Vixen ED102SS and Takahashi FC100DL - brief comparison

[John]

Over the past couple of clear nights I've had both my 15 year old Vixen ED102SS F/6.5 and my new Tak FC100DL F/9 on the same mount to compare them. The targets have been Jupiter, Mars, Saturn, the Moon and some tightish double stars. This post is just a summary rather than anything in-depth on the scopes though. The Vixen is an ED doublet which uses an ED element which is probably FPL-51 and the Takahashi a doublet with a Fluorite element.

While the Tak showed no CA whatsoever on anything whether in or out of focus, the Vixen did pretty well and just showed a very small splash of CA around Vega. No CA around the lunar limb, and the planets at focus and the usual ed doublet CA traces showing in the intra and extra focal image.

The star test on the Tak was pretty much identical inside and outside focus and textbook at focus. The Vixen again does quite nicely but the 1st diffraction ring is a little brighter than ideal and certainly brighter than the Tak's. Tight, uneven brightness, double stars are easier to split with the Tak because of this I think.

Both scopes showed more or less similar detail and contrast on the planets but I was conscious of having to look harder to find it with the Vixen and, as the magnification exceeded 200x, the image in the Tak remained sharp and well composed while the Vixen started to lag a little. The Tak handles 200x plus pretty much as well as my (rather good) ED120 does with just slightly dimmer images. 257x and even 300x make you forget sometimes that you just have 3.9" of aperture to play with !

So the Tak FC100DL outperformed the Vixen ED102SS by a small but noticeable margin on these nights at least. The Vixen is still a lovely little refractor IMHO and it's wide field capability combined with pretty decent high power viewing will keep it in my possession  

The Tak FC100DL is my 1st Tak and my 1st refractor with a fluorite lens element and I can now understand what the owners of similar Tak models and the Vixen FL's are so enthusiastic about

[michael.h.f.wilkinson]

Very nice comparison. I would think the difference in focal ratio is at least as important as the difference between FPL51 and fluorite, if not more so. The fast the scope, the harder CA correction becomes.

[Chris]

Very interesting comparison John  Sounds like th Vixen held up pretty well considering it's faster and uses FPL51, and the Tak is definately the one to have for very high power critical observing. Sounds amazing for doubles for instance

Now has anyone local to you got an ED100?  We could then throw out the uncertainty created by the Vixen and Tak having different F/ratios. 

 

[nightfisher]

What Chris says about an ED100/Tak comparison would be a good shootout, John nice swift comparison short and to the point 

[Pondus]

Two Premium instruments. A very Nice report, interesting to read

even for People like me, who never had the privilege looking through anything remotely near that top class.

 

Rune

[Knighty2112]

Nice comparison John. Well done!  

[spaceboy]

I had the pleasure to look at the sun in WL through a fluorite refractor the weekend and the contrast hit me straight away. Even with cloud passing (and no doubt poor seeing because of this) it was obvious how sharp the optics were.

Glad to hear the new purchase was money well spent and that the Vixen is still a performer after all these years.

[John]

2 hours ago, Chris Lock said:

...Now has anyone local to you got an ED100?  We could then throw out the uncertainty created by the Vixen and Tak having different F/ratios. 

 

That would be a good comparison and I expect that a good ED100 would produce strong competition for the Tak FC100. Having the Tak has enabled me to see just how good the optics in my ED120 are - the star tests are very, very close in terms of quality. I did used to own an early (blue tube) ED100 but it was a long time back. I seem to recall being surprised that the Vixen managed to more or less match the CA control of the ED100 (the Vixen followed on from the ED100 more or less in my fleet) which shows that Vixen's choice of glass types and their lens figuring and coating is very good.

I'm picking up another F/9 apochromat later this week with a bit more aperture which will prove a very interesting scope as well I think

[Pig]

Nice little read John... two lovely scopes to have side by side and all them lovely eyepieces too :-)

[Chris]

19 minutes ago, John said:

 

I'm picking up another F/9 apochromat later this week with a bit more aperture which will prove a very interesting scope as well I think

Now John, you know we're going to ask more about this  Please tell, what is it ? ? ?

[Stu]

9 minutes ago, Chris Lock said:

Now John, you know we're going to ask more about this  Please tell, what is it ? ? ?

Two choices for you ?

I'm voting for option 1)

[Chris]

Hi was looking at that second one the other day, I would need a mount head upgrade though... Hmm?

Back to the first one, wow I hope John is getting that just so I can hear about it!

[Stu]

1 minute ago, Chris Lock said:

Hi was looking at that second one the other day, I would need a mount head upgrade though... Hmm?

Back to the first one, wow I hope John is getting that just so I can hear about it!

I would have had it if I had the funds. One day!

[Highburymark]

2 hours ago, michael.h.f.wilkinson said:

Very nice comparison. I would think the difference in focal ratio is at least as important as the difference between FPL51 and fluorite, if not more so. The fast the scope, the harder CA correction becomes.

And maybe John's new Zeiss prism contributed too?

[John]

Stu has been an effective detective !

I'm collecting the APM TMB LZOS 130mm F/9.2 on Thursday.

They seem to have a pretty good reputation

 

[John]

3 minutes ago, Highburymark said:

And maybe John's new Zeiss prism contributed too?

Thats possible - I wasn't swapping the diagonals between the scopes which was a bit remiss to keep the playing field entirely level. The Vixen did have a TV Everbright dielectric in it though so I hope it was not too disadvantaged.

 

[nightfisher]

52 minutes ago, John said:

Stu has been an effective detective !

I'm collecting the APM TMB LZOS 130mm F/9.2 on Thursday.

They seem to have a pretty good reputation

 

OMG, John that is going to be one heck of a frac, once you use that beauty a few time i can see you selling just about all the other scopes as they just wont get used again, the TMB 130 is my dream scope, large enough to really perform but small enough to use on a nice sensible mount, John your a lucky man and i wish you many clear skies with it, might even invite myself down for a look if i manage to visit my brother

[Piero]

Nice brief comparison, but I think you will see more and more differences with time when evenings with very good or excellent seeing come out. 

A Ferrari and a BMW do both a very good job on normal and moderately fast roads.. Take them to a motorway without speed limits and any difference between the two will become much clearer!

To me this is the same for very good and excellent eyepieces. It's the battle ground which can show the margin.  

[Chris]

59 minutes ago, John said:

Stu has been an effective detective !

I'm collecting the APM TMB LZOS 130mm F/9.2 on Thursday.

They seem to have a pretty good reputation

 

Oh yes! Nice one John!  There are lots of words there to like, such as LZOS and APM, then theres TMB, then particularly for visual work f9.2. Put all that together and wow it can only really be superb   

I think your very good ED120 might be having a little cry

[A McEwan]

Excellent post. I look forward to comparing my Tak FC-100Df with my ED120 when it starts getting dark again (or at least when I can get a clear view of anything again)!

I remember just how good my various ED100's have been - excellent scopes - so I hopethat if you do a shootout between the Tak and an ED100 there is still a noticable margin between them, John! 

 

The 130mm looks superb. Most drool-worthy....

 

[RobertI]

3 hours ago, John said:

Stu has been an effective detective !

I'm collecting the APM TMB LZOS 130mm F/9.2 on Thursday.

They seem to have a pretty good reputation

 

Jealous, jealous, jealous.  

[John]

Thanks for all the encouraging comments both on the 4" comparison and my forthcoming 5" aquisition

To be honest I didn't expect to get the latter scope but it was close to me, owned by someone with whom I share mutual acquaintances and who has owned the scope from new so I thought it worth making a bid.

 

 

 

[GavStar]

John, Fantastic 5 inch apo which I have also considered. Great value second hand at less than half the new price! I noticed your questions about cool down time on cloudynights  so will be very interested to hear what you find it actually it is? (And obviously how it compares to the DL!)

[DirkSteele]

I was about to write that you are very lucky to own TWO excellent instruments in that aperture class. But I continued to read the thread and saw what you are picking up on Thursday. Now I have to write "incredibly lucky to own THREE exceptional instruments." Cannot wait to read about your experiences with the LZOS 130 f/9.

[jetstream]

Congrats John!

The APM 130 has been on my list for a while and I can't wait to hear the reports on it and also a comparison between it and your SW120ED! ...be gentle... Actually no, just present the cold hard facts - "it is what it is"- I'm really interested in them.

Congrats again for this fine instrument!