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Comparison Between Filters For Astrophotography

After having happily owned and used a Lumicon 1.25" Deep Sky filter for almost 2 years I finally upgraded to a Hutech IDAS LPS Canon Mount Front filter. I actually started looking out for such a filter as soon as I got my Canon EOS 20D; but it is rarely found on the used market. The main reasons for this upgrade were the vigneting introduced but the 1.25" housing of the filter which has a very thick edge, the halos around stars and the distorted colour balance.

A comparing tests of the Lumicon Deep Sky filter (1.25") and the Hutech IDAS LPS filter (Canon EOS 20D Front Filter). The test was done in a sub-urban region with highly disturbing lunar illumination (77% phase at 40 degrees from M42). The vigneting in the images with clear and IDAS filters is mainly due to the use of a 1.25" to T-thread adapter. The 1.25" Deep Sky filter add a lot of vigneting to this.


Raw Images

All exposures with Canon EOS 20D and Takahashi FS-102 at ISO 800 with identical colour balance. No processing but resizing was done.

Exposure

Clear

Lumicon Deep Sky

IDAS LPS

60s

clear 60s deep sky 60s idas 60s

120s

clear 120s deep sky 120s idas 120s

240s

  deep sky 240s idas 240s

Processed Images

Both exposures with Canon EOS 20D and Takahashi FS-102 at ISO 1600 and 240s. Both images were processed in a very similar way to display the differences between the filters. These are not very aestetic but give an idea of the properties of both filters.

deep sky 240s idas 240s

Conclusion

The main issues that made me upgrade to the IDAS LPS filter have been resolved. Additional vigneting due to the filter is non-existant inherent to its design. Also the bright halo's around stars have disappeared. In addition it renders far more beautiful colours than the Lumicon filter. The Lumicon filter on the other hand has a less wide pass band allowing for longer exposures under really bad conditions.

A job well done Hutech!


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