# Infrared photography Question



## Ebag17 (May 15, 2009)

I got my IR filter and took a few shots in my backyard. I'm trying to figure out what all these spots are. Are they hot spots? They were taken with a Canon 40D and Sigma 10-20mm

Here are the photos... 

Flickr: Ebag17's Photostream

Thanks for your time and help.

-G


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## Josh66 (May 15, 2009)

That's not hot spots.  A hot spot will be a large spot in the center of the frame, the more you stop down the bigger it will get.  Not all lenses will produce them.

Were you shooting into the sun?  Looks like lens flare, or maybe water droplets on your lens...?


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## Ebag17 (May 15, 2009)

Hmmmm. Thats what i thought at first. In those photos the sun was behind me and a lens hood. I made sure the filter and lens was clean. I went to a camera shop and they did'nt really have an explanation either, except that light could be gettng in between the filter and lens?


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## Josh66 (May 15, 2009)

Ebag17 said:


> except that light could be gettng in between the filter and lens?



Not really sure how that could happen, and if it did - it wouldn't be red (since it would be unfiltered).

I really have no clue what that is...  I've never seen it in any of my IR pictures, and it's definitely not a hot spot.

I would bet that it's some kind of flare though.

Just had an idea-

Did you cover the viewfinder?

Since this was likely a long exposure (5-10 sec?), I assume that you didn't have your eye to the viewfinder the whole time.  If left uncovered (your camera probably came with a cover for it), light could enter through the viewfinder.  Maybe that's what's causing this?

edit
But that light would be unfiltered too, so it still shouldn't be red...


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## Dwig (May 15, 2009)

O|||||||O said:


> ...
> Since this was likely a long exposure (5-10 sec?), I assume that you didn't have your eye to the viewfinder the whole time.  If left uncovered (your camera probably came with a cover for it), light could enter through the viewfinder.  Maybe that's what's causing this?
> 
> edit
> But that light would be unfiltered too, so it still shouldn't be red...



Not light through the VF because during the exposure the mirror is up sealing the mirror box. Light entering through the eyepiece can't get to the sensor during the exposure. Eyepiece covers and blinds are to prevent light getting into the VF through the eyepiece and influencing the _meter_ prior to exposure.

The spots are obiously bright, very out of focus, and in front of the IR filter as evidenced by their having a noticable hexagonal shape and the same color as the rest of the image. Given that no bright light sources are in the primary distant portion of the image they are most likely something very near the lens that is either emitting or reflecting substantial amounts of light (more than the rest of the scene). These could be water droplets or dust near the lens lit by some source (flash??) or possibly smoke particles (was the photographer smoking at the time??).


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## Josh66 (May 15, 2009)

Dwig said:


> Eyepiece covers and blinds are to prevent light getting into the VF through the eyepiece and influencing the _meter_ prior to exposure.



Ah-  Gotcha.


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## Ebag17 (May 16, 2009)

Nope. Don't smoke. Neither was there a flash. I have a UV filter between the lens and IR filter? I don't know if that could have any effect. Playing around with the white balance seems to help a little but, there's still obvious spots everywhere. 

Also when you said exposure time of 5-10 sec is that how long IR is suppost to be? those images where taken for 60sec?

As pertaining to it being dust. The spots seem to be random. Would there not be a somewhat pattern to them if they where fixed spots of dust on the lens.

The filter I'm using is a 77mm Tiffen 87 filter. Have you ever heard of any problems with these filters?


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## Josh66 (May 16, 2009)

Ebag17 said:


> I have a UV filter between the lens and IR filter



That could be the problem.  If not, it sure isn't helping.

I would remove it when you have the IR filter on.

If you're using it to block UV light, the IR filter is doing that.
If you're using it for protection, the (much more expensive) IR filter is doing that now too since it's on top.

I wouldn't move it to the top of the IR filter either.  Just remove it, then put it back on when you're done if you like using it.


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## Garbz (May 16, 2009)

What IR filter is it? Is it a screw on filter or a plate type sitting in a Cokin holder.

I say this because it looks like there may be light leeking into the side of the filter lighting up the dust specs on the lens. Now due to the long exposures these dust spots suddenly really matter.

Remove the UV filter, Place the IR filter flush against the lens and maybe surround it in electrical tape. See if it still happens. If not maybe there's some problem in the filter.


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## Josh66 (May 16, 2009)

Ebag17 said:


> Also when you said exposure time of 5-10 sec is that how long IR is suppost to be? those images where taken for 60sec?



That's how long my exposures typically are, but that doesn't necessarily mean your's will be the same.  There are too many variables for your settings and mine to match up.


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## benhasajeep (May 17, 2009)

I think your getting reflection between your filters.  The spots have moved and are a different size when you went from one scene to another.  The light is bouncing around and creating the spots, they are octagnal shapes becasue of your aperture blades (reflections).

I would take off the UV and use just the IR filter.


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## Ebag17 (May 18, 2009)

Alright I think I've got it figured out! Thanks all for your help

-G


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## Garbz (May 18, 2009)

Care to share so we all know what the problem was?


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## Ebag17 (May 19, 2009)

I think it had to do with using the UV filter. It helped a lot after it was removed. 

Could using a really low aperture cause lens flare in IR photos? I read this in an article I found. 

-G


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## Garbz (May 19, 2009)

Low as in large aperture? Yes. The the wider area of the glass used means that any problems that are located towards the outside of the lens elements would becomes more apparent. This is also why CA is more of a problem at large apertures since there's more deformity on the edges of each element. 

If whatever was wrong with the IR filter was away from the centre of the filter a smaller aperture may have fixed the problem.


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## Josh66 (May 22, 2009)

Garbz, how much do you usually stop down for IR?

I almost always shoot IR wide open.  I can't say that it's ever really casued any DOF issues.  (I've never really tested for sharpness issues though.)
If you have a lens that causes hot spots, shooting wide open will help.  It probably won't completely get rid of the hot spot, but it will make it smaller and less pronounced.

I need to go through my lenses again and figure out which ones produce a hot spot...
(I think I have a link somewhere in my bookmarks that has all of that in it.)

For the ones that do not have it, I think I'll try to start using 'normal' apertures.
I was just wondering if you had been doing the same, or if you use the same aperture as you would in visible light.


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## Garbz (May 22, 2009)

I don't use the same as I would with visible light because I hate waiting for 20 second exposures. I have a D200, notoriously bad for IR photography. But I do often stop down 1 or 2 stops. Whereas with normal landscapes I often shoot at the f/11 mark, when doing digital IR I typically stick to around f/5.6 or f/6.3. 

I have no idea how this impacts hotspots since I am lucky enough not to have any lenses that I use for IR that do it.


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## Josh66 (May 22, 2009)

Today I shot a few IR photos at f/8.  I posted them in a thread I started...

I think I'll stick to shooting wide open - somehow the wide open shots seem sharper to me.  The only nice thing about stopping down that I noticed today was that I got some motion blur on the clouds.  I never got that shooting wide open.


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## Sachphotography (Jun 19, 2009)

Maybe I am jst ignorant about it but how do you shoot IR with a DSLR?

Daniel Sach
Sachphotography Fine Art Photography The homepage of Daniel Sach and his photography Company


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## Josh66 (Jun 19, 2009)

Basically - you just need an IR filter.

It will filter out everything except for IR light.


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## Sachphotography (Jun 19, 2009)

Oh. I see. I have used IR films and filters on 35mm before but never on a DSLR. I never thought about it really. Sweet. I may have to look into this. 
Thanks.

Daniel Sach
Sachphotography Fine Art Photography The homepage of Daniel Sach and his photography Company


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## ann (Jun 19, 2009)

just and fyi, some of the newer cameras have issues with IR , they don't response well. Pick up an older sony 717 or dimage 7 and even some canon powershots if you want to play around as they do a better job of IR. Of course this is depended on which dslr you already own.

i do some IR with my D100 with a wratten 87 but only on a tripod as the times are long. On the other hand i have a converted fuji 9100s that can be handheld.


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## Garbz (Jun 19, 2009)

It's not newers cameras, but rather completely variable. In fact the D100 is only one or two stops better than the D200 for IR which is possibly the worst camera to use. It depends on the strength of the low pass filter used to match the sensor and algorithms on the image processing chip.


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## Josh66 (Jun 19, 2009)

See this page to get an idea how well IR will work with your camera.


I used to have a better page bookmarked - but I can't find it right now...


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## Sachphotography (Jun 19, 2009)

Hmm.. SO I am guessing that the D80 might not be the best camera for IR. 

Daniel Sach
Sachphotography Fine Art Photography The homepage of Daniel Sach and his photography Company


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## Josh66 (Jun 19, 2009)

I'm not sure...  I don't see anything submitted from a D80 on there (that doesn't necessarily mean anything).

I used to have a link to a page with a lot more information on a lot more cameras...
I'll see if I can find it, but in the mean time you should be able to get some results by googling "D80 ir photography", or something like that.


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## Garbz (Jun 20, 2009)

Hardly, the D200 is probably the worst for IR but I still managed to squeeze out some great IR shots.


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## Sachphotography (Jun 21, 2009)

Hmm.. Who knows. I may look into IR in the future but right now I have to many other projects to work on. Thanks for the info.

Daniel Sach
Sachphotography Fine Art Photography The homepage of Daniel Sach and his photography Company


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