IR frequencies. The Wratten 87,
>>>>87C, and 89B are completely opaque to visible light. i.e. They
>>>>only let IR through.
>
>
>>>These are very high up in the spectrum - the lightest of them, the
>>>Wratten 87, has a cut-off point of 795 nm, and the Wratten 87B is at
>>>930 nm. These are filters that will only work with with the most
>>>infrared sensitive cameras.
>>>
>>>I suggest you get a Wratten 89B or Hoya R72 (both 720 nm) and give
>>>the 7Hi a new chance. The Heliopan RG715 may also work well.
>
>
>>Uh, read it a little closer. I have tried an 89B. It didn't work
>>either.
>
>
> Sorry, my bad. I misread it as 87B.
>
> The Wratten 89B actually let through some visible light, so I am
> surprised that it gives you such poor results.

OK, your request for a sample made me retest my 7Hi. I retract
everything I said. The 7Hi works pretty darn well with the 89B (R72).
That looks like the pictures in that web site. I'm going to have to
start using that more.

The 87 and 87C work less well, but still have some image in the hot
spot. I'd stick with the 89B.

Man oh man! What was I thinking when I tested a couple of years ago? I'm
loosing it at 48 years old. <sigh>

Clyde
December 28, 2004 11:01:10 AM

Archived from groups: rec.photo.digital, rec.photo.misc (More info?)

Very nice. What camera did you use? Is there a difference between a
just a green 58 and a "narrow cut" green 58?

Thanks,

Dave
Anonymous
December 28, 2004 5:53:41 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

Could also be worth trying red (25) and green (58) narrowcut Wratten filters
together. Results should be similar to 89B but with a little more visible
passed, as shown in these film shots:
<http://gadgetaus.com/photos/displayimage.php?pos=-267&g...;
<http://gadgetaus.com/photos/displayimage.php?pos=-76&gt;
<http://gadgetaus.com/photos/displayimage.php?pos=-78&gt;
Cheers, Jason
Folio: www.gadgetaus.com/photos
Anonymous
January 23, 2005 3:43:39 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

anyone4tennis@hotmail.com wrote:

> Clyde <lughclyde@attbi.comedy> writes:
>> Gisle Hannemyr wrote:
>>> Clyde <lughclyde@attbi.comedy> writes:
>
>>>> I'm beginning to wonder if the 7Hi is IR sensitive through the
>>>> center filter at the very nearest IR frequencies. The Wratten 87,
>>>> 87C, and 89B are completely opaque to visible light. i.e. They
>>>> only let IR through.
>
>>> These are very high up in the spectrum - the lightest of them, the
>>> Wratten 87, has a cut-off point of 795 nm, and the Wratten 87B is at
>>> 930 nm. These are filters that will only work with with the most
>>> infrared sensitive cameras.
>>>
>>> I suggest you get a Wratten 89B or Hoya R72 (both 720 nm) and give
>>> the 7Hi a new chance. The Heliopan RG715 may also work well.
>
>> Uh, read it a little closer. I have tried an 89B. It didn't work
>> either.
>
> Sorry, my bad. I misread it as 87B.
>
> The Wratten 89B actually let through some visible light, so I am
> surprised that it gives you such poor results.

My Sony S-70 gave good results with a Hoya R72 filter, either in regular
auto mode or night-time mode. Remember, broadleaf trees reflect the most IR.
Evergreens as well as tree branches reflect much less.

Fully opaque filters are difficult to use as the camera assumes the lens cap
is still on and besides framing is a pain.
Anonymous
January 29, 2005 8:58:46 PM

Archived from groups: rec.photo.digital,rec.photo.misc (More info?)

In message <Xns95BAE4FCE7DAFLessThanPerfectInc@24.71.223.159>,
Jon Pike <Anonomoose@spamlesshotmail.com> wrote:

>voice_of_reason@australia.edu wrote in news:1102656394.820059.293200
>@z14g2000cwz.googlegroups.com:
>
>> Greetings:
>>
>> I just read an article concerning digital IR photography. It said that
>> "most" digital cameras are not sensitive in the IR range...but the
>> Minolta Dimage 7 was. I own the newer Dimage 7Hi. Anyone know if this
>> version is suitable for IR photography?
>
>You should be able to find out by looking in your manual.
>Or at the very least, checking the web-page.

You're right, you should be able to do this, IMO. However, most, if not
all manufacturers exclude such information.

Everything is for "dummies" nowadays. People who want to know exactly
what products do are insignificant demographic dinosaurs.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
January 29, 2005 9:00:23 PM

Archived from groups: rec.photo.digital (More info?)

In message <10396-41BEB5C3-365@storefull-3215.bay.webtv.net>,
TinyJohnsonn@webtv.net (Tiny Johnson) wrote:

>i do IR photos with my Sony, using a R72 IR filter and ND+4 filter, i
>have a couple examples on my recent pics webpage

In my experience, ND filters tend to be NIR-pass, by themselves (at
least the ones I own).
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
!