Impressions Of Optics Past And Present

[gordyb]

I am interested of remarks about optical quality through the decades,say what were optics like in the 1920's for example,in the 1950's and in the 1970's,can you get optics from say 30 years ago that would compete with optics of today or has technology moved so far ahead in todays time period that selection from todays offerings are so far ahead.What are good second hand examples of worthy items for yesteryear.Its a seemless paradise for today's astronomer with the items available today regarding price and choice its almost an embaressment of riches.

[John]

I only started buying telescopes in the 1980's but there have been absoloutely huge changes / improvements in what is available now against what was around then. We really have never had it as good as we have it now, IMHO.

I've seen catalogues of what was available to the UK amateur astronomer in the 1970's and, to be honest, the offerings looked rather crude and very "homemade".

[sunoficarus]

Optics today are not only light years better than in the 60's and 70's, they are far more consistent too. I can remember browsing telescope makers catalogues in the 70's and seeing A, B and C grade optics listed.

A Grade: Fairly near what was intended after many hours of hand finishing and testing.

B Grade: Oh well, almost got it right.

C Grade: It's optically rubbish but hey! Its cheap!

Off the shelf Computer modelling programmes for optics means it's easy to design first class optical elements, and CNC lens and mirror generating and polishing machines means that first class and repeatable quality is easy to achieve. A good example is the classic Celestron C8. A 1960's one is nothing like as good as a current one. Infinately better optical coatings, a highly refined design and tolerances held so tight the days of 'getting a good one' have effectively gone.

If someone had told me in the 80's I'd be able to buy a top quality 3" APO short focus refractor in 2010 for half a weeks wages I'd have fallen off my chair laughing.

[Astro_Baby]

I think at the very top end the lens making would have been as good as anywthing we can do today but you would have been spending out some serious dosh.

For example (its not astro but) I had a Nikon Photomic with its original lenses in the early 80s, the photomic was a 1960s SLR. The lenses were superb and in many ways far better than more modern ones in the 80s at least from the semi-pro market. To get glass as good you'd have really had to spend some cash but then in the 1960s a Photomic was probably priced out of range for anyone except a professional phtopgrapher and the very seria amateur.

The glass in places like Palomar is probably still as good as it gets and was made in the inter-war period but look at the cost .....

Commercial stuff for the likes of you and me - we never had it so good.

[brianb]

I dunno guys ... sure, there was some junk around in the 60s and 70s, but the serious end of the market was no worse than the top end today ... except that modern multicoatings have improved transmission & contrast especially with reflectors. You always did pay for top quality, nothing's changed there.

If anything I think the mechanical standard of mounts sold with "beginner's scopes" has declined, they seem to try to make them light rather than solid these days ... and they spend too much money on electronic gizmos when mechanical hand slow motions are all that's really needed for a beginner's visual scope.

[johninderby]

I agree, while the optics of the very best that was available decades ago is as good as the top end stuff nowadays, where they loose out big time is in comparison to the coatings that are available today. Although if you had those old optics brought up to date with some modern coatings?

John

[sunoficarus]

1962 adverts

Average weekly wage 1962: £16 p/w, it's about £530 p/w now

[gordyb]

£57 for a 3" refractor in 1962 i wonder how much that is in todays money,a evostar 3 and a half inch refractor with a az3 mount costs £133 or a startravel 3" with an eq1 mount is £115 frightening.

[sunoficarus]

£57 for a 3" refractor in 1962 i wonder how much that is in todays money,a evostar 3 and a half inch refractor with a az3 mount costs £133 or a startravel 3" with an eq1 mount is £115 frightening.

£57 was 3.5 weeks average wage in 1962…

So about £1,850 at current rates.

[barkis]

Putting aside modern computer technology, exotic glass and coatings, engineering equipment, and techniques, The old lens and mirror makers would compare very favourably in my estimation.

I own Albert Ingalls 3 volumes on telescope making, and they contain a wealth of information. I just wish I understood more of what's in them .

Ron.

[Astro_Baby]

Prices would have been shocking - I remember in 1976/77 I was in my first serious job as a secretary and earning serious money compared to most people back then working for a major company. I remember pressing my nose up to the window of BC&F back then and realising a serious telescope would cost more than my car.

Someone told me that back in the 60s and 70s one of the first companies to do Hire Purchase deals were Unitron - some of their adverst say stuff like 'yours for only £2.50 per week' because these things were so pricey few could afford them outright.

I dont know if that true about Unitron being one of the first in the HP field but it wouldnt surpise me.

Look at those ads ( I have seen similar in the past ) £57 for a 3" refractor on an alt/az - if you use the Consumer Price Index that would mean the scope would cost £410 today. By comparison an Evostar 90 on an Alt/Az costs £132.

The Frank Refelector cost £32 - that would be £196 in todays cash - today for the same cash you could have either 4.5" refelector on a fully computerised GoTo or a 6" Dob both with far superior optics to the ones back then.

[philj]

Mel & Brian have it right.

Just like theres a lot of poor to mediocre glass around nowadays there was the same in the past. Top notch optics from years gone by however are a match for modern top notch optics.

Its just modern manufacturing techniques and materials have made better quality optics more affordable.

Unfortunately there is this opinion around these days that modern optics are far better than old optics, a generality like that is incorrect. I know from experience because I have scopes dating from 1890 all the way to 2010 Apos and I know which ones I prefer for planetary and lunar. But then I wouldnt use my 1890 80mm for ccd imaging either.

Philj

[SiriusB]

I agree that affordable optics have never been so affordable

I was looking at £250 for a 4.5" reflector in the early 80's. Thats an awful lot of weeks pocket money & no chance of Santa dropping one off for Christmas at that price back then.

Small wonder that for many years the 6" reflector was the aspired to instrument for many amateurs.& to think now its almost dismissed as a "beginners" scope.

As to optical quality, well the best of yesteryear was excellent, period.

Generally optical glass was less transparent & homogenous the further back in time you go.& mirror makers "only" had plate glass to utilise befor pyrex et al appeared on the scene.

That said, the master opticians knew how best to utilise the materials available.

Not so sure about the affordable end of things, though i think you'd be hard pressed to find a scope as bad as the one i started with, so i suggest the "low end" has improved somewhat with time!

Heres some interesting links about some early English telescope makers.

newell refractor

OASI - Biography of George Calver

History - English Silvered-Glass Reflecting Telescopes

[Astro_Baby]

Yes - I remember looking at a 6" reflector back in the early 80s and almost fainting at how expensive it was Mine you my indifferent 4.5 refelector had a clock drive - that was as close to GoTo as I would come for a long while

[Altair]

Yes I remember back in the mid 60s Patrick Moore in his book said you needed a 3 inch refractor or a 6 inch reflector to do any decent observing and work as an amateur getting into the hobby. I drooled over those Charles Frank pics.. knowing i would never own one! Luckily for me my dad found a kit for sale in London for a diy put together 4 inch reflector scope for around ten pounds!

That scope was with me for over 10 years and believe me it worked just fine! Never dreamt i would own anything better than that!

[Peter Drew]

A set of David Hinds "A" quality optics would give ANYTHING a good run for its money. .

[starguest]

Maybe not exactly relevant to O.P.

Just remember what Galileo used to find Jupiter's moons and then all those after who began to catalogue the heavens. What point in the available range from just FLO as an example would be comparable or easily surpass the gear from way back?

[FraserClarke]

I agree with the general view here that good optics are always good optics, and the issue is more to do with improved quality control and bulk manufacture these days.

However, at the very top end (professional level telescope optics), there has been a revolution in the past 15-20 years, and professional astronomical optics these days are significantly better than what we had in the 70/80s. The control of form and surface finish through modern metrology in immense. For example, the 200-inch mirror at Palomar is not actually that good (by modern standards) -- it's f/3.5 and barely 1/4-wave (yet still a huge achievement!). These days you wouldn't really think of a primary mirror slower than ~f/2, and it would probably be at least 1/10-wave or better...

I'm sure this must filter down into amateur level optics in some way, though it could be in driving down prices more than driving up quality. Though I guess the proliferation of exceedingly high quality telescopes in the ~0.3-0.5m class shows that opticians are really quite good at making excellent optics these days.

[brianb]

These days you wouldn't really think of a primary mirror slower than ~f/2, and it would probably be at least 1/10-wave or better...

Having the figure correct to 1/10 wave isn't helpful if the computed figure is incorrect - viz Hubble.

Commercial SCTs use f/2 primary mirrors (except for the C925 which is f/2.5).

f/2 Newtonians are simply impractical - the coma free field would be about the size of a full stop and you'd never get the thing collimated. Professional observatory scopes are built up to a specification rather than down to a price, weight and bulk are simply not considered, rigidity is everything; that makes a big difference to the usability but of course also to the price tag.

[russ]

The real difference is the bottom end, budget options. Massive improvement over the last 10 years alone. I remember buying a new Orion Optics 200mm F4 in the 90's and thinking i could have knocked up something better aged 12 in metal work class. And that standard of scope making in the budget class carried through until the early 00's. Although the optics weren't brilliant on the early Chinese scopes, it was immediately apparent that their ability to knockout good looking, well built scopes was sign of the future. The age of the 'Blue Peter' scope was at an end. I remember getting one of the first Skymax 127's in the UK and thinking this is truly amazing for the money. Orion Optics, Meade and Celestron are stuffed! They will have to dramatically change their ways to compete....which of course they have (moving production from the US to China).

[sunoficarus]

The real difference is the bottom end, budget options. Massive improvement over the last 10 years alone. I remember buying a new Orion Optics 200mm F4 in the 90's and thinking i could have knocked up something better aged 12 in metal work class. And that standard of scope making in the budget class carried through until the early 00's. Although the optics weren't brilliant on the early Chinese scopes, it was immediately apparent that their ability to knockout good looking, well built scopes was sign of the future. The age of the 'Blue Peter' scope was at an end. I remember getting one of the first Skymax 127's in the UK and thinking this is truly amazing for the money. Orion Optics, Meade and Celestron are stuffed! They will have to dramatically change their ways to compete....which of course they have (moving production from the US to China).

A very good point. Even makers of first class optics and mounts like Vixen have had to bite the chinese bullet and move some production to China as the quality is there now and the manufacturing costs are unbeatable. I've owned a US made C5 OTA with 'hand corrected optics' and replaced it with a fairly recent mass produced in China C6, the C6 is optically and mechanically better and cost less than that C5 cost new.

[russ]

A very good point. Even makers of first class optics and mounts like Vixen have had to bite the chinese bullet and move some production to China as the quality is there now and the manufacturing costs are unbeatable. I've owned a US made C5 OTA with 'hand corrected optics' and replaced it with a fairly recent mass produced in China C6, the C6 is optically and mechanically better and cost less than that C5 cost new.

I did a very similiar thing. My US made Celestron C5 was one of the worst SCT's i've owned. But the Chinese C6 i had a year later was very good.

[michael.h.f.wilkinson]

I think the main changes have been in available optical glass, and in EP design. In the past no-one thought 82 -100 deg EPs were possible. Erfle at 65-70 degrees was about as wide field as you could get.

By contrast, there have been few major redesigns of the main types of objectives. A good Newtonian of 40 years ago is still a good Newtonian, albeit badly in need of a new coating, I assume. What has changed is the ease with which we can make aspherical surfaces. the Ritchey-Chretien design has been around for quite a while, but was impractical except for those with VERY deep pockets.

[FraserClarke]

Having the figure correct to 1/10 wave isn't helpful if the computed figure is incorrect - viz Hubble.

Absolutely -- but remember that HST has a 70/80's mirror...

[gordyb]

The HST also had its mirror ground slightly flat if i remember.There was an excellent Horizon programme on at the time.