Orion 80 mm PST MOD
Posted: Sun Jan 29, 2017 2:05 pm
I completed a new PST-MOD using an Orion 80 mm achromat removed from an Orion Wide Field 80 mm refractor. I built a new tube from 4-1/2" OD
6016 grade aluminum tubing, and machined a new lens cell which is slidable within the OTA. The lens cell was arranged so that it almost touches the racked-in focus tube. I used a Meade 102 focuser with a large bore drawtube (2.5") so that the fast f/5 light cone would be fully fielded in a steep (f/5) light cone and in such a short scope. The OTA tube itself was made short so that it would just focus the PST collimator lens at -200 focal ratio. The little scope can also be used as a white light solar scope using a Lunt Hershel wedge, or just a good little deep sky instrument because the focus travel of the Meade 102 focuser is a whopping 11" out-travel. I anodized the OTA Gold with a black machined front ring that takes a Lunt 60mm Ha making it also a double Ha filter instrument, but I find the wider 80 mm aperture perfoirms better alone without the restrictive 60 mm Lunt Ha doubler. The whole outfit performs well in all modes. The 80 mm achromat is also available at Surplus Supply on the web for less than $50.00 The expensive part of the fabrication was machining the lens cell but it was more than worth the money. It would be worth my while to buy the achromats and focusers and build this scope for
people as it performs much better than my Lunt 60mm PT Ha with its wider aperture plus it is an all-around versatile instrument
6016 grade aluminum tubing, and machined a new lens cell which is slidable within the OTA. The lens cell was arranged so that it almost touches the racked-in focus tube. I used a Meade 102 focuser with a large bore drawtube (2.5") so that the fast f/5 light cone would be fully fielded in a steep (f/5) light cone and in such a short scope. The OTA tube itself was made short so that it would just focus the PST collimator lens at -200 focal ratio. The little scope can also be used as a white light solar scope using a Lunt Hershel wedge, or just a good little deep sky instrument because the focus travel of the Meade 102 focuser is a whopping 11" out-travel. I anodized the OTA Gold with a black machined front ring that takes a Lunt 60mm Ha making it also a double Ha filter instrument, but I find the wider 80 mm aperture perfoirms better alone without the restrictive 60 mm Lunt Ha doubler. The whole outfit performs well in all modes. The 80 mm achromat is also available at Surplus Supply on the web for less than $50.00 The expensive part of the fabrication was machining the lens cell but it was more than worth the money. It would be worth my while to buy the achromats and focusers and build this scope for
people as it performs much better than my Lunt 60mm PT Ha with its wider aperture plus it is an all-around versatile instrument