Pentax scope is coming back

[E621Keith]

With a Vixen label, but this is clearly a Pentax 100mm SDUF

http://www.vixen.co.jp/en/

A prototype 125 SDP was present at CP+ earlier this year. It looks like it will go into production.

Well done Vixen. Well done.

[E621Keith]

The Vixen 125 SDP at CP+

http://vixenmarketing.seesaa.net/article/317434408.html

[Naemeth]

I really admire the quality of Vixen products (the ones I own anyway), lets hope these scopes perform (which they certainly should do) .

[swag72]

Thats great to know, my original Pentax is a superb little scope. interestingly you can still get the Pentax 100SDF over here in one of the dealers, new not secondhand.

[John]

Very nice

I'm a big Vixen fan too. I wonder if we will see XW eyepieces with their logo on sometime in the future ?

[Naemeth]

Very nice

I'm a big Vixen fan too. I wonder if we will see XW eyepieces with their logo on sometime in the future ?

While I like the idea, I think it is unlikely Vixen will make XW eyepieces - they are almost in direct competition with the LVWs.

[E621Keith]

I'm a big Vixen fan too and a Pentax fan as well. I wonder how much these Vixen will cost. Pentax Petzvals were VERY expensive when they were still available and they are still very expensive second hand.

Looks like Vixen is going for a complete clone rather than adapting the Pentax for Vixen's own line of accessories. The finder shoe attachment in both 100SDUF and 125 SDP looked like a Pentax shoe rather than a Vixen shoe. Hopefully Vixen will keep using the Pentax rear accessories thread and Pentax finder shoe but include an adapter for a Vixen shoe.

A photo of a Pentax 125 for comparison

While I like the idea, I think it is unlikely Vixen will make XW eyepieces - they are almost in direct competition with the LVWs.

The Vixen LVW is an old design that was due for an update. XW seems to be a good way of getting a good designs without the R&D cost, especially the discontinued 2" XW. Meanwhile, both Vixen and Pentax must be suffering from Nikon's very aggressive pricing in the Japanese home market. Nikon lowered the price of the NAV-SW, and some are now 10% cheaper than Pentax XW.

btw, Vixen LVWs target a different market segment in Japan. They are 40% cheaper than the XW and cost less than the ES82.

[Naemeth]

The Vixen LVW is an old design that was due for an update. XW seems to be a good way of getting a good designs without the R&D cost, especially the discontinued 2" XW. Meanwhile, both Vixen and Pentax must be suffering from Nikon's very aggressive pricing in the Japanese home market. Nikon lowered the price of the NAV-SW, and some are now 10% cheaper than Pentax XW.

btw, Vixen LVWs target a different market segment in Japan. They are 40% cheaper than the XW and cost less than the ES82.

Thanks for the clarification Keith - if the LVWs are so cheap in Japan it does make sense to clone the XWs. I wonder if Nikon are making a loss on purpose with the NAV-SW to price Pentax out of the market .

[E621Keith]

I don't understand Nikon at all. They don't even sell it outside Japan.

I have a feeling Nikon made the NAVs as a marketing stunt for the International Year of Astronomy 2009 and they are now just trying to get rid of old stock.

[NickK]

Pat's his Pentax 105SDP ... They'll probably not duplicate that because it doesn't have the helical focuser!

[E621Keith]

You are right. The 105 SDP clashes with AX103s, but he AX103S is a lot slower, so they may replace that instead

[Gissajob]

Er - what does the advertisement tag line mean? "Decent to earth this autumn" - do they mean descent? Or Descend? Because 'decent' doesn't make sense. Or is an astro term I'm not familiar with?

Alan

[NickK]

Er - what does the advertisement tag line mean? "Decent to earth this autumn" - do they mean descent? Or Descend? Because 'decent' doesn't make sense. Or is an astro term I'm not familiar with?

A bit lost in translation.. rather like Coke's wakes up our ancestors.. but at least it's still space-themed

[E621Keith]

Probably a combination of typo and machine translation. A lot of Japanese can't speak any English, so the graphics guy probably didn't understand what marketing sent him and his manager probably can't proof read it either.

In the Japanese and Chinese versions of the site, it says '今秋降臨' which can be translated as 'Arrives this autumn'. In Chinese at least, the second word, '降臨', doesn't just means arrive, as in it gets here, but a more dramatic version of arrive, like how god or an angels descend from the sky type of arrive. That was probably where the 'Descend' came from. Google translates '降臨' as a noun rather than a verb, which give them 'Descent'. Add the typo and it becomes 'Decent'.

For the price they will charge, it better be a VERY GOOD scope. A decent scope is not good enough

[NickK]

Hmm the current 103 optical path is a triplet with a single (http://www.firstligh..._Back_Focus.pdf) not quite the same as the pentax which is a doublet with a double set (the flattener).

Heres some Pentax unlike the normal photos - serious build quality - flocking:

The focuser tube:

The internal cell set:

[E621Keith]

Hmm the current 103 optical path is a triplet with a single (http://www.firstligh..._Back_Focus.pdf) not quite the same as the pentax which is a doublet with a double set (the flattener).

...

True, but if both scopes offer back focus independent flatfield, they'd compete against each other. Optically, the f8 AX103S (3+1 flattener) is closer to the older f7 Pentax 105 SDHF (2+1 flattener) that was replaced by the SDP (2+2).

Pentax SDP and SDUF are modified petzvals. The rear doublet acts as a reducer, a flattener and also corrects residue aberrations from the front group. The SDP front group is a F8, the rear group reduce it down to F6.5. Vixen's closest equivalent is the NA140SSF achromat and the discontinued DED-108SS.

Whether AX103S stays depends on how much it costs to make the 105SDP. From what I understand, AX103S was not selling well, people either save up for the preimum Takahashi or APM or stick with Chinese scope. If Vixen charges £4k for the SDP (based on the last 105SDP price I found - €4.7k) then there is enough room for the AX103S. If Vixen is more aggressive and charges £3.5k then the AX103S may disappear.

Talking about Chinese scopes, I think these Pentax clones are Vixen's attempt to enter the top end market, differentiate themselves from the Chinese scopes, and compete directly against the like of Takahashi and APM. To do this, they need use Pentax's pedigree, which would explain what they copied every last details of the Pentax, down to the finder base and cone shaped visual back (which is the worst feature on a Pentax). The new Vixen livery on these scopes will probably differentiate them from the rest of Vixen's line up and identify themselves as top tier scopes, a bit like the red ring on Canon lenses)

[NickK]

Interesting. I note one key difference between the two models; where the rear elements are help on the focuser on the AX103 and held stationary on the SDP. I'm still convinced that, although the outside looks a bit retro, the internals of the SDP still rival Takahashi based of the images I've seen.

From experience I will say this - keeping focus during cool down is not a strong point of the SDP and attempting to attach a motorised focuser is hard work as the focuser does not have a flat edge or screw holes to connect a plate to hang things off.

Don't worry about the rear odd shaped visual back. It's actually a russian doll of different connectors (ending with 1.25") that can be unscrewed and replaced with a Baader 4-1 adaptor to give a M84, M68, M54 screw threaded and finally a 2" push fit that will take a standard 2". The three screws around the end of the focuser where the scope attach can be loosened and the whole imaging train aft of it can be rotated.

Edit - better image showing the 4-in-1:

This has thread has got me stoked to get the design of the new adaptor needed to attach the borg helical focuser to it as the 4-in-1 blocks the focuser and the pentax M68 thread is pitch 1.0 not the normal pitch 0.75 of borg and everyone else..

[NickK]

Ok.. to add.. as I was editing, got distracted and now I can't finish the edit

In term of images - pinpoint and very flat star field across a kodak 8300 sensor (670mm fl, f/6.38). I did note Olly's spark of interest "what focal length was that?" with the M42 core showed stunning detail (even with my crappy tracking!).

I have noted that running with the Televue 2x powermate does cause some coma around the edges at 1340mm fl) with the 383L's 5.4um pixels - well.. compared to the normal pinpoint stars. This could be related to the varying gap between the PM and the rear element.

The built in lens hood is solid, with only a dew heater strapped just behind the hood required - the internal cell doesn't fog as long as you don't pull the imaging backend off at dew point! (only have done that once and learnt my lesson).

Annoyingly I could go all screwed if it wasn't for the pesky Televue 2x not having a screw thread!

I should have seen if the SDP image circle covered the ATIK 11000M whilst I was over at olly's however the scope was setup for a multi-night M42.. Ok.. this has turned into a SDP review - apart from desiring a faster f2-3 capture rate.. safe to say, it's still the best scope I've seen/used in both versatility and image quality. (you know you want to start saving pennies now don't you? )

[FLO]

Vixen have confirmed it is a real product and due for delivery in approx three months. We should have more details like specs, pricing, etc around the end of this month.

Vixen will be running a three month long teaser ad' campaign intended to give this new scope something of an air of mystery.

We'll post details as soon as we have them

[E621Keith]

Vixen have confirmed it is a real product and due for delivery in approx three months. We should have more details like specs, pricing, etc around the end of this month.

Vixen will be running a three month long teaser ad' campaign intended to give this new scope something of an air of mystery.

We'll post details as soon as we have them

Do you have any idea whether accessories made for the Vixen clones will be compatible with the original Pentax SDP. I want to get a RC 0.77x67p reducer for my scope, but they are almost impossible to find.

Anyway, I'm looking forward to their official announcement

[FLO]

We won't have details until later this month Keith.

[E621Keith]

PS: looks like Vixen has corrected the spelling in the ad

In case, anyone wondering what's all the talk about 'Decent to Earth...', this is what the ad used to look like

[FLO]

But it still caught your attention

[NickK]

One vital question is if they will source a 2" adaptor as part of the package as the standard back does not support 2" and the threads are P1. If not the Baader 4-in-1 is going to be like gold dust!

[andrew63]

PS: looks like Vixen has corrected the spelling in the ad

In case, anyone wondering what's all the talk about 'Decent to Earth...', this is what the ad used to look like

They must have been following this forum !

andrew