A few Mods to my Finderscope

Just thought I'd post some photo's of some of the mods I did to my Stellarvue F80 Finderscope. Its an 80mm F3.7 Achromat with a 300mm Focal length. I got this largish apeture Finderscope way back when with the intention to use it as a Rich Field and Spotting scope with the purchase of a mount. I finally picked one up a few weeks ago from Martin (Nerro). Its an old Nexstar 80GT. Got it for a great price (Thanks again Martin). After working out the foibles of the handset (buggy Firmware) and stripping down the mount and cleaning the gears/clutches etc and finally getting around to RTFM'ing I am able to get decent Goto's and tracking.

So now I finally had a mount to use the scope for its other intended purposes. I figured out a way to mount it to the GT tube clamp without having to remove the rings and dovetail bar that are used to affix the Finder to the mainscope. Just had to shave a few millimetres off the mount clamp so it fit between the rings. Then I mounted a dovetail shoe to the OTA after I figured out the best orientation that worked both when the scope was mounted on the main scope or when mounted on the Nexstar. My home observing is right under street lights and even with a baffle half way down the inside of the tube, the incidental light from the streetlight would turn the sky background orange. So I took the OTA apart completely and flocked the inside of the OTA and the dewshield. If the fact that I had a terrible time seeing the dovetail shoe nuts to blacken them in broad daylight is anything to go by then this should do the trick. Its like a black hole in there now and it was very tricky guiding the black nail varnish brush to the nuts

I found a few odds and ends and with the drilling of a small hole in the fork arm casing I was able to mount the handset bracket on the arm putting the handset right where I want it where it moves with the OTA so thats one less cable to worry about with regard to cordwrap.

I also cut off the old D-Cell battery pack from the cable and wired on connectors to connect the scope to a spare 5ah 12v battery I had.

Now I'll be able to quickly and easily swap the scope between finderscope duties on the mainscope and Richfield/Spotting/Lunar Outreach duties on the Nexstar. The RDF is permanently mounted and aligned to the Finder OTA, so I only ever have to align the OTA to the mainscope and then both are aligned to the mainscope.











Anyone got a spare Firmware version 4 Nexstar handset btw. Brings some nice improvements to this mount and no foibles/bugs but I can't afford the price of a new handet. They're about 6 times the price I paid for the mount!! Could stretch to 30 or 40.

Nicely done Keith, turns it into a very versatile piece of kit. If I could ask what did you use to flock the inside of the scope and where did you acquire it. Planning to do something similar with a CG5 mount to use for viewing while my main scope and mount are taking images. : cheer:

It was leftover flocking paper I bought from US company Scopestuff a few years ago when I was flocking the OTA of my Dob. Protostar now do a product called flockboard which is basically the same flocking material but on a plastic backing rather than self adhesive on paper. You cut the circumferance and roll it up and slide it into the OTA and it springs out to fit the OTA perfectly because of the elastic resistance of the plastic backing. It can be removed as easily as it is installed. A far cry from the frustration of the self adhesive flocking paper I used.

My future plans for this 'little' scope/mount is to fabricate some brackets that will bolt to the azimuth mounting to hold the 5ah 12v on one side and an eyepiece tray on the other side to counterbalance the battery. No more Cordwrap

Thanks Keith.

nice, so did you get a chance to use it yet ?

I've used it twice now for Lunar outreach outside our shop. This is before I tuned the mount and figured out the alignment routine foibles though, so I was just letting the moon drift and recentering every few minutes with the arrow keys. From now on though it'll track itself because I worked out why the two star align wasn't working.



Looked comical with the Televue 3.7mmSX Ethos in the focuser though. As tall as it was long I had lots of people asking me how much 'that lot' cost. €1000 I said. That IS expensive??!! No, No, the telescope and mount were €250. The eyepiece was €750 .......actually, I just made that up, I just told them the price of the scope and mount.

I learnt some things with regard to eyepieces though. As much as I wanted to let the public look through the premium glass with the spacewalk AFOV going forward, I found that there was more mascara on the lenses afterwards than I was comfortable with I also found that some people found it hard to find the sweetspot with the <15mm eye relief of these eyepieces and were suffering blackouts or just plain missing the light cone altogether and ending up looking at the inside of the EP barrel

Thus I am glad I never got around to selling my Hyperions after I got all the Ethos. I'll be using the Hyperions for outreach purposes in both my big Dob and the small scope from now on.

Had a bit of luck. As I mentioned in a previous post I wanted to mount the 5ah SLA battery and an eyepiece tray above the azimuth pivot so they turn with the scope so I don't need to worry about cordwrap. Handily the Eyepiece tray performs double duty in that the EP's are close to hand and also act as counterweights to the battery mounted on the other side so as not to strain the azimuth motor. Cordwrap is usually a problem with this mount because the DC connecter is a very loose fit and easily pulls out. This is a nightmare when the old firmware handset has a long 2 star align routine that would need to be redone if the plug pulled out cutting power. The cordwrap setting in this old handsets firmware doesn't work either :smashpc: So as you can see, I am not modding for no good reason {Keith, You will ALWAYS find a reason to mod your scopes!! ]

The 'bit of luck' was that I had a nice strong thick sheet of metal that I had cut into a circle for use as a cooling fan baffle on the main scope with a smaller centre circle cutout for the fan. I will no longer be using this particular baffle on the main scope. Turns out it is perfect for the battery/EP 'tray' on the Nexstar mount. The centre cutout fits the Azimuth assembly like a glove All I need to do is strip the motors and encoders out of the nexstar, install the metal plate, re-install the nexstar internals, cut out some 1.25" holes for the eyepieces to sit in and finally give the plate and the battery a coat of gloss black spraypaint.

Heres the proof of concept with the plate just sandwiched between the Tripod head and nexstar mount for the test.