1.25" star diagonal with 99% reflection, dielectric coating, L/10 PtV
(Gross prices are calculated with 19% or 7% VAT. If your country-specific VAT is higher, we take over LACERTA GmbH the additional tax costs)
Connention: 31,7mm Reflection: 99% Degree: 90°
Shipping weight: 1kg (Shipping costs)
(The stock is for information only and includes items that have already been reserved) Wien:
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... for a dielectric zenith mirror with 99% reflection?
99% reflection and long life
Thanks to dielectric (non-metallic) coating, the Castell zenith mirror not only has a high reflectance of 99%, but also a long service life. The long service life is achieved because the non-metallic dielectric surface reacts much less with the acids and bases in the air than an aluminum coating with a quartz protective layer.
Ring clamping instead of fixing screws
The 31.7mm socket has a ring clamp with a large knurled screw.
Test: checking the reflection
Test procedure: Take a test photos
with a camera through the diagonal (ISO200, manual mode), then measure
the brightness value in Photoshop using a histogram. This test serves as an estimate of the zenith reflection. The following models were tested:
(nominal value:99%) Measured: Luminance = 98.9% Green / Visual = 99.2% (Very high
reflectivity in the entire RGB range, but also the most expensive zenith
mirror in this test series. It is identical to other well-known models)
(nominal value:99%) Measured: Luminance = 96.1% Green / Visual = 95.3% (evenly in the entire RGB range, but shows less reflectivity than advertised both in luminance and in green / visual)
(nominal value:99%) (Visually, it
reaches almost 99%; in the blue area, however, a little less
reflectivity and therefore a slightly yellow tinge; but is advantageous
for Fraunhofer refractors with blue halos) Measured: Luminance = 95.3% Green / Visual = 98.2%
(nominal value:91%) Measured: Luminance = 90.3% Green / Visual = 92.4% (As
advertised, a good zenith mirror without higher reflectivity criteria.
The image is, however, much darker than in the other three zenith