Refractor upgrade

[R26 oldtimer]

I have really enjoyed my bresser 127L for the past years. It's the hexafoc focuser version, and I was most satisfied by it's optics, the focuser and the overall build quality. I thought it would be a life scope, but as funds now permit, I started thinking of an upgrade. So... where should I go? Being so pleased by this achro, one choice would be the bresser 152L. But there is always that SW 120ed.

What would you choose? It's the classic aperture vs quality dilemma....

P.S. I already own an ed80 for grab 'n go and A.P. and a bresser 150s newtonian for deep sky eaa style.

[CraigT82]

Well it's always nice to help someone spend their money! First question is... what's your budget? 

[emadmoussa]

At some point, I had the Teleskope Service 152L achro and it was on par with some apo refractors. The colour aberration was very minimal and the contrast very impressive. I think Bresser has the same optics as the Explore Scientific achros  (https://www.365astronomy.com/Explore-Scientific-AR152-152mm-f-6.5-Air-Spaced-Doublet-Refractor-Telescope.html?gclid=CjwKCAiA9K3gBRA4EiwACEhFe2iQkysBKLT21KyRgy9Qz5iteAtl8f2awgwK-AW4isle1sRL2YikBhoC5i4QAvD_BwE ). Although, the ES focuser is much better. 

Have a look at this, it's a replica of the Teleskop Service 6" achro.  

https://www.rothervalleyoptics.co.uk/altair-starwave-v3-152mm-f59-achromat-refractor-telescope-with-3-crayford-focuser.html

[R26 oldtimer]

7 minutes ago, CraigT82 said:

First question is... what's your budget?  

Well, taking into account that the 127L will go to fund the upgrade, the budget stretches as far as a new 152L or second hand 120ed, so the total budget is £700 max.

[CraigT82]

20 minutes ago, R26 oldtimer said:

Well, taking into account that the 127L will go to fund the upgrade, the budget stretches as far as a new 152L or second hand 120ed, so the total budget is £700 max.

So what aspect of your current frac do you wish to improve?  What mount are you using? What kind of observing do you mostly do? 

[R26 oldtimer]

I consider my frac to be my main scope, my all rounder. Where for deep sky my other scopes are more capable combined with a ccd, I really enjoy the deep sky views, a 5-6" lens delivers. And of course it excells in planetary, doubles, clusters (compared to my other scopes).

It will live on an Azeq5.

[mikeDnight]

There's no dilemma, It has to be the 120ED! You won't regret it. The 120 ED's optics are in a whole different league. 

[R26 oldtimer]

The only thing that troubles me is the loss in focal length, where the bresser fracs have 1200mm and the ed120 has 900mm. I know it's better for imaging, but for visual, will I miss it?

[Stu]

13 minutes ago, R26 oldtimer said:

The only thing that troubles me is the loss in focal length, where the bresser fracs have 1200mm and the ed120 has 900mm. I know it's better for imaging, but for visual, will I miss it?

You will just have to use shorter focal length eyepieces, the 120ED will be capable of similar mags I'm sure.

[R26 oldtimer]

10 minutes ago, Stu said:

the 120ED will be capable of similar mags I'm sure. 

That's what I thought too. In theory, the telescope's max magnification is dependant on aperture and lens figuring, not focal length, so shorter focal  length eyepiece it is!

But the 150L is a whole inch more than the 120ed meaning 40-50x more mag. Or the better optics of the ed will outweigh that extra inch? My guess is that since the difference is only an inch, it will....won't it?

[rl]

I'm seeing a lot about magnification here....

I guess I date from a similar vintage and, for me, the usual 50* per inch rule does not apply ...the 0.5mm exit pupil shows up too many floaters to be really useful. Not the scope's fault, just ancient eyes. Might something that can provide the same mag but with a bigger exit pupil be worth consideration, like an 8" newt? Of course there are other tradeoffs like bulk and collimation...

If this is not an issue then the 120ED has a fantastic reputation.

RL

[Stu]

22 minutes ago, rl said:

I'm seeing a lot about magnification here....

I guess I date from a similar vintage and, for me, the usual 50* per inch rule does not apply ...the 0.5mm exit pupil shows up too many floaters to be really useful. Not the scope's fault, just ancient eyes. Might something that can provide the same mag but with a bigger exit pupil be worth consideration, like an 8" newt? Of course there are other tradeoffs like bulk and collimation...

If this is not an issue then the 120ED has a fantastic reputation.

RL

That is very true. I find 0.5mm to be the minimum I can go these days, in fact most of the time I binoview when at high power to reduce the effects of floaters. It is a good point to raise.

[CraigT82]

34 minutes ago, rl said:

I'm seeing a lot about magnification here....

I guess I date from a similar vintage and, for me, the usual 50* per inch rule does not apply ...the 0.5mm exit pupil shows up too many floaters to be really useful. Not the scope's fault, just ancient eyes. Might something that can provide the same mag but with a bigger exit pupil be worth consideration, like an 8" newt? Of course there are other tradeoffs like bulk and collimation...

If this is not an issue then the 120ED has a fantastic reputation.

RL

Very good point... I think we often get so hung up on the optical elements of the scope,diagonal and eyepiece, we often forget the most important link in the optical train... our good old mk1 eyeballs! 

[R26 oldtimer]

14 minutes ago, Stu said:

That is very true. I find 0.5mm to be the minimum I can go these days

Same here. 0.5-0.6 seems to be the lower limit except for Luna.

[mikeDnight]

On 08/12/2018 at 17:25, R26 oldtimer said:

The only thing that troubles me is the loss in focal length, where the bresser fracs have 1200mm and the ed120 has 900mm. I know it's better for imaging, but for visual, will I miss it?

You won't miss the extra focal length. The 120ED's will take much higher magnification while still remaining sharp and contrasty. On a clear steady night, the ED will deliver 100X per inch on lunar and some planets such as Mars and Venus. If you like using longer focal length eyepieces then use a SW Delux 2X Barlow in the scope. It won't add false colour or degrade the image in any way. SW Delux barlows are very good quality. I use one on my 100mm Takahashi scope and its razor sharp and the definition is breathtaking. 

[KP82]

The lesser weight and length of the 120ED will make it a more enjoyable experience than AR152L on your AZEQ5 when used in AZ mode. Since you've already got a 6" newt that covers DSOs, I don't think you will miss the aperture here.

And like others have said the ED should be able to deliver the same mag as the 152L by using shorter focal EPs.

[R26 oldtimer]

Thank you all for your advice.

ED 120, is on it's way...