Prior saying of what my quick research revealed to me about this old generation of telescopes, I must inform the readers of this topic that I am at the age of 50 years old, and in the past 15 years I am hobbyist photographer from the ones spent approximately over 3000 Euro for several Olympus digital cameras and lens accessories.
I am very familiar of chromatic aberration term, focus length, expensive Olympus Japan (zoom – wide – macro) lenses, Hoya filters and lens hood.
It is a fact and known rule of the game, that the diameter of your lens (if they are fixed on the camera) this is your guide speaking of compatibility with other add on lenses.
For example my Olympus C2100 UZI has a barrel diameter of 49mm, all my Lens accessories they starting from that diameter and I can use even larger in diameter lens with appropriate adapter rings.
My finding about these (old technology) telescopes sold as telescope for starters, this is that they using diameter of eyepieces and accessories of 0.965" or 0,96 “ or 24.5 mm in metric which today this is obsolete. Mother China (the real maker of this telescope) still has (0,96 inch or 24.5 mm) eyepieces and accessories but quality of optics and of housing plastics of eyepieces and adapters, they are at toy level (manufacturing quality).
New to me awareness and fact, this is that telescopes industry moved ahead adapting 1.25 inch as standard and this is now followed by all major telescope parts manufacturers, the outcome is that quality eyepieces and filters they are produced only at 1.25 inch. New economy telescope at identical dimensions (made in china), they sold on eBay today with tripod and all relative accessories for a total of 60 Euro.
One Set of three spare eyepieces’ 20MM + 12.5MM + 4MM (0,96 inch / 24.5 mm) they sold for 10$ , and an 90 Degree mirror adapter for 3$ USD.
Speaking of expectations, specific model of telescope this can not use modern high quality eyepieces as is.
Now I am thinking that it is neither cost effective, to replace focus system mechanism with a modern paying another 25 Euro just for it.
Personally I made the decision to pay and get the cheap compatible parts so to make this telescope functional.
Because of old tripod design and mostly of average performing rotation head, I am thinking that 4mm Eyepiece this will be useless.
At 700mm lens this 20MM Eyepiece the gain is 35X of magnifications and alternatively one 12.5MM Eyepiece this will deliver 56X of magnification.
In the positive side of things, because of specific telescope age and brand, the front lenses they are of true glass.
And also it 90 Degree mirror adapter this is also a part made by quality metal and plastic plus the mirror.
I did ordered right away another 90 Degree mirror adapter, this sold at 3$ and it is entirely made of plastic. I am now examining the possibility of transferring just the 0.965" eyepiece holder (barrel) of it at my (Bresser branded) 90 degree accessory.
New rule in this game, if you do not trust the newer produced part, then use it so to rebuild the old one which was produced at higher quality standards.