jetstream

Excellent Gavin, were you in the city or out in the country? these views are very good and congrats for having a fine year of observing.

8 minutes ago, vlaiv said:

Maybe best type of unit to be used is mag/arcsec^2, or simply magnitude (surface brightness - not to be confused with stellar magnitude although it is the same thing).

Magnitudes are better suited to our visual perception than physical quantities because our eye/brain works on close to logarithmic scale.

Surface brightness of targets is also given in these units (or mag/arcmin^2 and here it is simple conversion as add 8.89 to get mag/arcsec^2 - but these tend to be average brightness) and you can estimate visibility from that.

According to SQM calculator page (found here), to convert from cd/m2 to mag/arcmin2 use:

or rather opposite one in above case.

We have 0.24 mcd/m2 and 0.21 mcd/m2, let's convert that to mag/arcsec2

-2.5*log(0.00024 / 108000)  = 21.633

-2.5*log(0.00021 / 108000) = 21.778

How big a difference is 0.14 magnitudes? Not much - change in transparency from excellent to very good will make about 0.1 mag attenuation of targets. Single air mass has about mag 0.16 attenuation.

Hey Vlaiv- I'm curious- how many airmasses at the horizon compared to around 45 deg up and also zenith? I uses visible horizon stars as part of sky assesment.

I can say that there is a big difference when the sky reads 21.8 mag from a 21.4/21.5  transparency being equal, however the lower readings are associated with lower transparency levels usually around here.

That being said- I would take a 21.5 mag super transparent sky over a higher SQM reading at lower transparencies. Transparency is a major factor in how well DSO show in the eyepiece.

7 hours ago, alan potts said:

Nice report Gerry, have you tried the extended alphabet on the the trapezium yet H G etc.

Alan

Thanks Alan, yes I've seen the extra 2 inner stars at times and another session revealed a star just outside the trap which I think to be H1 or H2. I find these stars to be seeing and mag sensitive and the odd time that great seeing and transparency coincide sure helps on these stars. The 17.3 Delos with the Paracor II is a big asset in this telescope on the trap under avg conditions and under better ones the Docter 12.5mm/10 Delos/orthos are the ticket.

I'm puzzled why there is not more consistent views of these fainter stars, it must be seeing and or cooling issues. Have you noticed this Alan?

Dec 27 offered a much different level of transparency than today with the 18" of snow that fell (is falling). The 27'th was a super night of dark transparent skies so out went the 24". I finally received the 8mm Delos and also a Baader pushfix and the TV in travel adapter. Both work very well.

I had a good view of NGC 891 a while back so I figured to try again with it at zenith. This galaxy gives up a massive central lane and the 17.3 Delos gives a great bright view in the dob, with the central large "core" showing well. As the mag was upped a truly unique view appeared and with the 8 Delos @360x  the outer galaxy was dimmed but the inner core split into 2 large bright sections, very very similar to the Cheeseburger Pn, NGC 7026.  This is quite a sight.

The Delos series perform so well, so comfortably on these DSO, their transmission is apparent as is the contrast.

Over to M42 and I can say this is the first time that I definitively see blue around the core, intermixed with green and also faint pink at the edges as well as under the wings. The 17.3 Delos gives such a bright,clear, pure view on this object- but boy did it wreck my dark adaptation...

M33 is showing more and more spirals now, much different than the skewed "S" of before. The Docter and 10 Delos really worked here.

As far as sky conditions rating- I could see the HH unfiltered in the dob, no more needs to be said really.

Thanks for reading, Ger

On 25/12/2019 at 14:37, MarkRadice said:

Gosh I always think of the Cocoon as a photographers target. I had nil success with a 20” dob at Olly Penrice’s place in south of France hunting for the cocoon - the Barnard dark Nebula alongside is wonderful though.  

 

 

This is tough but do able. My 15" shows it nicely and the 24" pulls out some inner structure with my Lumicon UHC under skies similar to La Granges. Were you looking in the right place using that dark lane (dark neb) as a guide?

A friend in Sweden can detect it in his C8 under dark skies. Keep at it, you will find and see this underwhelming (to me) object. Question- what eyepiece were you using and what f ratio is the scope?

7 hours ago, Paz said:

I have 3 eyepiece sets that I settled on after some experimentation with other options.

Nice choices.

1 hour ago, John said:

Markus did commission a 3rd run of the Supermonos I remember

Maybe we could get FLO to commission a run of XO's with Pentax? through pre orders?

2 minutes ago, John said:

Markus did commission a 3rd run of the Supermonos I remember. The longer focal lengths didn't sell too well as I recall. When I owned my 5mm TMB Supermono (2nd run) they chaange hands for around £100 apiece having been originally retailed at around £200 each.

I guess Vixen had a crack at this market niche with their HR Planetaries and a bit later Takahashi with their TOE's. Both really creditable efforts from the reports I've read. Yet to actually try one myself though.

The Vixen HR's are a steal of a deal IMHO. Well documented and tested as well. In reality I think Pentax might be our hope for some new top tier orthos after seeing their renewed interest in the 30mm and 40mm XW.

It would sure be nice.

18 hours ago, scarp15 said:

It would be interesting to take a look at Betelgeuse with all the talk concerning it dimming. 

It would be interesting to be around to observe Betegeuse when it goes supernova.

21 hours ago, JTEC said:

What’s stopping equal quality from being produced and on offer now? 

My guess is cost and limited market. I wonder how fast the ZAOII's sold at the time of offering? or the Super monos? I think Ludes had the Supermonos hanging around for a fair bit.

Question to all- would any of us pay $600-$700 USD or more for one new ZAOII level ortho?

3 hours ago, Stardust1 said:

Gerry, I haven't used the Nikon with a Paracor in the dob. I might look for a Paracor soon (as soon as I recoup from the docter 😉). 

Seeing Orion nebula at a dark site with the Nikon HW 17 in a 16" (F/5) dob is a unforgettable experience. A friend of mine was peaking through the Nikon, the only think that I heard from him is, I wan't one 😁

Absolutely agree on the Nikon 17 HW- for me the Swan nebula that this eyepiece presented in the 24" f4.1 (no PCII) is burned into my brain. The pillars of creation were easily seen in the Eagle neb too as dark lanes.

1 minute ago, John said:

I'm sure Gerry will explain his meaning.

Meanwhile, there is some interesting stuff here on eyepieces and deep sky observing from folks who use very big aperture scopes under very dark skies:

http://www.faintfuzzies.com/OR-Sept022011-OSP.html

 

Same link at the same time! it is a good reference for sure.

1 hour ago, markse68 said:

What does this mean Jetstream? Keep hearing it but what does it mean? You can see deeper into space with it?

Some eyepieces will show more faint stars than others and it is an indication of its transmission. These eyepieces can show more detail in nebula ( lots more to it than this though ie AFOV, contrast) and also will for sure show fainter galaxies.

Alvin at faintfuzzies describes it.

http://www.faintfuzzies.com/OR-Sept022011-OSP.html

5 hours ago, Piero said:

My copy of 10mm Baader BCO was not at the level of my ZZ or Docter, suggesting that there is some variability unfortunately.

This is unfortunate as some of these 10BCO are pretty good- great color on the planets, very sharp and my copy is the deepest eyepiece I own. All for about a hundred bucks. My Tak 12.5mm is very sharp but not deeper than the Docter and it seems to lack a bit of "pop" on nebula.

All I can say is we are very lucky to be in a position to try and own this equipment.

1 hour ago, Stardust1 said:

I have Nikon HW 17

Me too-do you know how to make it work with a Paracor II? I removed the sleeve from the bottom and the whole thing is so long...

11 hours ago, Stardust1 said:

By the way how is the performance of the doctor with the Baader VIP?

Excellent.

I have never used a ZAO but I think that the ZZ would be right there with it for planetary/lunar sharpness and contrast. The ZZ does not have as high a transmission as my 10BCO, a vg copy, so it will fall short of the ZAO here. The Docter competes with the Delos for the deepest widefield and both are deeper and sharper than Ethos IMHO. I am however a hyperwide low power enthusiast, where to me the Ethos shines.

The Docter is a bit sharper than the Delos as is the Zeiss zoom, again just my opinion...

you should see the core of M42 in a large fast dob with the Docter...

Heres mine

16 minutes ago, Stardust1 said:

Thanks Gerry! Do you mean this Zeiss zoom:

https://www.idealo.de/preisvergleich/OffersOfProduct/812353_-okular-vario-d-15-45x-20-60x-zeiss.html

I have never tried the Zeiss zoom, would love to try it. The focal length is great. What is the FOV across the range? I assume you would need an 1.25" adapter. Is the Zeiss zoom sharper then the Leica 25-50x WW?

I have at the moment a pair of Tak LE 30 and one LE 7,5. I loved the LE 5 as well, but couldn't justify keeping it as I had already the XW 5, XO 5. The LE 5 sample that I had was sharper then XW 5 sample.

 

I couldn't get the site going as its in German but I think it is. Its a narrow, ortho like FOV and responds very well to the Baader VIP barlow.  Zeiss sells expensive adapters but Piero and I run Baader adapters that are focus point friendly.

I have the Leica Asph zoom- its a warmer tone with a wider FOV and is VG but with a bit of EOFB. It is really sharp but I feel the Zeiss works better for me. The Leica seems a bit less sensitive to f ratio IMHO.

I'll have to go look at the zoom to see if its the one your referring to. I always wanted to try the fixed fl 12.5mm Zeiss as well... and a 5mm XO!

Some of my very best planetary/lunar views have been with the ZZ. To my eyes there might be a bit of sharpness fall off at the low end of the zoom/barlow- but this was at over 500x on the moon... my seeing here can support 762x using the 2.4mm Vixen HR and my 15" dob- and razor sharp. It could be the conditions affecting the ZZ at the high end, not really sure.

Regardless, the views through the ZZ are stunning- maybe @Piero can chime in.

4 hours ago, Stardust1 said:

I would love to try the docter 12.5mm

Another very sharp eyepiece in the centre of the FOV is the 25.1-6.7mm Zeiss zoom. It is great in slowish newts and excellent in refractors across the whole field. It maintains incredible centre sharpness in my f4.8 and I'm working on its use with the Paracorr at at both f4.8 and f4.1.

@Piero has extensive experience with this set up. Then there are the lowest scatter eyepieces I've seen, the Vixen Hr's.

I also find the Tak abbes VG but not the best, the Zeiss zoom is sharper IMHO. I differ from you with regard to Tak LE's- my 12.5mm does not excel in any area at all.

On 17/12/2019 at 09:44, davekelley said:

Now I have a tracking scope I wonder if fov is not so critical on planets (no need to keep nudging it along to keep the object in the fov)

I use orthos on a tracked refractor with ease as well as the Vixen Hr's. Long Perng made some really nice 5mm planetary eyepieces with 20mm eye relief. Zumell, Stellarvue, Orion (Edge ON?) and Williams optics offer variants of these or did. The 5mm I have is VG.

1 minute ago, johninderby said:

And bring a zoom so you can try different mags to see what works at the time. 

Absolutely, a zoom with "catch" the seeing very well. I own 3 nice zooms one of which gives ortho like views in the centre of the field. I;m playing around with it in the ParacorrII for f4.

Also for the OP - there is also the idea of matching eyepiece tone to the target- I like an icy tone on Saturn but a warmer tone on Jupiter for example.

26 minutes ago, Rob Sellent said:

As such, all options should be explored when observing, or at least those which maximise the observer's experience.

There is a hillbilly saying "run whatcha brung"! (and bring lots lol!)

9 minutes ago, John said:

Thats the same eyepiece as the APM XWA 20mm isn't it Gerry ?

Yes, I believe it is John and I think the Myriad is a variant as well? with a bit different ergos. I got my HDC from Wolfi at TS in Germany. I would really like to compare the 13mm XWA with my other EP's ie the Doc.

@Maniek the 20mm Lunt HDC is a very worthy contender in this focal length and compares nicely to the 21E...