I've watched the classifieds for quite a period and its not scientific what I'm about to say, but I see especially in the refractor crowd people trading up from a 3" to 4" or 4" to 5" OR maybe someone owns a 4" and a 6" refractor. Does one or two inches actually make a big viewing difference? Is there really a huge performance difference between an APO and an achromat are the differences only most apparent to a veteran observer? Finally, I know two gentlemen one owns a 24" Starmaster, the other the 8" Astrophysics AP0 (thats correct the 8" AP) the AP owner said his scope does a great job on the planets and he had the opportunity to view through the Starmaster, which he said gave him the best views of the planets even surpassing his superb AP, does that surprise you? If not why do people drop that kind of money for an APO refractor when they could have so much more aperture for an equivalent or much less money? Thankyou for your comments.
An aperture question - refractors and dobs
Started by Gary S., 02/04/2004 01:40AM
Posted 02/04/2004 01:40AM
Opening Post
Posted 02/04/2004 02:12AM
#1
I've watched the classifieds for quite a period and its not scientific what I'm about to say, but I see especially in the refractor crowd people trading up from a 3" to 4" or 4" to 5" OR maybe someone owns a 4" and a 6" refractor. Does one or two inches actually make a big viewing difference? Is there really a huge performance difference between an APO and an achromat are the differences only most apparent to a veteran observer? Finally, I know two gentlemen one owns a 24" Starmaster, the other the 8" Astrophysics AP0 (thats correct the 8" AP) the AP owner said his scope does a great job on the planets and he had the opportunity to view through the Starmaster, which he said gave him the best views of the planets even surpassing his superb AP, does that surprise you? If not why do people drop that kind of money for an APO refractor when they could have so much more aperture for an equivalent or much less money? Thankyou for your comments.
***********************************
A 24" Starmaster that is cooled, collimimated and has the excellent Zambuto optics will beat out any 8" refractor, unless seeing is very bad! But a good APO can't be beat for that perfect clean snap in focus image.
I would love a 8" APO, but cost , weight and size would turn me off from getting a large APO! And then you need a super big mount for that big APO, and that is gonna be heavy and cost some big bucks.
I think a 10" to 24" well built Dob with super optics is the way to go, unless you wanan do CCD work, or photo work.
Chas P.
Posted 02/04/2004 06:44AM
#2
I sold a C102HD, Orion 127, and a Stellarvue AT1010 and got a Stellarvue 85S APO. My reasons for doing so are multiple and apply only to me, so what I tell you may not have any bearing on what you would have seen. (I have a 16" Discovery sonotube also - I really love that scope.)
I also use my scopes both day and night.
First and formost, my wife is much happier with one scope instead of three! All other reasons pale in comparision:-)
The 85S cools down much quicker than the Mak 127, I often only go out for 30 minutes or so. The Mak needed an hour or more to cool down. The purple in the two acromats really bothered me. I could see it in the daytime and on the planets. The acro's put a purple fringe around birds that just killed details such as eye color and intruded on Jupiter too much for me. The 85S is easier to take for trips and quick outings (as was the Mak and AT1010). I noticed in the day, that the Mak really seemed washed out when compared with the acro's and Apo. I only would notice this on low contrast views such as the trunk of a tree in deep shade or wildlife in the same location. At night about the only time I noticed the loss of contrast was on Jupiter. Colors on Jupiter were a bit more vivid in the acro's and the apo. Otherwise I liked the views best in the Mak and the apo for both day and night. Keep in mind that the achro purple only bothered me on a few things at night. Jupiter, Mars, and Rigel - often couldn't find the companion. It was daytime use that I really objected to the purple.
This is getting too long winded - sorry. Suffice to say that there are several other equally minor reasons why I went with the apo (and having a 16" dob to fall back on doesn't hurt either). The apo seemed to give me the best of all worlds.
Michael
I also use my scopes both day and night.
First and formost, my wife is much happier with one scope instead of three! All other reasons pale in comparision:-)
The 85S cools down much quicker than the Mak 127, I often only go out for 30 minutes or so. The Mak needed an hour or more to cool down. The purple in the two acromats really bothered me. I could see it in the daytime and on the planets. The acro's put a purple fringe around birds that just killed details such as eye color and intruded on Jupiter too much for me. The 85S is easier to take for trips and quick outings (as was the Mak and AT1010). I noticed in the day, that the Mak really seemed washed out when compared with the acro's and Apo. I only would notice this on low contrast views such as the trunk of a tree in deep shade or wildlife in the same location. At night about the only time I noticed the loss of contrast was on Jupiter. Colors on Jupiter were a bit more vivid in the acro's and the apo. Otherwise I liked the views best in the Mak and the apo for both day and night. Keep in mind that the achro purple only bothered me on a few things at night. Jupiter, Mars, and Rigel - often couldn't find the companion. It was daytime use that I really objected to the purple.
This is getting too long winded - sorry. Suffice to say that there are several other equally minor reasons why I went with the apo (and having a 16" dob to fall back on doesn't hurt either). The apo seemed to give me the best of all worlds.
Michael
Posted 02/04/2004 02:56PM
#3
>>If not why do people drop that kind of money for an APO refractor when they could have so much more aperture for an equivalent or much less money? Thankyou for your comments.
Most APOs are 4 and 5 inchers. Part of the equation is optical. Nice wide field views, no problem with cool down. Sharp optics that do not need collimation..
Part of the equation is physical. A refractor is quite handy.
jon
Most APOs are 4 and 5 inchers. Part of the equation is optical. Nice wide field views, no problem with cool down. Sharp optics that do not need collimation..
Part of the equation is physical. A refractor is quite handy.
jon
Posted 02/04/2004 03:36PM
#4
I can't compare refractors with reflectors, but can add something on the refractor aperture/apo/achro question. At the end of last summer I did a side-by-side with a Stellarvue 80/9D achro and a Televue 102.
First, I was mightily impressed by the Stellarvue, which gave exciting views of the moon, the south polar cap on mars, M27, and the ring nebula. In each case the view through the Televue was noticeably, but not hugely, better. I don't think it would have taken an expert to see the differences, but it might have taken a connoseur to want to pay for them.
However, there was one target, M13, where the difference was large. On a night of above-average seeing under mag 4.5 skies the 80/9D showed the globular as a condensed ball of light with a very few resolved stars at the edges. As usual, the TV-102 resolved stars all the way across the face of the globular. It was a big difference and anybody would have noticed it.
With such small apertures I don't even try faint fuzzies unless I can get to a dark site, but my guess is that the differences I noted in brightness and resolution on M13 would apply as well to almost any galaxy observations done with these scopes.
Hope this helps.
Steve
First, I was mightily impressed by the Stellarvue, which gave exciting views of the moon, the south polar cap on mars, M27, and the ring nebula. In each case the view through the Televue was noticeably, but not hugely, better. I don't think it would have taken an expert to see the differences, but it might have taken a connoseur to want to pay for them.
However, there was one target, M13, where the difference was large. On a night of above-average seeing under mag 4.5 skies the 80/9D showed the globular as a condensed ball of light with a very few resolved stars at the edges. As usual, the TV-102 resolved stars all the way across the face of the globular. It was a big difference and anybody would have noticed it.
With such small apertures I don't even try faint fuzzies unless I can get to a dark site, but my guess is that the differences I noted in brightness and resolution on M13 would apply as well to almost any galaxy observations done with these scopes.
Hope this helps.
Steve
Posted 02/04/2004 04:34PM
#5
I don't think that anyone's addressed the "Does one or two inches actually make a big viewing difference"?
If that's a leap from a 3inch to a 4 or 5 inch, then yes, it makes a significant difference. The difference between my old 70mm scope and a 100mm refractor is dramatic, for example, and that's just over 1 inch difference.
A 3inch scope has only 75% of the resolving power and about 1/2 the light gathering power of a 4inch scope; 60% of the resolution and 36% the light gathering of a 5 inch scope. These are noticeable, even big, differences.
If you're talking about the difference between a 15inch and 16 or 17inch scope, you're talking about hardly noticeable differences.
Small APOs are great for photography, convenient, give great views of doubles and planets that are pleasing even under less then perfect seeing conditions, capable of widefield viewing of extended deep-sky objects, and are "cool".
Worth the money? Moot point, I don't have the money. But I like checking out other people's.
If that's a leap from a 3inch to a 4 or 5 inch, then yes, it makes a significant difference. The difference between my old 70mm scope and a 100mm refractor is dramatic, for example, and that's just over 1 inch difference.
A 3inch scope has only 75% of the resolving power and about 1/2 the light gathering power of a 4inch scope; 60% of the resolution and 36% the light gathering of a 5 inch scope. These are noticeable, even big, differences.
If you're talking about the difference between a 15inch and 16 or 17inch scope, you're talking about hardly noticeable differences.
Small APOs are great for photography, convenient, give great views of doubles and planets that are pleasing even under less then perfect seeing conditions, capable of widefield viewing of extended deep-sky objects, and are "cool".
Worth the money? Moot point, I don't have the money. But I like checking out other people's.
Funding Member
