Test Reports

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Testing, testing, and more testing...

I am a curious chap.  After my initial pass through my filter research material, I went back and started looking at it again in more detail. My purchase of a deepsky astro-video camera in January 2011 (a Mallincam Xtreme) opened up an opportunity to test many different things, not just filters but also focal reducers, different telescopes, all sorts of things.  I have always tried to write my test results up in the form of a report, and I will do my best to get them posted here for all to read.


Jim T.

Title Description Date
"Omega Optical Improved NPB DGM Filter", 4.1Mb Omega has produced the LP filter I have been searching for: two very narrow high transmission band passes around Hbeta/O-III and Halpha.  This report summarizes my testing of the filter both visually and with an astro-video camera. Jan 2015
"Optolong Preliminary Filter Test Report", 0.8Mb Summary of some initial testing that I did on a batch of sample filters from Optolong (Yulong Optics Co., Ltd). Aug 2015
"Optolong L-eXtreme Filter Comparison", 5.9Mb Summary of my testing where I compare a range of Optolong brand light pollution filters, including the new L-eXtreme. Aug 2020
"Radian Triad & Triad Ultra Performance vs F-ratio", 3.7Mb Test report summarizing my more detailed investigation into how the performance of the Radian Triad and Triad Ultra filters are affected by optics f-ratio. Oct 2020
"IDAS Filter Comparison Testing", 10.0Mb Test report summarizing my evaluation of all models of filter sold by IDAS.  Report includes bench testing (spectrometer) and field testing (imaging). Nov 2021
"Optolong L-eXtreme F2 Testing", 25.5Mb Test report summarizing my evaluation of the prototype Optolong L-eXtreme F2 filter.  Spectrum measurements and images are used to compare the filter's performance to existing Optolong filter models. Dec 2021
"Antlia ALP-T Filter Comparison Test", 16.0Mb Test report summarizing my testing of the new Antlia ALP-T filter.  Spectrum measurements and images are used to compare the ALP-T to four existing multi-narrowband filters:  IDAS NB-1, IDAS NBZ, Optolong L-eXtreme, & Radian Triad Ultra.  Rev. 1 w/ updated spectrum data using upgraded spectrometer. Jun 2022
"Narrowband Halpha Comparison Test", 9.4Mb A back-to-back comparison of performance between Halpha filters with different FWHM, from 40nm down to the 3nm wide Optolong and Chroma brand filters. Aug 2022
"SHO Filter Comparison Test", 5.1Mb Comparing Sulfur-Oxygen-Hydrogen narrowband filter sets against each other and comparing performance, one set with ~7nm wide pass bands (IDAS) and the other with 3nm wide pass bands (Optolong). Aug 2022
"3nm Multi-Narrowband Filter Comparison", 28.3Mb A comparison test between the Optolong L-uLtimate and Askar Colour Magic 3nm Duo-Narrowband filters.  Filters are compared based on their measured spectrums and imaging results. Oct 2022
"Testing Multi-Object Type Filters", 26.2Mb A comparison test between two new filters:  the Antlia Triband RGB Ultra, and the IDAS Galaxy & Nebula Booster (GNB).  I compare the performance of these two filters to that of other pre-existing filters, both by spectrometer measurement and imaging. May 2023
"Testing the Player One Pro Dual-Band Filter", 6.1Mb Player One's Pro Dual-Band is the latest offer in the 3nm multi-narrowband filter category.  I put the filter up against the Optolong L-uLtimate and Askar Duo-Band Narrowband. Oct 2023
"Testing the Optolong L-Quad Enhance Filter", 7.6Mb Optolong's new L-Quad Enhance Filter (L-QEF) is compared to other existing filters in the multi-broadband category.  Performance is compared in terms of predictions based on the measured filter spectra, as well as comparison images of various deep-sky target types. Nov 2023
"Testing the Antlia Quadband Anti-Light Pollution Filter", 26.9Mb Antlia's new Quadband Anti-Light Pollution (Quad ALP) filter is compared to other similar filters with the objective of finding which filter is the best general purpose filter, i.e. what filter delivers good performance on all deep-sky object types. Nov 2023

"Band Pass Filters For Visual & Video Astronomy - Part 1" , 3.9Mb

A redo of the Deep-Sky filter portion of my original filter research web-paper, this time including the Mallincam CCD as well as the human eye.  Added several new filters, including Halpha filters.  Contains test results for a large number of LP filters.  Part 1 is the body of the report.

Apr 2012

"Band Pass Filters For Visual & Video Astronomy - Part 2" , 4.7Mb Part 2 contains the appendices that accompanies the report.  The appendices are mostly the images that were collected from my Mallincam during testing with a large assortment of different LP filters.  The target was M42 Orion Nebula.

Apr 2012

"LP Filters Under Dark Skies" 2.2Mb

A presentation of theory and observations surrounding what happens if you use light pollution filters under dark skies.

May 2013

"LP Filters & Monochrome Cameras", 11.6Mb Screen captures made during some testing using a monochrome astrovideo camera and a range of LP filters.

Sep 2014

"Polarizing Filters & Nebulae", 0.9Mb A short test to examine the impact of using a linear polarizing filter on an emission nebula from a light polluted location.

Jan 2015

"Multi Narrowband Filters", 7.1Mb A detailed series of tests comparing the various brands of multi narrowband filters that are available today.

Feb 2020

"Narrowband Filters & Fast Optics", 3.3Mb Using a combination of measured filter band shift data and theoretical narrowband filter spectra, I predict the impact of using a narrow band pass filter on fast optics.

Nov 2020

"Narrowband Filters & Fast Optics - Addendum", 10.1Mb An addendum to the main report containing additional performance prediction plots for different telescope types.

Nov 2020

"Understanding Filter Induced Star Halos", 8.6Mb This report summarizes a series of different tests I performed in an effort to better understand how and why filters cause halos around bright stars.

Nov 2022

"How Narrow is Too Narrow?", 12.3Mb Using H-alpha filters as a proxy for all narrowband, this test report compares the impact of filter band width (FWHM) on contrast increase and SNR.  FWHM values from >100 to 1nm are considered.  The objective was to determine if there is an optimum filter bandwidth.

Jun 2023

"Multi-Narrowband Filters + Monochrome Cameras", 6.5Mb This article discusses the idea of using a multi-narrowband filter, meant traditionally for use on a one-shot colour camera, on a monochrome camera.

Oct 2023

"Managing IR in Video Astronomy - Part 1" , 2.2Mb A test report summarizing the visual impact of IR Cut filters on the Mallincam.  Testing was with an 80mm APO, with the target being primarily the nebulous region around Sadr (gamma Cygni).

Aug 2011

"Managing IR in Video Astronomy - Part 2" , 400Kb Part 2 of my testing of IR Cut filters on the Mallincam, using my 8" SCT and the targets M27 and M57.

Aug 2011

"Managing IR in Video Astronomy - Part 3" , 1.8Mb Part 3 of my testing of IR Cut filters, focusing specifically on the galaxy M31 using a 102mm TV camera lens.  Some time spent evaluating IR Pass filters.

Sep 2011

"Managing IR in Video Astronomy - Part 3 Addendum" , 1.0Mb A re-look at the white balancing of my images from the Part 3 test report.

Sep 2011

"Managing IR in Video Astronomy - Part 4" , 3.3Mb

Part 4 of my testing of IR Cut filters, focusing on the galaxy M33 using an ED80 APO refractor reduced to f/3.  Spent more time evaluating IR Pass filters, as well as comparing the results to my computational method for evaluating filters.

Feb 2012

"Video Astronomy Using LP+IR Blocker" , 2.5Mb

A re-look at using an LP filter with and without an IR Cut filter added. In this test I also evaluate the custom IR Cut filter I had made by Omega Optics.

Jan 2012

"Filters & Galaxies for EAA Rev 1", 3.2Mb A fresh look at evaluating how a number of different LP filters work to improve the contrast of galaxies when observed with a camera under light polluted skies, both by analysis and by test.  Revised to include prediction of filter performance under different levels of sky darkness. May 2021
"Playing With Focal Ratio 1" , 3.9Mb An extensive test using my ED80 APO refractor, visually comparing the effect of different focal ratios and different integration times.

Jan 2012

"Playing With Focal Ratio 2" , 1.1Mb A follow-on test that repeats my focal ratio work using my 8" LX-10 SCT.  The test visually compares the effect of different focal ratios and different integration times.

Jan 2012

"Detailed Look At Focal Reducers", 2.2Mb

Summary of a large number of tests using various focal reducers, varying spacings to see what kinds of reduction factors and changes in focus position result.

Sep 2013

"Medium Sized Sensor FR Testing", 1.8Mb

Summary of testing a variety of FR configurations using a camera with sensor 13.4mm diagonal size.

May 2016

"Medium Sized Sensor FR Testing - Follow-up", 0.7Mb

A followup to the test report from earlier in May, examining the Meade f/6.3 SCT focal reducer in more detail.

May 2016




"Mallincam Xtreme Warm Pixel Test" , 9kb

A quick test of my Mallincam Xtreme with lens cap on, to determine how many warm pixels are visible at different AGC and INT times.

Mar 2012

"Video Ritchey-Chretien 8" , 10.6Mb

A summary of my extensive back-to-back tests of the VRC8 versus my 8" LX10.

Apr 2012

"Video Ritchey-Chretien 8 - Appendix A" , 606kb

An appendix to the main test report that discusses the different optical coating systems available today, including how they impact the observed performance of the VRC versus an SCT.

May 2012

"ICX825 Based Astro-Video Camera Comparison", 1.3Mb & "825 Camera Comparison Table"  91Kb

A three-way comparison test between the ICX825 based Atik Infinity-C, Starlight Xpress Ultrastar-C, and Mallincam Starvision-C

Oct 2016

"CCD vs CMOS for Video Astronomy", 2.0Mb

Summary of a side-by-side comparison test between a CCD based camera (Lodestar X2C) and a CMOS based camera (ASI290MM)

Nov 2017

"ASI294MC Pro vs DS10C-TEC Camera Comparison - Part 1 - Physical", 1.9Mb

A thorough comparison of two high performance cameras that use the Sony IMX294 sensor.  This first part reviews the overall physical properties of the cameras.

Nov 2018

"ASI294MC Pro vs DS10C-TEC Camera Comparison - Part 2 - Dark Frames", 2.2Mb A continuation of my comparison testing, this time looking at dark frames generated by the cameras for a range of camera settings.

Dec 2018

"ASI294MC Pro vs DS10C-TEC Camera Comparison - Part 3 - Signal to Noise Ratio & TTOI", 2.8Mb Part 3 of my comparison testing, this time looking at the SNR produced by each camera for a range of gains and exposure times.  I also present a new parameter for comparing camera performance:  Time To Observable Image (TTOI)

Dec 2018

"ASI294MC Pro vs DS10C-TEC Camera Comparison - Part 4 - Physical", 1.7Mb The 4th and final part of my comparison testing.  This final report compares the cameras in terms of fixed pattern noise, and resistance to fogging.

Jan 2019

"Measuring My Backyard LP Spectrum", 2.5Mb

A brief review of the sources of light pollution, my attempt to model it, and a summary of validation measurement I made of my backyard LP spectrum.

Nov 2021

"Solar Camera Comparison Test", 2.8Mb

A back-to-back comparison test between monochrome cameras with 4 different sensors:  IMX290, IMX183, IMX226, and IMX432.  The Sun was imaged in multiple wavebands using these four sensors:  Calcium-K, Solar Continuum, Helium-D3, and Hydrogen-alpha.

Aug 2022

"Spectrometer Configuration Impact on Spectrum Measurement", 2.4Mb

A report documenting my investigation of how a spectrometer's wavelength resolution affects its ability to accurately characterise the spectrum from a narrowband filter.  Also documented is the work I did to upgrade my spectrometer to deliver a better resolution.

Aug 2022

"Choosing a Solar Imaging Camera", 2.4Mb

An article I wrote presenting a basis for choosing the best suited camera for solar imaging depending on the particulars of your scope and waveband.

Jun 2023




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Last updated: 06-Dec-23

Copyrights to all content from the webpages hosted here belongs to Jim Thompson. 2009-2023.