IDAS P2 Light Pollution Suppression Filter

IDAS P2 Light Pollution Suppression Filter

  (3 Reviews)
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About this product

Model:  hutech-idas-lps-2

The Japanese-made IDAS P2 LPS is in our opinion the BEST Light Pollution Suppression filter for astro photography with DSLR, colour and mono CCD cameras. 

Light pollution suppression (LPS) filters are designed to suppress the common emission lines generated by artificial lighting, yet allow the important nebula emission lines to pass, thus enhancing the contrast of astronomical objects, particularly emission nebulae (see filter plots).

Unlike other light pollution suppression filters, IDAS filters are specifically designed for balanced colour transmission using the IDAS unique Multi-Bandpass Technology (MBT) process. The balanced transmission allows colour photographs to be taken with minimal colour cast to broadband emission objects such as stars, galaxies and globular clusters.

IDAS LPS filters utilize the unique IDAS Ion Gun Assisted Deposition (IGAD) coating technology for superior coating durability (quartz hardness) and safer cleaning. IGAD coatings also improve temperature and humidity stability, reducing spectrum shifts down to +/-1nm from the +/-3 or 4nm shift of standard coatings. 

CCD imaging can also benefit, because although CCD imagers can already shoot through light pollution to some extent, including an LPS filter to the setup gives an added (signal-to-noise) edge. The filter also blocks infrared so a separate IR blocking filter is not needed.

Note, however, that light pollution suppression filters are not a perfect substitute for dark skies.

LPS filters are available in 1.25" and 2" threaded cells and photographic filter sizes 52 & 72 mm.

Customer reviews

Average Rating (3 Reviews):  
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Genuinely Impressed!
Wednesday, 22 July 2020  | 

I am on the edge of a Bortle class 5 sky. Some nights are better than others. My main sources of light pollution are cool blue LED lights from street lighting and an industrial area about 4 miles away. Up until 5 years ago a long exposure would have yielded an amber sky, now it is blue white. I also have to deal with a million watts of security lights on adjoining properties and garages.

Without the filter I was able to shoot 45 seconds at ISO800. On some targets I could push this to 1600. (I use an unmodded EOS50D).

When I introduced guiding I could push to ISO 800 for around 2 minutes before the sky became blue.

So far I have been taking a slow approach to exposure time. Last time out I imaged M17 at ISO1600 with a 3 minute exposure. The nebula lay in the direction of some of my most polluted sky and was quite low.

During this session I forgot to fit the filter for my first test images and the result was an awful washed out mess. Adding the filter brought the shots well into the usable range and showed my I could push the settings a little harder.

So far I have had 3 nights of using the filter (given how the summer has been I consider myself very lucky!). So far I am impressed. I'm a filter noob, so I'm comparing no filter to filter and so far I'm exceptionally pleased. It has more than trebled my exposure time. I know there is plenty more to had from the filter and I'm sure I'll see greater benefits as I progress.

Now this is an expensive piece of kit (it cost more than my guidecam). I have to say so far it's worth every penny. While no substitute for a proper dark sky I'm to pulling out detail I never thought possible.

I've not encountered any issues with distortion, reflection or artefacts.

For reference my setup is SW Explorer 200pds, coma corrector and an EOS50D (Unmodded), Currently waiting for an ASI294 and can't wait to see what that pairing will achieve.

Rating (max 5):  
Beware reflections
Saturday, 24 January 2015  | 

I've personally found only 1 combination of my own optics that does _not_ produce unacceptable reflections (A Televue refractor without using the reducer), all other times I've tried to use it (10" SCT with f/6.3 reducer, 127mm Refractor with 0.8x reducer, 80mm refractor with field flattener) the results were unusable. It must be said that the IDAS is a very effective LP filter but the internal reflections it produces render the results useless under many circumstances. YMMV.

Rating (max 5):  
Top-end Light Pollution Suppression Filter!
Wednesday, 21 August 2013  | 

This filter is widely-known to be the top-end light pollution suppression filter and is very well-worth the money. Using this filter in front of my LRGB filters when imaging (I use a monochrome CCD camera) allows me to set exposure times more than twice the length before yielding some light pollution. Moreover, it does not produce a visible shift in the colour produced.

Needless to say this filter does its job and it does so brilliantly. I do however want to mention that there is a level of minor internal reflection produced by this filter. This is expect though because the light pollution wavelengths are reflected back out. Hutech reports that with high-quality multi-coated optics on telescopes, this does not present an issue. On my Skywatcher Exploer 150PDS however, my images produce a reflection of the internal optics around very bright stars on long exposures. Hutech assures however that this is not always the case so I guess it depends on your telescope! It does by no means destroy your image but is worth mentioning.


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Q1. What is the difference between the IDAS D1 filter and the P2 Filter? Which is best for a DSLR?

The only difference between the P2's and the D1's is that the newer D1's block a little more of the red, specifically the SII emission area. Whilst there's not usually much SII available it does help the overall colour balance of an image.

This effect is most useful on a DSLR - on a mono camera you'd be using other filters and we'd recommend a P2 filter. For DSLR's the D1's are more suited.

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