Small aperture APO for visual

[SwiMatt]

I expected this to be the kind of discussion I would find all over the forum, but weirdly enough nothing that answered my doubts came up by searching old threads. 

I regularly see that the marketing for APOs is targeting astrophotographers, but I understand that they are lovely scopes for visual astronomers as well. I have been thinking for a bit now to buy a small aperture refractor (<= 4") to complement the great views I get with the Mak 127: I have been missing the wide views necessary to frame large star fields and the larger open clusters. My first thought was to get a small achro, like a StarTravel 102, but then I realized that, in terms of price, I could stretch my budget and get a smaller aperture APO - say a Sky-Watcher Evostar 72ED. Some of these smaller scopes come with much better quality (not only optics, but e.g. in terms of focuser). The 72ED would also be a very light setup - extremely important for me since I need to be able to put my set up in a backpack.

What do I gain from going apo 70-80, compared to e.g. a StarTravel 102? Is this a noticeable difference for a visual-only astronomer (given equal targets)? Am I better off buying better eyepieces for an achro? Would an apo with "basic" eyepieces be a sort of a waste of resources? Would I for example get views with better contrast and detail, even under heavy light pollution? 

NB: I'm not talking about aperture - I am perfectly aware that 20-30mm of aperture is a huge difference. For fainter objects I already have a 5". I also understand that chromatic aberration can be an issue in achromats, but from many reviews the ST102 has very low CA when used for its intended use (wide field). I know the technical and theoretical differences. Give me your opinions! I want to hear your experience, how do you feel about it?

Edited January 16 by SwiMatt

[Elp]

I've had an acro, but it was a cheap acro. Views of the moon were fine but we're tinged with a yellow hue at the edges if I recall. Planets also did a similar thing with some blue too.

Viewing through my Z61 and Starfield 102 though there's none of that. The moon is a crisp sharp disc, so are planets.

Depends on how good you want the experience to be. I mostly image which will show the deficiencies of any optics, and both scopes again are great but you start to see star bloat as they're not triplets.

Personally I don't think you'll gain much going down aperture, maybe if you go to around 60mm you can see more FOV, I love just browsing the skies with the Z61.

[mikeDnight]

Hi Matt. I see that you're thinking about an apo with less than 4" aperture because you want it to complement your 127 Maksutov. I can see the sense in that, but if you were to push the boat out and buy a 4" apo, I would be confident you would use the 4" in preference to your 127 every time. The 4" would give wider fields at low power and sharper, better defined views of the Moon and planets virtually every time despite the smaller aperture, and I'd suspect brighter views of deep sky objects. 4" apo's seem to come up for sale quite regularly on the second hand market, and all you'd really need is a doublet, but there's a new kid on the block that really seems to be a bargain - the 103mm Askar. It's a triplet and so may be better colour corrected than some ED doublets, yet is small enough to be carried by a relatively lightweight mount such as an AZ4 or EQ5. It's a beautiful looking scope as well as a nice performer!

Available from FLO.

Edited January 16 by mikeDnight

[Stu]

Light the blue touch paper and retire… 🤣

I’m sure this will be a lively debate 😁

I’ve had more apo scopes under 4” than I care to remember, Televue, Tak, Vixen, Stellarvue, TS and William Optics, over ten of the little blighters 😜

For me, there is just something about the aesthetics of the view in a small apo which is very beautiful. Small aperture scopes show larger airy disks than larger apertures, and this makes them easier to see at lower mags and in poorer seeing. Put simply, a star that might look a spikey mess in a large scope may well look like a beautiful bullseye on velvet in a small apo. So that’s the first thing; do aesthetics and pure enjoyment of the view motivate you vs say splitting the tightest double possible?

Second thing is widefield views. With a four or more degree field of view, you get an almost binocular type perspective on objects like the Pleiades, but with none (or far fewer) of the aberrations which come with most binoculars. With a dark sky and an OIII filter you can fit the whole of the Veil of North America into the field of view, two of my favourite targets.

Then there is portability. A 72mm say is a take it anywhere sort of scope and can be used on a light mount and tripod. I use a ScopeTech zero for anything 4” and below, not available any more but the Sightron from FLO is very similar, possibly better, or there are the AZ4 and 5 which are excellent too, and cheaper. I took a 66mm WO to Tanzania where the skies were just amazing. I confess I was slightly too worried about getting eaten to properly concentrate on the scope but it performed more like an 8” than a 2.5” under Bortle 1 skies.

Of course a scope of that size is never going to be a planetary hero, but you can still see interesting views; GRS and shadow transits are visible in a 60mm apo with patience and good conditions. There is however a big difference in size, portability and capability between 70mm and 100mm. A full 4” apo can show you some spectacular planetary and lunar views (as evidenced by John’s recent sketches) but is less likely to be airline portable and requires a bit more thought to travel around with. Many people are surprised at just how capable a 4” apo is.

So a lot depends on what you want to achieve with it. A 4” scope is a great all rounder, and I’ve had better views with mine than with 5” or 5.5” maks. They are also more versatile in being able to offer wider fields of view as well as high power lunar, planetary and doubles capability.

Dropping down to 70 ish mm ups the portability and loses a fair amount of planetary performance, whilst gaining wider fields. So much depends on what you want to do with it.

I currently have Taks in 60 and 76mm and they give lovely results, but in many ways I miss my old TS 72mm. The 76mm Tak is f7.5 and needs to be split in two to pack down properly, whereas the TS I had was f5.9, and already short enough. With fpl-53 glass it was an excellent scope with a fantastic R&P focuser.

A 72mm sat next to the Mak would complement it very nicely, whereas a 100mm may well compete with it more than you expect.

That’s the end of my rambling, hopefully something relevant in there!

[mikeDnight]

26 minutes ago, Stu said:

Light the blue touch paper and retire… 🤣

 

LOL! 

 

[Elp]

37 minutes ago, Stu said:

I confess I was slightly too worried about getting eaten

It's not exactly a risk free hobby after all...

[Elp]

I too prefer my shorter FL refractors over my C6, you just can't complain about those pin point sharp details. Newtonians are a bit similar in terms of sharpness.

[RobertI]

I had a 72mm APO which was about the biggest scope I could fit in my astro-backpack with eyepieces and accessories - it was an excellent travel scope and went surprisingly deep on DSOs, also light enough to sit on a decent tripod - I would thoroughly recommend something like this. A two inch focuser allowed for 2” eyepieces for those extra wide views. Stupidly, I sold it! I still have my 66mm, the views are similar, but the focuser is pants and only 1.25”. The Skywatcher 72mm does not have a retractable dew shield which is a bit of a pain for fitting into a backpack I imagine. The Stellalyra 66mm or 80mm look nicely specced and there are some offers available.

[jjohnson3803]

I have a SkyWatcher ST102 achro and an Astronomics AstroTech 72EDii (not quite an APO), so I'd say get one of each.  😉

If I had to choose between them, I'd likely keep the 72ED.  I originally bought a 102ED but it was a beast compared to both the 72 and 102 achro.  

 

 

 

 

 

Edited January 16 by jjohnson3803

[SwiMatt]

Exactly the kind of discussion I need! Keep it coming! I might have to wait longer and streeeeeetch my budget for a 4" apo, the Askar looks HOT 

[MalcolmM]

I'm a great fan of small APOs, primarily for their ease of use and portability, the ultimate in grab 'n' go.

With that in mind, I would skip 100, 90, 76 and jump straight to 60mm ish. If you're going small, go proper small and reap the benefits of a small scope. Keep it setup inside and you can take advantage of the smallest gap in the clouds or a short 5 minute session before heading to work. To say nothing of being able to pop it into carry-on luggage on planes.

I'll not add petrol to the torch paper by saying what my recommendation would be, but just say 'go for it'. My 60mm is probably my most used scope.

Malcolm 

 

[RobertI]

3 minutes ago, SwiMatt said:

the Askar looks HOT 

Another plus point for the Askar is that it has a detachable section which allows the OTA to be shortened - this should allow you to get some delicious low power views with a binoviewer - if I were in the market for a 4” this would be top of my list I think.

[Stu]

50 minutes ago, RobertI said:

Another plus point for the Askar is that it has a detachable section which allows the OTA to be shortened - this should allow you to get some delicious low power views with a binoviewer - if I were in the market for a 4” this would be top of my list I think.

Hadn’t noticed the removable section, great feature and likely makes it airline portable. Weight is relative high still but it’s still doable. Not too many 4” scopes that are 👍

[SwiMatt]

Yeah the weight of a 4" is a bit of a turn off: at 3.2 kg, the Mak is great but already on the heavier side for a truly portable set up (especially when travelling - I do have access to better skies from time to time, but meed to fly). I see lots of advantages in getting down to 72 (or even 60?? Your passionate speech didn't fall on deaf ears @MalcolmM). But it's a lot more money for something similar in weight and portability to a ST80 or ST102, which is why I'm loving to hear all your positive experiences. It seems worth it.

Now that I think about it, I have yet to hear someone complain about small apos...

[GrumpiusMaximus]

I have a little bit of recent experience here - although I do not pretend for a single second that I have anything like the experience of many in this thread as I am a relative beginner to the hobby.

I've owned a C5 for a couple of years and really like the scope.  It gives good views of DSOs and planets but I've always found it a little lacking on stars.  It's the scope I bring out for looking at Messier objects, etc.  I'm very fond of it, I like it and I use it (I've had it out this evening, in fact).

Recently a 70mm ED refractor came up for sale on the forum and I purchased it.  It's ostensibly Altair but is also branded as TS and a few other models.  It's a quality little scope, with a 2" Crayford focuser, integrated dew shield and is well built.  The first night I got it out - and every night since - I have been absolutely thrilled with its widefield performance.  It's fair to say that I didn't 'get' refractors before buying the scope.  After all, why would I not want the extra aperture that my C5 affords me?

Well, the contrast is better and although it doesn't pick up the DSOs in the same way, the views are sharp and clear.  At just 42X I was able to pick up IO ending its transit of Jupiter last week (a slight elongation) and with higher magnification I've managed to get the GRS.  Easily done in the C5 - but the 70ED punches well above its weight by the nature of the optical system.

I have also made a 2" eyepiece out of a couple of old pairs of 10x50 binoculars (loads of tutorials online on how to do this - look up Red Henry) and whilst the eyepiece is actually too wide for the scope to really take advantage of, I can scan at 8X.  I picked up loads of satellites and a meteorite with that ridiculous eyepiece.

I do not regret buying my 70ED for a moment and having a C5 that I can also bring out and stick on the same mount is great.  I can change OTAs in less than a minute.

Now the only challenge is holding back the desire to source a 4" refractor...

[JeremyS]

The small scope I never ceased to be amazed by for its gem like quality: Tak FOA 60Q.

The 3-inch scope that thinks it’s a 4-inch, but can go everywhere, even on a plane: Tak FS 76DCU

The 4-inch scope which could be the one and only lifetime scope: Tak FC 100DZ

The almost  5-inch scope that masquerades as a 4-inch scope by virtue of is low weight and compact size: Tak TSA 120

[mikeDnight]

1 hour ago, SwiMatt said:

Exactly the kind of discussion I need! Keep it coming! I might have to wait longer and streeeeeetch my budget for a 4" apo, the Askar looks HOT 

It may well be worth the wait. The Askar 103mm also comes with an amazing padded carry case, which I think paulastro posted pic's of after he bought his. Looks awesome!

[SwiMatt]

34 minutes ago, GrumpiusMaximus said:

I have a little bit of recent experience here - although I do not pretend for a single second that I have anything like the experience of many in this thread as I am a relative beginner to the hobby.

I've owned a C5 for a couple of years and really like the scope.  It gives good views of DSOs and planets but I've always found it a little lacking on stars.  It's the scope I bring out for looking at Messier objects, etc.  I'm very fond of it, I like it and I use it (I've had it out this evening, in fact).

Recently a 70mm ED refractor came up for sale on the forum and I purchased it.  It's ostensibly Altair but is also branded as TS and a few other models.  It's a quality little scope, with a 2" Crayford focuser, integrated dew shield and is well built.  The first night I got it out - and every night since - I have been absolutely thrilled with its widefield performance.  It's fair to say that I didn't 'get' refractors before buying the scope.  After all, why would I not want the extra aperture that my C5 affords me?

Well, the contrast is better and although it doesn't pick up the DSOs in the same way, the views are sharp and clear.  At just 42X I was able to pick up IO ending its transit of Jupiter last week (a slight elongation) and with higher magnification I've managed to get the GRS.  Easily done in the C5 - but the 70ED punches well above its weight by the nature of the optical system.

I have also made a 2" eyepiece out of a couple of old pairs of 10x50 binoculars (loads of tutorials online on how to do this - look up Red Henry) and whilst the eyepiece is actually too wide for the scope to really take advantage of, I can scan at 8X.  I picked up loads of satellites and a meteorite with that ridiculous eyepiece.

I do not regret buying my 70ED for a moment and having a C5 that I can also bring out and stick on the same mount is great.  I can change OTAs in less than a minute.

Now the only challenge is holding back the desire to source a 4" refractor...

You're describing the exact type of experience I hope to get by buying this type of scope, this is encouraging

Now the only challenge is to not let the "mean" people on this forum convince me to go straight for the 4" apo that would make the Mak redundant 

[GrumpiusMaximus]

11 minutes ago, SwiMatt said:

You're describing the exact type of experience I hope to get by buying this type of scope, this is encouraging

Now the only challenge is to not let the "mean" people on this forum convince me to go straight for the 4" apo that would make the Mak redundant 

I'm not going to try and persuade you against a 4" apo...

[globular]

14 minutes ago, SwiMatt said:

go straight for the 4" apo that would make the Mak redundant 

Your signature says you have an AZ5 mount. If you're going to be tempted with the Askar 103 (and I wouldn't blame you!) then you'll have to get a new mount too. (See paulastro's threads on his experience with his Askar).

[Cjg]

@SwiMatt I had an ST102 many years ago, gave it away to a school teacher. Hopefully the newer versions have a better quality focuser that does not flop about. Anything other than a really lightweight eyepiece and it was a frustrating experience...Good luck, and hope you have plenty of popcorn at the ready for the ensuing debate 🤣

Chris

[Elp]

1 hour ago, JeremyS said:

Tak

Do you get commission or something?

[mikeDnight]

1 hour ago, JeremyS said:

The small scope I never ceased to be amazed by for its gem like quality: Tak FOA 60Q.

The 3-inch scope that thinks it’s a 4-inch, but can go everywhere, even on a plane: Tak FS 76DCU

The 4-inch scope which could be the one and only lifetime scope: Tak FC 100DZ

The almost  5-inch scope that masquerades as a 4-inch scope by virtue of is low weight and compact size: Tak TSA 120

And so it begins.....

[dweller25]

Once upon a time there was a little girl called Goldilocks.

One day Goldilocks was walking in the forest and saw an observatory.

She knocked on the door and went inside. Nobody was there.

Goldilocks saw three refractors so she decided to look through them.

This 3”  is too small and dim she said.

This 5” is too heavy she said.

This 4” is light, bright and shows good detail and is just right she said.

And she lived happily ever after.

The End 🙂

[HollyHound]

1 hour ago, JeremyS said:

The small scope I never ceased to be amazed by for its gem like quality: Tak FOA 60Q.

The 3-inch scope that thinks it’s a 4-inch, but can go everywhere, even on a plane: Tak FS 76DCU

The 4-inch scope which could be the one and only lifetime scope: Tak FC 100DZ

The almost  5-inch scope that masquerades as a 4-inch scope by virtue of is low weight and compact size: Tak TSA 120

Have to agree with @JeremyS here, as I own the first three of these scopes. They're all superb scopes.

The FC-76DCU is my most used and grab and go scope... I could easily live with jus this scope if necessary 😃

However, the FOA-60Q is sublime for double stars and lunar... it just keep delivering magnification when required, far outweighing it's (small) aperture 😍

Good luck with your choice, there are loads of superb scopes out there 🤞