Hi Fred
Heres a thought for you.
If you want to check if your ir tv remote is working, take your cell phone camera which doesnt have i/r blocking (or so i an led to believe) and focus on the led of the remote. when you activate the remote, if it is working you will see the cell phone camera responding to the ir.
Now use the cell phone camera with the tv remote and insert the filter in between. this should give you some idea of whether the filter passes ir or not.
Am not to sure of the wavelength of the tv remote but should be well into near ir
Worth a try???
And, Eric, I suspect you will need an astro UV/IR filter (allowing Ha, and flat thereafter) other than the daylight filter for terestial. The lack of "green leaves" the way it is tells me it will be problimatic for astro.
Steve, sheesh, now your getting silly , I use a cell phone for voice calls, it doesnt have a cam bloody hell, why would it need a cam, but I get yr point. Just wait for the crap I produce from the SPSP.
It is very simple folks. The sensor is sensitive to far IR. Your standard Bayer matrix colour filters will pass IR. If you remove the filter designed to give the sensor the same colour sensitivity as human eyes (this attenuates the HA by a factor of about four or five) it will be sensitive to HA and far IR and so bloat your stars as your optic will not be in focus for that wavelength.
You must put a decent UV/IR antireflection coated filter that allows HA through but not far IR. As for colour balance after this there are filters available from Hutech or use AWB or PS.
Feel welcome to ask any questions and if I know the answer will try to help.
Thanks for your reply Bert appreciated. Yes i have invited Bert to share his wealth of knowledge in this area. Bert, as you may know, the canon 40D have 2 internal filters. A low pass UV/IR filter (which acts as the anti-dust shake) and the Phaser IR filter (the main filter which blocks HA). It is the phaser IR filter which requires replacement for astro use.
You can see the spectrum graph attached in this post of each of the filters. If the phaser IR filter gets removed, without daylight balancing just AWB, leaves should not be green? only adding a UV/IR filter will make this green?
nice image bert very sharp! was that image colour balanced using CWB, or AWB?
If the phaser filter gets replaced with a baader BCF Filter (see attached graph) no uv/ir filter used, will the leaves turn green? with my, the leaves are still red. I suspect it is because there is an IR leakage at 1100nm (spike) that is the reason?
Ezy I did say Canon WB. I Have a filter that fits on the front of my 24 to 105 mm F4L from Hutech that converts the camera back to 'normal' and that picture was taken without it with the 300mm F2.8L from about four meters away. below is a cropped image autocolour balanced in PS.
If any foliage looks red in your images you are definitely getting IR and/or far IR onto your sensor.
I did not make it clear but my 5DH has the 1A UV/IR filter fitted by Hutech.
Hi Eric and Fred
Did the remote test with my cell phone camera and the canon40dh.
Cell phone camera shows the IR and the canon doesnt.
The response of the 1b filter cuts off sharply at 700nm and there are no leakage spots above 700nm. See hutech site for the filter response curves.
The result wasnt obvious on a quick test to start with at all. But I took a closer shot, and heres the result. Seems I have taken the internal filter out.
Well, it seems we are still at square 1 Eric, you and I both have the phasor filter 2 out, and the shaker filter in, yet you have much higher response to IR. The BCF filter replacement cant produce a higher response than my no glass at all !!!.
hmmm, this is really strange. im trying not to think too much of it until the daylight filter comes in. Is there a 3rd filter? the 3rd filter in the image (filter2) is the actual CMOS sensor.
Hi Fred
Did you take any pics with your 40d this weekend.
If so please post so i can see what the effect of the filter removal is.
Thanks
Well Steve, heres the Tarantula I took, its 5 off 5min exposures at 800ISO with no darks. Due to the cold,grog,endless stuffing around and grog, it was mistakenly taken at small jpeg. It has no colour rebalance applied. Colour wise it seems OK by me, but I may well be typically woefully wrong. To recap, this is only with the phasor filter removed (not 2 as hutec apparenty do) and an AStronomik UV/IR lens filter on the front.
Hi Fred
Even after all the grog and stuffing around still a pretty neat image.
So you had 2nd sensor filter removed and you used uv/ir external filter.
So I assume you were limited to a max wavelength of about 700nm.
Did you take any without the external filter?
, I use a cell phone for voice calls, it doesnt have a cam bloody hell, why would it need a cam, but I get yr point. Just wait for the crap I produce from the SPSP.
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