Calling Filter Guru's, help me pleasee

[Bassnut (Fred)]

There is more to this mod that meets the eye. Before anyone launches into this themselves, wait till Eric or/and I gather some more details.

[tornado33]

many thanks for showing us Eric. The daylight filter is definately the go
thanks
Scott

[skwinty (Steve)]

Originally Posted by Bassnut

There is more to this mod that meets the eye. Before anyone launches into this themselves, wait till Eric or/and I gather some more details.

Well, am I glad I bit the wallet and let Hutech do it for me.
If I had to go through the trials and tribulations that Eric and Fred have, I would be crouched in a dark corner crying.
Hats off to Eric and Fred for their resolve and fortitude.

[Escortitis]

Originally Posted by Bassnut

There is more to this mod that meets the eye. Before anyone launches into this themselves, wait till Eric or/and I gather some more details.

I reckon I'll be waiting for the 3rd edition of the hard back book Fred!

As the astro photo's keep rolling in showing how much benefit these type's of mods are, I'm sure yourself and Eric will be expressing your findings to quite a large audience.

[teiresias]

Hi together,

- this was edited -
I've choosen to clarify it with the manufacturer first- I'll keep you informed

regards from - seen from your place - down under ;-)

rudi

[Ian Robinson]

Just to add to the confusion , found this http://www.lifepixel.com/digital-infrared/samples.html by accident and it gives YET ANOTHER OPTION .... as if we need another ....

[teiresias]

Now, like announced, these are my observations:
After having modified a canon300d last year by complete remove of the filter glass and, of course, resulting inusability for daylight photography, I tried to test the Baader BCF 40/400 replacement filter for the canon eos 40/400d standalone first, before dissassembling my new 450D.
IR LEDs from tv remote ctrls usually have emissions of about 850-950 nm wavelength, so - after the filter courves on different bcf-suppliers' websites - I expected a complete extinction of their light, but unexpectedly it shine practically unweakened through the baader filter.
Already slightly confused i made a second test and took a picture of my bathroom heater glowing dark red for the eye with the bcf put in a cardboard holder in the filterless 300d; it looked like a headlight on the photo.
Also, a shot out of the window showed the well-known orange coloured trees that can't be corrected to green with custom white balance - no difference with/w'out the bcf.
So I repeated the tests with that original part of the filter, that will stay in the cam ( that one with the ultrasonic dust cleaner piezo element) when modifying it.
Seems to me this one does the "real work" of blocking unwanted IR: The IRLED is significantly darkened and the trees look much "greener" ;-)
The now modified cam - bcf insert instead of the glued in second filter for maintaining the optical path length - takes nearly perfect daylight pictures, oK, the automatic white balance isn't really satisfying any more but that's not a real problem with RAW format.
Hope to have CS soon for a decent M27 or ngc 6960 take, but at the moment it's permanently cloudy here.

rudi

[Ian Robinson]

Originally Posted by teiresias

Now, like announced, these are my observations:
After having modified a canon300d last year by complete remove of the filter glass and, of course, resulting inusability for daylight photography, I tried to test the Baader BCF 40/400 replacement filter for the canon eos 40/400d standalone first, before dissassembling my new 450D.
IR LEDs from tv remote ctrls usually have emissions of about 850-950 nm wavelength, so - after the filter courves on different bcf-suppliers' websites - I expected a complete extinction of their light, but unexpectedly it shine practically unweakened through the baader filter.
Already slightly confused i made a second test and took a picture of my bathroom heater glowing dark red for the eye with the bcf put in a cardboard holder in the filterless 300d; it looked like a headlight on the photo.
Also, a shot out of the window showed the well-known orange coloured trees that can't be corrected to green with custom white balance - no difference with/w'out the bcf.
So I repeated the tests with that original part of the filter, that will stay in the cam ( that one with the ultrasonic dust cleaner piezo element) when modifying it.
Seems to me this one does the "real work" of blocking unwanted IR: The IRLED is significantly darkened and the trees look much "greener" ;-)
The now modified cam - bcf insert instead of the glued in second filter for maintaining the optical path length - takes nearly perfect daylight pictures, oK, the automatic white balance isn't really satisfying any more but that's not a real problem with RAW format.
Hope to have CS soon for a decent M27 or ngc 6960 take, but at the moment it's permanently cloudy here.

rudi

The heater will emit NIR , IR and FIR .

Astronomers typically divide the infrared spectrum as follows:

• near: (0.7-1) to 5 µm
• mid: 5 to (25-40) µm
• long: (25-40) to (200-350) µm

Wein's Law will give the peak wavelengths based on the temperature of the heater see http://en.wikipedia.org/wiki/Wien%27s_displacement_law.

[teiresias]

Hi,
the whole thing with the heater should only prove, that a remarkable amount of radiation beyond the red end of the visible spectrum is passing the filter. This was of course not at all a measurement, only a test with a continous spectrum in contrary of the narrow one of an LED.
Imho, the sensitivity of cmos fotodiodes at wavelengths over 1100-1200 nm
should be very small, so the middle and far IR shouldn't be of much relevance.

After all, the filter does a good job in the modified cam ( I made m27 and ngc 6992 this morning, poor seeing, but the Ha regions are much brighter then before.

Regards
Rudi

[teiresias]

seems to work ...

http://www.baedasui.de/bilder/astro/pelikann.jpg

vixen r200ss, modded 450D, 4*900sec. HII , 4*300sec RGB

regards
Rudi

[cfranks (Charles)]

Hi,
I don't have anywhere near enough knowledge to understand what you guys discussed so may I ask for a bit more basic info. I have a Hutech modded 40D plus a blue clip-in filter behind the lens. It is marked VLC-FF but Eric says, in another post, that it should be VLC-FF1 for the 40D. Do I need to worry? Secondly, I have just bought a Canon 10-22 Lens which, of course, is an EF-S so I can't use the VLC-FF filter. Is there a screw-in equiv. filter for in front of this lens or does anyone have the colour curves etc that I can apply to the reddened, non-astro image resulting when I remove the VLC-FF?
Thx
Charles

[Jeff]

Hi Charles,

Have another look at posts #4 and #6 in this thread. They provide some options (eg. B+W 486) for screw in filters for the front of the lens to restore white balance. Costs for the 58mm sizes are around $149.

As an aside:
Since I seldom use my 450D for daytime photography, I have not yet purchased a correction filter. I'm happy using the "custom white balance" option for now. Eric has kindly outlined how to do this in his webpage FAQ (2nd question):
http://www.ezystyles.com.au/faq.html
I purchased a white lens caps to occasionally use as a "white sheet of paper". Allows me to quickly setup "custom white balance" under various lighting conditions.
http://cgi.ebay.com.au/ws/eBayISAPI....m=150277545651

Cheers,
Jeff

[cfranks (Charles)]

Thanks Jeff, I will try the White paper pic first, if we ever get sunlight again.
Those links are interesting too.

Many thanks
Charles