Does beautiful imperfection have appeal in stargazing?

[Emperor!Takahashi!]

I've noticed that we stargazers tend to discuss optics in terms of perfection - sharpness, scatter, corrections for various aberrations, and so on. I am curious how we feel about instruments' unique aesthetic presentation. I used to be deeply into 35mm film rangefinder cameras. The sharpness, edge correction, and contrast of lenses are certainly discussed and debated. But there's also space for appreciating beautiful imperfection. There are old Leica and Zeiss lenses that have plenty of what we might call either "scatter" or "warm glow," subjectively. I was thinking about this while looking through a telescope that I recently acquired, a 1990s Vixen 120S 5-element petzval achromat refractor. There is a little false color on the brightest objects, and the 3-element petzval assembly introduces mild scatter that's visible at high magnifications. So, we might assess these as imperfections. But this old(ish) Japanese refractor is known for having carefully figured lenses, and there's a quality about the view that is just beautiful. It reminds me of some of my decades-old Leica lenses that had magic in them. When I was using those lenses, I didn't crave perfection because what they offered was thoroughly gratifying in its own right. That's how I felt when looking through the Vixen.

What do we think? Does beautiful imperfection have appeal in stargazing?

[Stu]

6 hours ago, The60mmKid said:

What do we think? Does beautiful imperfection have appeal in stargazing?

I certainly enjoy old scopes with some character. For example, I have a fine specimen of a Televue Genesis which I don’t use often but love when I do. It is an achromat really, despite the Fluorite rear element so shows false colour at higher powers and on bright objects. It’s not awful, and the scopes main strengths are being able to show a ~5 degree field with beautiful flatness using a 31mm Nagler. Wonderful for trawling the Milky Way from a dark site, yet the figure is excellent and it will happily split tight doubles at x250 which is as high as I can easily get with a 2 to 4 Nag Zoom.

Another old yet flawed scope is the Zeiss Telementor. These have a fearsome reputation which is partially deserved I think. Mine gives cracking views of the Moon and splits doubles very well considering its 63mm aperture! The downside is the CA which is easily noticed in comparison with modern apos. I love the large airy disks produced by these little scopes; they hide a multitude of sins in terms of seeing, plus the show doubles beautifully. Izar for instance looks like a tiny grey blue gem on a ring around a perfectly round diamond. Lovely 👍

I even recall the Telementor showing a little more than my FS-60Q when I did a comparison 👍.

 

[John]

I'm a little surprised that this topic has not attracted more responses 

My Vixen ED102SS F/6.5 is a great little scope but it's optical figure is not quite as good as that of my Tak FC100-DL. The star tests from the Vixen are excellent with perfectly concentric diffraction rings either side of focus but at sharp focus the 1st diffraction ring around moderately bright stars is slightly more prominent than the Tak's -  I think that means that the Vixen objective probably has a touch of spherical aberration.

However, when observing, the slightly more obvious diffraction ring can actually lead to aesthetically pleasing results when observing binary stars such as Castor, Algieba, Gamma Virgonis and Epsilon Lyrae. The pairs of stars, being roughly equal in brightness with these targets, have a delicate and thin figure of 8 shaped fine line of light encompassing them, like this:

With the Tak, on the same targets, the diffraction rings are either invisible or so thin that they are not obvious. 

I actually enjoy this "slightly-less-than-perfect" presentation of these brighter star pairings 🙂

With uneven pairs the effect can be like a "diamond ring" with the fainter star appearing to sit on the edge of the diffraction ring of the brighter component. Again, that can be very attractive.

Where the stronger diffraction ring is less helpful is with close pairs of highly uneven brightness (eg: Zeta Herculis) where the fainter component star can be partially masked by the diffraction ring around the brighter one. With such stars, getting the positive split is easier with the Tak.

On occasions in the past I have described Zeta Herculis diffraction ring as looking like a thin snake that has swallowed a tennis ball with the dimmer secondary star seemingly embedded within it !

So it depends on how exacting my targets are I guess but sometimes I do appreciate beautiful imperfection at the eyepiece 🙂

[Franklin]

On 26/06/2023 at 23:37, The60mmKid said:

That's how I felt when looking through the Vixen.

What do we think? Does beautiful imperfection have appeal in stargazing?

I believe there is definitely some kind of optical trait inherent within each brands manufacturing process, whether it be glass types, coatings, optical design, the figure or the whole package and this trait is visible at the eyepiece. I am in no way an expert but I have looked through some pretty nice refractors over the years and I know when I'm looking through a Takahashi, which is different to when I'm looking through a Vixen. Now the Takahashi, being Fluorite, is optically superior to the Vixen but this will only come to light when the scopes are pushed to their limits, the Tak will hold up whilst going that little bit further. But when used at low to moderate powers the two would appear pretty much the same, yet to me there is a difference and that difference is how far from perfection each is. It's not just high end scopes either, basic "old school" achromats all have their own traits as well. Look at the following the old TAL100 achro's have, they give great performance because of their superior optical figure, the Russians gave them a good lens with good coatings. I have a Vixen SD81 at F7.7 and it's a fantastic little scope which is perfect for grab and go observing but I also have an A80M at F11.4 and I just can't let it go, it's a brilliant 3" achromat, yet I know it's not perfect, anything beyond about x120 and some slight CA becomes visible but that's inherent in the optical design, that's what it does and in no way does that detract from enjoying it's use. 

There is no such thing as optical perfection although high end telescope manufacturers do get very close, but ultimately it's the seeing and your own eyesight that will be the deciding factors in what you actually get to see through these superb instruments.

Edited June 28, 2023 by Franklin

[Stu]

59 minutes ago, John said:

I'm a little surprised that this topic has not attracted more responses 

My Vixen ED102SS F/6.5 is a great little scope but it's optical figure is not quite as good as that of my Tak FC100-DL. The star tests from the Vixen are excellent with perfectly concentric diffraction rings either side of focus but at sharp focus the 1st diffraction ring around moderately bright stars is slightly more prominent than the Tak's -  I think that means that the Vixen objective probably has a touch of spherical aberration.

However, when observing, the slightly more obvious diffraction ring can actually lead to aesthetically pleasing results when observing binary stars such as Castor, Algieba, Gamma Virgonis and Epsilon Lyrae. The pairs of stars, being roughly equal in brightness with these targets, have a delicate and thin figure of 8 shaped fine line of light encompassing them, like this:

With the Tak, on the same targets, the diffraction rings are either invisible or so thin that they are not obvious. 

I actually enjoy this "slightly-less-than-perfect" presentation of these brighter star pairings 🙂

With uneven pairs the effect can be like a "diamond ring" with the fainter star appearing to sit on the edge of the diffraction ring of the brighter component. Again, that can be very attractive.

Where the stronger diffraction ring is less helpful is with close pairs of highly uneven brightness (eg: Zeta Herculis) where the fainter component star can be partially masked by the diffraction ring around the brighter one. With such stars, getting the positive split is easier with the Tak.

On occasions in the past I have described Zeta Herculis diffraction ring as looking like a thin snake that has swallowed a tennis ball with the dimmer secondary star seemingly embedded within it !

So it depends on how exacting my targets are I guess but sometimes I do appreciate beautiful imperfection at the eyepiece 🙂

 

Nice post John 👍

[Mr Spock]

My Helios 120mm achro is one of those scopes. It can provide decent lunar views, obviously with CA, but where it really excels is deep sky. Turn the magnification down and it's surprisingly capable. I've had some lovely views of M42 with it. With the 22mm/17mm/13mm LVWs it comes to life. 

I don't know why. I wonder if because the elements are thin it transmits light really well. I'm sure there's a reason. It seems well corrected for spherical aberration and I think that helps too.

[Ratlet]

Towards the end of the planetary season I started using a combination of a yellow and moonglow filter for Jupiter with the advice that it would improve the contrast whilst giving the view a slightly yellow tint.  Apart from the (to me massively) improved contrast I found the yellow tint to be aesthetically very pleasing.  It reminded me of the old photos of Jupiter from Voyager, or at least the tone the images had after processing and printing in old science magazines and books.

On the imaging side of things, I like a bit of 'grain' in the image.  I'm not sure why I prefer it though.  Don't get me wrong, I love the images where you can see huge amounts of detail but I prefer that little hint of roughness you sometimes get as well in the fainter regions.  Also I prefer diffraction spikes in my images where possible.  This is almost certainly due to Hubble lol.

[Mr Spock]

Thinking about the wide field views I get with the 120mm I've decided to recommission it. The focuser is dire so I've ordered a replacement, and I'll need to get some white spray paint as the dew shield has gotten flaky.

[Franklin]

40 minutes ago, Mr Spock said:

The focuser is dire so I've ordered a replacement

The SW/GSO dual-speed units fit straight in, I put one on an Evostar150 I had a while back. The 150 F/8 achro was, as you say with the 120, super for low/medium power deep sky. A very good RFT though a pain to mount, the 150 dwarfs the 120, it's no wonder they call them "Yard Canons".

[Stu]

I’ve got a very nice Celestron Omni 120 XLT in the attic room. Must give it a go again sometime.

[Mr Spock]

So, here we go (again lol) - I was in the middle of this when the site went down 

New focuser:

Refurbished scope:

I have to say that focuser is really nice. Sadly the weather intervened in testing. I did have a good look at a (misty with poor seeing) Izar at x250. Surprisingly good - nothing like the Tak of course - but very satisfying. 
Given the size and weight v performance I can't say it's going to get much use v the 4", but it's there when it takes my fancy.

 

[The Lapwing]

That’s an interesting question. I don’t think any astronomy gear is perfect, not perfect for everyone that is. What is perfect for one person is probably less than ideal for the next. I would never claim any of my gear to be perfect and probably wouldn’t recommend any of it to anyone, but to me it’s just the most wonderful gear to use and own and I wouldn’t dream of changing or parting with any of it. I love the fit and finish and retro quality that only Tele Vue and old Vixens provide. My gear is in immaculate condition, but years and years old, but If you love your gear you love your gear and it really doesn’t matter what anyone else thinks. 
 

Clear Skies to you all.

Edited July 3, 2023 by The Lapwing

[The Lapwing]

BTW I felt very much the same about my old TAL 100 RS. I’ll probably buy another one day if I can find one in really good condition for white light solar 

[neil phillips]

I've enjoyed some cheap refractors over the years, warts and all. In fact I've just purchased another after needing some funds and selling my entire collection. But thankfully when i want performance without spending many thousands of pounds a large mirror being either a SCT Mak CC Newtonian will always come to the rescue. But flawed optics can be enjoyed wholeheartedly. Both visually and imaging Though for me some flaws are more tolerable. CA not a biggy. spherical aberration and astigmatism more troubling. For lunar greyscale imaging what CA ? Bresser 5 inch achromat. cost me £180 secondhand. Lovely refractor. Would prefer a 5 inch Tak yes. Maybe one day i live in hope. For imaging cheap refractors in greyscale are less flawed 

Example both 5 inch achro 

  

Edited July 3, 2023 by neil phillips

[Coco]

 

Yes very! There is something extremely satisfying about achieving great results using poorer tools.

My Bresser 127L achro has plenty of 'faults', some here scoff at the thought of owning one, however it splits doubles very well, shows extremely nice Luna detail, seeing permitting separates stars in M13 and similar globs, green shows in M57, various shades in M42 always 5 stars in the trapezium , dust around M45, in fact come to think of it I should use it more than the 12" dob as it is wonderful mounted on the Skytee with extension post! Adjustable lens cell if it ever needed it  

My Celestron 102/6.5 achro with 24mm UFF is fabulous for wide field sweeping, shows some nice star colour, North American nebula shows up nicely with an OIII filter & Maxvision 24/82 its massive!  If out of collimation it can go in the  for parts bin! 😉

I gave up checking in and out of focus star patterns, clear nights in Lancashire are too precious ! 

 The  12" GSO dob is kept in cool garage attached to barrow handles, its just to convenient to wheel out, I can be up an running in 5 minutes that why its used most. But again, some would say the mirrors are tat! I thinks it brilliant at what it does.

[Mr Spock]

My 12" SL is big and bulky, but, optically it kicks into touch any premium 6" apo on sharpness and detail by a significant margin at a fraction of the cost. Just add up the cost of a 6" apo and mount and you'll faint... 

[F15Rules]

It's an interesting question, but as a relative oldie of 67 orbits, other factors come into play too, usually to do with getting older..

I am fortunate enough to own a lovely Tak FS128..for visual, arguably as good as it gets. However, not long after I acquired it 6+ years ago, my right (observing) eye began to deteriorate. I had to re-train my better left eye to become my cyclops observing eye..I now find for much of my viewing that binoviewers are more comfortable for me, especially on Lunar and planets.

I actually think that c10 years ago, I got as good, and sometimes better views through my then main scope, a 5" F 15 D&G achromat..because my eyes were better.

So, at least in my experience, I would take "Beautiful Imperfection" in a scope over "Frustrating Deterioration" in my Mark 1 eyeballs, any day!

Several posts have mentioned the older and relatively cheap 120mm - 127mm achromats positively..I'd heartily endorse that view.

I had an older Meade AR127L F9 I think it was called (John, I think you bought it from me?), and I got loads of great viewing through this scope, despite it's CA on bright objects and too short, stubby dewshield. And my eyes then were significantly better than they are now..

So no one will ever hear me belittling those scopes - Galileo would have given his right arm for one!😁

Dave

[F15Rules]

15 minutes ago, Mr Spock said:

My 12" SL is big and bulky, but, optically it kicks into touch any premium 6" apo on sharpness and detail by a significant margin at a fraction of the cost. Just add up the cost of a 6" apo and mount and you'll faint... 

🥱🥱🥱🥱🥱🥱🤪😋

[Mr Spock]

2 hours ago, Coco said:

My Bresser 127L achro has plenty of 'faults', some here scoff at the thought of owning one, however it splits doubles very well,

 

32 minutes ago, F15Rules said:

I had an older Meade AR127L F9

These sized achros are surprisingly capable. There's plenty of enjoyment to be had and, at the price, they are a great starter scope too. 

[John]

1 hour ago, F15Rules said:

....I had an older Meade AR127L F9 I think it was called (John, I think you bought it from me?), and I got loads of great viewing through this scope, despite it's CA on bright objects and too short, stubby dewshield.....

Yes I did and it was an excellent refractor. My first taste of a "big" refractor 🙂

There is a pre-owned one on a certain vendors website at the moment for just £200 which seems an absolute bargain to me.

Interestingly, I also had the Meade branded version (the AR5) of the same scope a couple of years later. The optics on the Meade one were just not as good not matter how much I fiddled with the collimation. 

 

[neil phillips]

1 hour ago, John said:

Yes I did and it was an excellent refractor. My first taste of a "big" refractor 🙂

There is a pre-owned one on a certain vendors website at the moment for just £200 which seems an absolute bargain to me.

Interestingly, I also had the Meade branded version (the AR5) of the same scope a couple of years later. The optics on the Meade one were just not as good not matter how much I fiddled with the collimation. 

 

Their lies the rub. Figure variance. Lottory anyone ? With a little luck a first taste of a big refractor can be a really enjoyable experience. A poor mans highlife. Theirs something inspiring about a large frac on a mount