I'd also recommend the Svbony 7-21mm zoom that you're saving up for. One zoom eyepiece will cover multiple focal lengths and so is really excellent value for money.
Despite having high quality fixed focal length eyepieces, I use my zooms a lot more often. The zoom plus a Barlow lens and a low power, wide field eyepiece is often all I use the whole evening. For the time being your 25mm eyepiece can fulfil this low power role. You've probably already found it's sharper than your 10mm.
Fixed focal length eyepieces may be slightly better corrected when compared with a zoom at the same magnification. But that's not always a fair comparison as that magnification may not be the optimum for a given object. This is because one of the many advantages of a zoom is to be able to dial in precisely the best focal length. For instance, this may be 13mm or even 13.1mm, which may actually show more detail than shorter or longer fixed focal length eyepieces - even better quality ones.
I particularly like the ability to increase the magnification to make use of brief moments of good seeing (a steady atmosphere). It takes more time to swap out an eyepiece, and the opportunity may then be missed. You can't see anything if you haven't got an eyepiece in the focusser!
Zooms also enable the field of view to be varied to frame an object to get the prettiest view. For this reason I particularly like them for clusters.
They're also handy when you're using filters. You don't have to unscrew and then replace the filter when you change magnifications.
Many of those who post here and advocate fixed focal lengths are experienced observers. It's so easy to forget what it was like as a beginner! A zoom eyepiece enables beginners to easily learn what difference a change of magnification makes on all the various classes of object. It also shows them what focal lengths would be most useful to their eyes, their telescope, and their observing conditions. They then have the option of buying/not buying the most appropriate fixed focal length eyepieces for them. For these reasons I'd always recommend that beginners buy a zoom as their first eyepiece.
I'd supplement the zoom with a Barlow lens - I wouldn't be without mine (in fact I own 3 of varying powers).
Especially with your fast f/5 scope the Barlow will almost certainly improve the sharpness of your views.
The multiplication factor varies, but 2x is most common. Some of these 2x Barlows can also be used at 1.5x, although it's not always mentioned in the blurb, and it's one of these I'd recommend. These dual 1.5x/2x Barlows allow the black lens cell to be unscrewed from the body of the Barlow and then screwed into the filter thread at the bottom of an eyepiece to give approx 1.5x.
The exact amplification varies from eyepiece to eyepiece depending on where the field stop is located. 2x amplification with a 7-21 mm zoom will give you magnifications of approx 62-186x. I don't know what the seeing (atmospheric turbulence) is like in Croatia, but here in the UK it would mean you wouldn't be able to use more than 186x very often. Additionally, your equatorial mounting is very lightweight and so may shake a bit with high powers.
However, you'd get more use from the approx 46-139x that 1.5x amplification will give you. Additionally, at a given magnification the field of view will be bigger with 1.5x amplification. This is because the vast majority of zooms have a wider field of view at the high power end.
Most would recommend that filters come after a basic range of eyepieces. So I agree with your plan to buy the 7-21mm zoom first, then the Barlow.
Edited by Second Time Around, 22 April 2021 - 04:57 AM.