Hey Alex, I see you are looking at the Astroshop, which means you must be from Europe.
I bought my Skywatcher 150p dobson there. And that is the scope I also recommend over the Bresser 150mm, the one you linked in your first post.
Despite both having 150mm (6") aperture, there are some optical differences, in which the Skywatcher (SW) is better in every way.
The Bresser scope has a focal ratio of f/5. Now compared to the f/8 from the SW, that means that the SW can better handle cheaper eyepieces. But thats is not all. The f/5 ratio also needs a bigger secondary mirror.
The Bresser has a secondary mirror of 55mm diameter.
The SW has a 34,5mm secondary diameter. That is quite the difference.
Doing simple math, if we calculate the central obstruction of both scopes, the SW dobson actually has 10%! more light gathering area than the Bresser, despite having the same aperture. That is because the larger secondary on Bresser blocks more of the incoming light, together with relatively thick secondary mirror supports, which also has a greater negative impact on the contrast of the image.
The light gathering power compared to the human eye (7mm pupil) is x395 for the Bresser, and x435 for the SW 150p dob, which is quite the difference. The resolving capacity is also better (lower the better) on the SW dob (0.77) compared to the Bresser (0.92)
Now to be realistic, will you see that 10% difference in better light gathering? I dont know. An experienced observer would very likely see a difference in brightness, and in contrast. As a beginner perhaps not as much or not even at all, but being on a budget, you would want the best optical performance you can get for the money.
About the money. The Bresser is 300€, and it comes with two EPs, of which the 9mm is said to be of very low quality. Its only what Ive heard, I dont know personally how good it is.
The SW 150p dob starts at 275€ on astroshop.eu and also comes with two eyepieces, of which the 25mm is very good and my regular eyepiece, and the 10mm is quite ok, and gave wow moments on Jupiter and Saturn in good seeing conditions.
I can guide you on how to get that SW 150 dobson for perhaps as low as 235€! like I did. Send me a private message if you are interested.
That would mean you would have money to spend on a good low power (35mm) eyepiece, and a 2x Barlow (I can also send you a link for quality one for 15€ that I have tested and works perfect).
Send me a private message if you are interested. I can try to help you out on a better deal, since I was in a tight budget myself, so I researched everything into oblivion.
Edited by Recretos, 06 January 2019 - 05:43 AM.