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hammerhead
professor emeritus
Reged: 02/18/07
Posts: 718
Loc: MA
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Last weekend I had my 12" LB out here in MA. It was a very dewy night but I had heaters running on just about everything... EP's, finder, Telrad, secondary, etc. The gear was performing well and keeping the views clear despite the dew literally running down the (outside) of the UTA and LTA and everything else.
Towards the end of the evening I went back to Jupiter. I re-collimated and was ready to really crank up the power as I figured my primary (with fan running all night) was as close to equilibrium as it was gonna get. I put in my 7mm T6 and was disturbed to see and bright whiteish, cloudy looking "halo" (for lack of a better term) around Jupiter. Through this smudgy, Jupiter actually look very good....obvious color in the cloud bands and some very crisp moments as the seeing came and went. But that cloudy haze was horrible. This strange cloud didn't fill the FOV, but was a circle around Jupiter... in total about twice the diameter of the planet in my FOV.
At first I figured the EP must have somehow got dewy but when I looked at it under red light it appeared clean and dry... besides, I'd been keeping my EP's capped and in my case with the lid closed all evening... and wrapped with a heater strip when in the focuser. I also checked my mirrors as well and they too appeared clean and dry.
Was this just atmospheric humidity highlighted by the (very bright) Jupiter that I was seeing? FWIW, I also saw the same issues with my 5mmT6 as well... but I gave up on that EP quickly as it was just too much magnification. And the view in my 10mm Pentax XW was just fine.... along with all my other EP's in fl longer than the 10mm XW.
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-Brian
CPC 1100
WO Megrez 110ED
Televue Gibraltar with Sky Tour
31mmT5, 26mmT5, 20mmT5, 13Ethos, 10mmXW, 7mmXW, and 5mmXW
Oberwork 15X70, Coronado 10x25 Solar, Orion 7x50.
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L. Regira
super member
Reged: 07/10/05
Posts: 193
Loc: Theriot, LA 29' 25"N; 90.46W
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I have never experienced that type of fogging that wasn't caued by something in the optical path dewing up (mirror, secondary, eyepiece, etc.). Could it be just your body heat and moisture getting on the eye lens as you peer into the eyepiece? I had an eyepiece once that fogged up on one of the internal lenses. It seems to me that atmospheric humidity would affect the naked-eye view of Jupiter and you would have noticed it when looking up.
Lawrence
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CaveAstrola 12.5"F5(1979)Refigured by Swayze(2002)
with 1/13 wave Protostar Quartz secondary
Criterion RV-6 Dynascope (1975)
Denk Big Easy(7/20/07)Siebert OCA,and Mag Wheel
Sears #6332 Classic Blue-Green 60mm F11.7(thanks to Glassthrower Mike G.)
8x12 Roll-Off Roof Observatory
Eyepiece pairs:
Meade Research Grade 20mm Erfles
Garrett Optical 32mm Plossls
Garrett Optical 15mm Plossls
Orion 10mm Plossls
Tak LE 7.5mm
One 32mm Meade Research Grade Erfle (2")
Edited by L. Regira (08/02/08 11:40 AM)
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hammerhead
professor emeritus
Reged: 02/18/07
Posts: 718
Loc: MA
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Thanks for the response Lawrence... I'm perplexed by this. Thought maybe someone might have an obvious answer that I'm over looking.
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-Brian
CPC 1100
WO Megrez 110ED
Televue Gibraltar with Sky Tour
31mmT5, 26mmT5, 20mmT5, 13Ethos, 10mmXW, 7mmXW, and 5mmXW
Oberwork 15X70, Coronado 10x25 Solar, Orion 7x50.
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Mr. Mike
scholastic sledgehammer
Reged: 11/08/05
Posts: 855
Loc: Churchville, NY
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Quote:
Thanks for the response Lawrence... I'm perplexed by this. Thought maybe someone might have an obvious answer that I'm over looking.
I had a similar thread and issue with a Nagler 5mm T6. Hmmm... maybe there is an issue here? Your symptoms and mine are exactly the same. No other EP I owned exhibited this. I wonder if the huge FOV and short focal length are the culprit?
Most replies in my thread pointed towards the humidity being the issue. That has merit... but regardless, the T6 was the ONLY eyepiece that showed this problem. I have a few other high-power eyepieces en-route so well see what happens with those. I ended up selling my 5mm T6, by the way...
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Stellarvue NG 80mm ED
Meade 7x50 Binos
Pentax XW 5mm
Meade 5K UWA 8.8mm
Vixen LVW 13mm
Vixen LVW 22mm
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hammerhead
professor emeritus
Reged: 02/18/07
Posts: 718
Loc: MA
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That's really interesting Mike, thanks for sharing your experience. I have to admit... I'm not overwhelmingly impressed with the T6 Naglers on the whole. I used to own the 13mm in addtion to the 7mm and 5mm that I currently own. Selling it was not a tough decision to make when the 13E became available.
I've been thinking about selling the 5mm and 7mm ones as well.... just don't know what I'd like to replace them with yet. I really don't feel as though I need the 82 degree field of view in those focal lengths as I primarily use them on planets. Hmmmmmmm........
But I must add.... I AM overwhelming impressed (repeatedly) by my T4 and T5 Naglers!
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-Brian
CPC 1100
WO Megrez 110ED
Televue Gibraltar with Sky Tour
31mmT5, 26mmT5, 20mmT5, 13Ethos, 10mmXW, 7mmXW, and 5mmXW
Oberwork 15X70, Coronado 10x25 Solar, Orion 7x50.
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Shawn H
Pooh-Bah
Reged: 05/16/07
Posts: 1080
Loc: Southern France 43°56'N-4°50'E
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Brian
I use a 7XW for high power in my xt10i and am totally pleased with it! But contrary to what you said about not needing a superwide ep for viewing planets, I find it annoying that I have to bump the Dob soo often to keep the planets centered! The 7mm gives me 171.5x mag in my xt10i and at that magnification the targets move pretty fast through the ep! I was thinking that the new 8mm Ethos would be perfect come high power ep for my Dob, and that its 100° AFOV would keep "bumping" to a minimum. I see that you have the 13E, soo what do you think about this?  Shawn
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xt10i with Telrad on 4" risers & feather touch focuser & huge Boston Red Sox decal
Starblast
15x70 Celestron Skymasters
35Stratus
27Pan
13 Ethos
8 Ethos
Orion ultrablock
Astronomik OIII
Tele Vue 2x barlow
Antares 1.6x barlow (2")
CATSEYE collimation tools
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mikey cee
Carpal Tunnel
Reged: 01/18/07
Posts: 2306
Loc: bellevue ne.
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Brian...From one carpenter to another....I've experienced the same phenomenon through my 8" refractor and 12.5mm ortho. That would give me 216x. I really can't see it with the 9mm and 6mm orthos. I've come to the realization that it must be humidity because I don't recall seeing it in the preceeding months here.   Mike
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Mike 10x50 sears tower binocs, 3" f/10 edmunds reflector, 2.4" f/11.7 manon refractor, 6" f/8 jaegers refractor, "The 8 Ball" 8" f/13.3 brandt refractor, 3" f/15.8 sans&streiffe refractor, 3.1" f/15 selsi refractor(towa 339), 2.4" f/15 sears refractor, selsi 30x30mm spyglass, criterion 5-draw 25x45x75x spyglass(1957).
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Mike Hosea
Post Laureate
Reged: 09/24/03
Posts: 3226
Loc: "Metrowest" Boston
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Jupiter is generally shrouded in a cloud of scattered light. It's not just atmospheric humidity, also dust and the air itself. Take a look at your Clear Sky Chart and note the variations in transparency. Ironically, the most amazing planetary seeing is usually accompanied by humid, still air, which scatters a lot of light. I suppose it's a different sort of detail (high spacial frequency rather than low contrast). There is planetary observing and there is planetary observing. People are looking for different things, but at any rate, I'll never forget the best night of seeing I've ever had, and the air was so heavy you could hardly see anything but the brightest stars.
Eyepieces do scatter light, but telescopes, especially reflecting telescopes, do, too. When you hear experienced planetary observers talk about such things, you must understand that they (hopefully) are not talking about the mere presence of a glow, as this is expected. Rather, they are talking about a relative level of glow versus other eyepieces of the same focal length used on the same night. Obviously, the best eyepiece will not eliminate the glow if it is actually there in the sky, but if one eyepiece shows more glow than another of the same focal length, then the difference, at least, is attributable to eyepiece characteristics. Even so, it is tricky to conclude that less glow is better because an eyepiece with lower transmission may fool you, although it's unlikely that this is the dominant factor because transmission usually doesn't vary all that much. Anyway, just to complete the thought, you can easily diminish the glow with an ND filter. What happens is that the planet is bright enough that losing, say, 50% of its brightness is no big deal, even welcome, perhaps. But losing 50% of brightness on the surrounding glow may drop it below the brightness where it is readily apparent in the macular region of the retina.
Note that eyepieces of different focal lengths cannot be compared in this fashion--the results are convoluted with other factors and pretty much meaningless.
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Mike
- 7" f/6.7 home-built planetary Newt
- 35mm Panoptic
- 13mm Ethos
- 5mm Tak LE
- 2x TV Barlow
- Canon 10x30IS Binoculars
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payner
sage
Reged: 03/22/07
Posts: 230
Loc: Bluegrass Region, Kentucky
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Absolutely, nights of relatively high humidity increase detail (steady skies) when planetary observing. I have had similar effects in oculars where one must "seal" them with the eye in order to view the object. This happened regularly with T6s I used to have, but it is an uncommon event in my SuperMonocentrics, focal lengths being equal. I think the difference in this observed lack of fogging has to do with the SMs having a flat top, no eyeguard, thus allowing ventilation reducing the build-up of moisture on the objective lens.
Randy
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CGE1400 w/XLT & FT MicroFocuser
Russian-Intes MK 91 Rumak
Takahashi FS-128
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hammerhead
professor emeritus
Reged: 02/18/07
Posts: 718
Loc: MA
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Hi Shawn,
I appreciate your thoughts and we're actually thinking along the same lines. I'm pretty much sold on replacing my 5mm and 7mm T6's with Pentax XW's of the same focal length. I do like the extra field of view when observing planets with the dobs. But at the same time I don't think I 'need' the 82 degrees... especially if I'm not really happy with the T6's anyway. What I really like for planetary is my TV plossls... but only if I'm using a scope with tracking, not my dobs.
I really enjoy my 13E but, truthfully, I think the FOV is actually a big excessive... perhaps unnecessary is a better word. But there are other reasons for loving the 13E other than just the 100 degree FOV.... and those are the real reasons why I keep it. If I had come across an EP that made me as happy at 13mm at my Ethos does but had "only" an 82 or even 70 degree FOV then I would certainly consider it an option. But so far, I haven't. And I already own the 13E so no sense in getting rid of it if I enjoy it.
That being said, I truly think I'll be very happy with a 7mm Pentax XW. I did consider the 8E for awhile, but in the end I've decided that I really want to try out the XW's in some more focal lengths seeing as I couldn't be happier with the 10mm XW I've had for quite awhile now. I think 70 degrees will be enough apparent FOV for me in those focal lengths with the dob.
But really.... what the heck do I know!?  I could very well be on here selling the 7XW in six months because I don't like it and want to try the 8mm Ethos!
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-Brian
CPC 1100
WO Megrez 110ED
Televue Gibraltar with Sky Tour
31mmT5, 26mmT5, 20mmT5, 13Ethos, 10mmXW, 7mmXW, and 5mmXW
Oberwork 15X70, Coronado 10x25 Solar, Orion 7x50.
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hammerhead
professor emeritus
Reged: 02/18/07
Posts: 718
Loc: MA
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Quote:
Brian...From one carpenter to another....I've experienced the same phenomenon through my 8" refractor and 12.5mm ortho. That would give me 216x. I really can't see it with the 9mm and 6mm orthos. I've come to the realization that it must be humidity because I don't recall seeing it in the preceeding months here. Mike
Maybe it was sawdust in our eyes! 
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-Brian
CPC 1100
WO Megrez 110ED
Televue Gibraltar with Sky Tour
31mmT5, 26mmT5, 20mmT5, 13Ethos, 10mmXW, 7mmXW, and 5mmXW
Oberwork 15X70, Coronado 10x25 Solar, Orion 7x50.
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hammerhead
professor emeritus
Reged: 02/18/07
Posts: 718
Loc: MA
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Mike,
Thanks for a most informative post. That really does shed some light on the situation.... no pun intended!
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-Brian
CPC 1100
WO Megrez 110ED
Televue Gibraltar with Sky Tour
31mmT5, 26mmT5, 20mmT5, 13Ethos, 10mmXW, 7mmXW, and 5mmXW
Oberwork 15X70, Coronado 10x25 Solar, Orion 7x50.
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Shawn H
Pooh-Bah
Reged: 05/16/07
Posts: 1080
Loc: Southern France 43°56'N-4°50'E
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Well if you do get the 7XW you'll love it! I do! Did you see how well Jason Bay did for the Sox sweeping Oakland? And Manny's had a hot start with the Dodgers  Shawn
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xt10i with Telrad on 4" risers & feather touch focuser & huge Boston Red Sox decal
Starblast
15x70 Celestron Skymasters
35Stratus
27Pan
13 Ethos
8 Ethos
Orion ultrablock
Astronomik OIII
Tele Vue 2x barlow
Antares 1.6x barlow (2")
CATSEYE collimation tools
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bbcoltrane
journeyman
Reged: 05/07/08
Posts: 5
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I've had the same problem with my Antares 5mm Plossl and my Meade QX 15mm w/a 2.25x barlow. Both are similar magnification with my 5" Achromat, but the QX has a greater FOV, which helped me figure out what was happing here.
I don't believe it's dew or moisture. What I've noticed is that the bright Jupiter disc actually reflects off of my own cornea and back onto the EP glass. If I keep Jupiter off center in the EP, the affect goes away. But, if I center Jupiter and move my eye around, I notice that when the reflection converges with the disc, the haze appears. The 5mm Plossl has such a small opening that I can't really get Jupiter off center enough to negate the affect, so the EP is kind of useless (same problem with Saturn & Mars @ opposition)
So, the real question here is... what EP's have better anti reflective coatings on the top glass?
I'm thinking of posting this as another thread to get more feedback.
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hammerhead
professor emeritus
Reged: 02/18/07
Posts: 718
Loc: MA
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That's a really interesting theory. I'd be curious to read the comments of some others who are more 'in the know' than myself.
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-Brian
CPC 1100
WO Megrez 110ED
Televue Gibraltar with Sky Tour
31mmT5, 26mmT5, 20mmT5, 13Ethos, 10mmXW, 7mmXW, and 5mmXW
Oberwork 15X70, Coronado 10x25 Solar, Orion 7x50.
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Bowmoreman
Carpal Tunnel
Reged: 09/11/06
Posts: 2981
Loc: Bolton, MA
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Quote:
Well if you do get the 7XW you'll love it! I do! Did you see how well Jason Bay did for the Sox sweeping Oakland? And Manny's had a hot start with the Dodgers Shawn
And Bay's 4-fer last night was tasty as well! "as close as you can EVER get to an HR without actually getting one" - took two outfielders to prevent it! 
BAck On Topic: I've had this effect in some of my EPs as well Brian; these last few clear (ha!) chances we've had unfortunately came with 99.99% RH conditions (dripping everything)...
I found that just the closeness of my face to the EP surface would push the local RH just "over" the condensation line, and result in instant dew on the EP...
Dew that would go away literally within 2-3 seconds of "pulling away" (even with my Kendricks system operating/heating!)...
The effect on Jupiter was exactly as you described...
heck when I tried viewing with my glasses ON, just getting close to the slightly heated EP would cause them to fog up the instant I moved the slightest bit...
Can't wait til we get a great night and we can checkout your 7Pentax against my 8E! (and maybe setup the Sox as bkgnd entertainment, via WCRN or something so that it preserves dark adaptation!)...
clear enough skies
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Dave
Ustream
YLive
XT10i, RTP, CGE, R200CF, TMB80SS
31T5, 22T4, 13Ethos, 8Ethos, TV 3-6 Zoom; Paracorr
MallincamColorHyperPlus,SBIG STV&237A;CanonRebel Xti
WilderSkiesObservatory(BYO #90)
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