Lacerta Herschel-LAC1s 1.25"

Why Brewster Angle?

The Lacerta 1.25 "Herschel prism with Brewster angle has some advantages over 90 degree prisms. Since the polarization at Brewster angles is almost 100%, the Lacerta Herschel prism with the mandatory ND3 neutral density filter AND with an additional polar filter enables practically full light attenuation - in reality a dimming range between ND4.07 and 6.37 - mostly even more. Without a polar filter, the Herschel prism works at the lowest light attenuation (ND4.07) and can thus be used for photography. With the "traditional" 90 degree Herschel prisms, this value is only between 4.24 and 5.00.

The visual perception at different neutral densities is shown in the picture below. It is easy to see that the granulation in traditional Herschel prisms can only be observed well with an additional THIRD filter (ND3 and polarizing filter are required!). Herschel prisms with Brewster angle do not need an additional filter because the dimming range is continuously possible up to ND6.37!

How do you use the 1.25 "Herschel prism?

• The ND3 filter is already screwed into the T2T2pM28 adapter on the eyepiece side and is absolutely necessary
• The polar filter is simply screwed into the eyepiece, the overall brightness is adjusted by turning the eyepiece.
• Please note that the optical elements must strictly have the following order: telescope - Herschel prism - ND3 filter - polar filter - additional filter (e.g. UV / IR block or contrast filter of your choice) - eyepiece (or camera)
• When changing the eyepiece, it is essential to ensure that all filters are screwed around and reassembled in the correct order.
• The light path is 83mm from the edge of the housing to the 1.25 "eyepiece socket

Why is the Lacerta Herschel prism open at the bottom?

• The open design enables much better ventilation than other Herschel wedges on the market
• The proportion of scattered light that comes through the opening is negligible against the sun from the telescope
• No shoes will catch fire as no light escapes through the opening

Light path:

• 1.25 "version: 61mm from T2 to T2 (" S "version approx. 89mm)

Weight:

• 1.25 "version: 308g

The 1.25" wedge with 1.25" / T2 connection is sufficient for:

• f/6 for 1000/1500mm
• f/8 for 1200/1800mm
• f/10 for 1500/2000mm focal length