102mm compared to 120mm

[John]

I thought I'd post a few pics of my 2 ED refractors, a Vixen ED102SS which is around a decade old and a Skywatcher ED120 Pro which is probably around half that age. The Vixen is F/6.5 and the Skywatcher F/7.5.

The physical size difference is not all that much but the Vixen weighs 3.5kg wheras the Skywatcher is at least double that. The Skywatcher needs a more stable mount of course.

Despite their relatively fast focal ratio for refractors, and being doublets, rather than triplets, the control of chromatic aberration in both scopes is rather good. I don't see any CA on the lunar limb or Jupiter at focus and only a tiny amount of purple around the brightest stars

The light baffling in the Vixen's tube is more comprehensive but the coatings on the objective lens of the Skywatcher ED seem a little more effective though.

The Vixen ED102SS seems to be quite a scarce scope as far as I can tell - I've not seen many around either here or in the USA.

Both scopes have belonged to other SGL members in the past so they have "stayed in the family" so to speak !.

[nightfisher]

Nice scopes John, the baffles on the vixen are very similar to those on my 80m custom, a sweet little achro

[spaceboy]

Very nice John.

I would like very much to own a 120ED one day.

[angusb1]

That Vixen is a lovely looking scope John.

[nightfisher]

John, just out of interest does the vixen suffer a poor thread on the dew shield, mine does and i have heard of this on another vixen

[John]

Thanks for the comments folks

@ nightfisher,

My Vixen has a push fit dew shield Jules. It has a felt lined rim that pushes securely onto the objective lens cell.

[Damo636]

Two lovely scopes John.

[ollypenrice]

I do like refractors! Both are lovely. I think it incredible that a good five inch apo can now be had so cheaply - at a fraction of the cost they were when I started out.

Olly

[dweller25]

John, two very nice scopes - we have similar tastes

Here are my 102mm and 128mm refractors, both are F/8......

[andrew63]

I know the 120ED has more light gathering, resolution etc etc - but i know the one i would use most! Thanks for posting John.

andrew

[Mark at Beaufort]

Why do I have the feeling you like refractors John

I am likely to be away from the Friday of SGL7 but if you are around on the Thursday it would be great to have a view through the 120mm.

See you soon.

Mark

[John]

Thanks again for the comments folks

Olly - I think the pricing is amazing too. When I started out even a 5" achromat was a dream scope. I'm wondering if the affordability "bubble" will burst soon though - lots of "rumblings" on that on other forums.

David - you have two of my dream scopes there. Our taste in carpet seems quite similar too !.

Mark - I do love the views through refractors. I'm often feeling guilty that my 10" newtonian does not get as much use but it can "strut its stuff" when I fancy a night of galaxy spotting.

I'm hoping to be at SGL7 for the duration so it would be great to meet again. I'm sure I'll have the ED120 with me

[spaceboy]

What do you observe with the 120ED out of interest. I found the achromatic EVO 120 gave good views of most DSO's. Planets were of a good image scale showing plenty of detail but not so enjoyable for me as I was easily distracted by the CA. The views of planets must be superb through 5" of ED glass though. Despite the colour correction of the C100ED I really do miss that extra 20mm I had in the EVO.

[John]

I use the ED120 on the planets, binary stars and the Moon primarily. It does give nice views of the brighter DSO's though - the Veil nebula looked superb a couple of months back (with an O-III filter). When I say planets, it's been Jupiter really, since I've had the scope. I've seen more detail on the giant planet this year than in any previous years - I'm really looking forward to Saturn and Mars.

[jam1e1]

saturn is fantastic through the 120 Not seen mars through it though so also looking forward to it!

Out of interest did you sell your Mak-newts? Also how did you find they compared visually?

[John]

I bought the 6" Intes Mak-Newt and the ED120 from the same SGL member separated by a few months. Both were scopes that I've wanted to own for some time and I did get the chance to try them "back to back" on a few occasions. Their performance was very similar in many ways. The extra aperture of the MN showed itself when viewing deep sky objects but otherwise there was little or nothing to pick between them. In the end I could not justify having two scopes of such a similar spec so I rather reluctantly decided to part with the MN principally on the basis that it's cool down time is longer than the refractor and I do have to keep my scopes indoors. I'm pleased to say that it's with another SGL member now who cares for it well

[RikM]

Which mount do you use for the 120 John? Is it a bit much for the AZ4?

I am looking at getting an altaz for Christmas to mount either the 127mm f/9.4 achro or my 150P Newt. A little torn between the AZ4 and and the Vixen Porta II. Any suggestions?

[andrew63]

Just my opinion - I've owned the two mounts you mention, both good in different ways but with one big problem. The regular tripods on these or the GEMs are just not high enough for long focus refractors. I was not happy with them with a 4" F9 as in some situations your virtually on your knees!

I am a lot happier with the porta now i have a 4" F7 - in fact it's a very good setup and the shorter tube makes all the difference.

andrew

[John]

I have used the ED120 on the AZ-4 for short sessions. With the 1.75" steel tubed tripod legs the mount is a little overwhelmed by the scope. When I use my CG5 2" steel tube tripod it's better but not perfect.

My primary mount for the scope is a Giro-type alt-az mount made a few years back by Ambermille Engineering. It's rock solid with the ED120 on board. I have a 16" pillar extension which gets the eyepiece up to a comfortable height to use standing, even when viewing the zenith region. Combine the Ambermille alt-az, the CG5 2" steel tripod and the 16" steel pillar extension and you have a very solid mounting platform that I've used with refractors up to 6" F/8

All that does put a dent in the "grab and go" aspect of the setup though

[andrew63]

The 16" pillar is ideal - but a mount without one on a 50" tube?

[John]

The 16" pillar is ideal - but a mount without one on a 50" tube?

Not ideal - I agree.

I can remember when the Chinese 6" F/8 refractors were sold on EQ5 mounts sitting on an aluminum tripod

Quite apart from all the contortions when viewing the zenith area (almost lying down at times !) the whole lot vibrated like a tuning fork at the slightest touch