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Old 29-12-2008, 09:46 PM
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Matty P (Matt)
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Imaging with a LPS Filter?

I am wanting to purchase a Hutech IDAS LPS Filter and was wondering if it increases the exposure time of your images?

Say I take two images with and without the filter of equal exposure time. Will the image with the filter be much darker and captured less light than the one without the filter?

Or does the filter allow you to increase your exposure time without reaching your skyglow limit?

Hope that makes sense.

Thanks in advance.

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Old 29-12-2008, 11:18 PM
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RobF (Rob)
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Hi Matt.

You might be interested in these 2 pics of HH neb area I took last week when playing with effect of different ISOs, filters, exposure times. Both 180sec single frames, ISO 800, no flats, ICNR turned on (with unmodded 450D, 8" F5 newt, MPCC)

I get a lot of sky glow here. The first shot is typical of the orange cast to pics without filtering. 2nd one shows overall blue cast IDAS LPS lends to pics, but I think you'd agree a cleaner pic with greater potential.

I scooped Jerry Lodriguss' CD book on DSLR astrophotography for XMAS, and he talks about IDAS LPS filters giving the potential for 2 - 3x greater exposure times. I really haven't had time yet to do a lot of imaging with my setup, but seems to me up to 2x longer exposure times seems reasonable before pollution fogging, albeit with loss of some light. That is, a 10min frame in city with LPS will never be as good as 10min from a dark sky site.

Ezystyles and other gurus here have mentioned before that the IDAS LPS seems to be easier to colour correct where necessary than harsher filters (eg. UHC-S)

I'm happy with mine!
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Old 29-12-2008, 11:22 PM
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turbo_pascale (Rob)
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This is a great filter.

It will be darker, but for all the good reasons (supressing unwanted bits of light)

You will definately be able to go longer before reaching the skyglow limit.

Have a look at this thread:
http://www.iceinspace.com.au/forum/s...ad.php?t=28782

and this one:
http://www.iceinspace.com.au/forum/s...ad.php?t=33687

The best feature of this filter is that the colour balance is great compared with others. Apparently there is a newer Orion Skyglow filter (compared with the one I had in the comparisons above), but I don't know how that one performs.

This filter in my opinion is well worth every cent. One of the best value for money astro purchases I have made.

Turbo
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Old 29-12-2008, 11:25 PM
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dugnsuz (Doug)
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Quote:
Originally Posted by Matty P View Post
I am wanting to purchase a Hutech IDAS LPS Filter and was wondering if it increases the exposure time of your images?

Say I take two images with and without the filter of equal exposure time. Will the image with the filter be much darker and captured less light than the one without the filter?

Or does the filter allow you to increase your exposure time without reaching your skyglow limit?

Hope that makes sense.

Thanks in advance.

Hi Matty,
I did a direct comparison in a recent post - I was looking at internal reflections with and without filter but it may give you some idea as what to expect.
I haven't pushed exposures past 10 mins but I feel that the LPS2 filter would allow me to test the limits of my autoguider!!

Check out first post in this thread...
http://www.iceinspace.com.au/forum/s...ad.php?t=38991


Doug
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Old 01-01-2009, 01:22 AM
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Matty P (Matt)
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Thanks guys. I really appreciate your responses. It has cleared up my worries about using a LPS filter.

I will have to put one on order ASAP.

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