Finderscopes: are they redundant?

"When it comes to GoTo systems, it becomes a little less clear just how useful a finderscope can be."

Credit: iStock

Once upon a time we were lost without them. The trusty optical finderscope allowed us to get a wide field of view to visually home in on targets, or help us star hop to the next one.

They featured greatly in BBC Sky at Night Magazine's telescope reviews and were considered to be a vital part of the equipment.

Now don’t get me wrong, in terms of any basic or manual telescope, the finderscope still serves that purpose very well, and is a necessary piece of kit.

But when it comes to GoTo systems, it becomes a little less clear just how useful a finderscope can be.

"What?" I hear you cry, "you still need it for the initial alignment for the GoTo to work accurately don’t you?"

Well I think the answer is yes and no to that.

If your initial polar alignment is rough or you have a system that you need to move around a lot, perhaps for public outreach, then I agree that the finderscope remains useful, but only for the alignment phase of setting up.

After that, if your polar alignment and star alignment is accurate then your target should always be in the view of a wide field eyepiece if not bang in the centre.

However, if you are able to conceive a permanent setup for your mount, you can get polar alignment very accurate indeed. Once done, you will likely find you hardly ever use the finderscope, as the target should be in the centre of the view or imaging system you are using every time.

But today manufacturers have spotted an opportunity amongst all this, and we are now seeing finder/guidescope combinations.

In other words, the fact that many astronomers are now using the finder as a guidescope for deep-sky astrophotography may well mean we haven’t seen the last of the finderscope just yet! 

Read the latest telescope and equipment reviews, image processing guides and 'How To' projects in the March 2018 issue of BBC Sky at Night Magazine, out now!