Hoya v. Ohara

[Relpet]

An APO refractor is likely to be my biggest and probably last major purchase  So I'm taking my time making my mind up.

When comparing costs of 'scopes with similar apertures, focal lengths and so on there seems to be a jump in price between Hoya FCD1 glass to Hoya FCD100 glass then a bigger jump to Ohara FPL-53.  What I really need to know is, at the age of 78 with severe short sight and glaucoma in my observing eye am I really going to notice the difference in quality between these glasses?  Other aspects need to be taken into account, of course; weight, quality of focuser; what add-ons come with it.  I feel comfortable making a judgment on those.  It's the glass that foxes me.

Thanks, as always, for any advice.

[Alien_Photons]

The short answer is no. Who made the lens, how well it's been made and assembled tends to make more difference. Just as important is the focuser which needs to allow you get the best from the lens. It should make finding and keeping focus easy.

Stick to the respected and trusted brands, don't worry about it but remember nothing is perfect.

Edit. 

I bought a Takahashi as much because they provide a five year warranty on the optics (trust) and anyone that owned one always said how good they are (respect).

[SonnyE]

Would it be possible to order all 3, try them, then return the ones (or all) that don't prove worthy?

I've done such things on rare occasions, buy something because it sounds worthy. Then throw it back because it is not.

[Relpet]

4 hours ago, Alien_Photons said:

The short answer is no. Who made the lens, how well it's been made and assembled tends to make more difference. Just as important is the focuser which needs to allow you get the best from the lens. It should make finding and keeping focus easy.

Stick to the respected and trusted brands, don't worry about it but remember nothing is perfect.

Edit. 

I bought a Takahashi as much because they provide a five year warranty on the optics (trust) and anyone that owned one always said how good they are (respect).

Since posting my message I found a very lengthy exchange of views on glass in Cloudy Nights. from a few years ago.  The consensus supported your view that the design of the objective, its quality of manufacture and how it is used is as important as the specification of the glass.  I have also been reading up on the specs of the Hoya and Ohara glasses.  The Hoya FCD100 being used by ES is reported to be on a par with the Ohara FPL53.  ES are offering a ten year warranty.  I am increasingly drawn to one of their carbon fibre models, hence my query regarding the glass.  I shall not be making a purchase until I can be sure of getting some use from it, though.  Two clear nights in 28 days here hardly justifies the expense at present - but one lives in hope.

Thanks

[Relpet]

3 hours ago, SonnyE said:

Would it be possible to order all 3, try them, then return the ones (or all) that don't prove worthy?

I've done such things on rare occasions, buy something because it sounds worthy. Then throw it back because it is not.

It's an enticing thought but I don't think I'd get away with it in Europe.  I shall be back in Britain for a couple of weeks soon and my best bet is probably to visit a few dealers while I am there, check the look and feel and see where I go from there.

Thanks for the reply

[Alien_Photons]

I couldn't or wouldn't justify the cost for years. Then I realised that forty years of looking through telescopes at the skies made it a simple choice to buy a very good quality telescope. I haven't regreted it.

[Relpet]

What I'm looking at is more than I would usually pay for a second-hand car and I might well expire before the warranty!  But I share your philosophy.

[John]

I was in the fortumate position of being able to buy a "lifetime" refractor last year. In the end I actually bought 2 - a Takahashi FC-100DL which uses Fluourite in it's doublet objective and a pre-owned APM / TMB / LZOS 130mm F/9.2 which uses LZOS own glasses in it's triplet lens. I reckon these refractors are about as good as it gets in their respective apertures. The purchases cost me around the same as a decent used car as well !

They have proved to be superb scopes

[Peter Drew]

I wouldn't want the telescope my car's value would match.  

[ronin]

The general view is that the FPL-51 is a match to FCD-1, and that FPL-53 is a match with FCD-100. So it is "easier" to consider them a match as far as we are concerned. Minor differences there may be but as said minor.

The 2 groups differ by the dispersion and for whatever reasons FPL-53/FCD-100 is "better". In a telescope lens that means that you can "push" the glass more. The real effect is that an f/5 lens with FPL-53/FCD-100 will perform in terms of potential "chromatic aberration" better then the FPL-51/FCD-1 glass.

At one time everyone was trying to make a faster lens and were pushing glass very much to it's limits. Something I never quite understood.

I noticed a few years back that WO who were often producing fast lens suddenly switched to making their apo's slower. Their FLT-132 is f/7, and I am sure I have read of an F/7.5 apo from them. All make with FPL-53 as well.

I would say that at f/7 you could not tell any difference between an good lens that used any of the glasses mentioned. F/7 should be easily within the abilities of any, as long as it can be defined as a well designed lens.

If the use is visual then I would suggest that you consider a scope that is on tne "slower" side, here I would say f/6 and slower and personally I like the idea of the f/7 WO's. There is just little reason to go overboard on the fastest possible lens/scope. Even for imaging I would rather an f/6 scope over one a bit faster. This likely comes from the old days of using a camera where the sort of optimum was f/8. Again they didn't have the glass types then.

Suppose a "simple" idea is if f/6 or slower then any of the glasses should be good, if f/6 or faster then preferably go for the FPL-53/FCD-100. What you do at f/6 might depend on cost. Maybe the FPL-53/FCD-100 would be safer although not exactly necessary.

I assume from the mention of getting a scope you are not thinking of putting your name down on the AP 20 year waiting list for one of theirs.

If you search there are now lens that use 2 ED elements instead of 1. Not sure if they are any improvement however, as I guess that the design is "similar" in that you have 2 bits of 1 type of glass and 1 bit of another.

[Relpet]

36 minutes ago, ronin said:

I assume from the mention of getting a scope you are not thinking of putting your name down on the AP 20 year waiting list for one of theirs.

 

I think a waiting list of any more than three weeks might be pushing it at my age.  But thanks for the very informative answer which I hope other members will appreciate as well.  I just spotted a s/h WO doublet on a French website at what would be a very attractive price if it was genuiinely Apo as described by the advertiser and the maker.  I thought genuine Apos had to have at least three elements - but that's a completely new subject I guess.

Thanks again

[John]

The Tak Fluorite doublets are APO's. The FPL-53 Synta doublets get very close. Lots of manufacturers use the term "APO" rather loosely though I think.

I think you need to assess the spec of the scope and the glass used plus the credentials of the brand and manufacturer (not always the same !) to guage whether or not the scope will be "APO" in your eyes.

 

[Relpet]

Thanks, John,

I shall never be able to afford the best, only the best I can afford.  Lots of groundwork to do now I'm clearer on the glass.

Peter