Haze in Celestron NexStar 6SE

[greglloyd]

Hi all,

Sorry if this has been discussed before (I have read through previous posts and through several websites, but still looking for opinions from people with similar setups).

I've a 3 month old Celestron NexStar 6SE. About a month ago I had the scope out in cold, damp conditions and then brought it back into the house. Dew formed rapidly as expected. It usually clears very fast by itself - but for some reason that evening I decided to take the hair dryer to it and this quickly cleared the dew to show a primary mirror now covered in dew (I suspect the warm air from the hair dryer got inside and condensed on the mirror).

The dew naturally cleared away within 30 - 60 mins from the primary, but the next day I noticed that at certain angles when viewing into the OTA and the kitchen lights caught the mirror you could see a very thin film covering 80% of the mirror. The same appears to be on the corrector plate. Extremely thin but can be just seen at certain angles (The primary is more noticeable and can be seen in daylight at certain angles).

I haven't panicked. I've left the scope alone and decided to do some viewing to see if this haze makes any difference to the viewing at all. My eyepieces are all Celestron X-Cel LX (25mm, 12mm, 9mm, 7mm) - All show the same effect.

Weather has been rubbish for weeks, but I got 3 chances this week to test the scope and found that images looked sharp still, but (and I cannot remember if this is normal or not) - bright objects such as Jupiter and Cappella, etc show glow / glare around them. If you pan the scope a little, the glow / glare moves with the object.

My thoughts on this have been :-

1. It's moisture in the atmosphere. Viewing temps have been typically 0c to -2c with relative humidity at around 90%+ However I cannot see the haze around Jupiter or stars with the naked eye. However, the moon had a large amount of glow in the sky last night.

2. It's light in the eyepiece as it's a 6 element model

3. It's the haze that has formed on the corrector plate (fogging the view)

4. It's the haze that has formed on the primary (fogging the view)

1 and 2 I am fine with - but I'd more more concerned if it was 3 or 4.

Incidently, we had the most steadiest atmosphere here last night since I bought the scope and I carried out some high mag collimation of the scope. It was already good from a previous collimation I carried out, but last night I got the Cappella razor sharp in focus with the first concentric ring totally symmetrical around it and several outer rings almost fully formed right around it. As close to text book as I could get it.

Checked out Jupiter afterwards at 167x and 214x and it looked fab. The best views yet with this scope. Very sharp edge to the planet right the ay around, lot's of cloud band detail on the surface and polar shadowing, and could resolve two of the moons into disks. the scope is giving it's sharps views ever afer that collimation, but that glow around Jupiter remained - as it also did for the brighter stars.

What's your opinions on this phenomena I am seeing? Is it normal to see a glow / glare around these objects or is it the haze that formed on the optics causing it. I must say it's not bothering so much that I will rip the scope apart. With direct vision you cannot see it so much, but with adverted vision you not this glow more so. My main concern is if it is actually haze on the optics then it might cause a dimming of DSO's?

[No-i-dear]

I get a bit of glare on my Fullerscope when viewing very bright objects. Was thinking of cleaning the eyepieces as they are a bit grubby, then trying a filter.

[greglloyd]

Thanks. The eyepieces are new and clean so not suspecting dirt in the eyepieces as the problem, but wondering if the X-Cel LX eyepieces give a glare around bright objects in general? Most reviews don't really mention this.

Also, humidity has generally been around > 75% during the day and > 95% at night. Is this likely to be playing a role?

[Dunkster]

If it's moisture, you could mop it up by putting a silica gel pack in the diagonal or bottom of the baffle tube (before replacing the cap) or use one of the desiccant caps that FLO sells. If the former, just be careful to keep the ota upright so the packet doesn't end up out the other end of the baffle tube and sliding around on your mirror

[greglloyd]

Did try that actually. I stuck the gel pack that came in the scope's box into the visual back. It was a little too big to get fully in. Also left the scope pointing up for a day with the visual back open to let warm drier air into the scope. Didn't remove anything though and I'm not sure when looking at it carefully if it is actually moisture in there. I've a feeling it's something left behind from when the moisture evaporated off. It's extremely thin and general hard to see though except from specific angles with bright light shining on it.

A striaght on view of the mirror and corrector plate shows them both sparkling.

[dweller25]

Is the haze blue/purple in colour ???

[greglloyd]

Different colours I would say. Sometimes appears slightly blue. Other times it appears slightly yellow. It's a slightly more blue tinge than anything else though.

[dweller25]

I have seen that before - its outgassing from the paint/grease inside the OTA and it may have been there for a while. It will be on your primary and on the inside of the corrector. It's nothing to worry about and can be cleaned off easily.

[greglloyd]

Yeah, but does it warrant cleaning though? I've no experience with opening up and cleaning SCT's (only had Newts before). Don't want to wreck something when there wasn't going to be much to gain from doing it in the first place :-)

The views in the scope are still excellent. I'm just wondering if the glare I see around planets and bright stars is being caused by this deposit?

What's the general consensus on this?

[greglloyd]

p.s. So you suspect that the film may have been there for some time (possibly from new) and I only really noticed it when studying the primary more after the dewing up?

[Mark in Macc]

I have noticed some haze on the inside of my corrector plate as well. It was there from new and I only noticed it by shining a torch inside (fatal mistake). I contacted FLO and they said it's nothing to be worried about. And they were right. Nothing wrong with my optics.

[greglloyd]

As is typical - after posting this thread I discover my answer this morning. This link explains exactly what I am seeing (right down to the adverted vision I mentioned before) :-

http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/4486216/page/143/view/collapsed/sb/5/o/all/fpart/1

[greglloyd]

Just seeing if anyone else had opinions on this topic before I let it die? I'm particularly referring to the glare / glow / hazy phenomena that shows itself around bright objects such as Jupiter and Cappella.

[matsey]

I have had what sounds like similar experiences, especially with Jupiter - for me it's like a grey haze around the object and over it as well for Jupiter. The cause for me though is fogging/dewing in the eyepiece itself - its caused by the warmth of the eyeball against the cold glass of the eyepiece.

Could that be what's happening to you as well? If so the recommendation I was given was to try to keep the eyepieces warm - caps on in a pocket is what I do when it's very cold. A dew strip round the eyepiece can also help, but have to confess I find that a bit fiddly and gets in the way a bit so tend to only use that if it's really bad.

Matsey

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[greglloyd]

Had thought / read about that. I keep my eyepieces in my pocket purposely so they don't become cold and dew over, so I don't think it's the eyepieces. When I take one straight from my pocket and put it into the scope I see the glow from the bright object. It's a similar experience to yours though. It's a glow that lights up the centre of the eyepiece right around the object.

Note that the views remain incredibly sharp though. Stars are pin sharp right across the field and planets such as Jupiter reveal lots of detail and some of the moons esolved to little discs. The light gathering power of the scope appears to remain at 100%. I've deliberately tested it on challenging objects such at NGC2158 which remains just as easy as ever to spot and partially resolved (even at 60x). The is no glow / haze / glare phenomena from anything else I view except for the bright planets and stars.

Having read about SCT maintenance, I am not going to bother attempting to clean the primary at all. I think the risk of doing serious damage to a new scope is just too great. Don't even think I will try to clean the inside of the corrector as I've just got the scope perfectly collimated from two nice nights of extremely steady seeing.

I might have a go at cleaning the outside of the corrector with an isopropyl alcohol / distilled water solution as I sometimes see a very thin residue on the outside of it in certain lighting conditions. However, for the meantime I'm not going to touch anything at all until the weather conditions change. The last few nights I've been out testing and collimating, the temps have been low and the humidity 100%. Last night for example, the sky totally fogged over by the time I finished. There's possibly a good chance that the high amount of moisture in the air is causing this??

[earth titan]

I would strongly suggest making some dessicant caps to extract any stray moisture from the OTA. These can be simply fashioned from 35mm film canisters and packaging dessicant, which can be purchased for pennies off the net.

I did this with my C9.25, which lives in the obsy, after suffering dew on the inside of the corrector plate and the primary. Problems since.

Typed by me on my fone, using fumms... Excuse eny speling errurs.

[matsey]

Hmm yes from what you've said then possible not eyepiece dew - it tends to be ok on first view then gradually gets worse.

If humidity is very high then yes quite possible it could just be down to very bad seeing conditions and haze in the atmosphere.

I think you're right to not try cleaning anything inside the tube - if the outside of secondary needs a clean I'd recommend getting some baader wonder fluid I have some as do lots of people and it's very good. There are tips about how to do the cleaning I think small circular motions are best but definitely have a google - I've never really had to clean a large area before.

Matsey

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[greglloyd]

I've ordered a bottle, thanks! I'll give the outside of the corrector a clean with it and wait for less humid conditions before making any further judgements.

[matsey]

That sounds like a sensible plan - though reading earth titan's reply I would also second his suggestion to get some desiccant caps as well to get rid of any internal moisture in the scope. In fact, I'm very tempted to get some myself, they sound like very useful things to have around.

Hope it goes well anyway, and do report back how you get on when you do get some good conditions.

Matsey

[greglloyd]

I did try the silica gel pack that came in the box the OTA arrived in and this made no difference. It doesn't look like moisture to me but more like what the moisture left behind.

I've seen the dessicant gel caps on FLO and they do look good for removing moisture. Think it might be too late in this case though? But certainly good for preventing any similar incident.

[greglloyd]

Ahhh. A bit of relief. A nice clear sky again this evening so decided to test this issue again. There's less apparent haziest in the sky this evening and the moisture content is down a little with the dew point at 0c compared with 5c this time last night.

Took scope out and skipped the cool down to go straight to the eyepiece and check Jupiter while everything was far too warm for any dew to form on the optics whatsoever. There wasn't glow - but less than other nights this week.

So, I decided to grab the binocs out for a second opinion. Mounted them on the tripod and trained them on Jupiter. Exact same glow. Trained them on Capella and Sirius. The same.

it seems the scope and it's accessories are not the cause :-)

That leaves the atmosphere or my eyes. Both eyes see this effect so I'm guessing there is a thin layer of moisture or particles in the atmosphere causing it. Not complaining though because this week has given the most steadiest skies for a long time and has allowed me to collimate the scope very precisely. It's delivering it's sharpest views ever :-)

[greglloyd]

Sorry! This line "There wasn't glow - but less than other nights this week" was mean't to be "There was glow - but less than other nights this week."

[matsey]

Only just seen your update. Really glad the scope is ok, sure you'll now get many years enjoyment out of it

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[Northern Soul man]

Hi Greg, just dropped across this thread mate - As with anything new we all tend to worry about the optics being highly reflective and 110% "clear and very clean".

We all have to realise that the SCT scopes are prone to dewing up - its not the fault of how we "use" the scopes but the nature of the closed tube design - as with all SCT's, there's a closed compartment - the mirror at 1 end and the inside of the corrector plate at the other end - when temperatures differ from the inside to the outside of the OTA - your going to get dew.

DON'T PANIC - my scope is only a few months old - and what your explaining is exactly what happens to all owners of SCT'S - just that the bigger the scope - the larger surface area of the mirrors/corrector - the more prone to dew you are - just as you have explained - my mirror looks exactly the same as yours, and if you ask other owners, they will tell you exactly the same.

We all use our scopes in the same way - changes in temperature are inevitable when moving the OTA from its resting place to the outdoors and no matter how carefully you handle the scope - the change in temperature causes the dew.

So long as the dew marks are all the same, both on the mirror and the inside of the corrector and there are no signs of mildew or fungus - THEN LEAVE WELL ALONE. You can control the dew to a certain extent with heater tapes and dew heaters - I have been observing for years with different SCT's and have found that the smaller the aperture - the less dewing you will experience - my 11" CPC is an absolute dew magnet - I had an 8" Meade before - still suffering with dew - but not as much as my current SCT.

I know its hard, but forget about it and don't let it worry you too much - its not you - its the scope!!! and just put it to the back of your mind and just get out there, set up and observe - even with the dew problem - I was still tracking 3 Earth sized white ovals embedded in the North Equatorial Belt of Jupiter around 7 ish on Monday night (4/3/13) - and here's me worried about not seeing any detail on Jupiter except the Great red Spot!!!.

Really Greg - not to worry - ask any SCT owner and they will tell you exactly the same if they store the scope inside and move it outside to observe. Regards Paul.

[greglloyd]

Thanks Paul. Great write up and much appreciated!