Explore Scientific 6.7mm 82*

[brian nordstrom]

:DHi all just a word to say my new ( to me ) Explore Scientific 6.7mm 82* eyepiece arrived the other day and I can say that its a beauty , very solid and well made .

It feels very like my TelVue eyepieces in the hand and that's very high praise indeed .

Looking down into the eye lens shows perfect greenish FMC's without any blemishes or sleeks , nice .
The TV's are a more purplish/green ( very un-scientific I know ) and looking up from underneath shows the same quality coatings as the eye lens. Oh yes its blackened and threaded for filters down there as well :thumbsup:.

On the eyepiece body its-self I can see straight away that ES put pride in their manufactureing process , seeing that the engraving , machining , rubber grip and general fit and finish is top notch , just like TV's , I am very impressed with it so far but as they say , the proof is in the viewing but the weather at this time is really BAD!! so that will have to wait .

On the viewing/testing I will be putting this ES 6.7mm up against some stiff very opposition in the way of my 5 and 8 mm TV Radians , 9mm TV Nagler and a few Plossl's of around this focal length , I am looking forward to doing this :D .
I will be using my 2 refractors at f5.5 and f8 and my f10 Celestron SCT on the moon , planets and double stars . I know the TV's perform very well in these scopes so this ES will have to be up to it , I really hope it is as I like this eyepiece so far and if its capable it will live in my eye piece case filling a nice hole in my useable magnifications .

I will post more as the testing is being done , so stay tuned ;) .

Brian.

[glend]

Brian, As I have the ES 6.7mm, as you know, and a couple of TVs in that range (5mm being the closest) I can assure you that the ES 6.7mm is good value for money (even at the new price) when directly compared in observation sessions. The advantages that TVs have is that they are pretty much parafocal in that swapping them doesn't require much (if any) focus adjustment, whereas the ES will (in direct comparison). Not sure if the Argon filling is just a sales gimick or not, but never had a problem with internal fogging on any EP of a recent design. Enjoy and looking forward to your comparison report.

[AG Hybrid]

I have advocated for this eyepiece for a long time. My only gripe is that if your goal is to see the full field of view all the time - the eye relief is a bit tight. Manageable and compared to a plossl of similar focal length comfortable. But, tight all the same.

[Astro_Bot]

Never let it be said that I shy away from a "me, too" opportunity. ;)

The 6.7mm ES82d is one of my favourite eyepieces.

[Don Pensack]

If comparing it to another eyepiece (such as a TeleVue), don't look in the center; look at or near the edge. Focus the stars there the best you can. Go back and forth through focus. Look for elongation in a radial manner on one side and a circumferential manner on the other side of focus. If you see this elongation, that is astigmatism. You're unlikely to see any above f/6.
Look also for field curvature: focus the center as sharply as possible. Then, without touching the focuser, look at the edge. Are the stars still perfectly in focus, or can you move the focuser slightly and sharpen the edge of field stars. If you have to move the focuser to tighten up the edge stars, this is field curvature. Even if it's a lot, you might simply focus on a star halfway from center to edge and let your eye's natural accommodation focus all the stars in the field.

Place a bright star just outside the field. Can you see any glow inside the field of view from the star outside the field? If you can, is it minor, or does it cause spikes or glare to appear inside the field even though the bright star is outside the field. This can be indicative of an eyepiece with a lot of scattered light in the field.
then, put the bright star in the center of the field and look at or near the edge. Is the background sky lighter out in the outer field than it is only 1/3 of the way out from center? That's also indicative of scattered light.

Then, look at a bright star-filled field of view. Is there any visible brightening of the edge of the field in the background? This is known as EOFB, Edge of field brightening, and it is better controlled in some eyepieces than others. I've seen some where the entire outer 50% of the field had a soft gray background while the center was a black background.

You can create a little graph with the comparisons between your eyepieces with None, a tiny bit (minimal), a fair amount (moderate), a lot, and Horrible (severe) as your grade points.

Last, just remember there is no perfect eyepiece, but some are more perfect than others.

[Tropo-Bob]

Most of the range of ES EPs seem to have the same specifications as now defunct ranges of Meade EPs. Are they really the same optical configerations redesigned in new exteriors, or are there more significant differences (besides appearing to cost less)? Any thoughts on this?
I have the Meade 4.7 & 6.7 EPs, and I think 5 & 7mm Nagles give a slightly better image, but I like the extra eye-relief of the Meades (14mm). However, my Radians EPs are better both in image quality & eye-relief, but then of course, they have a much smaller field of view.

[Don Pensack]

The ES have been sealed and purged with dry gas. The Meade's were not.
There are also additional focal lengths. And the 18mm is a 2" now, where it was a 1.25" before.
But, it does seem that they may be identical internally except for that.
JOC made the Meades and makes the ES. Your guess as to whether they changed any internal configurations that changed the eyepieces (i.e. coatings, glass types, etc.).
The lower prices are probably because a middleman has been cut out of the supply chain.

[brian nordstrom]

Yes Don , their prices are very good alright .
I still have not looked thru it yet , just finished a 7 day shut and I am a little tired and the weather has been horrible , I am starting to get itchy feet waiting ;) , and waiting .

Brian.

[MattT]

I'm a fan of ES…just look at my sig. Had a brief look through some of mine as it's been so long I'd forgotten what's they do! The 6.7 is easily the best of my 82º ES 82's . ER is longer than 11 8.8 and 4.7 and is 'easier' to look through than the others. Also have the 18mm 82º which is similar to the 6.7.
Like to hear for thoughts Brian. I'm real tempted to buy an 11 or 9mm Nagler and do a comparo, maybe the 27mm Panoptic too, to go up against the ES 28 68º.
Matt

[brian nordstrom]

:) Well over the last nights I have had the chance to use the ES 6.7mm in my SKY90 and LP 60mm triplet and in these 2 short focal length scopes ... F5.5 and f7 it performs extremely well , brilliantly actually :thumbsup:, I like this eyepiece and it fills a gap in my Radian collection so it will be staying .
Great sharpness to the edge , the moon in the 60mm triplet is spectacular ! , filling the fov perfectly and once its in focus ( you know when its in focus in this little APO ) its in focus :D , no a great eyepiece that I am proud to own .
You were right Matt , special and I wont hesitate recommending these to anyone .
Brian.

[MortonH]

In viewing the moon recently, including the occultation last week, I discovered that my 6.7mm and 4.7mm had horrible glare when part of the moon was outside the field of view, i.e. any time you're looking at the terminator. This made observing the occultation pretty much impossible and I switched to my Pentax 8.5mm instead.

I've since read that this is a known issue with some of the ES eyepieces. I believe there is a fix involving dark felt or something around the inside of the barrel.

They are still very good on planetary, but for the moon they're a bit of a washout.

[rrussell1962]

I noticed the same thing on my ES but also noticed that the eye lens had fogged up on what was a very dewy night here in Bris. I assumed that was the cause and changed eyepieces. Thanks MortonH I will check again. Slightly off topic, I have a new Vixen 13mm LVW and it is absolutely wonderful. Sharp as a tack across the whole FOV and with great eye relief. Seems to be the perfect magnification and exit pupil in the Obsession.

[MortonH]

I've read a few posts on Cloudy Nights saying that ES sent felt rings out to owners who complained about the glare issue. So I've emailed them today asking for some to be sent out. I'll post an update when they respond.

Morton

[209herschel]

Hi there, I've seen similar prices for the ES 6.7 and Pentax XF 8.5. Would you say the Pentax is a better eyepiece? Do you feel the extra fov is necessary? And would there be a major difference between 6.7 and 8.5 if you were looking at Saturn for example? Thanks very much.

[MortonH]

For planetary I'd go for the ES 6.7mm. I have the Pentax XF 8.5mm as well and it's great for deep sky and has excellent throughput, but the ES has a flatter field and much wider view. In your non-tracking Dob I reckon the ES is more useful.

[209herschel]

Thanks very much for that. I've seen a 6mm televue Delos second hand for $270. Would that be significantly better than the ES? With postage, it'd be around double the price.

[MortonH]

The Delos is better than the ES. Whether it's worth the extra money only you can decide. I think you'd be happy with the ES and some spare cash!

[209herschel]

Thanks very much. ES it is. I'm moving up from GSO plossls so small steps! Cheers.

[209herschel]

Sorry for one more question. I've found the ES 8.8mm for $135 posted while the cheapest I can find for the 6.7mm is $190 posted. I'm keen on getting some great views of the moon, Saturn, Jupiter but also using it on clusters and some other where it'll work. I've got a 10" undriven dob, using it in the backyard almost all of time time with stray light, poor seeing sometimes, etc. Is the 8.8 the smarter buy? I'm worried I buy the 6.7 and it's fuzzy a lot of the time. Can the 8.8 give good views of the planets and moon? Thanks again for all of your help.

[MortonH]

The 8.8mm is very good too. Eye relief is slightly shorter but still ok.

[MortonH]

Took a few days but Explore Scientific have replied and are sending me out the "fix". It's some kind of adhesive ring that attaches to the bottom of the eyepiece.

The person that first replied to my email hadn't actually heard of the issue or the fix, so I had to be a little persistent!

Since the rings are adhesive they are probably not permanent. I have asked them to send me some spares as well.

There's no charge for this so I'd encourage other owners to test their eyepieces on the Moon and contact ES support if they have the same glare issue.

[David Niven]

I have seen the 8.8 going for $135 on ebay.
But if you look at the photo, it is the old N2 not the current Argon purged ones.

[209herschel]

Absolutely right. I didn't even know there was a difference! I'll be buying the 6.7 from vti (or anywhere I can find it cheaper) and this will be my lunar/planetary eyepiece.

I also have the 30mm GSO superview. For now, until I can afford a higher quality eyepiece for DSOs, does this seem sound? I also have 9mm, 15mm and 25mm plossls.

I haven't yet seen the Lagoon Nebula, galaxies, and many other things I'm keen to still find but I'm new to this and I enjoy looking at lunar craters, Saturn, etc. Thanks.

[MortonH]

As far as I know most of the current 82D eyepieces are still purged with Nitrogen. They are moving to Argon though.

As long as the eyepiece is unused I wouldn't care what gas is inside!

[MortonH]

That's a good spread of eyepieces you have. The 30mm Superview might give too little magnification unless you're under a dark sky. In light polluted areas the background sky will likely be too bright, making it harder to pick out faint objects. It will be useful to find objects in its wider FOV, but once you're centred on the object you'll probably want a higher power to increase contrast. The 15mm and 9mm Plossls will be very good for many, many deep sky objects.

[209herschel]

Thanks again. I also have a TMB 9mm. So I'll buy the 6.7mm ES for the added magnification and FOV, and use the other eyepieces. Then down the road I'll aim to get something like a TV Panoptic for DSOs.

[MortonH]

Sounds like a good plan.

By the way, the reason so many eyepieces are expensive is the wide field of view. But in many cases a good Plossl lets more light through because it has fewer glass elements. So for deep sky stuff at lower magnifications a Plossl may be all you need :).

[209herschel]

Thanks very much. I'll keep that in mind.

I just wanted to ask what the Lagoon Nebula looks like in a scope? I've got a 10" GSO. Using a 30mm eyepiece, I saw the Lagoon Nebula last night but not the red haze that it shows on Stellarium but a faint grey. I also saw the Triffid Nebula close by, smaller. 90% of the sky was thick cloud last night and the neighbours lights were very bright but I thought I'd see that reddish smear. Thanks again.

[209herschel]

Thanks everyone for your advice. I'm down to two choices: ES 6.7 and Pentax xf 8.5, both of which are around $200 delivered from VTI. If you have both or have used them, I'd appreciate your thoughts on what you'd recommend for use with my 10" GSO, used 95% of the time in my backyard, Inner City Sydney. My thoughts are the ES has an 82 degree field but I'm concerned the 6.7 might be too much on some nights so it won't get as much use. I already have a 9mm plossl so if the magnification of the 6.7 over the 8.5 is significant without too much loss of clarity, I'd probably go with the ES. Thanks again.

[MortonH]

I have both the ES 6.7mm and the XF 8.5mm.

The ES 6.7mm will give you around 186x magnification, which sounds about perfect for planetary unless you have poor seeing. It also has a flatter field than the XF 8.5mm (as well as being wider) so will allow quite a bit more time between nudges.

If you're worried the magnification is too high then I'd seriously consider the ES 8.8mm you saw for around $135.

[Camelopardalis]

It's unlikely that you'll see colour in DSOs, but not impossible.

Our eyes see things by the use of rods and cones. In simplistic terms, the rods take care of luminance and the cones take care of colour. In low light, the cones are inactive and only the rods are active, which is why we see essentially only in monochrome in the dark.

Some objects - brighter planets for example - can activate the cones again, which is why many of us see coloured feature on them.

Read up on photopic vs scotopic vision for more details.

[Steffen]

Just regarding the flatness of field, I can't detect any lack of it with the XF 8.5 in my (totally flat field) Mak. It obviously has a much narrower apparent field of view than the ES 6.7, but from memory the field that it does show is sharp all the way across. I shall double check to be sure as soon as the clouds part.

Cheers
Steffen.

[209herschel]

Thanks very much. My 9mm GSO plossl is the highest mag eyepiece I've got, giving 133x on my 10" dob. My concern with the Pentax is that it would only give a fraction more. I could barlow it but then I'm down to 4.25mm and I think I'd lose all clarity in my backyard almost all of the time. The ES 6.7 seemed a good amount of magnification but still allowing a lot of use. Does that sound right?

[MortonH]

Sounds right to me! :)