Photonist

Andrew, Yes, I also noticed the Steeltrack dovetail diameter in the “Recommended accessories” section the “Base for Newtonian focusers for tubes with…” where they say “Diameter of the central hole ... 78mm. Fits for all telescope focusers with a male dovetail with that diameter. The focuser is held in place with two slug screws from the side.” That would seem to fit the Lunt body exactly (if the Steeltrack dovetail is long enough, that is 6 mm). I’m afraid the Steeltrack refractor version is too long and the drawtube protrudes too far into the telescope. The TS Monorail is also interesting, but it may be a bit long (70 mm) when using a focal reducer. I think there was just enough infocus using a 0.5x FR with the Lunt focuser. Viljo

Hi, I’m responding to Ken’s private tip of this interesting topic. Unfortunately, I don’t have a final solution, yet… I have planned to replace the poor Lunt focuser from the beginning and probably will do it if my Lunt 60 telescope mod using the SW150/1200 mm turns out to be successful. Unfortunately no sunshine here since the first short test 3 weeks ago and not much hope next week either. I have skipped the FeatherTouch model as too expensive compared to the Lunt 60 telescope price. So far I have not searched seriously for other options. As a first aid I installed a cheap Sky Watcher Motofocus which made the focuser more usable but bulky. The Lunt focuser is attached to the telescope body with a dovetail and 3 recessed hex screws (4 mm diameter) very near the edge. The dovetail front diameter is 78mm and its length 6 mm The Lunt body takes a 78 mm diameter focuser so it is perhaps not a common standard. The Lunt focuser body length without the dovetail is 52.3 mm plus the 2” adapter 14 mm and has a 34 mm travel. Many refractor focusers have a long focusing tube protruding far inside the telescope body. The Lunt body can take only 33 mm because of the etalon module. The Steeltrack refractor model may have a too long focusing tube (looking only on the image). The Steeltrack Newtonian version is very nice and short and even has a dovetail, if only the dovetail diameter would match, but I haven’t found any measurements for it. First I would research the Steeltrack Newtonian dimensions and then consider the much cheaper TS TSFOCR2M for 148 EUR. However, the TS diameter is only 72 mm, so a simple 3 mm spacer ring would be needed. I use the TS SCT version (158 EUR) in my PST mod and it works great. Best wishes, Viljo

Merlin66, Great to read about your excitement with this DS mod. I hope you are still as enthusiastic. Are you satisfied with the Meade telescope you used for this mod or what would be the optimal specifications? I have both etalons and a few achromats around. I have used the PST II mod with a 1200 mm scope stopped to 120 mm with quite good results (especially when using a Barlow) of course turbulence permitting. Viljo