Refractor vs reflector!

[Nair al Saif]

Hi Nair Al Saif (Iota Orionis)here,

Recently on this forum I have had a discussion about 6 inch reflector vs a 90mm refractor on an eq Mount.

I like planetary visual astronomy, and deep sky visual astronomy. 75:25 split really.

Many people say the frac is better eg(Allan hall), many people recommend the flector. I know that aperture rules but I would like not to participate with the nudging ritual as I do have family that also like astronomy (would probably like to see Saturn rings etc) and personally I need a bit of tracking.

 

The way I see it is: The reflector though better views, looses on contrast, maintenance, cool down, tracking, air currents and dew. Portability isn’t a major factor since I will be observing from my backyard.
The refractor has Ca (negligible for me as the model is close to the Sigwick standard) but looses on aperture however as it doesn’t have a secondary mirror, it has far better contrast and  the aperture gap is not as big. Btw the models are evostar 90 and 6inch dob from skywatcher.

There is also the startravel 102 (maybe the 120) but that is a fast frac.
 

Also, thanks for the guys on the previous chat (Alkaid) for providing their opinion. I ask this question again to try and see what the masses would recommend. Lastly if anyone has any other recommendations less than 300 quid. Please don’t hesitate- tryning to get the full board here!

Ps: I haven’t seen the moon, mars the red smudge above my neighbours house, Saturn and Jupiter that are two white smudges following each other, or any stars in ages, darn dirty clouds!

 

Edited August 15, 2020 by Nair al Saif

[John]

I would not consider the Startravel refractors for mostly planetary observing. They have too much false colour. Stick to F/10 refractors, F/11-14 mak-cassegrains (which they all are) or F/6-F/8 newtonians.

Getting something on a tracking mount for £300 or less is going to be the challenge I think.

 

 

 

 

[jetstream]

1 hour ago, Nair al Saif said:

The reflector though better views, looses on contrast, maintenance, cool down, tracking, air currents and dew.

A reflector with good optics and around 25% obstruction or less will not lose much contrast-assuming the interior of the scope is flat black or flocked. Stray light control is very important for the reflector.

There is a reason that a 6" f8 newtonian is called an "APO killer"... such a scope cools fast and is easy to collimate. It will show so much more than a 90mm scope its not funny. There are mounts that can easily handle such a scope- but they will blow the budget apart.

1 hour ago, Nair al Saif said:

The refractor has Ca (negligible for me as the model is close to the Sigwick standard) but looses on aperture however as it doesn’t have a secondary mirror, it has far better contrast

the refractor wont necessarily have better contrast and in fact the mentioned one most likely will not. A 300 pound budget mandates a 6" dob if you want a good telescope IMHO. Tracking costs lots of cash.

Edited August 15, 2020 by jetstream

[Nair al Saif]

Their is a 150pl on eq3-2 same stats as the dob made by skywatcher. Ok if the difference is so much more I am interested then.

[jetstream]

3 minutes ago, Nair al Saif said:

Their is a 150pl on eq3-2 same stats as the dob made by skywatcher. Ok if the difference is so much more I am interested then.

That is an f5 scope that will be more heavily obstructed- best to be asking more about this one IMHO...

[Nair al Saif]

No no there is a f8 lol here’s the link. https://www.firstlightoptics.com/reflectors/skywatcher-explorer-150pl-eq3-2.html

 

My apologies, tracking for me doesn’t mean GoTo it means eq mount.

Edited August 15, 2020 by Nair al Saif

[Nair al Saif]

If it’s possible can you post an image of planets/dso using a 6inch reflector.

[Nair al Saif]

Out of 10 how noticeable is the difference and is it worth shelling out an extra 155 quid.

 

yeah Ik Ik it’s not funny, just like to make the world a joke-ier place.

Edited August 15, 2020 by Nair al Saif

[Shimrod]

5 hours ago, Nair al Saif said:

If it’s possible can you post an image of planets/dso using a 6inch reflector.

If you haven't seen it already, this thread is well worth reading to get an idea of what you might see with various telescopes

[A McEwan]

The Skywatcher 150PL will get you most of what you seem to be looking for, but you will still have to add at least a Right Ascention motor to track.

The optics in the 150PL will be great for planetary, fine for DSOs, and are usually fairly good quality. You will get best results by blackening the inside of the tube, and paying particular attention to collimation, but at f8 it will be easy to do and should hold collimation for long periods of time. Mine certainly did. Down the line you may want to replace the 4-vane secondary spider with a curved variant which will eliminate the annoying diffraction spikes seen when viewing bright stars or planets. A light/dew-shield will also aid in increasing contrast.

So that package is certainly a good start, but you may find something similar with tracking already included on the second hand market if you're willing to shop around or wait patiently.

As much as I'm a fan of refractors, I'd say that a 150mm f8 is a very good option with great "bang for buck" score.

[John]

6 hours ago, Nair al Saif said:

Out of 10 how noticeable is the difference and is it worth shelling out an extra 155 quid.

 

yeah Ik Ik it’s not funny, just like to make the world a joke-ier place.

The link that @Shimrod posted is worth a look. I posted these approximations in your other thread yesterday:

Exactly what YOU will see will depend on factors such as seeing conditions, how much time you spend observing and the positions of the planets when you observe them. This is not an exact thing to do and the quality of the view will vary session to session and even hour to hour.

Placing a quantified value on additional performance potential is not really useful I feel. I think the consistent message though is that the 150mm Skywatcher dobsonian will give you the best potential performance for the budget you have available.

 

 

 

[Guest]

7 hours ago, John said:

I would not consider the Startravel refractors for mostly planetary observing. They have too much false colour. Stick to F/10 refractors, F/11-14 mak-cassegrains (which they all are) or F/6-F/8 newtonians.

Getting something on a tracking mount for £300 or less is going to be the challenge I think.

 

 

 

 

Deleted, sorry.

Edited August 15, 2020 by Guest
updated info, just read above replies...

[Peter Drew]

I've had both the 90mm F10 refractor and the 150mm F8 Newtonian.   No contest, the Newtonian every time.  The Dobsonian will be much more stable for the high powers needed for planetary viewing.  The 90mm refractor will have the edge on double star appearances and be more convenient for white light solar observation.  The minor quirks of the reflector are more than offset by the overall performance.   

[Nair al Saif]

Thanks so much. I shall buy the dobsonian Mount then probably upgrade to an eq Mount. Or I could (most likely save up to the 319 eq Mount)

[jetstream]

13 hours ago, Nair al Saif said:

Thanks so much. I shall buy the dobsonian Mount then probably upgrade to an eq Mount. Or I could (most likely save up to the 319 eq Mount)

Great choice!

Starting out with good optics and a stable mount goes a long way to ensure early success.  Add a nice low power wide field for nebula at some point and a couple of good planetary eyepieces and your all set.