45 replies to this topic

[Agreegator]

So a friend of mine was looking for suggestions to upgrade from his Celestron C90 MAK to something significantly larger so he can view DSOs. He was more interested in an 8 inch CAS or a 10 Inch DOB.  He emailed his University's Astronomy dept head for suggestion and the quite experienced professor (almost 65 years with scopes) sent the below reply:

 

"Back in the day, aperture was quite a relevant. Tracking had not matured and films could get limited exposure, so aperture was all the game. These days more and more people are getting better and better results with smaller apertures  - as imaging and tracking technologies advance and owner of a 4 inch scope who has good equipment and is good at post processing can get far better results than someone owning 8 inch but not having a stable mount or knowing good image processing.

 

Unless someone already owns a large scope that they have invested a lot of time and money in  - Or they are advanced professionals - I always suggest the below:

• If you live in light polluted city, get a 5 inch MAK or 80mm APO  - max, then spend like crazy on mount and accessories  - and focus on planets and bright DSOs
• If you live in less light pollution, get a 6 inch Reflector (or 8 inch if you have a lot of time to collimate) - again, spend crazy lot on mount and accessories and focus on DSOs  
• Your learning curve will be extremely fast, you will enjoy the nights your equipment will be specialized.
• People do get amazing results with large apertures but those people are more rare than you would think - They work hard through difficult learning curves. In reality - most people get aperture fever, get too large of scopes and then the scopes sit there collecting dust because they don't have the stamina, time and equipment to use those devices and they can't handle the learning curve.

Unless you can dedicate a lot of time to astronomy - Keep it small, keep it specialized, follow my suggestions and you will have no regrets."

  

My friend thought the apertures suggested were too underwhelming and sent this email to me for an opinion. I strongly agree with the professor and understand that large apertures are not for everyone to handle and that technology is helping smaller scopes a lot now (my friend is n professional either - with a busy work life). I thought that the more experienced people here would also know a lot .. Are apertures larger than suggested really that difficult to use & learn on and are the above the best options for amateurs, these days ? Will also be useful for people looking into suggestions in the future. Thank you           

Edited by Agreegator, 04 December 2020 - 06:23 AM.

[Jon Isaacs]

My friend thought the apertures suggested were too underwhelming and sent this email to me for an opinion. I strongly agree with the professor and understand that large apertures are not for everyone to handle and that technology is helping smaller scopes a lot now (my friend is n professional either - with a busy work life). I thought that the more experienced people here would also know a lot .. Are apertures larger than suggested really that difficult to use & learn on and are the above the best options for amateurs, these days ? Will also be useful for people looking into suggestions in the future. Thank you

 

 

The professor seems to be mixing both astro-photography and visual observing.  Mounts are important with astro-photography, not so much visually. 

 

The professor's advise is certainly contradictory with my experience and with what I see with my friends for observing visually.  

 

- An 80mm apo, a 5 inch Mak, these are both limited by their apertures as planetary scopes.  An 8 inch Dob is a better planetary scope than either one and less expensive.  It doesn't take much time to collimate an 8inch F/6 once you learn how.  

 

- Aperture fever:  Most scopes like most bicycles are purchased with hopes and dreams that are probably not realistic.  As a result, most scopes large or small as well as most bicycles sit in garages unused.  I have seen numerous cases of aperture fever on Cloudy Nights.  Aperture fever is a form of consumeritis, being unsatisfied with what one has and thinking buying something "better" or "bigger" will result in a satisfying experience.  Instead of learning and developing observing skills, the victim of aperture fever buys larger and large scopes, never learning to observe, just looking for the BIG WOW that comes with a larger scope.  It disappears.

 

Jon

[joepharms]

Was the professor referring to EAA?

 

...as imaging and tracking technologies advance and owner of a 4 inch scope who has good equipment and is good at post processing can get far better results than someone owning 8 inch but not having a stable mount or knowing good image processing.

Edited by joepharms, 04 December 2020 - 07:22 AM.

[Beeham]

I agree with Jon Isaacs' comments above.

 

For visual, aperture is still important.  For astrophotography, the professor's comments seem reasonable.

 

Upgrading from a C90 Mak to something like a C8 or a 10" dob would likely reveal considerably dimmer DSOs than can be seen with the small Mak.

 

I hope that's helpful - cheers!

[MellonLake]

I agree with Jon above.

 

It really sounds like the professor is talking about astrophotography which is very different from visual.  Because a camera can take exposures for many minutes and those exposures can be digitally stacked, relatively small telescopes can take amazing deep sky photographs.  For planets though, aperture is still what is needed for good resolution in astrophotography.  If you want to do astrophotography ask questions in the beginners astrophotography forum.  

 

For visual, aperture generally helps view objects. The larger the aperture the more detail in planets and the more light gathering power to show faint deep sky objects.  The light gathering power goes up with the square of the radius so going from a 5" to a 10" is an increase in light gathering power of 4 times.  Aperture very much helps with visual.

 

I started with a 10" Dob.  It is easy to use and set up and shows great detail on planets and shows me thousands of deep sky objects.  I actually find setting up and using my 10" Dob much easier than setting up my 4.75" refractor.  The 10" is not so large that I can't transport it or move it easily. 

 

So are larger apertures (8", 10") harder to set up and learn, not for visual.        

[sg6]

Well the title say "aperture vs practicality" and then practicality is ignored/absent.

So what is the "practicality" requirement - portability? WHAT???

 

Standard answers especialy in the dobsonian side "Aperture".

Notice the absence of "quality". Reading the responses it would be easy to have the option that a 14" spherical beats the daylights out of any 10" Parabolic and a well figured Zambuto does not even count.

 

What matters at the end is what you can see and how good it is. Aperture is or may be one aspect. Certainly more aperture usually means more light collection, it also means harder to produce and so usually a poorer final image. Or a huge cost.

 

Professors reply is AP related, talks of Film, Tracking, Post Processing, so did the friend ask about AP? Kind of seems that they did. People do the same here. Of all the professors I know none are that easily moved off the topic. If he has answered so specifically and included the terms Film, Imaging, Tracking, Post Processing, that I expect was what they were asked about. So I would suggest we do not have the full tale.

 

And what reads as an elderly professor likely has little concern with AP. If they have some 65 years scope experience then even if they started at 10 they are now 75ish. So I guess they were asked somewhat specifically about AP.

 

Anyway as initial: What is the "practicallity" aspect? I get the idea that "practicality" is which is the more practical scope for AP? Large aperture or otherwise. That answer is simple: Quality optics.

 

They say "People are promoted to their level of imcompetance". Basically they get promoted until they are unable to do the job. Over the years I have realised that many buy scopes with a similar approach "Increase scope size until too large to use" And rather unfortunately I have seen it too many times, both with scopes and mounts.

[epee]

The professor seems focused on AP.

 

My own experience with aperture and visual use is that you can't get enough of it. However, this needs to be tempered with the practical demands of use; set-up and deployment, observer comfort, observer physical condition, the location the scope will see most of its use, and ability of transportation.

 

Taking all of those things into account, I landed on a 12" truss Dob. This was based mainly on the weight of components that I expect to be able to deal with as I age.

[Bill Jensen]

So a friend of mine was looking for suggestions to upgrade from his Celestron C90 MAK to something significantly larger so he can view DSOs. He was more interested in an 8 inch CAS or a 10 Inch DOB. ,,,

  

My friend thought the apertures suggested were too underwhelming and sent this email to me for an opinion. I strongly agree with the professor and understand that large apertures are not for everyone to handle and that technology is helping smaller scopes a lot now (my friend is n professional either - with a busy work life). I thought that the more experienced people here would also know a lot .. Are apertures larger than suggested really that difficult to use & learn on and are the above the best options for amateurs, these days ? Will also be useful for people looking into suggestions in the future. Thank you           

I agree with Jon and the other responders. Your friend ought to consider joining a local astronomy club, especially one focused (no pun intended) on observing, not astronomy theory, cosmology or the like. He may be able to try larger scopes and ask for views on the same object, using about the same power. My club has a very active email listserv, and offers loaner scopes of all types for someone to try before buying. 

 

Per the quote, he wanted something significantly larger so he can view DSOs, so a 6, 8 or 10 inch dob, depending on your friend's storage and transport situation, would be much better than a marginal increase using a 5 inch MAK. His C90 would be nice for quick views (although it too needs to cool down, harder with a MAK) and a larger scope for when he has the time to spend observing dimmer DSOs. The technology may help him find an object, but unless he is doing EAA or AP, it is not going to increase the impact of that DSO visually. 

[Asbytec]

Aperture fever is a form of consumeritis, being unsatisfied with what one has and thinking buying something "better" or "bigger" will result in a satisfying experience. Instead of learning and developing observing skills, the victim of aperture fever buys larger and large scopes, never learning to observe, just looking for the BIG WOW that comes with a larger scope. It disappears.

Jon

In my experience, the above is the most important lesson we can realize. Not that aperture cannot show more, it can and almost always does. But practicality with visual exists when where happy with what we can see and not worried about what we don't see. This scales with aperture, /almost/ as if aperture really does not matter in terms of satisfaction with what we can see. We can learn to see more, and that causes us to experience some real satisfaction. Consequently, such a satisfying scope gets used because we learned to use it and it pleases us. Thus, the axiom the best scope is the one we use is true.

[therealdmt]

With his emphasis on an expensive mount, the professor certainly does seem to be conflating astrophotography and visual, but even for visual he has a point in that too big a scope could well sit unused due to the hassle of dealing with it.

 

I tend to agree that a novice might be better served by learning on a smaller scope and then moving up if desired. Heck, I’ve basically been doing it the old fashioned way myself by starting from the ground up after originally having started out as a kid with a scope that was physically too big for me and, with its GEM mount, more complicated than I wanted to deal with. Like the professor is warning, that first scope ended up sitting unused in the basement.  Later, with lesson learned, when I got back into astronomy I started out just naked eye and have been moving up slowly from there. But not everybody has to follow my path. Not at all. I’m sure some people start out at a giant observatory because that’s what they have access to. Others start anywhere in between. And, due to price if nothing else, I’m sure there’s many more unused/abandoned small scopes out there than unused/abandoned large scopes. People simply don’t keep up with every hobby they try.

 

Meanwhile, your friend has already been using a 90mm scope and finds he wants to see DSOs beyond what his current scope allows. Well, that’s a pretty good reason to try a bigger scope! My only caution to your friend would be that unless he gets something huge (quite a bit bigger than what he’s contemplating, from what I understand), the DSOs he sees will still mostly be "faint fuzzies" (the other name for DSOs). He’s not going to see through an eyepiece the beautiful, colorful astrophotography images of these objects so easily found on the internet. 
 

If he can’t try out a bigger scope for himself such as at a local observatory or through a friend or club member, etc., have him do searches for sketches of some of the objects he hopes to see that have been done by people using similarly sized telescopes. As long as he has realistic expectations about what he’ll see and he is still interested, and as long as he has realistic expectations of how big of a scope he’ll be willing to deal with in practice, I say go for it. He already knows he wants to try something bigger than 90mm, the question is really just how much bigger, and like a lot of people, he might just have to take his best guesstimate, pick something, and then jump in and try it for a while to find out

Edited by therealdmt, 04 December 2020 - 08:46 AM.

[Jaimo!]

Of course the professor is focused on AP, he is a professional...  not too many professionals doing visual these days.

 

What we are forgetting, is the best scope is the one that gets used the most.  Just got rid of my 12" Dob as I live inside the NYC nebula and I no longer had a car large enough to comfortably schlep it do a dark site, and I have began dabbling in AP.  For visual, although smaller, my 4" Refractor or 6" Maksutov gets used the most for visual.  Similar scopes to the professors recommendations, which seem to be geared toward a beginner, steering away from concepts like collimation and large scopes, focusing on the time spent observing.  Just like everything, there is always a balance.

[BlueMoon]

 

I strongly agree with the professor and understand that large apertures are not for everyone to handle and that technology is helping smaller scopes a lot now (my friend is n professional either - with a busy work life).

"Busy work life." Bang! Right there. Been there, done that. For most, astronomical observing and astro-photography are leisure pursuits. However, busy schedules are not conducive to having leisure time. From a practical standpoint, larger aperture telescopes need and require substantially longer cooling times than smaller apertures. It begs the question, "Does your friend have time for this?". Smaller APO scopes with good ED glass will cool down faster, be simpler to transport (grab n go) and can give extraordinary views. Invest in a few quality eye pieces and there you are ...

 

Anecdote: I sold a 10" dob and 6" refractor and downsized to what you see in my sig because I didn't have the time to devote to using them properly. Hours of cool down time that I simply didn't have time to plan for. Now, I don't worry about what I can't see but enjoy more of what I can because I'm out observing more frequently with my smaller, lighter gear.

 

Clear skies. 

Edited by BlueMoon, 04 December 2020 - 10:37 AM.

[Asbytec]

"Busy work life." Bang! Right there. Been there, done that.

Anedote: I sold a 10" dob and 6" refractor and downsized to what you see in my sig. I don't worry about what I can't see, but enjoy more that which I can because I'm out observing more easily.

Clear skies.

Yep, due to busy life, kids, golf, flying, and night school my 18" Dob got used maybe one weekend a month near new moon if I felt like driving to a dark site when the weather cooperated and I decided not to take my 10" LX200. I miss that huge scope (both actually) and wish I still had it. But such a schedule doesn't afford much eyepeice time.

A decade ago I downsized from a 12" Dob and C11 to a 6" MCT. I've learned to rely less on the equipment and gadgets, and more myself as the active component in the observing process. The smaller aperture kind of forced that on me, but it became my longest owned and most used scope. Ever. Because it was a great scope I learned to use, and being retired helps a bunch, too. I am currently working with my 8" Dob to take its place.

[Jon Isaacs]

Meanwhile, your friend has already been using a 90mm scope and finds he wants to see DSOs beyond what his current scope allows. Well, that’s a pretty good reason to try a bigger scope! My only caution to your friend would be that unless he gets something huge (quite a bit bigger than what he’s contemplating, from what I understand), the DSOs he sees will still mostly be "faint fuzzies" (the other name for DSOs). He’s not going to see through an eyepiece the beautiful, colorful astrophotography images of these objects so easily found on the internet.

 

 

The friend is contemplating an 8 inch SCT or a 10 inch Dob.  Either of these would be far more capable than a 90mm Mak.  In any scope most DSOs are faint fuzzies but in an 8 or 10 inch, there will be many more that are not faint fuzzies than in the 90mm Mak.

 

In terms of size and use.  Very often the statement is made that scope that is most used is the best scope and that a smaller, more manageable scope is best.

 

The other side of that coin is that a larger scope may be more effort to setup and transport but it will show more... The excitement of the thought of looking through a larger scope can be a huge motivating factor.  Think about "I'm driving 70 miles to look through a 4 inch scope" versus "I'm driving 70 miles to look through a 20 inch scope."

 

Jon

[Muffin Research]

Well but those 70 miles can make a 4 inch scope also very much worthwhile looking through.. a good dark site do you really need a scope? I can just lay on my back all night and just take in the incredible amount of stars and spot nebulosity you can spot galaxies and clusters naked eye even, just point at the fuzzy with the telescope and it will reveal itself.

[jmohme]

My first quality telescope was a 10 inch SCT. I really enjoyed it but it was destroyed in a fire. 

Just recently I was finally in a position to replace it and found a great deal on another SCT, but an 8 inch this time.

While I do miss additional image brightness, I do find the smaller size has made it just enough easier to transport and set up that I am using this scope much more often than I did the 10.

So yes, Aperture vs Practicality is a relevant thing to consider.

 

I still miss my 10 though.

[DSOGabe]

The professor's response is partially correct.

If one is focusing primarily on AP, then aperture is no a major concern-to a point.

However, if the primary goal is visual observing then aperture is still king. It then falls on one to figure out just how big a scope the individual can afford and comfortable move around.

[Jon Isaacs]

Well but those 70 miles can make a 4 inch scope also very much worthwhile looking through.. a good dark site do you really need a scope? I can just lay on my back all night and just take in the incredible amount of stars and spot nebulosity you can spot galaxies and clusters naked eye even, just point at the fuzzy with the telescope and it will reveal itself.

 

Does that work for a regular basis?  I can lie back for an hour or two, but spending several nights in a row, I want something that will show me more.  And from my light polluted backyard, I want something that will perform on the planets and double stars.

 

My main point is that there are good reasons to own an 8 or 10 inch scope, that the effort required can pay off.  

 

Jon

[Muffin Research]

Does that work for a regular basis?  I can lie back for an hour or two, but spending several nights in a row, I want something that will show me more.  And from my light polluted backyard, I want something that will perform on the planets and double stars.

 

My main point is that there are good reasons to own an 8 or 10 inch scope, that the effort required can pay off.  

 

Jon

Well I don't get those skies often so when I do just naked eye really goes a long way, then the first instrument that comes to mind to enhance on that is not so small binoculars or a fast 4-5" refractor, then indeed a 8 to 10 inch mirror to cast more light and detail on all the things you're picking up on, unless you're really blessed with good dark & stable skies any larger aperture is rather a curse than a blessing

[tommm]

It seems to me that the prof was considering only AP since his rational for not needing larger aperture is post processing, etc.  I didn't notice any direct comments on visual only use. So, is that your friend's interest, or is s/he interested in visual use, or both?  If AP, I agree with the prof that most money should be spent on getting a very rigid mount with accurate, smooth tracking. If the target is visual use, that is not so important as others have said, but, you still want something that doesn't shake around in breeze, moves smoothly, and stays put where it is moved. A quality dobsonian will do that.  So for visual, go to larger aperture, as large as you think you will be comfortable moving around, and dob's are hard to beat in price/performance. For AP you might post in the AP Beginner forum and see what they recommend. I expect they will mostly agree with the prof, but have some specific suggestions.

[John Fitzgerald]

Using my years of experience as a guide, I think that most refractors exceeding 140mm and f/8 and any Dobs or SCTs larger than about 12 inches, are too unwieldy to be regularly transported away from the home base.  Anything larger, to get maximum use, should be made as portable as possible at home, or be in a dedicated observatory.

[tommm]

All these comments, including my own, strongly depend on the user's interest, patience, health, physical fitness/strength, and ease of access to dark skies.  Those vary widely so you get a variety of responses. As said, the easier a scope is to use the more you are likely to use it (as much as YOUR life permits). That said, to me most of the time investment is in driving 1 1/2 to 3 hours to a dark sky site, so loading/unloading, and setting up a scope, big or small, is a small part of the time investment. So I'll take the big one because I get much better return (in views) on that time investment as Jon mentioned.  Even setting up at home, the difference in setting up the smaller scope versus larger one is about 15 minutes. I'm going to use it for 2 to 3 hours, so 15 minutes is negligible to me.  BUT, I'm in good health and fairly fit - I hike 10 to 15 miles and 2000 to 5000 ft elevation gain regularly in spring/summer/fall, backcountry ski in winter and have been doing so for decades.  So your friend has to decide what suits THEM.  Lot of good info in the answers here for things to consider. And again, if their interests are AP, post in the AP forum where people with more experience in that will respond.

 

Edit: One other comment, I don't understand the prof's comment on the difference in collimating a 6" vs 8" (Newtonian presumably) scope. In my experience there is no difference, and 6" to 2x" are all easy to collimate except when you are new at it. I typically spend around 5 minutes collimating my 22.4". It's almost always a very small tweak each to the secondary and primary.

Edited by tommm, 04 December 2020 - 11:54 AM.

[havasman]

So a friend of mine was looking for suggestions to upgrade from his Celestron C90 MAK to something significantly larger so he can view DSOs.          

Seems to me Il Professore didn't read the question very well and responded with his advice mantra. And repeatedly stressing the expensive mount only reinforces that impression.

 

If your friend wants to better view DSO's and has only the experience of a highly obstructed 90mm scope then even a 6" f8 Dob would be revelatory for him and 8 or 10" aperture should amaze.

[davelpg]

I kinda agree with the professor. I've recently rekindled my long time interest in Astronomy and purchased 2 new telescopes. Interesting they were an 80mm AT80ED and a 127mm Mak Cat, just as he recommended. Of course, YMMV but those new gadgets will I suspect keep me busy and interested well into the future. 

[VeloBob]

I'm a year into the hobby (after years of celestial navigation and bino viewing), and can empathize with the friend.  I don't expect Hubble views, but I would like to see more of the DSOs than I can visually, so I've started lurking of the EAA forum.  I've no desire to go into astrophotography, but I want to see more than I can with my EVO 8 visually, so EAA seems to me to be a winner.  I can use my current equipment with the addition of a camera, using the laptop that I already own, and actually make out some details of the "faint fuzzies", including colors.  I love the immediacy of visual, and EAA, to me, is simply adding an extra capability to my visual repertoire.

 

Bob