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Old 01-11-2015, 11:00 AM
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Camelopardalis (Dunk)
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DSLR antialiasing filter

Folks,

I've been tinkering with a sacrificial Canon 1100D for a cooling solution, but while I'm thinking about it I'm wondering if the front LPF1 antialiasing filter is necessary for astro?

It's a dedicated modded cam, so fair game. Will I notice increased sharpness in my images, if I were able to compare the two under the same conditions?

Appreciate your thoughts and feedback.

Cheers,
Dunk
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Old 01-11-2015, 11:34 AM
glend (Glen)
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Dunk, It is supposedly there to slightly smear inbound light across pixels to prevent the creation of artifact patterns. Removing it is said to give increased 'sharpness' but at the risk of artifact production. I recall that there are some photos posted on the web that demonstrate the difference and artifacts. Check this link for an example:
http://www.lifepixel.com/blog/anti-a...filter-removal

It has minimal spectrum affect like blue cast filter 2 does; i believe the spectrum passed is much like a Baader UV/IR Cutoff which cuts below Ha. There is a discussion on IIS about it in relation to filter removal pros and cons. It can be considered a form of dust protection as the piezo shaker function depends on its special dust release coating to function.

I removed my LP1 on my colour camera but later put it back because I was getting strange light leak like saturation of my sensor - putting it back appeared to have solved the problem - but I am usure if it was the actual cause. It maybe that I introduced the leak by removing the black plastic frame as well.
I am removing it on my new mono 450D, just the glass, as that will have no bayer colour matrix and I want all 12mega pixels as sharp as I can get them.

There is a discussion of its merits here:
https://www.flickr.com/groups/350343...918/?ytcheck=1

Last edited by glend; 01-11-2015 at 12:10 PM.
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Old 01-11-2015, 01:20 PM
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Camelopardalis (Dunk)
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Thanks Glen, looks like I've got nothing to lose, but I might off until I've got a clip in UV/IR filter.

The 1100D doesn't have sensor cleaning so that's not an issue.
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Old 01-11-2015, 01:41 PM
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Merlin66 (Ken)
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Removing the AA filter (Filter #1 in the graph) certainly increases the spectral response towards the nir. Great for spectroscopy....
For "conventional" AP you probably need to add back a clip in UV-IR filter - this will also allow the use of std camera lenses.
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Old 01-11-2015, 04:02 PM
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Camelopardalis (Dunk)
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Thanks Ken! I'm thinking of using the cam for narrowband anyhow so that looks like it should work. Any increase in sharpness, however subtle, without any side effects is welcome.
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