60mm v 120mm

[Seafury]

Hi for the first time since I replaced the lens in my old Prinz 550 with a Carton lens I managed to compare it with my Bresser 120 and I have to say the views through the smaller scope are brighter,clearer with more detail visible on Jupiter and more contrast. I was very suprised and I wonder if this can be the case.

[estwing]

the view through my 63mm is wonderful!

[Seafury]

Is the Carton that good or the Bresser that bad ?

[Peter Drew]

Must be a bad Bresser, a 120 theoretically has 4 times the light gathering and twice the resolution.

[alan potts]

It can be the case but as Peter states maybe somewhat unusual. Apart from the CA that you always get with these scopes I thought it was always considered to a reasonable scope in this price range.

My first scope I believe was Prinz sold by Dixons I believe back in 1975, I wonder if it's the same Company, I though it was the biggest scope on Earth and it was only 3 inches, but at F8 it was fairly good from what I recall.

Alan.

[Seafury]

Hi Alan it is the same company mine came from Dixons in about 1968 although I have now replaced the objective lens

[E621Keith]

If you are observing Jupiter, it is possible atmospheric turbulence is affecting the view. Larger scope is more susceptible to bad seeing than smaller scope. One way to check is to put the lens cap back on the Bresser without the centre small cap. That should stop down the Bresser and eliminate the aperture-seeing variable. Carton objectives have a good reputation, while the Bresser has a 13yrs old Synta 120 f8.3 objective, so I'd expect the Carton to still outperform the stopped down Bresser in contrast and sharpness, but stopping down the Bresser should reduce the differences caused by bad seeing.

However, it's odd the Carton produce a brighter image than the Bresser, since the latter has 4 times the light gathering area. The only reason I can think of is the Bresser got knocked badly out of collimation during shipping.

Jupiter is a bright target, so it's not a good test for brightness. Try pointing the scopes at M42 or M81. If the 60mm Carton shows a brighter and more detailed image than the 120mm Bresser, then something is very wrong with the Bresser.

Obviously I could be bias, since I sold you the Bresser last year. If you are not happy with it, I'm more than willing to buy it back. PM me.

[Seafury]

Hi Keith hope you are well, trouble is we get so few nights where you can spend any time doing much in the way of comparing the scopes, I must do it again doing as you suggest I might have been imagining the differences, a kind offer from you but I shall hang on to the old girl for the time being she has served me well up to now lol, as you say its just that the Carton is so good it makes you wish for a 120mm one

[Ohmless]

carton = quality when it comes to refractor objectives. dunno about their mirrors. Maybe the larger scope has poor scatter or worse CA. I like the focal length of the 4" optic and want to maybe get that as an upgrade to my synta 4" f/10.