'Sweet Spots' in quality gained vs $ spent in astro equipment?

[Amaranthus]

I've been musing about getting a 'quality' apochromatic refractor for imaging on a 'solid' mount with a 'good' CCD and 'sufficient' autoguider, etc. You can see a lot of adjectives I've put in quotes here - these things are relative, not absolute. This has led me to think about the general issue of 'sweet spots' in telescope purchases (for both visual , imaging, as well as mounts, CCDs etc).

There is a general rule that applies in a remarkable number of situations, the Pareto principle (http://en.wikipedia.org/wiki/Pareto_principle). Basically, you get 80% of your 'value' from 20% of your 'investment' (to generalise). It is strongly related to the law of diminishing returns (http://en.wikipedia.org/wiki/Diminishing_returns).

For just one example, let's say you buy an apo OTA for $8000. Will this yield an image that 4 times better than an apo that cost $2000, all else being equal (mount, imager, person, etc.). No, it may be twice as good, or 50% better or whatever - the exact value is always 'it depends' and to the degree that quality of images can't be quantified, it is a personal choice.

But to generalise this, given the wealth of experience here, I wondered if people had formed opinions on the 'sweet spots' for astro equipment? It could be for an imaging apo, or a visual Dob, or a grab-n-go (and could expand to eyepieces, imagers, mounts etc. - the list is almost endless).

The key to addressing this question is to consider the trade-off/incremental gains relationship between quality gains and $$ spend. Indeed, in theory, if you could plot quality per $ spent, in most cases the function would be non-linear and typically have a peak value (or range) that could be optimised. Although it is difficult to precisely quantify 'quality'...

So going back to my original example, say I was looking for a 'quality' apochromatic refractor for imaging on a 'solid' mount with a 'good' CCD and 'sufficient' autoguider.

In one case I might spend what I thought was a sweet spot:
$3500 on the OTA, $2000 on the mount, $1000 on the CCD and $500 on the autoguider = $7000

Or I could be on a budget and spend: $1000, $1500, $600 and $400 = $3500

Or I could say quality is paramount and money is no object, and spend: $8000, $10000, $5000, $2000 = $25,000.

The 3rd example will yield the best image and the 2nd the worst, but at what point does a normal guy on a normal income stop along the quality vs $ curve? This is my overarching point -- treat the above as just an illustration.

Thoughts?

[Kunama]

Interesting topic Barry, sure to have as many 'correct' answers as there are amateur astronomers on the planet.
Not being an imager, but being rather pedantic about quality assurance aspects, I prefer to spend more initially as I know how much it would bother me to have to deal with QC issues.
Seems that to get that last 5% you have to spend 3 or more times as much from purely optical quality aspect. But then there is the aesthetics, perceived investment values, peace of mind, pride of ownership etc.

No doubt the imagers will advise that the mount and its tracking ability is paramount to get great results. Personally I think the key to great images is equally in the post-processing ability and commitment.
Some of my favourite images were actually done with a 60mm Tak FS60 on a Vixen GPDX mount, a modestly priced combination by today's standards.

Obviously if one was earning their living from this equipment the situation would differ markedly from the casual hobbyist.

[cometcatcher]

Or to put it in 5 words, "best bang for your buck". :D

Firstly, you have to have a clear idea of what you want to achieve and what you want to image. Solar work, solar system photography and deep sky require different equipment. The Jack of all telescopes do exist, but it will be a master of none. Keep that in mind.

Does it have to be a refractor, a Newtonian, an RC? You may not like certain types of scopes. I personally hate short fast Newtonians, even though they are probably the scope of choice of many for deep sky. They are one of the best bang for buck with deep sky. I don't mind the longer f/L Newts, they are another good bang for buck for planetary imaging. But you may hate newts of all flavors.

Let's face it, it's probably better to use a scope you like over a scope that may be best for intended purpose. That's why I like refractors. Easy, grab and go no mucking about with collimation, no flex, they are wonderfully lazy scopes. :)

One of the best refractor deals at the moment I think is the Skywatcher ED100. I'm saying that cos I just bought one. :P It's no Tak or Televue but bang for buck it's awesome.

As for cameras, best bang for buck again is probably a modified DSLR. CCD's are way better, but way more expensive.

[Amaranthus]

Will be interested to see some images coming out of the ED100, Kevin!

My point above was a more general one that me asking advice about which apo/mount/imager etc. to buy. It could apply to any setup (DSO, planetary, visual, videoastronomy, AP, etc.). I just wondered if people had accumulated a particular consensus in these different fields. :)

Matt's point about buying for the long term is a good one. That is why I invested in top quality eyepieces (Naglers, Panoptics, PowerMates) - I figured I was buying 'em for life, to service any OTA I might present them with!

[brian nordstrom]

Barry , I am with Kevin here on the 'bang for buck' theory as some of the best amature AP's ever have been made with the awesome ED80 , HEQ6 and DSLR , a category #2 set up in your post

You don't need 25k worth of gear to take good AP's just modest equipment and lots of computer time ;) .

ps. I am like Matt here , strictly visual but do see the talent here on IIS and respect the people that take the time to process beautiful images and post their awesome results for us to admire .:thumbsup::thumbsup::thumbsup: .

Brian.

[cometcatcher]

I'm still in testing mode with the ED100. The end goal is to get a focal reducer for it to take it down to around F7 at which time it will be one of my main imaging scopes. I'm also really enjoying the scope for visual use. The contrasty field makes spotting comets amazingly easy. It's a Jack of all trades scope, but so easy to use which is why I like it.

If you take a look at Justin's images, I think we all agree that his setup works 80% as well as gear that is ten times the price. The 8" F4 astrograph if combined with a modified DSLR and cooler box is a killer combination and Justin does this with a standard Canon 1100D DSLR, a tribute to his processing skills.

Fast Newts all make great imaging scopes for DSO's with DSLR's or CCD's.

[g__day]

I wondered about this a few years ago, my determination was spend as much as possible on the mount, then add the right gear to it as you can.

Being on my 5th OTA I have finally reached spending as much on OTAs as the mount. I only use modded DSLRs - so I haven't gone down the serious mono CCD route yet.

Must say I am very happy with the 110mm triplet Williams Optics APO coupled to a PC controlled Moonlight focuser - that's a keeper.

Into your equation I would add two questions:

1. how many times will you invest to upgrade equipment - an be willing to sell and buy new gear when you need a quantum step forward in your gear? (account for the time and effort and loss due to depreciation)

2. At your ending point what is the longest focal length you will wish to image from and what duration shots given your night sky quality? (again longer focal length shots coupled to long duration need really excellent tracking and guiding - the mount has to be up to it. If you go over 1.5 metres on say and SCT and/or over 10 minute shots you will need a very rigid setup held securely on high quality mount).

Back then I got a 2nd hand Vixen Atlux controlled by a SkySensor2000-PC that after tuning turned out to be a total winner. If I was buying today I don't know what I'd buy; maybe an EQ8 or an AP900 at double the price. Once you go beyond a EQ6 you really have to do your homework and work out how you will be using the gear and how precise the control and ability of your mount must be.

I have never heard anyone spending too much on the mount then regretting later - never!

[LewisM]

A LOT of it depends on the person imaging.

Take Richard Muhlack. Humble scopes, modded DSLR, Chinese mounts, and turns out fantastic images. Same with Justin Tilbrook.

Or you can spend a small fortune, and still be collimating it 4 months later... (where is that whistling emoticon Mike uses when you need it).

A craftsman never blames his tools. A craftsman knows how to make the best of what he has.

I am not completely satisfied yet. Spent $5k on a scope that I cannot YET see any improvement over my old FL102S - YET. It might come, it may never come, and I am only a rank amateur, no where near a craftsman in any respect.

The FL102S was my sweet spot - I could do a lot with it. The Takahashi is wonderful, but... yes, I have regrets as odd as that sounds! I believe in things that are just meant to be.

[tlgerdes]

Spend as much money as makes you happy......... or spend someone elses money (thanks Dad :lol:)

[cometcatcher]

Don't forget to factor in an observatory, if you don't already have one.

[DJT]

Spend the most of your money on the mount first. Don't mess about.

This hobby is about getting repeatable results that you will be able to subsequently process to the best of your abilities. You need a mount that just does its stuff..

Then get (and this is the important bit) the CCD and scope COMBINATION that gives you the best imaging scale for the objects you are interested in. There is no "best scope" without the right CCD. You can buy a top of the range Tak and still struggle to get the detail you want without the right CCD.

if you can get a self guiding CCD with the guiding Chip in front of the filters then the you do away with a lot of the anguish around guiding.

So with your reference to the point around 80/20, I personally dont think it works that way.

It's not about getting a small increase in data quality, its about generating repeatable and consistently good data capture results. Whilst lens or mirror quality will add value, local conditions will have a big part to play, but being able to consistently and repeatedly generate good quality data will give you the better overall outcome.

If you get to a repeatable process then that's when the subsequent extra bung on lens/mirror comes into play. This is why Martin Pugh's presentation on his "war cry"at last years AAIC was so interesting. He didn't mention "brand", but focused on setup and process.

Good question.

[g__day]

It might help if you think of "sweet spots" and they do exist, as combinations of gear that are well matched and suited to purpose.

[astro744]

I think a sweet spot for imaging is vastly different to one for visual. Imaging is more processing than capturing and good images can be extracted using modest optics. I do think though that the mount is the most important part and that is where most of ther money should go.

As for visual (which no one has talked about much), I think the sweet spot depends on your taste for all things sweet. I do like my off axis stars to be just as sharp and in focus as my on axis stars but such sweetness is not to all tastes.

[Amaranthus]

We've talked a fair bit about mounts here so far, my current likely choice is the AZ-EQ6 for its balance of price, load capacity, flexibility and smoothness. Obviously I could save a bit with the NEQ6, or spend a lot more for the EQ8, but it seems to me that the AZ-EQ6 hits the sweet spot (I'm unlikely to ever want to mount an OTA heavier than 10-12 kg on it [i.e. 5" triplet apo]).

Talking of apos, I would obviously love something like a Televue NP127is (I'm a TV fanboi), but it's a massive $ step up. So I was thinking that an apo for imaging in the $3-5K budget 'sweet spot' might be much more realistic (I'm thinking of an astrograph that I'll be happy with for at least 5 years...) Is that reasonable?

[rustigsmed]

If you're not looking at throwing too much weight ontop then an AZ EQ6 or losmandy G11 would be what i'd consider.

i'd also be budgeting for an off axis guider and a quality focuser.

i don't know the answer to this - but i'm wondering whether you are better off spending more of your money on a better ccd (and filter wheel and filter$) than the telescope. but whichever way you go either the scope or the camera can be upgraded at a later stage.

[g__day]

I note there is a G11 with Gemini 2 for sale for $2,800 http://www.iceinspace.com.au/forum/showthread.php?t=118101

That seems like a huge bargain and quality step up from EQ6. I remember when that sort of set up brand new was > $5K.

A poorly performing mount will wreck anything you wish to do, can't stress all the serious folk here will tell you the mount is the key component.

Good luck with your decision, hope this advice helps!

[tonybarry]

Hi Barry

I saw your post and it got me to thinking. I see the evidence of the Pareto principle in many things, including the use of astronomical instruments.

I note that with SCT telescopes, the sweet spot appears to be about 8" (200mm) aperture. Over that size, the weight goes up, the portability suffers, the cost really goes up, and the field of view gets ever smaller. Under that size, the light collection ability is compromised.

With Dobs, the sweet spot appears to be changing. It used to be 8", but the recent influx of Goto dobs with collapsible truss would appear to be driving the sweet spot nearer the 12" (300mm) mark. Over that, they are getting too heavy, awkward (not portable) and costly.

Now if one were fitting out an observatory, weight and portability would be a lesser concern. If the mount can tolerate the weight, then bigger is better … sort of. The field of view will diminish as the aperture goes up, although the Newtonian mirrors with f4 ratio (or even less) can make the use of a crazy-big scope (think metre class Dob) still worthwhile. There is an article about such a monster scope in AS&T this month.

For an observatory fixed location, I think a 30" (750mm) f/4 Newtonian is probably as big as one could reasonably go before the field of view is compromised too much and the usability starts to be impacted. The club I am a member of has access to a telescope of this size, fitted with ArgoNavis and StellarCat … it takes two people to work it (despite the goto), and while the views are simply stunning, the trouble of operating it means it's as big as I would consider usable.

Regards,
Tony Barry

[Amaranthus]

I agree with the 8" sweet spot in SCTs Tony, I thought long and hard when buying mine about getting a larger (or smaller) aperture, but the 8SE seemed just right in the performance vs portability & FOV spectrum.

I'm moving to a dark site in about 5 months, and plan to set up an observatory then. I have my eye on a 16" Dob for that - well above the 12" sweet spot, but the consideration is that I don't ever plan to move it! So as you note, the sweet spot can vary depending on the circumstance.

[N1]

You know you've reached the sweet spot if you own a telescope that you would never ever part with (bar desperate situations) regardless of any other gear you've got.

If you don't own a telescope yet, think about what could always serve as your porthole to space no matter what life throws at you.

To me, this could never involve house-sized dobs, $10,000 mounts or, for that matter, electronics.

[rmuhlack]

Interesting discussion.

From an imaging perspective, and as a general comment, it seems to me that there is a tendency amongst the imaging community to "upgrade" to more expensive gear as a quick means to improve the resulting images, rather than addressing the underlying issues and inefficiencies in one's imaging process. I believe this means that there is therefore considerable scope (pun intended...) for quality images even with seemingly humble equipment - good news for those of us with more modest budgets!

For example, I seemed to have happened upon a sweetspot with my 130mm f5 newtonian astrograph. In terms of focal length (and therefore FOV) and f-ratio it is similar to your desired NP127is. Being a newtonian it is by design "apochromatic". Mine has been retrofitted (by the previous owner) with a 2" focusser. I have since fitted a Robofocus unit as well as top and bottom losmandy rails to minimise flexure (see here (http://www.astrobin.com/51303/)). At f5 it is right in the sweetspot of the MPCC, giving a flat field right to the corners of an APS-C chip.

As I see it, I basically have the same specs and "performance" (apo, flatfield, same FOV) of the NP127 but at less than a tenth of the cost. I currently use this with a modded (but not cooled) DSLR, on a HEQ5 mount. The scope is well within the imaging weight range of the humble HEQ5.

As Lewis mentioned previously in his post, it's modest gear for sure. Processing has a lot to do with the final result. This (http://www.astrobin.com/82767/C/) is my latest image with the setup just described. I have recently moved to dark skies myself and am now in the process of building my own obs, so i'm looking forward to the benefits of a permanent setup.

[Astro_Bot]

^^ That is the most reassuring post on acquisition and use of equipment I've read in a long time. There may be hope yet. :thumbsup:

[gregbradley]

The overriding factor is how much and how far you are interested in doing quality AP. That determines what level of quality is acceptable to you.

I think you work these systems out in reverse. What type of image do you want to produce? At what standard? What would that require? What posted images do I admire? What equipment did they use? What is my budget? Where will I image from and what are the conditions there?

If you live in suburbia then high end deep sky imaging with any setup is unlikely to yield the high end results you may want. You would need to go narrowband which has different choices of camera and filters.

The cost of good gear is coming down with many CCD manufacturers now, GSO RCs being quite good etc etc.

The sequence is 1. A good imaging location. 2. A good mount. 3. A good camera 4 a good scope.

6 inch APO is the sweet spot for refractors but they are usually expensive although I see APM offers some 6 inch APOs that are likely to be very good.

Greg.

[Amaranthus]

Great summary Greg.

One point of pride, beyond getting the very best image, is getting the absolute most out of a given set of equipment, whatever the price point. I've ended up going mid-range for now, and so I'll reconsider my future investments after a couple of years of milking my new setup for all it is worth!

[IanW]

Honestly I don't believe in "sweet spots" for aperture as you are going to be entirely limited by the seeing at your observing site. The best most of us in Australia can hope for is a bit under an arc minute on a good night, unless you have an exceptional location such as near the AAO.

Given the seeing limitations, as long as you can reduce the Periodic Error of a mount to under 5 arc seconds you'll get a quality image. Far more important in a mount is no flexure and that means big heavy EQ mounts or well designed Alt-Az mounts and rotators.

Small apertures simply cannot capture enough photons, even using current techniques and CCD's. Compare a shot with a 100mm refractor vs a 1m Reflecting telescope and tell me which has more detail if exposures are identical and you use the same post image processing techniques.

Just my 2 cents worth. For the record I've been doing AP since the early 70s. Back then in the pre autoguider days AP was not for the faint hearted.

[Amaranthus]

Ian, thanks. There is at least one undeniable aperture trade-off. Larger aperture (more photos) = longer focal length at the same f/stop (smaller FOV)

[tones-]

i wouldnt go as far as to say smaller aperture cant show good detail, even something as small as the tak fs-60 series will produce exceptional images.

ive always had a thing for tak scopes though so i ended up with a fs-102, add a feathertouch 10:1 and its the scope i'd never part with for both visual and imaging.

[graham.hobart]

I think it comes down to what or where your interests lie.
IF you like wide vistas then an FS 60 with a dslr is great.
If galaxies are your thing then you have to go for a longer focal length heavier scope and with that a bigger mount.
Sometimes owning a few scopes before hand makes it easier to find the ones that suit your personal interest. I know that's what happened to me- but I spent a small fortune getting there! Luckily I don't have any other hobbies!!
What ever makes you happy if it is a tasco jobby or a $10K Orion optics.
I dream of the lotto where I could kit all my new obs out with the best- just because I could afford it! I know it won't make me happier or a better person but I would enjoy it immensely!!
I personally went from a Meade on a wobbly wedge to an EQ 6 to a PMX. I never regretted spending that money on the PMX because it's been great and looks fab too. I aim to get years of service from it.
If my Wife new how much money I have spent over the years I would be in deep deep doggy dooh! But as she says, I don't go out anywhere much and she always knows where I am!!
Graham

[marc4darkskies]

Yep, spot on Greg!

IMO there is no such thing as a sweet spot - only a "sweet spot" for your aspirations and budget in the hobby using the spend-as-much-as-you-can-afford paradigm. Spending less than you can afford is a false economy.

I've been saying for years a) your goals will dictate what you buy and b) do your research. Keep asking yourself what you want to do and achieve. Forums like this & Google will eventually inform you what you need and your bank manager (or SWMBO) will tell you what you can afford. Forget about sweet spots. There is no simple recipe because the spectrum of goals (technical and aesthetic) is so variable.

Cheers, Marcus

[IanW]

True but it really doesn't matter if you mosiac your images.

An F10 SCT can be reduced to f6.3 with commercially available focal reducers, and down to f5 or lower if you are prepared to pay a professional optical fabricator (optician) to make you a special unit.

The latest Meade ACF OTA's run f8 and though there's no Meade focal reducer as yet, the Optec unit will work and give F5. That's a good wide field of view and can resolve to the limits of atmospheric seeing while giving a larger image scale which is vital for capturing detail.

[Brian3.]

Just a point out of "left field."
For visual astronomy I have learnt one sad fact and that is "age equals deteriorating eyesight." At this point the eyes need all the help that they can get which in turn means the best optical quality which again in turn means more money. Sad but true...
(Also a damned good excuse to "get what you want!")

[Brian3.]

:eyepop::eyepop:

[brian nordstrom]

:) I find my 127mm f8 Istar on its HEQ5 to be 'Just Right' in quality , performance and price .
Oh yes , my TV eyepieces help :lol: .

Brian.

[Paul Haese]

LOL, how much money do you really want to spend and how persistent will you be to obtain your goals.

The later for instance can mean you get great results with modest equipment but using everything at your disposal. Peter.M is a good example. He has very modest equipment but is doing unattended all night imaging with Sequence Generator Pro and associated software and his results are very good. He gets lots of data from doing this and that makes processing easier and produces of clean images that he is very happy with.

If on the other hand you have lots of money to work with you can spend as much as you like. Though you still need to know how to set everything up, problem solve and process data. All this takes time.

The cheapest things in my RC12 dome is in fact the telescope. It has had issues and I am working through them but I am producing pretty reasonable results. However, having a good camera, focusor, dome, software for acquisition and good mount make a huge difference.

There is no sweet spot, there is just how much you really want something to fulfil your goals. You can work hard with a small budget and you can work hard with a large budget. Persistence pays off.

[cometcatcher]

Everyone has made very good points. One major point Paul mentions is the all important "good data". You can do much with low budget modest equipment if you have good data. That usually means shooting near the meridian away from the smogosphere and collecting as much good data as possible with a cool as possible camera.

And live on a mountain. :D