F15Rules

1 hour ago, Uplooker said:

Hi F15,

Sorry to say I am not familiar with the Parks brand. How do they perform? Are they more suited to slower / longer FL optics?

Hi, Uplooker,

These are quite old eyepieces, but back in the 1980s and 90s they were highly regarded..

The Celestron Axiom/ Ultima range were probably the best known, also the Takahashi LEs which are a very similar design.

They give very good, sharp views with very good edge correction down to c F5,and are often favourably compared to Tele Vue plossls, but with a slightly wider view and better eye relief.

HTH ☺..

Dave

Today I picked up a nice little parcel, and this is what it contained...a nice selection of Parks Gold eyepieces, made in Japan, and of the "Pseudo-Masuyama" design, optically the same or very similar to Celestron Ultima, Antares Elite and Orion Ultrascopic ranges..

They are all in excellent condition, boxed and with smooth barrels (NO undercuts to snag on?).

I have also sourced a 3.8mm sample (new old stock) in the USA which isn't arrived yet.

I'm very much looking forward to trying  these out in the Tak.. the 25 and 30mm in particular look fantastic.

I'll post more in the eyepiece forum when I've had first light (ie after The Beast from the East has passed over!).

Dave

10 hours ago, 25585 said:

SW ED100 case, for my Tak 100

Takahashi are missing a trick here...buy a load of identical cases, slap a Tak logo on them and charge £200 each...Kerrrchinng!!

Dave

2 hours ago, rwilkey said:

Hi Dave, getting my 'eyeguards' mixed up, what I mean is the rubber covering on the twist-up feature (which works perfectly well), unless this is just a odd one that failed quality checks?

Ah, I see, well it's possible of course. I've owned 3 XFs and all were fine in that respect, but maybe a bad one got through..

Dave ☺

Pentax XF every time for me. I've owned both XFs and just the 12mm SLV. I didn't like the latter and returned it to FLO (I know most people like the SLV range though).

The XF is Japan made, has superb mechanics and optics (including Lanthanum element I believe), and is rather like a mini XW or XL.

It has a significantly wider field of view and is sharp to the edge in my scopes (F7.7 & F8). The 12mm has minor field curvature, which didn't bother me personally. The XFs used to have an RRP of £149, so at around £99 now they are excellent value. I would say the build quality is better than the Vixens (and I'm a big Vixen fan, the LVW 22mm is one of my all time favourites).

Regarding the "fold up rubber eyeguard", I wasn't aware the XFs had such a feature..a twist up click lock feature for comfort, certainly, but not fold up as far as I'm aware? The top part of the rotating/twist up cup has a directional arrow to indicate which direction to turn to adjust the cup up or down, so if the cup also folded up it would obscure this? (See photo below, image credit to Microglobe Ltd).

I've certainly never had an issue with that excellent feature?.

Dave

On 19/01/2018 at 13:29, Saganite said:

This beauty arrived this morning amazingly, as it was ordered just yesterday afternoon from Telescope House. Along with the MRG 7mm from Stu, this now completes my high power bino pairs. 

Congrats, Steve. The 13T6 is the best TV ep I've looked through/owned, cracking eyepiece ?.

Dave

On 17/01/2018 at 17:30, Alan White said:

The Post person today brought me.........

A brand new Meade Series 3000 5mm Plossl, Made in Japan, still in its plastic bag and BC&F price tag of £53.
It really is unused and I opened the plastic bag.

Bought out of curiosity and to go with my treasured Series 3000 9.5mm Plossl (Japan).

Sadly this may now turn into a series 3000 Japan obsessive run of purchasing, fortunate they are so reasonable in price.
The EP is obviously short eye relief, but the eye lens is recessed and very comfortable to nuzzle your eye into.

Does it show it has been cloudy?  

Hi Alan

The series 3000 are a great range of eyepieces IMO, rather underrated. For me, the absolute pick of the range is the 16mm, a really lovely eyepiece if you can find one..?

Dave

On 05/02/2018 at 20:01, Dave1 said:

Well guys believe it or not, I haggled with the guy for the Vixen 80mm F15, I got it down to £186. I did some more thinking last night and today. I really like working with 80mm telescopes. I also thought, when is the next time I am going to see a Japanese Vixen 80mm F15 telescope for sale? In like new condition? Not only does it have Vixen optics, it also has 4 baffles in the tubes, and a modern dual speed focuser. This telescope has the potential to be great.

So in short I will compare the two 80mm's and keep the best one! 

Tonight I have flocked the focuser end of my Towa, I will flock the other end tomorrow, and maybe add a baffle as well.

Dave

Dave,

Pictures are required please! ??

Dave

On 28/01/2018 at 19:51, Tyson M said:

One will stay, one will go

Based on my ED103s, my money is on the Vixen?..

1 hour ago, Dave1 said:

That's great the 150mm F8 are good, but surely they are more suspectable to chromatic abbration

Yes, they do have CA, but I have used several CR6/Eco 150s and a couple of the 120s and I always much preferred the views of the latter..

1 hour ago, Stu said:

That FRT looks a lovely scope, long focal length ED, I bet that performs well!

I couldn't agree more. If the lens is well figured and polished it should deliver stunning views. And it would be as rare as Skylights too!

Dave

15 hours ago, Dave1 said:

I already own a 120 F8 Helios refractor. Whilst it is good, I don't actually use it much, I guess its just one of those things

I know what you mean. I have in store for my son in law an Evostar 120mm F8 and I just don't like it. I found the 150mm F8s much better, and at 150mm they really give the wow factor on clusters such as the Pleiades and double cluster in Perseus.

For low power wide views at reasonable cost, I'd recommend the TS Optics 40mm Parocor. I have one and it's excellent (same as TMB Paragon and SAW Aero). The 40mm will give you x30 at 1200mm focal length, and a 30mm is also available giving x40. Both will be pin sharp to the edge at F15?.

Dave

That's great Dave,

Out of interest, have you knocked out the baffle in the original really long draw tube at the focuser end? 

It's something that a lot of owners have done, I think the original baffle inside the drawtube can vignette the views, and at F15, you want the largest image circle possible to pass light through to the eyepiece.

But these really are cracking scopes when you consider the age, early coatings and modest aperture and price!

Just one other thought. Have you considered buying a 6" F8 achromat? The Celestron C6R or the Skywatcher Evostar 150 F8 are very similar optically. But they can give stunning views of clusters and nebulae compared to the 80mm, but you can also mask the aperture down to 100mm to give you an F12 achromat, which would have very good CA correction. So making two or more (with different aperture masks) scopes in one.

The only drawback is that this scope is quite heavy. However, I used one quite happily for a couple of years on a CG5 class mount with ADM saddle upgrade to hold the tube more firmly. It worked really well for visual and went up to around x250 on good nights with some great views

Good luck,

Dave

2 hours ago, Dave1 said:

. The Vixen should be better than the Towa 80mm. If I get the Vixen 80mm F15, I will sell my Towa F15 80mm. 

With great respect I don't think you'd see much difference. They are both 80mm F15 Japanese achromats and both optically very good.

The Vixen will be mechanically better, no doubt about it, with a better finder and focuser, but detail wise I think they are very similar (I've owned a Vixen Custom 80m F11, not the F15).

A 102mm Vixen SP102 F10 will be a different kettle of fish.. superb optics and that 22mm does make a very noticeable difference☺..

Dave

4 hours ago, Stu said:

Could give that f15 a try Jules?

How about trying THIS F15??

Dave, this is my former D&G 5"  F15 USA built achromat, "Andromeda", now lovingly owned by Steve ("Saganite") and properly pier/EQ6 mounted by him (Steve's photo?).

The second picture shows Andromeda with a Tal 100RS for scale comparison.

An amazing achromat.

Dave

+1 if you want to go more modern.

I've owned both and liked both. The ED100 is superb for the cost and almost free of CA visually, the AR127 is larger, shows more, but with a bit more CA on bright objects☺.

Dave

Hi Dave,

I too really like long achromats, and F13 is loooong, no doubt about it?..

My only comment would be that perhaps a 3" aperture would be too restrictive?

A 4" would show you a lot more and go a bit deeper. 

Do you have a particular budget in mind, and would you consider a modern scope? 

Finally, what would you mount it on? A longish refractor would need a decent mount. That said, so would a Mak 180, so you may well have something suitable already.

Once we know a little more, we can hopefully help a bit more. Jules is right though, Phil Jaworek is a guru on matters long refractor, so hopefully he will chip in too.

If you really want a long 3", they are to be had now and again, like this one attached...it started life as a Meade 300, then was transformed into a modern looking scope by Moonraker. The original is an 80mm F15 (1200mm FL) Japanese achromat and is very good optically for its' size.

They are sometimes on eBay in good used condition, under brand names like Towa, Topic, Meade, Tasco and carry a Circle T (Towa) or Circle K (Kenko) logo on the focuser. Expect to pay c£50 up to £150 for one in good original condition complete with mount..but you'd want to use a modern stable mount and tripod- they can take high power on good nights!

Mine below is shown on a CG5 on a heavy duty wooden tripod.

Dave?

1 hour ago, 25585 said:

Using eps from lightest an old 20mm Erfle to heaviest a 40mm ES Maxview, I use weighted wrist bands.

They can be wrapped round the scope tubes, and the weight upped or downed by removing the weights from pockets, but mostly by sliding the band toward the end for heavier counter-balance and centre for less.   

 

 

 

Clever, very clever ?.

Alan, what are you "weighting" for?? 

Dave

1 hour ago, Alan White said:

am considering delites or naglers too

Only ever had one Delite. Don't like it at all, lanky thing that it was?..Had a T6 13 Nagler, lovely eyepiece but short eye relief. PS..if you get the tube ring solution, they are fixed to the tube so can't skip off suddenly..

Dave

15 hours ago, Alan White said:

my only two 250g plus eye pieces are the 22LVW and the larger 10mm XW, all others about 160g Max or less.

...and I'll wager those two are among the best, if not THE best 2..?

Just get a tube ring(s) to counter the weight (sorry), and have done with it!??

Dave

Alan

Your decision of course but I sold my LVW22 and regretted it soon afterwards. I was lucky to be able to buy it back a bit later.

I get the weight balance thing, but couldn't you buy a single tube ring to compensate, but it at the front end of your tube?

SW rings are cheap as chips per pair, probably cheaper than swapping to a Pan 24 with very little optical improvement, if any?

HTH☺..

Dave

On 26/01/2018 at 01:54, Tyson M said:

Perfect for grab and go if you can get around the length. It is very light weight

How about this for length???

Mind you, it didn't claim to be "grab n go"

Vixen Pulsar 102mm F13 achromat..

Dave

2 hours ago, John said:

I think a 6" achromat needs to be f/15 at least to reduce the CA to levels that are not really visible in the eyepiece. My Istar 6" F/12 had a very nice objective (ie: nice, smooth figure) but the CA was quite obvious around the brightest targets I thought.

The 6" F/8 achromats I've owned showed more, until the Chromacor was installed and then it was controlled to ED doublet levels.

Sir Patrick Moore's 5" Cooke refractor is one of my very favourite telescopes

It was part of the motivation behind my decision to buy the 5.1" TMB / LZOS F/9.2 - the latter being a touch easier on the mount than an F/12 but having roughly similar lines and proportions perhaps ?:

 

Yes, I can see that John..Andromeda kind of reminded me of Sir P's Cooke too☺

Dave

11 hours ago, John said:

Interesting link.

The table below is quite a useful guide to the relative amounts of chromatic aberration that achromats of different specifications should show. It's a normal feature of the optical design though, in the same way that coma is to the newtonian design so we should not be overly concerned by it. Spherical aberration is present in many refractors and has more of an impact on performance than CA does.

 

 

I agree, John.

When I was a lad, virtually all the available refractors for amateurs were achromats. Most of them were F15, so in a long tube. Optically, many of the Japanese ones were very good (within the limits of their 60-80mm aperture), but they were nearly always under mounted, and so didn't perform well at high magnifications due to the poor mount stability and also the poor design of many of the then 0.965" eyepieces.

But chromatic aberration wasn't a big deal then. I actually grew up thinking Vega was a blue white star (partly because it was so described in Sir Patrick's "Observer's Book of Astronomy"), and partly because that's how it looked through my 60mm F15 refractor! But the important thing was that the image was super sharp and very pleasing, and below about magnitude 2 you just didn't see it.

In Andromeda, referenced above, (a USA built D&G 5" F15 achromat), the CA is almost invisible, even on Vega, and below mag 1.0 or so I would defy most Observer's to notice it. But what you would notice is a perfect Airy disk, with single diffraction ring and a real snap to focus. It really does deliver a Tak sharp image, but of course at the cost of an almost 2m long tube that needs a large and heavy mount.

But of its design type, it's pretty much perfect, and about 20-25% the cost of an equivalent apochromat.

It's no wonder that a 4" or 5" F15 design was the weapon of choice for many of the 19th century pioneer observers?.

And a 5" achromat was a favourite tool of our own late lamented Sir Patrick Moore as well?..

Dave

8 hours ago, Saganite said:

Sure does ! 

CA is Almost non existent  in Andromeda, shown in all her beauty....again ! 

In Latinized Greek Andromeda means ' Ruler of men' apparently, which is rather appropriate.

Dave ( F15 Rules) named her before I took ownership. 

Looking superb, Steve. 

I have to say, she looks fabulous on that pier and with your EQ6 under her.

I've never seen better views of the moon through any scope, than with my then Baader Maxbrights in Andromeda..just jawdropping. I think it was really worth having the tube shortened to allow native magnifications without needing an OCS?...

Dave