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Doubles trouble..scope choice


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Hi all,

New to the forum and I'm enjoying reading past posts.

Now to my query: I'm 74 with intermediate in experience  but new to doubles observing. In researching which scope for doubles for Scotland's iffy skies I narrowed it down to either a 4 inch f/10 or f/+ achromat ,or a 127 maksutov. With pensioners budget I've ruled out ED or Apo scopes. If choosing , say a Bresser 127 maksutov and adding say a Porta 2  mount the cost is 150 GBPs more than say a Sky Watcher Evo 102 on a Eq3-2 mount or a Bresser 102 on the same mount. I really like the idea of increased portability and slow motion controls on the 1st choice and will have to weigh that against cost, but optics wise is one better?

Any and all feedback welcome. Thanks in advance.

Cheers

James

Ayr Scotland

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If it were me, I'd go for the Mak. With an achro refractor, even at f10, chromatic aberration is going to be present. Not really welcome if you are wanting to see star colours. The Mak won't have any false colour.

The Mak will need more cool down time though, so you'll need to factor that in.

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I don't like Mak's for doubles as they have a bright first diffraction ring. So close doubles can be tricky. A slow achromat would be preferable IMO. 

cHvJbCs.jpg

Failing that I'd consider a smaller aperture ED refractor.

Qk0WCtVl.jpg

I split more doubles with my 72ED DS Pro than any other scope I own. The 72 has a limiting magnitude of 11.9. A 102mm has a limit of 12.74. Which is less than one magnitude difference. 

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What scope do you currently have ?

Although I tried this

on a large dob, if you have a smaller one already it may be worth a go.

In general I tend to prefer refractors for doubles. Anything about 100mm plus is good. You need a decent mount though. 

Doubles are good through newts too albeit slightly less defined. Aperture does matter as for many things. That said you can see a lot of beautiful doubles with a small decent frac as above.

 

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I have been using an F12  80mm scopetech refractor. It is extremely light and easy to handle and shows no false colour at all as well as being very forgiving to eyepiece. The latter obviously has scope (pun intended) to save you money, I use lowish costing eyepiece with both my refractors.

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1 hour ago, Zeta Reticulan said:

I don't like Mak's for doubles as they have a bright first diffraction ring

The ones you have must have poor optics. I used to have an OMC-140 which had little to no diffractions rings and at x313 gave me my best ever view of ε Lyr.

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16 minutes ago, Mr Spock said:

The ones you have must have poor optics. I used to have an OMC-140 which had little to no diffractions rings and at x313 gave me my best ever view of ε Lyr.

They're just Synta Mak's. There's nothing 'poor' about the optics. They just don't cost seven grand.  I'm not the only person who has noticed this with Synta Mak's. 

CxzChGc.jpg

I thought the OP was on a budget. I think it's not realistic to recommend a a seven grand scope. Comparing it to a Synta Mak is downright disingenuous.

Edited by Zeta Reticulan
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1 hour ago, Zeta Reticulan said:

They're just Synta Mak's. There's nothing 'poor' about the optics. They just don't cost seven grand.  I'm not the only person who has noticed this with Synta Mak's. 

CxzChGc.jpg

I thought the OP was on a budget. I think it's not realistic to recommend a a seven grand scope. Comparing it to a Synta Mak is downright disingenuous.

Michael was referring to the OMC-140, not the 200. 140s can be had for around £300 on the used market so it’s not an unfair comparison. The new carbon fibre ones in both sizes are crazy money, I agree.

3 hours ago, Zeta Reticulan said:

I split more doubles with my 72ED DS Pro than any other scope I own. The 72 has a limiting magnitude of 11.9. A 102mm has a limit of 12.74. Which is less than one magnitude difference. 

On this point, magnitude is one factor but resolution derived from aperture is equally important when it comes to splitting doubles. My FC100 certainly out performs the FS-60C or FC-76Q.

I do agree with the point about fracs; I enjoy doubles much more with a refractor vs a mak, and have split closer doubles with them despite the aperture differences. Much neater stars in the frac. Having had an OMC200 for quite a while, I also prefer the views in my 8” f8 newt. Probably due to better cooling and lack of the extra light pass through potential tube currents. Shame they are not made generally now, most newts seems to be f6 or shorter.

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3 minutes ago, Stu said:

Michael was referring to the OMC-140, not the 200. 140s can be had for around £300 on the used market so it’s not an unfair comparison. The new carbon fibre ones in both sizes are crazy money, I agree.

On this point, magnitude is one factor but resolution derived from aperture is equally important when it comes to splitting doubles. My FC100 certainly out performs the FS-60C or FC-76Q.

I do agree with the point about fracs; I enjoy doubles much more with a refractor vs a mak, and have split closer doubles with them despite the aperture differences. Much neater stars in the frac. Having had an OMC200 for quite a while, I also prefer the views in my 8” f8 newt. Probably due to better cooling and lack of the extra light pass through potential tube currents. Shame they are not made generally now, most newts seems to be f6 or shorter.

How much were the 140's new? I think the Synta Mak's are pretty decent for what they cost. I'm not the only person who has noticed the bright diffraction ring on them. I don't know what's going on with Newt's, getting an f/6 isn't so easy nowadays. My guess is that they're mostly aimed at the AP market. It's where the money is lol. I believe the OP wants a reasonably priced, portable scope with a rapid cool down. I think the 72ED is a contender. Unless he wants to spend more money.

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15 minutes ago, Zeta Reticulan said:

How much were the 140's new? I think the Synta Mak's are pretty decent for what they cost. I'm not the only person who has noticed the bright diffraction ring on them. I don't know what's going on with Newt's, getting an f/6 isn't so easy nowadays. My guess is that they're mostly aimed at the AP market. It's where the money is lol. I believe the OP wants a reasonably priced, portable scope with a rapid cool down. I think the 72ED is a contender. Unless he wants to spend more money.

Not sure, but they are over a grand now which is chunky money for a 5.5” mak.

I’m not saying a 72ED isn’t an option, they are certainly very capable and portable scopes, I’ve had a few and enjoyed them.

However, if doubles are the target as the OP has stated, then resolution and hence aperture are going to be important. With 74 year old eyes too, the larger exit pupil from a 4” scope would definitely help. I would likely favour a decent f10 or f11 4” achro with well corrected optics myself as I think it would give more rewarding views (read aesthetically pleasing) than a mak.

Not sure about mounts. @Jimboscotland I assume goto is off the wish list? A decent EQ mount can actually be great for higher power observing of doubles as it’s easy to track with just turning one of the slow motion controls. Personally I’m rubbish at finding things with an EQ mount, but I do enjoy them for lunar/solar and planetary observing. If you are sorted in terms of finding with an EQ then go for it, otherwise an Alt Az of some description may be easier. Not sure how steady the EQ 3-2 is, sure others can advise. 

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Another consideration worth factoring in is ease of viewing. A short tube refractor or a mak makes it a lot easier to see doubles well up in the sky. Otherwise, lying on one's back on the grass at 3 am is less easy when you're 70 plus - a refractor with a long tube requires you to be physically 100% and impervious to chill.

Chris

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1 hour ago, Stu said:

I also prefer the views in my 8” f8 newt.

There's a thought. The Skywatcher 150P Dob is f7.84. Not only is it more aperture, it's less expensive. Add in an EQ platform for tracking and it's still £60 less than the Bresser/Porta combination. It should be able to get sub 1" too. My 12" split a 0.6" comfortably a few nights ago in less than perfect conditions. At f7.84 it's more forgiving of collimation too - a laser collimator would be all you need.

That's a negative for the Mak. Collimation is best done by a star test and can be tricky. A refractor generally never needs collimating.

What we are saying is any one of the three, frac, Newt or Mak, will work, it's just about which you prefer.

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2 hours ago, Stu said:

Not sure, but they are over a grand now which is chunky money for a 5.5” mak.

I’m not saying a 72ED isn’t an option, they are certainly very capable and portable scopes, I’ve had a few and enjoyed them.

However, if doubles are the target as the OP has stated, then resolution and hence aperture are going to be important. With 74 year old eyes too, the larger exit pupil from a 4” scope would definitely help. I would likely favour a decent f10 or f11 4” achro with well corrected optics myself as I think it would give more rewarding views (read aesthetically pleasing) than a mak.

Not sure about mounts. @Jimboscotland I assume goto is off the wish list? A decent EQ mount can actually be great for higher power observing of doubles as it’s easy to track with just turning one of the slow motion controls. Personally I’m rubbish at finding things with an EQ mount, but I do enjoy them for lunar/solar and planetary observing. If you are sorted in terms of finding with an EQ then go for it, otherwise an Alt Az of some description may be easier. Not sure how steady the EQ 3-2 is, sure others can advise. 

I find the 72ED very easy to use, especially for doubles. Does it have limitations? Of course. The OP told me that he would prefer a light grab and go scope that could take advantage of breaks in the weather. I regularly use my 72ED on an AZ5 Deluxe. It's my most used scope.

tnOcF4kl.jpg

Everything fits into these two bags. In a perfect world I wouldn't have a physical disability and I'd take a six inch ED refractor out every night. Unfortunately we don't live in a perfect world. I thought the 72ED/AZ5 was a reasonable grab and go compromise.  335 quid is still good for an ED scope. 265 quid is pretty good for a mount with a decent tripod and slo mo. Furthermore, the 72ED sits very well on the mount with no real vibration return issues. IMO astronomy isn't always about the biggest aperture. I'd rather be out looking at the stars than sitting inside wondering about whether it's worth setting-up.

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4 hours ago, Zeta Reticulan said:

I find the 72ED very easy to use, especially for doubles. Does it have limitations? Of course. The OP told me that he would prefer a light grab and go scope that could take advantage of breaks in the weather. I regularly use my 72ED on an AZ5 Deluxe. It's my most used scope.

tnOcF4kl.jpg

Everything fits into these two bags. In a perfect world I wouldn't have a physical disability and I'd take a six inch ED refractor out every night. Unfortunately we don't live in a perfect world. I thought the 72ED/AZ5 was a reasonable grab and go compromise.  335 quid is still good for an ED scope. 265 quid is pretty good for a mount with a decent tripod and slo mo. Furthermore, the 72ED sits very well on the mount with no real vibration return issues. IMO astronomy isn't always about the biggest aperture. I'd rather be out looking at the stars than sitting inside wondering about whether it's worth setting-up.

This is about presenting options with pros and cons so the OP can decide. He doesn’t have a disability so will perhaps have a different view point. Perhaps @Jimboscotland could comment on particular aspirations for doubles observing? Are you bothered about targeting very tight splits or enjoying wider spaced doubles of different magnitudes and colours perhaps? Are you someone who enjoys the aesthetic beauty of a star through a frac, or is less bothered by appearance and more by achieving the split? Some input would help guide the advice, thanks.

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1 hour ago, Stu said:

This is about presenting options with pros and cons so the OP can decide. He doesn’t have a disability so will perhaps have a different view point. Perhaps @Jimboscotland could comment on particular aspirations for doubles observing? Are you bothered about targeting very tight splits or enjoying wider spaced doubles of different magnitudes and colours perhaps? Are you someone who enjoys the aesthetic beauty of a star through a frac, or is less bothered by appearance and more by achieving the split? Some input would help guide the advice, thanks.

I won't comment again on this thread. If the OP wants to communicate with me he can do it through a PM. I didn't answer this thread to start a flame war. I just gave an opinion. I have no idea why you are beleaguering this.  

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Hello @Jimboscotland and welcome to SGL.

In my experience the 4” F/10 refractor is a bit too long for an EQ3 type mount to hold it steady enough for higher power viewing.

Perhaps this may be a better balance, if you can live with an 80mm objective ……
https://www.firstlightoptics.com/scopetech-telescopes/starbase-80-refractor-and-mount-package.html

Edited by dweller25
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6 hours ago, Zeta Reticulan said:

I find the 72ED very easy to use, especially for doubles. Does it have limitations? Of course. The OP told me that he would prefer a light grab and go scope that could take advantage of breaks in the weather. I regularly use my 72ED on an AZ5 Deluxe. It's my most used scope.

tnOcF4kl.jpg

Everything fits into these two bags. In a perfect world I wouldn't have a physical disability and I'd take a six inch ED refractor out every night. Unfortunately we don't live in a perfect world. I thought the 72ED/AZ5 was a reasonable grab and go compromise.  335 quid is still good for an ED scope. 265 quid is pretty good for a mount with a decent tripod and slo mo. Furthermore, the 72ED sits very well on the mount with no real vibration return issues. IMO astronomy isn't always about the biggest aperture. I'd rather be out looking at the stars than sitting inside wondering about whether it's worth setting-up.

This is a good option too 👍

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One extra thing to contemplate if you wanted to go down the Evo 102 ‘frac option you mentioned is to get a Baader semi-apo filter to use with it. I use the semi-apo filter on some of my achro ‘fracs (Celestron Omni 120, Bresser AR-102S) and it works very well at reducing/eliminating any CA on any stars/doubles etc, and also improves the images any planets too when used.

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With a filter though you will loose the star colours, which is part of the attraction of double stars.

Another idea is to buy used. They don't come up very often but an 80ED apo would prove an excellent option. No false colour, convenient size, great performance - what's not to like.

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A second hand 80ED scope would be a great option if you could get hold of a second hand one. I have an 80mm and 102mm AA ED Starwave Ascent ‘fracs which I now always tend to use when observing doubles. I have not noticed that the semi apo filter reduces star colours much, but I’ll check it out again and see on my 2 achro ‘fracs I mentioned. Maybe my colour perception is not as good as others perhaps! ;) 

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The 80ED I have has remarkable star colours, plus pin point stars. It is a Celestron though and has that dire, sloppy,  r+p focuser you can't replace. Now I have the 102 it sits in a cupboard unloved :biggrin:

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2 hours ago, Zeta Reticulan said:

I won't comment again on this thread. If the OP wants to communicate with me he can do it through a PM. I didn't answer this thread to start a flame war. I just gave an opinion. I have no idea why you are beleaguering this.  

No flame war @Zeta Reticulan@Mak the Night, just answering as you seemed to be pushing the 72ED and, whilst it’s a nice scope, it’s not necessarily optimum for observing doubles due to the limited resolution. That’s why I’ve asked some further questions of the OP to understand what is most important to him.

Now please, let’s not let the thread degenerate. Thank you.

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