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Lacerta Herschel-LAC2s 2" (T2)
- 269,00 €
- Estimated delivery time 3-18 days
The LACERTA Herschel prisms differ from the other Herschel prisms on the market (INTES, LUNT, Scopium etc ...). They enable full polarization at the Brewster angle, in contrast to the 90-degree versions, which are easier to manufacture, where only partial polarization is possible.
Why Brewster Angle?
The Lacerta Herschel prisms with Brewster angle have some advantages over 90 degree prisms: Since the polarization at the Brewster angle (57 degrees) is almost complete, the Lacerta Herschel prism with the mandatory ND3 neutral density filter AND with an additional polar filter enables practically full light attenuation - in In reality, a dimming range between ND4.07 and 6.37 - usually even more. Without a polarizing 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 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!
When do you use the 2 "Herschel prism?
Below 2000mm focal length the 1.25 "prism is sufficient, and it saves the focus path that you might need for the filter adaptation. Above 2000mm focal length the 2" Herschel wedge is indicated, you need at least 130mm free focus path because of the additional structures for the filters The unit of rotation is a little more than that of a 2 "star diagonal.
How do you use the 2 "Herschel prism?
- First the ND3 filter is screwed in, it is mounted directly into the Herschel prism (output on the eyepiece side), in the initial part of the rotation adapter. If you do not have a rotation adapter, the ND3 filter is screwed into the eyepiece
- Then the polar filter is screwed into the rotation adapter end part. If you have a Herschel prism without a rotation system, the polar filter is also 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. 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. When using a rotation adapter, changing the eyepiece is much easier, as both filters are screwed into the rotation adapter, the ND3 sits in the rotation adapter, the beginning part and the polar filter in the rotatable end part. In that case (and only in that case) the eyepiece can simply be changed!
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 part of the scattered light that comes through the opening disappears from the telescope towards the sun
- No shoes will catch fire as no light escapes through the opening
NOTE! This is the T2 model!
- 2 "version: T2
- 2 "version: 685g
- PostNord Parcel locker
- 5,90 €
- PostNord Home deliver
- 19,00 €
- PickUp Parcel
- 5,90 €
- Delivery time to EU 2-5 days. Pick up delivery
- UPS Standard
- 14,90 €
- Delivery to Europe in 2 to 5 days.
- DHL Economy Select
- 14,90 €