In preparation for my "Ashen Light" observing attempts in June 2023, I did Venus observing and imaging tests using some of my various 1.25" and 2" filters. This article is a report on those tests, done on 3 June 2023, 4 June 2023, 6 June 2023, 7 June 2023, and 9 June 2023.

Visual Tests

1.25" filters on a 1.25" 5.5mm eyepiece (443X). Here are the results.

Light Reduction Filter (LPR): Good to reduce the glare from the bright planet. Shading near the terminator was evident.
#82 Light Blue: Very little effect.
#8 Light Yellow: Very little effect.
#56 Light Green: Reduced glare. Some near terminator shading visible.
#21 Orange: Very little effect.
Moon Filter: Reduced glare. Near terminator shading not as evident as with LPR filter.
Hydrogen-Beta: Considerable brightness reduction. Near terminator shading more pronounced.

2" filters on a 2" 5.5mm eyepiece (443X). Here are the results.

2" UHC: Reduced glare from the bright planet disk.
2" SII: Planet dimmed too much for visual use.
2" Hydrogen-Alpha: Too dim for visual use but better than SII.
2" OIII: Reduced glare from bright planet disk.
Variable Polarizing Filter 1 (VPF1): Nice reduction in the brightness of the planet's disk.

I rotated the eyepiece with the VPF1 attached to see if any polarization of the light from Venus could be detected. Nothing noticed.

I attached VPF2 to the star diagonal. I rotated the eyepiece with VPF1 attached to vary the amount of dimming of the planet's disk. Near maximum polarization provided a good view of shading near the terminator.

The 1.25" LPR and 2" VPF1 provided the best views of a half-illuminated Venus, 443X.

Photographic Tests

Mounted the D850 DSLR at prime focus + 2" 2X Powermate using a 2" to 1.25" adapter (to accept the 1.25" filters). Imaged Venus at various exposures using a White Balance of 4550K. The following images are cropped from the full-frame images, but otherwise are not edited.

No filter (1/400sec, ISO 400)


LPR (1/320sec, ISO 400)


#82 Light Blue (1/320sec, ISO 400)


#8 Light Yellow (1/250sec, ISO 400)


#56 Light Green (1/250sec, ISO 400)


#21 Orange (1/400sec, ISO 400)


Moon Filter (1/250sec, ISO 400)


Hydrogen-Beta (1/320sec, ISO 1600)

Mounted the D850 DSLR at prime focus + 2" 2X Powermate and did the following 2" filter test images, White Balance 4550K. The images are cropped from the full-frame images, but otherwise are not edited.

No filter (1/250sec, ISO 400)


UHC (1/250sec, ISO 400)


SII (1/250sec, ISO 4000)


HA (1/250sec, ISO 4000)


OIII (1/400sec, ISO 1600)


VPF1 (1/250sec, ISO 400)

For imaging, the 1.25" Moon filter and the 2" VPF1 filter provided the best images.

I also did a 1080p, 60fps, video recording, 1/400sec, ISO 400, of Venus, prime focus + 2X Powermate + VPF1. This is a stack of 1392 video frames.

Did a 1080p, 60fps, video recording of Venus, prime focus + 4X Powermate + Variable Polarizer Filter 1 (1/400sec, ISO 1600). This is a stack of 1366 video frames.

As Venus gets lower in the sky, using the ZWO Atmospheric Dispersion Corrector will be essential.

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