Telescope Focusing Problem

If possible, I would find a manual for it and follow the instructions, with little fear of making things worse.

You might just want to attach the scope to a heavy duty tripod so that the scope doesn't move when you turn the focus ring.
You could try letting a drop or two of lightweight oil wick into the focus mechanism to see if that would help, but you'd be taking the risk that the oil might find its way onto the primary mirror. (Though for bird watching that might not be such a big deal.)

I do not know the mechanics of this particular spotting scope but mechanical wear is the bane of all optical adjusting devices. If you are lucky, when you disassemble the focusing mechanism you will find that grit has lodged itself in some tight tolerance spaces and that all of the actual bearing surfaces are clean and pristine. Far too often grit and ancient decomposed grease have gouged and galled the bearing surfaces so that smooth motion will no longer be possible. If you are successful in finding a repairable problem like only a binding decomposing grease, reassemble using the smallest amount of optics grade silicone grease that you possibly can.

I must warn you.

If you do not have the manual dexterity and tools to attempt a cleaning of a jewel bearing mechanical watch then do not attempt to disassemble this scope. It is very unlikely that you will find a repair manual for a telescope. At best you will find an exploded diagram of your scope. Optics repair is a field that few people try because too often disassembly either reveals permanent damage or reassembly produces more problems than existed before the repair.

Are you using this spotting scope in cool or cold weather? That may account for difficulties in regard to focusing issues, as the optical grease with tend to become increasingly more viscous as the air temperature drops. This can happen a lot with all types of optical devices, from binoculars to telescopes to rifle sights.

Also, is the scope old, and what is it's age?

Is it used outdoors a lot? Has it been dropped in the dirt by accident?

As Fred stated, it just takes a small amount of dust, grit of grim to gum-up the focusing mechanism. It may be prudent to remove the old grease and replace it with a small amount of silicon-based grease as Fred mentioned....just make sure it's acceptable/compatible for use in optical devices and has less temperature sensitivity properties than the original grease.

Before you do anything to the scope, make sure you talk to the manufacturer's tech support about your focusing issues and the possible contamination of the focusing ring/jewels grease. They may offer technical repair services, especially if the scope is within warranty. They may also sell the correct optical-compliant grease for your scope repairs. You do NOT want to get any type of grease on either the primary or secondary mirrors as well as the eyepiece lenses, as it be nearly impossible to get them clean again without having them refinished or replaced.......most, if not all, eyepiece lenses any optically multi-coated and could be ruined by any type of grease!

Good luck with your scope!

Signed,

CaptMoosie, PhD/PE

[builder of homemade Newtonian Reflector scopes since I was 16...now 53]

I have used a Celestron MC type spotting scope for over twenty years and found the same issue as yours. Mine simply unscrews at the far end of the focus. As long as I am very cautious as far as dust on/damage to the mirror while disassembling it is a piece of cake. Mostly I just point it downwards when unscrewing to prevent things from falling in. I used denatured alcohol to remove some of the heavy grease used in assembly and applied a lighter grease to ease movement, especially in colder weather.

If you use it quite a bit it just become a maintenance item, but makes the scope much more enjoyable to use.

If the focusing ring has always been stiff, it could be the assembly tolerances and lubrication will not help. These Chinese made scopes have a poor reputation for build quality. Fabricating a lever for the focus ring, by clamping onto the focus ring a pipe bracket or U bolt at one end of a long bar, might make it easier to hold the scope steady while refocusing.

If the problem has developed over time while in use, lubrication is more likely. I would opt for a copper of silicone based lubricant rather than a grease based one, which would compromise optical quality if it migrated onto the lenses. (e.g. if stored or carried in warm/hot conditions in the wrong orientation.)

Why don't you just respect intimacy?

All great responses and advice.

However why not take it to a watch smith or a lens crafter to have them locate the issue and hopefully make the repair. It is then their warranty and guarantee that it will work for you.

Hi All

Thanks for your comments!

The focusing ring is half-way along the body of the scope, around the full circumference.

I tried using a light oil around both the ring/body interfaces and gave the ring a good rotational workout. This seems to have eased the problem. There is still a little oil exuding from the interfaces (getting less and less), but I'll see how things go.

I would expect that from the positioning of the ring and that there wasn't a great deal of oil used, that there shouldn't be any likelihood of oil getting on the lenses/mirrors at the extremities of the scope.

Thanks!

I have a unit just like that, in the colder temp that focal ring is extremely difficult to adjust. Go to the following website and read thier warrenty information........... http://www.konuspro.com/en/site/konus_life..........Basically it say's if you can justify the reason for return they will replace for the life of the unit, all you pay is P&H. I haven't done this yet, however this week its going to happen. By the way according to the website if they decide to replace and they don't carry that style anymore they send one of equal valve and equal power or as close as they can get. Regards,