Old digi P&S IR test images.

[fidget]

I love the look that I can get with SFX. Recently I tried to modify a P&S digi to see what could be done.
I learned a lot whilst tinkering with the 4Mp Minolta and more with the cheap Ebay purchases that didn't "make it" through the process on the kitchen table.
That was last year, I had put the camera away because
1: focussing was an issue, many shots well out of focus,
2: The winter was coming.
3: I had learned just how very difficult it is to cut and shape the glass filter,
4: And I learned how it is nearly impossible, on the kitchen table, to eliminate dust on the sensor/glass.

Anyway, having an afternoon free and having found it again, I tried a few test shots in the yard. I learned that the focus would work if not wide angle and that you can't see the marks caused by the specs of dust on the glass if the subject is varied.

Out to the park for a first few shots. I love this. I may buy a professionally modified P&S.

A Few......

Look West

West

Monument

Dawg

The dog is a Yorkie. It is brown with a black back.


Can anyone help with the way to cleanly cut a filter to shape, this is the bit that fails.........?

Dave..

 

[fidget]

Oh, another. A closer subject. Focus not bad...

Dave

 

[spaceman spif]

"I love the look that I can get with SFX." Sound effects? Not sure I get the reference, but it looks like you've somehow IR'd a digital. How, pray tell, did you do that? I'm fascinated...

 

[rxmd]

"I love the look that I can get with SFX." Sound effects? Not sure I get the reference

Ilford SFX 200 is a black-and-white film with extended infrared sensitivity.

How, pray tell, did you do that? I'm fascinated...

Rip out the IR filter in front of the sensor probably, that's how these things are commonly done.

 

[fidget]

rxmd has it right on all counts.

A newer range of items for sale on Ebay are a range of faulty digital cameras (Although in the past they were described as "near mint" and sold to me!). I bought a couple of these very cheaply to evaluate how easy it might be to work down to the filter and replace it.

The stumbling block was the cutting and finishing of the replacement filter.
I may look at it again, this time with the intention of using plain glass in front of the sensor and standard filters on the lens.

Edit: I didn't say, this one has a piece of a glass 720nm filter in it. What a *!" to cut!


Dave

 

[spaceman spif]

Being an absolute and total newb in digital IR, I'm sure I'm going to say something dumb here, but...

In the "old" IR film days we had to use the camera's focusing aids and then guesstimate the IR error and compensate accordingly, and doing all of that before the filter (in front of the lens) was in place. (They were too dark to focus through.) There was also considerable guessing as to exposure.

So with the LCD instant display, you can figure out the exposure on the spot, I'm guessing. And I'm also guessing that with the greater DOF on the smaller lenses, the focussing errors might not be quite as noticeable.

Is any of this correct, or am I all wet? This sounds like great fun to me...

 

[fidget]

Being an absolute and total newb in digital IR, I'm sure I'm going to say something dumb here, but...

In the "old" IR film days we had to use the camera's focusing aids and then guesstimate the IR error and compensate accordingly, and doing all of that before the filter (in front of the lens) was in place. (They were too dark to focus through.) There was also considerable guessing as to exposure.

So with the LCD instant display, you can figure out the exposure on the spot, I'm guessing. And I'm also guessing that with the greater DOF on the smaller lenses, the focussing errors might not be quite as noticeable.

Is any of this correct, or am I all wet? This sounds like great fun to me...

You've got it about right (not that I am any expert!!).
There may be a focussing issue with an SLR, but the P&S uses the image to focus and expose, so they can work well.

Dave

 

[fidget]

It's been a nice evening. I went out to walk around a local area good for a few landscape shots.
Hawthorne

Almost snow.

Horse walks on fence.

Dave....

 

[spaceman spif]

Could a person use something along the lines of a Wratten gel filter instead of glass? I'd think that'd be WAY easier to work with.

 

[fidget]

Could a person use something along the lines of a Wratten gel filter instead of glass? I'd think that'd be WAY easier to work with.

My first digi IR attempts used an old Olympus with a 720nm gel filter cut to shape and taped onto the front of the lens. The Oly allowed more IR through its filter, but it needed 1/2s for an average shot.

My problem with removing the IR blocking filter covering the sensor is that it must be replaced with something of a similar thickness and refractive index. This is because it alters the point of focus. I have tried plastic from a filter which worked to some extent. I expect that a very thin gel filter will cause the focus of the camera to be altered significantly.
The Minolta has thick glass in it but I have lost the wide end of the focus range from 35mm to 45mm (in 135 terms). This still works if I select a small aperture.

If I were to do it again, I would choose a camera that has a filter thread and use external filters (this is good too because it would allow me to experiment with the range of filters from full spectrum through 680nm to 900nm).
This would mean that I would have to put plain glass in place of the IR blocking filter. This would be very much easier to produce than filter glass. I would try some microscope slides.

It's easy to start. A 5 or 6Mp cam can be bought very cheap now, most of us may have a P&S redundant.

Do a search there are some resources out there, some have DIY mod instructions.

Dave

 

[Sonnar Brian]

Ilford SFX 200 is a black-and-white film with extended infrared sensitivity.



Rip out the IR filter in front of the sensor probably, that's how these things are commonly done.

You need to replace the IR absorbing Filter with glass of about the same thickness. I used clear glass when converting my Coolpix 950. The IR absorbing glass is in the optical path of the sensor, If you just rip it out, chances are the focus will be off.

http://www.abe.msstate.edu/~jwooten/camera/lense.html

I got the cover glass from Anchor Optical Surplus.

 

[fidget]

When images are shot in colour, with the custom white balance set to compensate for the heavy red due to the filter, images are recorded with a strange set of weak colours.
When looking at those images a spot of lower contrast or hue change is seen in the centre of the frame.
I read about this, it seems that many lenses are prone to this "hotspot" when filtering for IR. It appears that this cam is not so suitable for IR work, although the spot is difficult to see when in B&W.

Dave..