Review of Castell 2" Oiii Filter

[Moonshane]

Hi there

I have just bought a 2" Castell Oiii filter. This was £48 delivered from 365 Astronomy. The service from Zoltan has been first class and here's why:

• I ordered the filter and it was posted the same day and received the next business day.
  
• The process was silky smooth.
  
• After ordering I asked by email whether the filter can be cleaned using my usual method (Isopropyl Alcohol and cotton balls)
  
• He confirmed he was not 100% sure and would ask the manufacturer.
  
• He did so and came back to confirm they had used Acetone and therefore the much milder IA would be fine.
  
• All this within the same day - last reply 17.38pm.
  

This is the first 'proper' filter I have ever bought and I had high hopes that it would make some unaided targets better and some invisible targets visible. I was not disappointed. I can only provide brief details here as I only has an hour or two to observe and with a new tool.

I used the 12" Dob for this test and tried three subjects, M57 the Ring Nebula, M27 the Dumbell Nebula as well as the main targets of the test, NGC 6960 Witches Broom and NGC 6992/95 The Bridal Veil area of the Veil Nebula in Cygnus.

M57 Ring Nebula

I tried this first as it's easy to locate and the results were slightly disappointing as although the nebula was more obvious, it was harder to see detail. The result was that I preferred the unfiltered view - maybe a UHC would be better for this specific target?

M27 Dumbbell Nebula

This really stood out like the proverbial sore thumb with this filter. It really shone and there was a lot of structure visible. The subject could still be seen without the filter but the view was much less contrasty.

Veil Nebula

In my light polluted skies - pretty much as poor as it gets (I live between Manchester and Stockport) - I could not see even a hint of the Veil nebula with my 12" Dob. Putting the filter in (even with the current light skies - although I waited until Cygnus was at Zenith) made it possible to easily see the Bridal Veil and the Witches Broom with no problem. They really stood out well and I think when darker skies return again, even at home I think I'll be able to see a little more detail.It's a massive target and one I will return to again and again.

To summarise then:

Pros

• excellent value for money
  
• construction of cell very robust
  
• coatings seem smooth and well applied
  
• looking at the light pass results on the site and confirmed by my single experience last night, you can still see enough stars to be guided a little so it's not as harsh a some.
  

Cons

• quite harsh and reduces light tremendously/turns stars green
  
• makes focusing a little tricky - focus on stars rather than the DSO
  

On the basis of this one, I'd recommend you consider Castell products as a cost effective way to buy DSO filters.

I think the UHC filter would be a better all round one as it's less harsh. At this price though, buying both is not too out of reach for many people and with the 2" only £10 more than the 1.25" it's also a way to get 2" DSO filters for a reasonable amount of money. I'll certainly be getting the UHC filter in due course.

Cheers

Shane

[Doc]

Excellent report Shane, thankyou for posting.

It seems a good price and as you say at this price it's worth trying. M27 always looks slightly better in a UHC filter anyway, I think the O111 filter enhances the inner structure while the UHC enhances the lobes of the object.

I remember the first time I saw the Veil nebula through my O111 filter, it knocked my socks off, the filament structure came through so well, it looked like a spiders web, it was simply amazing.

These filters work really well and I think for £48 it's a bargain.

[step_hen]

Looking forward to see what you think of the UHC version. Seems a reasonably priced alternative to the baader UHC-S and i've been contemplating buying one

Stephen

[riklaunim]

Good that you like it. I wouldn't say it cuts a lot of light. It's quite broad O-III filter and there are Baader and friends that cut much more.

Last night I was looking at "Saturn Nebula" which due to small size looked like nice green blurred star in SCT 8" + 20 mm Magellan eyepiece (WO SWAN clone for half price). Without filter: dim small "star". With filter: bigger, much "brighter".

Using O-III/UHC-S filter for planetary nebulas you can check their spectrums to see what is the dominant emissions for given nebula - how much H-beta, and sometimes helium emissions.

[Steve_Max127]

Thanks for an excellent review Shane, I've been looking at the O-III and UHC filters but felt the usual 2" were a little out of my budget at the moment. I think I'll take the plunge and try the Castell 2" UHC first. Once again thank you very helpful and informative.

[Moonshane]

cheers all

definitely worth a go - it basically means you can see things you otherwise couldn't.

I suppose having the experience of just this filter does mean that I may have a slightly off axis viewpoint, especially re the brightness. Personally, I am happy that it lets more light through than less as it means as a relatively inexperienced observer, I still have a chance of finding things!

[Moonshane]

I have been asked if I have yet used the filter in the refractor (see below). I know others have with good results and when I get a chance I'll have a go myself - probably this weekend.

With the wider field, assuming I can see anything, it should be even 'better'.

I actually had the brainwave of gluing a smashed out cheap skylight filter off Astroboot into the aperture of a 50mm finder and then using that. Might try holding the filter against it first - you never know......

[russ]

Excellent report Shane and fits in nicely with my findings with the Skywatcher version. I bought mine mainly to see the Veil parts and was not disappointed on that front. But it does transform M27 and M76, adds a lot more. Another gem that responds well is M97. Oh, and the Eskimo.

I could see the Veil in the 102 f5 refractor from the backgarden using the OIII. Barely detectable in the 12 without the filter.

[Live_Steam_Mad]

Many Thanks for the report, that was very useful, and as a result I just ordered a 2 inch Castell OIII filter from 365Astronomy same as you did, I paid 59.60 GBP. This is for use with my much used combination of C11 SCT and CG5 ASGT, I am 1/2 way up Moss Bank hill (Hillbrae Avenue side of Moss Bank) in northern St.Helens, Merseyside, where I am 2 miles from the town centre of 176,000 people and 23,500 street lights, and where the Europe-fclpm Light Pollution overlay for Google Earth shows that I am in a light pink area, surrounded by dark pink to the North West, and almost white to the South (St.Helens town centre), compared to white for everywhere I checked that was between Manchester and Stockport, so it sounded just what I needed to see the Veil.

I have thought about seeing the Veil ever since I saw the pictures of it in Burnham's Celestial Handbook Vol.2. I do have a 19.5" F4 Dob that it could be used with but don't hold your breath on that one since the coatings are in terrible condition on the primary mirror. Robert Burnham said you need lowest powers and widest fields for best effect on the Veil so I choose the 2" filter, and if I want the 1.25" version later on then it's cheaper for the 1.25" version Castell OIII at 46 GBP.

I will be using the filter with my 2" Meade Series 4000 Super Plossl 56mm (4 elements, made in China) and with my 28mm SkyWatcher 2" Kellner 56 degree AFOV (but that has not good edge performance even at F10). I also have my Meade SN102 4" F8 refractor that I can use it with since I have the 2" Sieben adapter for it.

It's all very well thinking about the Lumicon 2" OIII filter instead for the Veil etc, but at around 180 GBP from Telescope House it is way too expensive for me, I saw one second hand on Astrobuysell UK recently (Jan 2015) at 120 GBP but it's still too much and I would be nervous about buying without Ebay guarentee etc. Also the Lumicon is possibly optimised for the Light Pollution present in USA (a lot of Mercury Vapor lamps still used there, not so in the UK), and I want something that works on the Veil from the kind of neighbourhood that I am in (LPS Sodium very few now, 10 per cent of all street lights now changed from LPS to super bright LED but with Full Cut Off shields, huge majority HPS Sodium on Cobra heads with prismatic refractors, hardly shielded, some CPO Metal Halide white light street lamps, sky looks mostly bright orange over my view of the Southern sky.

I'll have a go with the Castell OIII 2" and report back what I find with the C11. I am pure visual (no cameras yet, only eyepieces).

I found some graphs of the transmission spectrum of this filter ;-

http://www.reinervogel.net/Filter/spectra/Castell_OIII_TA_1.jpg

http://www.reinervogel.net/Filter/spectra/Castell_OIII_TA_2.jpg

http://www.reinervogel.net/Filter/spectra/Castell_OIII_TA_3.jpg

http://farm2.static.flickr.com/1328/4733532921_069eeaa813_b.jpg

http://www.teleskop-shop.at/testphotos/Filter_Spectra/Castell_OIII.png

http://www.svenwienstein.de/Pics/CastellOrbinarFull.gif

http://www.svenwienstein.de/Pics/CastellOrbinarDetail.gif

http://www.astrotreff-deep-sky.de/resource.ashx?image=144

http://www.astronoce.pl/UserFiles/Image/RECENZJE/GSO_Nebula/zakres_filtrow.jpg

http://www.rkblog.rk.edu.pl/site_media/filters/compare2.jpg

http://www.reinervogel.net/Filter/spectra/Castell_OIII_PS.jpg

http://forum.astronomie.de/phpapps/ubbthreads/ubbthreads.php/topics/725864/Re_Castell_O_III_SkyWatcher_Om

https://translate.google.co.uk/translate?sl=auto&tl=en&js=y&prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fwww.svenwienstein.de%2FHTML%2Fseben_orbinar_uhc_und_oiii.html&edit-text=

Best regards,

Alistair G.

[laudropb]

Thanks for a very full and interesting report.

[John]

I'll look forward to reading your reports Alistair

I first saw the Veil Nebula with a 100mm refractor and a Baader UHC-S filter. My current 102mm F/6.5 refractor shows the both the east and west sides of the nebula in the same low power field of view with a Nagler 31mm eyepiece and a Lumicon O-III filter. The Castell O-III gets decent feedback so it should work pretty well too I reckon.

Bear in mind that the Veil Nebula is a very large object so you will need a low power, wide field eyepiece to even fit one segment of the Veil into the field of view with your 11" SCT. You seem to have selected your eyepieces with that in mind

The 102mm refractor / Nagler combination I mention above gives me a 3.8 degree true field - just enough to fit all the segments of this wonderful deep sky object in !

It's a stunning sight with my 12" dobsonian but I can just fit either the E or W segment into the field of view with that scope and my lowest / widest eyepiece

It would be worth trying the filter on other objects such as M97, the Owl Nebula in Ursa Major and NGC 6888, the Crescent Nebula in Cygnus as these respond well to the O-III band pass width.

The "with filter" and "without filter" comparisons are worth recording - they can be quite surprising

Have fun !

[Live_Steam_Mad]

BTW for more info, I have just been told that "the manufacturing of these [Castell OIII] and the [Castell] UHC filters were moved to a different factory that could offer better quality control, so the new version of this filter is more reliable and better quality than the original filter, although the formula is unchanged and provides the same spectrum.", and "the original version [of the Castell OIII] came only in a small paper box, the new version comes with a plastic case".

Regards,

AG

[Live_Steam_Mad]

OK my Castell 2" OIII filter arrived on 29th July if I remember right (fast service from Zoltan at 365Astronomy.com) and it was in a small resealable plastic bag and inside a small plastic case. I was a little disappointed that the plastic case does not stay fastened closed (it has no fastening) and that there was no information on the case at all (but then I don't suppose that you get individual filter transmission test data with a 60 GBP 2" filter, if you want that then be prepared to pay double that second hand or 3x that for new), no transmission graph on a sticker (which would have been nice) on the box or anything. Filter ring is inscribed with "Castell OIII filter 2" " and is Aluminium (cold to the touch), with inner Aluminium (it seems) retainer ring.

Substrate seems to be extremely flat flawless glass and coating seems to be very high quality in appearance and extremely smoothly applied with no defects. Coating has the appearance of a mirror, and the reflection of the retaining ring in the coating is pink. with very far off axis reflections having purple hue and with double image of green (6" off axis looking with eye). When held up to the eye. the appearance changes markedly, it now looks like a half mirror and you can see through the filter under the room light and everything in the room looks mid to dark green. I was rather surprised by the transmission, it seems a lot higher than I was expecting, from what I read the OIII filters are supposed to be extremely harsh but this one is not as dramatic as I was expecting, i.e. it seems a lot brighter image than I was expecting. I looked across the street at a Cobra head 70 Watt Street Light of 2,700K color temperature approx of CPO Metal Halide (I think), not LED, with prismatic refractor, and the street light lamp looked green, where normally it looks slightly green-white without the filter. a This all being with just the eye looking, no camera.

Looking through a window in daylight shows everything mid green in color, again with high transmission, the sky looks blue / green. Again, with the eye, no camera.

However, through my image sensor on my Casio EX-Z750 camera, everything looked blue through this OIII filter!! NOT green!! Wierd. See pictures (I will post soon).

I tried this filter on July 29th (same night) and under full moon conditions, plus the usual moderate / heavy Light Pollution, with good transparency but awful seeing, and my first target was M27 (Dumbell in Vulpecula). With my C11 at 48x with 56mm Meade ep, M27 was initially not visible, so much so that I thought that my CG5 mount had gone off target, But I looked carefully with averted vision and it was just barely visible without the filter, with no color and no detail and no shape, they sky background was very bright and orange colored. I then put the filter on and was a little disappointed if I'm honest, I expected a dramatic improvement but I did get a very noticeable improvement. M27 gained a shape, still no detail, a very slight green color (almost none/grey), and was more visible than before. I noticed that the sky did not darken nearly as much as I was hoping for at 48x with the filter, there were many stars visible (all green color) and transmission seemed on the high side (of everything), I thought maybe this filter could be more harsh / narrower band and it would have been better?

The filter screws easily (almost loosely) on to the bottom if the 56mm Meade ep, and properly onto the 28mm Skywatcher Kellner ep with no looseness, so not the greatest with the Meade but it was secure and practical to use.

Then I put the filter into my 2" Revelation (GSO) quartz SCT dielectric diagonal (it went in with a clunk and stopped just on top of the mirror edging ring, not sure if the filter was in slightly twisted as it was too dark to tell and the reflections from my LED variable brightness torch were very bright when I tried to see and when I dimmed it I couldn't see it. I then put in some 1.25" eyepieces into the diagonal and had to be very careful not to damage the filter (do NOT try this at home!). I used 32mm Televue Plossl (88x) and 26mm (107x) Meade Super Plossl and the view began to be higher in perceived contrast, and started to get the best at about 107x (in comparison with M13 unfiltered which looks best at about x215), then I barlowed for 175x and 215x, then tried an 8mm Radian for 350x but M27 was very large and rather dim with 215x and 350x. I could see shape and the vaguest hints of detail but maybe I was expecting too much in full moonlight.

I then removed the OIII filter and was in for a shock - M27 was barely discernable at any magnification in the C11, whereas with the OIII filter it had been reasonably bright and rather obvious, and it was then I finally understood how well this filter works. Yes it has a very noticeable effect on M27, turning it from being barely able to see, to oh yes, there it is, and I can see it quite well. So it does what was promised and seems to be worth the money.

It certainly beats my Ostara Moon and Skyglow filter that I tried on M42, that made the smallest of differences, but in comparison this OIII filter does seem to be rather / very effective.

Later on I tried to find M97 which I have just barely seen before in the C11 with no moon, but with full moon I didn't even find M97 with the OIII filter on.

I would next like to try the filter in my 4" refractor (Meade SN102, F8 doublet) and report back, and I will also be trying again when the moon gets out of the way. I also have a 7" Meade Mak I can try it with. I just tonight cut / filed a piece of wood for my 19.5" dob's finder bracket (which has a 35mm wide non-standard ? dovetail) and I am trying to fit the shoe from my Antares Quick Release 50mm finder bracket to it and get the Dob back into use someday (the encoder / encoder attachment slips and was always a disaster and never worked properly), I never did have a finder for that thing, but I am loving the Antares item on my C11 with Celestron 9x50mm standard finderscope.

Regards,

Alistair G.

[Live_Steam_Mad]

Also, to add, with this Castell OIII filter, there were no double images seen of stars at any time, nor any unsharpness at all, and stars looked very sharp and clear, and the view at 700x on Arcturus showed a nice sharp Airy Disc in bright green color, surrounded by rather a lot of rings (like 4 or 5) which is more than I see normally (one fair brightness ring, 2nd one and 3rd much darker) and maybe slight Astigmatism in the star test at 700x with the filter, it seems like the correction for Spherical Aberration at 496 and 501nm is rather worse in my C11 than I see normally with no filter on (Sphero Chromatism or change of Spherical Aberration with wavelength is a well known issue in Meade and Celestron SCT's, and is worse in EdgeHD), maybe my C11 optics are not quite as good as I thought, oh well. Happy with the filter though, much recommended. I can only dream of what I would see with an M12 / C14 and this filter outside Merseyside's bright orange skies!

Regards,

AG

[John]

Very interesting reports Alistair - thanks for posting them

Your viewing conditions plus the bright moon sound very challenging for deep sky objects, filter or no filter !

I agree with your findings that you don't realise what the filter is doing for you until you try and observe the same object without it.

They are not "magic bullets" but do help see something under poor conditions and can be quite spectacular under dark skies. Also, some objects respond better than others. Ideally I prefer the views of M27 and M57 without a filter but, under some conditions, a filter can make the view at least worthwhile.

[Moonshane]

You would be advised to add a 14mm baader fine tuning ring to you 2-1.25 adapter if using for 1.25" eyepieces. Great review. I agree with your findings and have had one for years

[Live_Steam_Mad]

You would be advised to add a 14mm baader fine tuning ring to you 2-1.25 adapter if using for 1.25" eyepieces. Great review. I agree with your findings and have had one for years

I just realised that I can screw filters into the underside of my 2" to 1.25" adapter on my Revelation / GSO 2" dielectric quartz SCT diagonal (and I tried it, it screws in lovely with no looseness), instead of just dropping the filter into the eyepiece end aperture of the diagonal, but I still have to be VERY careful that I don't push an eyepiece or barlow in too far otherwise it will contact the filter! So I suppose that if I get that tuning ring you mention then it would space the filter from this potential contact. It's probably best in the near future that I buy a 1.25" OIII or UHC filter for when I use my 1.25" eyepieces though. I was thinking the SkyWatcher UHC looks best, as the sky background is always darker anyway with 1.25" eyepieces as they tend to be shorter focal length than the 2" eyepieces, and the transmission on the SkyWatcher UHC is higher than the OIII (all of the H-Beta 486, OIII 496 and OIII 501nm, with sharp cut off on either side) to compensate slightly for the darker sky in the 1.25" eyepieces.

Here are some pictures of the 2" Castell OIII filter that I took, see how it looks blue to the camera even though it only ever looked green to the eye! ;-

https://picasaweb.google.com/101932667412801910198/CastellOIII2FilterLooksBlueToTheCameraButGreenToMyEyes

Best Regards,

Alistair G.

[John]

I just realised that I can screw filters into the underside of my 2" to 1.25" adapter on my Revelation / GSO 2" dielectric quartz SCT diagonal (and I tried it, it screws in lovely with no looseness), instead of just dropping the filter into the eyepiece end aperture of the diagonal, but I still have to be VERY careful that I don't push an eyepiece or barlow in too far otherwise it will contact the filter! So I suppose that if I get that tuning ring you mention then it would space the filter from this potential contact.....

Thats excatly why Shane made the suggestion he did. No need to buy 1.25" filters for 1.25" eyepieces though. The 14mm Baader FT ring will ensure that no eyepiece barrel will contact the 2" filter and costs around £12.00 from First Light Optics. It screws onto the bottom of the 2" - 1.25" adapter and stays there ready for the filter when needed.

The fine tuning rings are basically extension tubes with a 2" external diameter and threaded for 2" accessories, male at one end, female at the other.  I use them as 2" barrel extenders for my Ethos eyepieces as well.

[Live_Steam_Mad]

Thats excatly why Shane made the suggestion he did. No need to buy 1.25" filters for 1.25" eyepieces though. The 14mm Baader FT ring will ensure that no eyepiece barrel will contact the 2" filter and costs around £12.00 from First Light Optics. It screws onto the bottom of the 2" - 1.25" adapter and stays there ready for the filter when needed.

The fine tuning rings are basically extension tubes with a 2" external diameter and threaded for 2" accessories, male at one end, female at the other.  I use them as 2" barrel extenders for my Ethos eyepieces as well.

Thanks for the info, useful stuff.

More tests done tonight - terrible conditions, cloud, always same location (back garden / patio) same amount of LP, but Moon very low and the cloud and houses were shielding me from the Moon, M27 was just about overhead, and WOW, what a difference. M27 went from being very hard to see with no shape and no detail at 48x in the C11 with full Moon nearby the other night, to now being rather obvious, and had the hourglass shape, at 48x in C11 SCT, but still no detail. However, I put the OIII filter onto the 56mm eyepiece and again WOW M27 was now extremely obvious, "bright", contrasty, and with large extensions (lobes) on the left and right, and with some fairly obvious detail within it, quite mesmerising, and again I was struck by how the filter tremendously darkened the sky but still allowed me to see a delightful amount of stars in the field of M27, very pleasing indeed. But alas I only got a 30 second glimpse at it before cloud came across yet again and closed me down for the night. The seeing was terrible also LOL. But I must say this 2" Castell OIII filter is well worth the money and I'd love to test it head to head with other filters visually in this 4.8 NELM / ZLM sky (with bright orange clouds).

Best Regards,

Alistair G.

[Davesellars]

I've had some really good results with this filter the difference with any local light pollution being that it made it possible to see the nebula whereas without it impossible or virtually non-existent.  I haven't tried this yet on the Veil so looking forward to seeing this again with this filter now!

I've found this really worked well with the following:  M1 Crab Nebula, M27 Dumbell Nebula, M42 (in harsh local light pollution made this visible), M97 Owl Nebula, M17 Omega Nebula and M8 and to a lesser extent M20.

[Live_Steam_Mad]

Having examined my TeleVue 32mm PL, Meade SP 26mm, Meade MA 25mm, Easy Tester Ronchi EP, TV Radian 8mm, and BST polarizing filter x 2 set, the worst offender seems to be my Revelation / GSO 2x Achromat Barlow, it sticks out 18mm from the bottom of my 2" to 1.25" adapter on my 2" diagonal, and I use the Barlow a lot, so I presume I will be needing the 28mm version of the Baader fine tuning ring, otherwise won't the end of my Barlow strike the glass of the 2" OIII filter when I screw the filter into the bottom of my 2 to 1.25 adapter if I try to use the Baader 14mm ring? I take it that 14mm denotes the entire total length of the tuning ring? Do I need the 28mm long ring?

Best,

Alistair G.

[John]

I guess it has to be the 28mm FT ring then. Make sure this does not cause problems in fully inserting the adapter + the FT ring into the focuser otherwise your focal positions for your eyepieces could be awkward.

I've just been observing the Veil Nebula with my 12" dob and Lumicon O-III filter - totally stunning tonight

[Live_Steam_Mad]

Finally I got a clear night with no moon, no clouds, very good transparency, and the Veil nebula almost directly overhead. I tried at 48x in the C11 SCT with 56mm Meade SP 4 element ep and used the Goto on the CG-5 ASGT handset and choose Deep Sky objects / Named / Veil nebula and it went to it but there was nothing visible at all no matter how hard I looked. I was quite disappointed!

Until I inserted the Castell 2" OIII filter into the end of the 56mm ep that is! THERE WAS THE VEIL , this is the very first time I ever saw it in these mag. 4.8 skies. The background again was not dark but rather brighter than I expected, there were very many faint stars visible, and the veil was seen very well, although it was like a ghostly glow, much dimmer than i was expecting, I didn't see hardly any detail directly, but it felt like I could "sense" a lot of large scale structure (filaments), and it started at the bottom left of the ep and ran all the way through to the top right, and as I panned around with the handset, it was spread in a huge arc that peaked in intensity at the top right then curled back round clockwise and stopped.

There was another "cloud" of the veil with a lumpy ghostly glow to it to the left of 52 Cygni. I am most pleased, the filter definitely works. But then it clouded over completely and I will have to wait for another night to try again at higher magnifications. Tonight has been a lot of waves of high cloud and all I attempted was on M35 Wild Duck cluster, without the filter LOL, at 48x it was barely visible but at 107x it was awesome.

Best Regards,

Alistair G.

[Commanderfish]

Yep i bought the Castell Oiii 2" on the strength of the above review, and I finally had a chance to try it out last night.  I don't have any other Oiii yet but I did compare it against my DGM NPB which is an Oiii and Ha filter designed for Nebula viewing.   I was using a Starwave 152mm F5.9 Achro wtih a 30mm 82 degree ES eyepiece generating a 5.1mm exit pupil at x30 and 2.7 degrees TFOV.

Viewing from moderate LP at home (only about 17 miles from central London) on a night of good transparency I got distinct views of the Eastern Veil, the witches broom, The Swan, and dected nebulosity around where the Cygnus Nebula and the North America Nebula ought to be.  Couldn't make out distinct features of the NAN, but I was dodging cloud all night.

The view was more contrasty and distinct on The Veil and Broom using the Castell compared to the DGM NPB.  Wasn't as clear cut on the Swan, both were good.  On the NAN the Castell was better but that's because it's Oiii, not Oiii and Ha combined as it is on the DGM NPB.

I got decent views of the Swan at x90 in my new Ethos 10mm using the Castell and would have pushed the power up for more detail if it weren't for more cloud.

At the price (£65 ish posted for the 2") I'm very pleased - I think the performance is well above the price point.

PS M11 Wild Duck was good last night.