ES 68deg 16mm Eyepieces

[alan potts]

Thank you very much for posting.. I have just ordered the 28 and 20.

Good choice I am sure you will like them, the 28mm was my favourite.

Alan.

[rory]

am i right in saying the focal lengths available in the 68* 's match the meade 5000 swa ? i.e down to 16mm.

if .. they are meades without the branding it would be a good deal indeed.

[rory]

am i right in saying the focal lengths available in the 68* 's match the meade 5000 swa ? i.e down to 16mm.

if .. they are meades without the branding it would be a good deal indeed.

( so good i wrote it twice .. )

[foundaplanet]

am i right in saying the focal lengths available in the 68* 's match the meade 5000 swa ? i.e down to 16mm.

if .. they are meades without the branding it would be a good deal indeed.

( so good i wrote it twice .. )

I understand that this the case yes. I have read that the Meades are very good eyepieces so these are one mighty good deal.

[nightfisher]

think i might order one or two of these, seems like they wont be about for long

[foundaplanet]

think i might order one or two of these, seems like they wont be about for long

Yes I think you are right there. If Alan P reckons they are a good eyepiece I doubt we are going far wrong with a couple.

[andrew63]

This is what they look like when they leave the factory with a meade sticker attached !

andrew

[nightfisher]

16mm paid for, im very happy with 18 and 25mm BST so will try just this one, having already spent a fair bit this month on OTA and bits

[russ.will]

I must confess, I'm tempted to pick up another one, just because the price is so good - The 40mm for the F9.4 frac would give 2.3deg TFOV over the 2.0deg of the 30mm ES82, but still only give a 4.23mm exit pupil.

Come to think of it even in the F4.9 Dob, it will give a 8mm exit pupil, but a useful increase to 1.8deg TFOV over 1.64deg of the 30mm ES82. Would the central obstruction start to be an issue though?

Russell

[Dave 2112]

I must confess, I'm tempted to pick up another one, just because the price is so good - The 40mm for the F9.4 frac would give 2.3deg TFOV over the 2.0deg of the 30mm ES82, but still only give a 4.23mm exit pupil.

Come to think of it even in the F4.9 Dob, it will give a 8mm exit pupil, but a useful increase to 1.8deg TFOV over 1.64deg of the 30mm ES82. Would the central obstruction start to be an issue though?

Russell

No idea, I wondered the same but the maths got me and my head hurt. So I just stopped thinking about it and ordered the 24mm.

[russ.will]

After a day of wheeling and dealing in the world of construction, I can't be bothered either. So, I use this. They have thoughtfully designed it to use both Papist and Colonial measurement systems.

I take my lead from Einsein, who said 'never remember what you can write down'. He didn't have the interweb, so I'm sure he would approve.

Russell

[russ.will]

Hang on. The 40mm is showing as 'presumably be in stock on Friday 30 August, 2013'. Presuming what? That Meade can't pay another bill? I may keep my cash trousered, pending firmer information.

BTW, where are people who protested so vehemetly about ES sale pricing in the US compared the EU UK? Surely, in the interest of fairness, they must be outraged that these products aren't being offered to our colonial subjects! I think we should be told...

Russell

[Dave 2112]

After a day of wheeling and dealing in the world of construction, I can't be bothered either. So, I use this. They have thoughtfully designed it to use both Papist and Colonial measurement systems.

I take my lead from Einsein, who said 'never remember what you can write down'. He didn't have the interweb, so I'm sure he would approve.

Russell

I'm going to use that too. And I heard a similar one, when asked why he could never remember anything he said "I don't have to, that's what books are for"...or something like that, can't quite remember.

[foundaplanet]

Cheers russ I like that link, very useful..

I have also just found out my scope is equivalent to 1575 of my eyes..

[russ.will]

Mmmm. Compound eyes.

Russell

[RikM]

Would the central obstruction start to be an issue though?

I see a pronounced central shadow with a 40mm in my 250px at f/4.7, not sure at f/5.

[John]

Apart from the possibility of seeing the secondary shadow, I can't see the point of an 8mm exit pupil, unless you are sure your dilated pupil is that large. Mine certainly is not

No point in stopping your scope down with your iris really.

[russ.will]

Okay, but sidestepping the potential visibility of the central obstruction for the moment - What do you actually loose by going for an exit pupil larger than the possible dilated puil diametre? Surely, it's just a loss of brightness? But isn't that what people get when using a 24mm 100deg, instead of a 30mm 82 deg? In that case, the darker image is seen as a bonus, or am I missing something?

I'm still tempted from the point of view of the refractor, none-the-less.

Russell

[John]

In effect you reduce the effective aperture of your scope because the bundle of light (the exit pupil) is too large to make it into your eye. I think the link to another webpage you provided in an earlier post explains the whys and wherefores better than I can.

No problem with the refractor though.

[cs1cjc]

You are assured of the widest possible true field of view and that is a bonus for most scopes I think. This is what Al Nagler says: http://www.televue.com/engine/TV3b_page.asp?id=102

[nightfisher]

will the 16mm maxvision/meade take to a barlow ok

[great_bear]

will the 16mm maxvision/meade take to a barlow ok

My Meade equivilent worked supremely well with the exception of eye-glint on Jupiter.

(oddly enough, the eyeglint not significant without the barlow - same story on 24mm - very odd... Very repeatable and I'm definitely not imagining it)

[great_bear]

In effect you reduce the effective aperture of your scope because the bundle of light (the exit pupil) is too large to make it into your eye.

This makes no difference: It is physically impossible to produce that same level of magnification other than by reducing the aperture by other means such as a smaller scope. The two options are entirely equivilent, so nothing is lost.

[great_bear]

Isn't that what people get when using a 24mm 100deg, instead of a 30mm 82 deg? In that case, the darker image is seen as a bonus, or am I missing something?

What you're missing is than in the case of moving from 30/82 to 24/100, the only thing getting darker is the sky, NOT the stars. With the other example (loss of aperture by either human iris or a smaller objective) then everything gets darker - both sky AND stars.

[russ.will]

Try a Meade Tele Extender/ ES Focal Extender. They're basically the same, but in a different class to the (limited range of) barlows that I've tried. My ES82 14mm plus 2x FE delivered the most artifact free, easy to view views of Jupiter I've ever had. My BGOs were a touch sharper and delivered a bit more contrast , but the ease of viewing through the ES FE makes it so much easier to spend time at the EP, I've flogged the BGOs. Your mileage may vary, as they say.

Russell