What is possible with this new fancy XW 5mm?

[JOC]

So I am a proud owner of a Pentax XW 5mm.  I have a 1200mm F6 Flextube 200p 8" Skywatcher Dob.  This gets me x240 and I'm in the UK at a medium dark site - In the countryside but with a factory next door and towns on the horizon in some directions.

So what should be possible with my new flash bit of kit please.  In particular will I get more than 4 stars out of the Orion Trapezium, and will I finally see all four stars separately in the double double?

 

[alan potts]

Congratlations on you new Pentax, a very fine eyepiece and one once had a place in my cases. Now, the double double should be a sure fire yes on a night of good seeing but the Trapezium I find requires lower power than the XW would give, around the X120 mark is best I find, much above this for me makes it very difficult.

Alan

[mikeDnight]

Personally I think the 5mm XW is one of the finest eyepieces available. I find with my 4" refractor that the E & F stars in the trapezium show up more easily in the 10mm XW, but atmospheric turbulence can wash them out easily. You'll have a ball revisiting your favourite DSO's with your new 5mm XW. Enjoy the adventure!

[John]

Very fine eyepiece as I've posted many times before

I find it an excellent lunar eyepiece with my 12" dob (318x) and it's shown me the finer lunar details than any of my other eyepieces. With my ED120 (180x) it shows me the E & F stars in the Trapezium so they should be fairly strightforward in a well collimated 8" scope. You might be able to see the "Pup" star, Sirius B when that star has risen reasonably high. Uranus and Neptune will show their disks well and you might even glimpse Neptunes brightest moon Triton if you observe very carefully. Mars and Saturn will be great with the eyepiece but it's probably a little too much power to get the best from Jupiter which seems better at slightly lower powers. Some of the planetary nebulae are well worth observing at really high power and can show internal structure if carefully scruitinised. The "Blue Snowball" (NGC 7662) and the "Cats Eye" (NGC 6543) plus good old M57 "The Ring" are all worth using a large image scale on. Globular clusters are great when they fill a good chunk of the eyepiece and then there are many double stars that you can prise apart with 240x under decent conditions 

You should get your moneys worth !

[Timebandit]

 

One of the best 5mm on the market. It is like a top quality Ortho optics, but in a useable eyepiece IMO. Great eye relief and fov of 70d and very well built. I use this in my 120ed and f/4.6 reflector and performs very well in both. Certainly planetary and lunar will be great and also splitting doubles, had my best view ever of Saturn in my Pentax XW's. You can have confidence in this eyepiece, that when it's in the scope then it is not going to be the weakest link in the optical chain. Unfortunately it is usually the atmospheric/seeing conditions that will hold this back in the UK. 

[jetstream]

7 hours ago, JOC said:

I finally see all four stars separately in the double double?

For sure.

Be certain the mirror is cooled and the scope well collimated- if the stars are bloated cooling issues or seeing issues are most likely to blame. Using a shroud helps keep body heat from causing thermal issues too.

Some of your other eyepieces should show it as well.

[Louis D]

8 hours ago, JOC said:

ill I finally see all four stars separately in the double double?

Maybe it's my Texas skies, but I have no trouble splitting them at 75x with my 8" Dob.  The 5mm would seem like overkill for this.

I use my 5.2mm XL mostly on globular clusters, Luna, Saturn's moons, the Trapezium, Uranus and Neptune, and some planetary nebula.  Teasing out E and F is actually easier in my small refractor than in my big Dob.  I think it has something to do with the tighter airy disks of the bright stars not obliterating the fainter companions.

The question for me is what to use my 3.5mm XW on.  I bought it just because I found it for $215 new and thought, why not?  I've used it mostly on Luna.  The tiny exit pupil interacts poorly with my floaters.  It's incredibly sharp and contrasty, but just way too small an exit pupil to be comfortable.

[JOC]

1 hour ago, Louis D said:

Maybe it's my Texas skies, but I have no trouble splitting them at 75x with my 8" Dob.  The 5mm would seem like overkill for this.

and

2 hours ago, jetstream said:

Be certain the mirror is cooled and the scope well collimated- if the stars are bloated cooling issues or seeing issues are most likely to blame. Using a shroud helps keep body heat from causing thermal issues too.

I'll watch out for the cooling aspect - I've found the double double several times and have had real good serious goes at splitting it into four.  I can usually tell that each of the pair is more than one, but I've never achieved a clear split between each pair as I can with something like Capella

8 hours ago, John said:

The "Blue Snowball" (NGC 7662) and the "Cats Eye" (NGC 6543) plus good old M57 "The Ring" are all worth using a large image scale on

I found all those for the first time on that great night I had the other week - sounds like an excellent reason to revisit :-D

 

9 hours ago, alan potts said:

Trapezium I find requires lower power than the XW would give, around the X120 mark is best I find, much above this for me makes it very difficult

Is that because you are too close?  I can get four to five out it easily and am looking for the others to be tight in relation to these - maybe I'm looking for things that are further away from the main than I think - though the start charts don't seem to suggest this.

 

9 hours ago, mikeDnight said:

You'll have a ball revisiting your favourite DSO's with your new 5mm XW. Enjoy the adventure!

I can't wait.  The next clear night that coincides with me being here you know what I'll be up to.  Way too much cloud around lately for any serious thoughts of observing :-( 

Many thanks everyone for sharing my excitement.  Thanks to the generosity of many folk on SGL offering their kit second-hand even beginners like me can start to build an interesting collection of EP's - Hopefully I shall amass a set I can still be using in many years time :-D

[Louis D]

20 minutes ago, JOC said:

Is that because you are too close?  I can get four to five out it easily and am looking for the others to be tight in relation to these - maybe I'm looking for things that are further away from the main than I think - though the start charts don't seem to suggest this.

E, and in particular, F, can almost appear as bumps on their nearest, brighter neighbors if the airy disks are bloated.  This is where having an unobstructed system helps greatly.

[25585]

Must try all your recommendations with my 5mm Radian which gives 100x in the Genesis, but too high for anything but short unguided viewing.