Refractor specs

[Peter Drew]

2 hours ago, Stu said:

******SGL Health Warning*******
 

Mr Hezzlewood suffers from a highly infectious form of refractorholism for which there is no known cure. The symptoms include a complete aversion to mirrors and the need for fluorite glass to be used everywhere, including the windows of his house. Proceed with caution, it can get very expensive!!

😉

Yes, a sad case.  As a long term friend I loaned him a very nice 10" OOUK Dobsonian, normally a cure, but despite an encouraging short period of remission, the problem has resurfaced.  Sigh!       ☹️

[mih]

2 hours ago, mikeDnight said:

Refractors can be good for all kinds of targets, including deep sky. Obviously the greater the aperture the deeper you'll be able to go, but how deep do you really need to go? There are countless deep sky objects that can be observed through a 100mm refractor, and a 120mm or 152mm refractor will take you deeper still. The best view i ever had of the Orion Nebula (M42) was through a 102mm Vixen F6.5 ED apo and a 20mm Nagler eyepiece. No other scope I've ever used, no matter how big, has ever given me a better view of that object. I've observed M51 (the Whirlpool galaxy) in many large aperture scopes, but the most memorable view was through a 150mm F8 achromatic refractor, which easily showed the spiral structure and the bridging arm between the two galaxies. Refractors make great all round scopes but their ability to produce piercingly sharp star images enables them to give some of the finest views imaginable of rich star fields and star clusters; views that no other design can match. A 150mm F5 achromat will give you arguably the finest view you'll ever have of the Double Cluster in Perseus. Other scopes may show it well but they'll never match the refractors view. So refractors can give you a lifetime of pleasure with deep sky targets in mind, but they can also excell at lunar and planetary too. 

I've attached some images to wet your appetite. This first one is a rich field achromat with a 152mm lens. This is a great deep sky refractor!

The second is another great deep sky scope, an NP101. At only 4" aperture you might think it wouldn't be so good, but its images of nebulae, galaxies, star clusters and comets are spectacular from a reasonably dark site.

Then there's the affordable but excellent Skywatcher 100DS Pro ED, which is a great all round refractor. If you like to do a bit of everything this scope will not disappoint!

Then there's the higher spec offerings from Takahashi, which again are great all round performers designed for very high powers when the seeing conditions allow.

 

There are many more you might consider too. Doublets are all you'll really need if you're a visual observer, as they cool quickly and will often be cheaper than a triplet. You might even find your reflector gets used less and less if you did buy a good refractor.

 

 

Thanks, i think i might consider buying one after all, you convinced me! I might need to save some money for a very good one. I'll buy it without the mount, which i'll buy separatley, since i want it to hold my reflector as well.

Edited May 31, 2020 by mih

[mih]

Also @mikeDnight, do you recommend an achromatic one or an apochromatic one?

[mikeDnight]

8 minutes ago, mih said:

Also @mikeDnight, do you recommend an achromatic one or an apochromatic one?

There are some nice achromatic refractors that you might consider. The old Tal 100mm F10 is a classic. Achromats are usually long and so can be come quite a handful. The 6" Star Wave I posted an image of is an achromat and will show significant false colour around the limb of the Moon and bright stars like Vega, but as a rich field scope you wouldn't notice the colour. If you want a top class colour free image on lunar and planetary, then an ED refractor would be a better choice. 

[John]

Another good but older (out of production) refractor is the Vixen 102mm F/9.8 achromat. Japanese made and fine optics often for quite a low price if you can find one on the used market.

 

[mih]

2 minutes ago, John said:

Another good but older (out of production) refractor is the Vixen 102mm F/9.8 achromat. Japanese made and fine optics often for quite a low price if you can find one on the used market.

 

Thanks, i'll check it out!

[mih]

Sorry, i am a bit confused. What is an optimal focal length, or focal ratio for a refractor, since i am seeing a lot of big ones, a lot of small ones, i dont know what i should look for

[Stu]

11 minutes ago, mih said:

Sorry, i am a bit confused. What is an optimal focal length, or focal ratio for a refractor, since i am seeing a lot of big ones, a lot of small ones, i dont know what i should look for

Did you read my post @mih? I tried to explain the differences in there.

[mih]

4 minutes ago, Stu said:

Did you read my post @mih? I tried to explain the differences in there.

Oh, sorry, ill check it out

Edit: Thanks, i must have overlooked it. Great explanation!

Edited May 31, 2020 by mih

[ollypenrice]

19 hours ago, Alkaid said:

 

Refractors just look better too. (Hope I haven’t started a war now). 

No, this war has been rumbling on for at least two hundred years...

Just one word of caution to the OP: when you read apo refractor nuts (which might include me) banging on about the quality of the image, they are generally talking about posh refractors. Expensive ones. I have two of those which cost, between them...   well, never mind...

As a general rule a budget reflector will beat a budget refractor.

😁lly

[Guest]

Hello mih.

I have a great skywatcher 80 mm Equinox ED refractor. It give nice wide field views. Point like stars when viewing. Good with observing moon and planets. I like the way it resolves stars. But I am considering buying a six inch f5 Newtonian to compliment the 80 mm. So why not keep the Newtonian and look out for an 80 mm or 100 mm ED refractor.

Edited May 31, 2020 by Guest

[mih]

4 hours ago, Grumpy Martian said:

Hello much.

I have a great skywatcher 80 mm Equinox ED refractor. It give nice wide field views. Point like stars when viewing. Good with observing moon and planets. I like the way it resolves stars. But I am considering buying a six inch f5 Newtonian to compliment the 80 mm. So why not keep the Newtonian and look out for an 80 mm or 100 mm ED refractor.

What is the optimal focal length for an ED80. I found one with a 600mm. Is that good?

[John]

1 minute ago, mih said:

What is the optimal focal length for an ED80. I found one with a 600mm. Is that good?

It is a popular focal ratio (F/7.5) with an ED 80mm scope because it's suitable for imaging as well as visual.

You do realise that your 150mm newtonian will out perform such a scope on practically everything though ?

An 80mm ED is a nice "grab and go" alternative though.

 

[mih]

5 minutes ago, John said:

It is a popular focal ratio (F/7.5) with an ED 80mm scope because it's suitable for imaging as well as visual.

You do realise that your 150mm newtonian will out perform such a scope on practically everything though ?

An 80mm ED is a nice "grab and go" alternative though.

 

Right. I found an Achromatic refractor AR152 AIR-SPACED Doublet, 988mm focal length. Thing is it is not ED

Its from Explore Scientific

Edited May 31, 2020 by mih

[Stu]

4 hours ago, ollypenrice said:

Just one word of caution to the OP: when you read apo refractor nuts (which might include me) banging on about the quality of the image, they are generally talking about posh refractors. Expensive ones. I have two of those which cost, between them...   well, never mind...

Well I bang on about my Telementor Ollie and it cost me about £200, even though Andrew thinks my airy disks are too big to enjoy 😉

[Stu]

1 minute ago, mih said:

Right. I found a Achromatic refractor AR152 AIR-SPACED Doublet, 988mm focal length. Thing is it is not ED

VERY different to an 80ED. I would only suggest thinking back to deciding what you want it to achieve. That would be relatively similar to your newt, whereas an 80ED would be a portable/widefield complement to it. A 152mm refractor takes a bit of mounting too.

[John]

2 minutes ago, mih said:

Right. I found an Achromatic refractor AR152 AIR-SPACED Doublet, 988mm focal length. Thing is it is not ED

Good for deep sky but not so good for planetary use due to CA. But I sure you realise that given the advice that has been provided

Also heavy as Stu says.

I think you need to think things through more carefully. You seem to be all over the place with your choices at the moment ?

 

[mih]

2 minutes ago, John said:

Good for deep sky but not so good for planetary use due to CA. But I sure you realise that given the advice that has been provided

Also heavy as Stu says.

I think you need to think things through more carefully. You seem to be all over the place with your choices at the moment ?

 

Yes, i am quite a bit. Which one of the two would you say is better in general? The ED80 has a focal length of 600mm.

I think I would be ok with the planet problem, i think DSOs are what interests me

Edited May 31, 2020 by mih

[Stu]

8 minutes ago, mih said:

Yes, i am quite a bit. Which one of the two would you say is better in general? The ED80 has a focal length of 600mm.

I think I would be ok with the planet problem, i think DSOs are what interests me

Then get a bigger dob!

[mih]

8 minutes ago, Stu said:

Then get a bigger dob!

I probably will, but i want to get to know refractors as well. Also, there are people saying refractors are good for DSOs, other saying they re not, idk what to believe

Edited May 31, 2020 by mih

[mih]

I think might buy refractor because of its portability, so i can go camping ans stuff and stick to the dob i have for now.

Edited May 31, 2020 by mih

[Stu]

25 minutes ago, mih said:

I probably will, but i want to get to know refractors as well. Also, there are people saying refractors are good for DSOs, other saying they re not, idk what to believe

Sorry to say, read my post again! For widefield objects a refractor can give views a dob can’t, because their field of view is too narrow. If you didn’t have the Newt already then a 152mm refractor would be fun on DSOs, but I don’t see that it gives you anything different enough.

A 4” f7 ish ED refractor would give you widefield DSO and planetary/lunar performance to get to know refractors.

What sort of budget do you have?

[mih]

28 minutes ago, Stu said:

Sorry to say, read my post again! For widefield objects a refractor can give views a dob can’t, because their field of view is too narrow. If you didn’t have the Newt already then a 152mm refractor would be fun on DSOs, but I don’t see that it gives you anything different enough.

A 4” f7 ish ED refractor would give you widefield DSO and planetary/lunar performance to get to know refractors.

What sort of budget do you have?

My budget is about 1200 dollars. Hope thats enough. Maybe even 1400. Did you ask me for the budget to do the looking for me? Cause you would be a god

Edited May 31, 2020 by mih

[John]

55 minutes ago, mih said:

Yes, i am quite a bit. Which one of the two would you say is better in general? The ED80 has a focal length of 600mm.

I think I would be ok with the planet problem, i think DSOs are what interests me

You can't compare them - totally different strengths and weaknesses.

If DSO's are more interesting then a larger dobsonian is both much less expensive than your budget and will do the job better on DSO's and will do a decent job on the moon and planets as well.

 

[mih]

5 minutes ago, John said:

You can't compare them - totally different strengths and weaknesses.

If DSO's are more interesting then a larger dobsonian is both much less expensive than your budget and will do the job better on DSO's and will do a decent job on the moon and planets as well.

 

Yeah, I've gathered that, but i'm curious about the strengths of a refractor. I will get a larger dobsonian as well eventually. The one I have seems to be decent, but you know, bigger is better.

Edited May 31, 2020 by mih