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Infrared Astrophotography

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#1 dunk1947

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Posted 25 June 2013 - 08:33 AM

I've just ordered an iOptron Skytracker for use with my DSLRs. One camera has been modified for B&W IR photography ie using an 830nm sensor filter - this was fitted several years ago before I became interested in astrophotography. Is this camera (i.e the 830nm filter) suitable for IR astrophotography ... and similarly, is a DSLR modified with 720nm IR sensor filter suitable for astrophotography? I have searched for the specific answers without success.

Thanks for reading

dunk

#2 NeilMac

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Posted 25 June 2013 - 10:44 AM

Some nice info here;
http://www.spencersc..._7cCFaVFMgod...

#3 dunk1947

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Posted 25 June 2013 - 12:06 PM

Thank you. I am beginning to realise that I'll need a camera with sensor cooling to avoid burning out my existing cameras with the heat from long exposures. And it's probably best not to use my existing 830nm IR filter equipped camera. I've found a supplier of astrophotography cameras in the UK.

dunk

#4 Falcon-

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Posted 26 June 2013 - 12:30 AM

Cooling has nothing to do with "burning out" the sensor. Cooling is used simply because there is less noise in an image from a cold sensor then a warm sensor. No damage involved, just a cleaner image. :)

As to the IR part of the question... I think the problem here is for astro uses the wavelengths you are talking about are a bit too far into the IR for general usability. You end up blocking the majority of the light the camera is sensitive to, especially a few wavelengths very important to nebula imaging such as Hydrogen-alpha emission light. So yes, I think you COULD use your IR cameras for astro, but the results will likely be a bit dim.

Now mind you it would be interesting to see just what do you *do* get out of an IR camera and some common astrophotography targets, perhaps M42... It could be we are missing out and just need a bit of patience to get some unique results. So... even though I do think a stock or astro-modified DSLR will do you beter it would be worth giving it a shot with your IR mod DSLRs at some point anyway!

BTW the "standard" astro-modified DSLR is in fact modified for the Near-IR, but the low-end cutoff is for an astro-modified DSLR is at above 700nm because H-alpha light is at 656nm. Thus the deafening silence on your initial question as both your 830nm and 720nm filters block that desirable wavelength. There is a second type of mod, the Full Spectrum mod that blocks no wavelengths. Such a camera could be used daylight, IR, or astro depending on what external filter you use with it.

#5 Toxic Coolaid

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Posted 26 June 2013 - 07:13 AM

IR is supposed to give good contrast for planetary photography. Like the Astronomik ProPlanet 742 and 807. I did try M42 with the ProPlanet 742 in Hap Griffin Full mod T2i. It wasn't all that interesting. However I abandoned the IR pass session after only a few images because I didn't want to lose the time for regular data that I knew would be good. I'll look in my files and see if I even kept the IR images. There actually should be some luminescence in the dark clouds where stars are forming but are hidden by the gas and dust.

#6 WillCarney

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Posted 28 June 2013 - 10:12 AM

I have a full spectrum Nikon D40x. So it gets all IR and everything else. Recently a club member got his 5DMarkii modified and I have tested it a few times. That Canon had a IR cut filter installed but will pick up H-alpha.

In testing both cameras with the same telescope my Nikon camera with full spectrum was much more sensitive and picked up much more h-alpha than the Canon. I picked up h-alpha in half the exposure time with more detail. Some test shots I used an IR cut filter but it still picked up more h-alpha than the Canon. Most IR cameras cut all light except that particular ban. What you want is more a full spectrum band. Most all astro ccd cameras are full spectrum which is why you have to use a IR cut filter with refractors.
So generally a dedicated IR camera is not of much use for astro unless it's full spectrum. If you already have one you might try it on the Moon. That target has detail that can be picked up with an IR camera.
William

#7 whwang

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Posted 28 June 2013 - 10:31 AM

http://www3.asiaa.si...M20_2012-IR.htm

Taken with a 825nm IR filter and a modified DSLR, no cooling.

Cheers,
Wei-Hao

#8 Zaid Jawed

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Posted 28 June 2013 - 11:44 AM

That image is absolutely amazing Wei Hao.

#9 Nils_Lars

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Posted 29 June 2013 - 01:41 AM

That shot shows the foot print very well , almost like a luminance layer.

#10 whwang

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Posted 29 June 2013 - 05:02 AM

This is another IR shot:
http://www3.asiaa.si...photos/M42.html

Here the effect of IR is clearer. Stars embedded by dust become more apparent in the IR picture. The H alpha line emission from the nebula is no longer there. However, the dust in the nebulas reflect some continuum emission from the stars so the shape of the nebulas is still visible. Here the optics doesn't work as well as in the visible light and stars are less sharp.

The camera is a full spectrum one. So if you want to take this kind of pictures, you have to replace the IR-cut filter with a clear glass, not an astro UV/IR-cut filter. This actually causes a lot of headache for me. To take normal visible light color pictures, I have to put an additional UV/IR-cut filter to remove the IR. Otherwise the stars look blurry. This is a big disadvantage unless you really want to spend lot of time on IR-only photography.

Cheers,
Wei-Hao

#11 dunk1947

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Posted 29 June 2013 - 01:09 PM

Thank you very much indeed for your comments. I will try my IR camera for lunar photography - and I have just seen a used Canon 60Da DSLR listed which as you know has a modified low pass filter. I am investigating purchase. My only experience with astrophotography was successfully imaging Hale Bopp comet 16 years ago - using Agfa Scala film pushed several stops. I joined a local astronomy club last September - we have only managed 5 club observing nights this year because most of the Friday evenings 'site booked ' have been too cloudy. Better luck next autumn when we resume club trips again.

Best wishes

dunk

#12 nofxrx

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Posted 30 June 2013 - 04:06 PM

dunk; The 60Da will NOT do IR imaging any better than a stock camera could....waste of $!!!
You NEED a Full Spectrum Modified camera..like mentioned above...which has ZERO spectral blocking filters in it...
A "modified low pass filter" means nothing in IR..

Good luck!

#13 Hilmi

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Posted 01 July 2013 - 02:12 PM

60Da is not useless, it's just not the most sensitive modified configuration out there. On the other hand, you do get factory warranty if that used one is still under warranty.

I have one and I am happy with it. There are better cameras out there, but nothing wrong with the 60Da

#14 nofxrx

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Posted 01 July 2013 - 10:28 PM

60Da is not useless, it's just not the most sensitive modified configuration out there. On the other hand, you do get factory warranty if that used one is still under warranty.

I have one and I am happy with it. There are better cameras out there, but nothing wrong with the 60Da


Oh my gosh...
I said that FOR INFRARED PHOTOGRAPHY the 60Da is useless; just like a Stock camera OR a Baader modified camera AS THEY ALL HAVE INTERNAL IR BLOCKING FILTERS! defeats the entire purpose of trying to capture ONLY IR!
That's it!
:tonofbricks:

#15 zerro1

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Posted 01 July 2013 - 10:36 PM

60Da is not useless, it's just not the most sensitive modified configuration out there. On the other hand, you do get factory warranty if that used one is still under warranty.

I have one and I am happy with it. There are better cameras out there, but nothing wrong with the 60Da


Oh my gosh...
I said that FOR INFRARED PHOTOGRAPHY the 60Da is useless; just like a Stock camera OR a Baader modified camera AS THEY ALL HAVE INTERNAL IR BLOCKING FILTERS! defeats the entire purpose of trying to capture ONLY IR!
That's it!
:tonofbricks:


:rofl5:

that's all I can say...

#16 dunk1947

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Posted 21 July 2013 - 09:27 AM

dunk; The 60Da will NOT do IR imaging any better than a stock camera could....waste of $!!!
You NEED a Full Spectrum Modified camera..like mentioned above...which has ZERO spectral blocking filters in it...
A "modified low pass filter" means nothing in IR..

Good luck!


I was not considering a 60Da for infrared photography. I already have an IR modified camera - which could be used for photographing the moon.

I've decided to buy a Canon 1100D which has been modified for astrophotography - they are available in the UK with various filter modification options and also optional non-Canon firmware.

Thank you to everyone for your suggestions.

dunk

#17 canukLX90

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Posted 22 July 2013 - 02:46 AM

Thanks for posting your images. A full spectrum mono DSLR
would be a fine addition to the DSLR imagers equipment list.
I took the liberty of combining your two images of M42 to
see what the result would look like.

PJ

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#18 whwang

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Posted 22 July 2013 - 05:22 AM

Hi,

That's interesting.

Because the QE in the near-IR band is lower than that in the visible band, to mimic what a real clear filter would produce, the visible image should have higher weight. In other words, the combined image may look much more like the visible image rather than the IR image.

Cheers,
Wei-Hao






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