APM TELESCOPES PM-HERSCHEL-2-DX 2-Inch Herschel Wedge Instructions
- June 5, 2024
- APM TELESCOPES
Table of Contents
APM TELESCOPES PM-HERSCHEL-2-DX 2-Inch Herschel Wedge
Instructions Design Safety information
The APM 2″ Herschel wedge offers a safe method for visual and photographic observation of the sun in white light. Due to the special reflection element inside, approx. 95% of the light and heat energy from the entering light path is switched Off. The special ceramic element (light catch) behind this Herschel element absorbes the residual heat and light energy. A safe observation now is provided. Since the light radiation is still too great, a neutral density filter ND 3.0 (0.1%residual transmission) and a polarization filter (2″, changeable) is installed for fine adjustment of the final image brightness.
Never use the Herschel wedge without a visual filter! The radiation is
still harmful to your eyes!
Back focus: 114.4mm
Due to the abstinence of reflective surfaces, Herschel wedges showing a higher-contrast, more detailed image of the sun than filter foils or glass sun filters. The direct comparison is immediately visible, granulation and shading of the umbra and penumbra areas around sunspots are clearly better contrasted, flare areas stand out very nicely and three-dimensionally. Also photographically the results with the APM Herschel Wedge are definitely better!
Usage:
The Herschel wedge is only suitable for uncemented refractor lenses without
correctors / reducers / flatteners in the light path! Additional optical
components in front of the Herschel wedge could overheat and be destroyed.
Connecting the wedge and centering the Sun image
The Herschel wedge can be inserted in the 2″ focuser, the sun should be
outside of the field of view beforehand. Moving to the sun should be done with
the lens cap on the front. A special sun finder scope can be used as an aid.
Finder scopes and Guiding scopes must be covered before moving to the sun,
risk of destruction! When centering the sun, you can also use the light spot
on the light catch for orientation; the light catch can be used as a “sun
finder“.
Adjusting the image brightness
The built-in polarization filter allows to adjust the brightness of the image
continuously in a certain extend. To do this, loosen the rotation clamping
screw slightly and turn the lower knurled ring until the image (e.g. without
the eyepiece) appears sufficiently subdued. If the image is still too bright
for visual observation, we recommend using additional ND filters with less
attenuation (ND 0.9 or ND 1.8, in example). Depending on the size of the lens,
different neutral filters are useful in order to adjust the image brightness
to the position of the sun, the transparency and the recording camera /
viewing habits.
A photographic adjustment of the image brightness can be done in the grabbing
software by setting the gain and exposure time values. It makes sense to use
low gain values and exposure times that are as short as possible in order to
keep the influence of atmospheric seeing as low as possible. The recording
camera can be used with an adapter 1¼” – 2″ (with the corresponding socket
adapter) or with adapters 2″ – M42. Most cameras have an M42x0.75 thread
connection, you will find the appropriate adapters in our range of
accessories.
To further increase contrast and especially to eliminate contrast losses, we
also recommend using a narrow-band green filter. A special solar continuum
filter with an FWHM of 10nm at approx. 540nm further improves the contrast and
resolution of most refractor lenses. 
Data:
Measures:117×63 x 127mm, Weight: 830g Optical Lenght (Back focus): 114.4mm
Delivery:
APM 2″ Herschel wedge, FastLock adapter 2, integrated N.D. 3.0 Filter, MC, 2″
Polarization filter, unscreweable, Sleeve adapter 2″ – 14, Transport case
