Finding and finder-scopes

With its high magnification and apart from the moon, finding objects can be very difficult for new and experienced observers. Technology can help but a finder will be essential for most telescopes.

In a nutshell, the combination of Telrad (for initial alignment of naked eye stars) and RACI (for next alignment of dimmer stars and asterisms) is the ideal combination. But avoid the RACI by itself.

 

Skywatcher 200P setup
My set up (L to R) – EP, phone, right angle finder , Telrad

Most telescopes will come with finder scope that is used to align the main telescope using cross hairs or reticule. The finder will need aligning using two or three screws and for the first time, I would do this in the daytime using a distant tree or antenna.

I found it difficult to use the straight-through finder that came with my Dobsonian telescope. First, at 9×50 it is quite powerful which meant that I was pointing at a star but it wasn’t appearing in the finder. Second, it is very close to the tube of the telescope which meant I was having to bend down a lot to see through it. After a period of time, this became very uncomfortable.

My first workaround was to attach a small plastic sighting tube to the finder. I was able to find the star in the tube and at long as my head was in the right place, it was usually in the finder. Not ideal.

Telrad

I decided to get a non-magnifying finder that displayed a red circle (reticule) at infinity; which means that as I moved my head, the circle would not also move. I was very intrigued by The Split-Pupil Finder and if I had access to a plastic lens, I would have made one. Another interesting DIY option I considered was this one.

The best-known reticule finders are the Telrad and the Rigel Quickfinder. Both get great reviews and recommendations from users. The Rigel is taller and not as bulky so would have been my first choice but I came across a used Telrad and got that.

The Telrad has been superb and I would recommend it for finding objects quickly. I can often go straight from the Telrad to the eyepiece without having to use the finder. But the finder was still useful when I needed magnification for aligning an object that needed a little magnification.

Tip – The Telrad does suffer badly from dew so here is my fix.

Tip – Some people add a “riser” to the Telrad mount to reduce the amount of bending. As I only spend a few seconds looking through it, I haven’t gone down this route.

Wide Angle Low Power Eyepiece

A used 42mm, 65° Revelation/GSO eyepiece lets me observe and get great almost 3D views of large clusters, star fields and objects like M31. It also has the advantage of being a finder-eyepiece. It is much easier to find an object in the wide field eyepiece and then switch to high power if necessary.
Finder rating 9/10

Right angle finder (RACI)

Even though the combination of the Telrad, Wide Angle Eyepiece and straight-through finder worked well, I decided to replace the finder with a right angle type. This eliminated the need to bend when using the finder and again it works in conjunction with the Telrad.
Finder rating 8/10

Tip – Do bear in mind that adding a RACI (480g), Telrad (308g) and a smartphone plus bracket will move the centre of balance. A counter weight on the opposite side (I use a magnet) will help especially when the OTA is near horizontal.
Further reading

Dim objects like galaxies and the Crab nebula may take more than these methods to find them.

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