Louis D

2" eyepieces will allow you to view wider true fields of view than are possible in a 1.25" eyepiece.  They don't really enable high power viewing.

Try observing open star clusters.  They are very rewarding in their twinkling diamond dust on black velvet appearance under dark skies.

6 hours ago, russ said:

Certainly looks impressive. The only other eyepiece offering those specs is the old Speers-Waler zoom with its constant 80deg afov.

Which is more correctly referred to as a varifocal eyepiece to borrow from camera lens terminology.  I've had the S-W 5-8mm for about 20 years.  It requires massive refocusing while "zooming", making it less enjoyable to use than a nearly parfocal zoom eyepiece.

1 hour ago, Ags said:

For less money, just buy an ST80 as a daytime spotter. It works well, unless an object is silhouetted against the sky, when CA wrecks the view.

Never cared for my ST80 due to spherical aberration on top of the CA.  Views were never very sharp or contrasty.  My 72ED fixed both issues.

1 hour ago, wimvb said:

So does distance.

I plan on my vacation/retirement home to be on a large acreage for just this reason.

2 hours ago, Barry-W-Fenner said:

Dont do that to me Louis..

I have recently been pondering the 12.5mm to replace the 14mm, However I dont know if it is really worth doing.

Regards

Too close.  I wouldn't bother.  I use my 12mm ES-92 at that focal length.  The presentation is completely different from the Morpheus.

If it has the same rear thread as the 127 Mak, and you're willing to plonk down "silly" money, you can get the Mak to SCT thread adapter, a 2" SCT visual back, a 2" diagonal, and a widest field 2" eyepiece to vastly increase the true field of view with mild vignetting as seen below:

The difference is breathtaking at night when viewing rich star fields.

42 minutes ago, Barry-W-Fenner said:

Wow, This thread has taken on a life of its own since my last post.  I will have to have a read through!

I have just been looking at the 12.5 on FLOS web page, it is currently out of stock along with every other FL. All that is in stock is 1no 6.5mm. The Morpheus range really do seem to be getting about!

Regards

Baz

 

Agena Astro in the US appears to have 8 of them in stock.

4 hours ago, Deadlake said:

How suitable would the EP be for bino use? I ask as I can imagine for portable use it would cover a lot of bases. Since bino's can be tricky to get working would the below restrict the choice of binoviewer model used?
Largest outer diameter : 53 mm , and thus suitable for binocular use for people with at least 53 mm interpupillary distance ( IPD).

It shouldn't.  It's more of an issue with the depth and shape of your eye socket along with your IPD.  The top of the eyepiece appears tapered somewhat, so that should help.

4 hours ago, russ said:

Then shout out the window later that I was keeping them up.

Makes me glad we rarely open our windows here due to our oppressive humidity.  Like good fences, closed windows make for good neighbors.

3 hours ago, Sargares said:

I found an omegon branded gso coma corrector in Europe so went with that plus the recommended spacer. Cheers. 

One last bit of experience with the GSO.  Immediately replace the two thumbscrews with (IIRC) M4 socket head cap screws.  While tightening one of the two in my CC, the head literally sheared off flush with the body thanks to their screws being made from molded pot metal instead of machined steel.  I have yet to be able to back out the screw section trapped in the eyepiece holder section, so I'm working with a single thumbscrew, which has been sufficient.

Matches up pretty well with what I saw in my 8" Dob Saturday morning.  I could not detect the lower band or the dark polar cap, though.

Very nice image overall.  Good work!

Good Lord, I have to put up with an AC compressor 15 feet from my master bedroom wall that is so loud when running, you have to shout over it when outdoors.  Imagine how loud that is through a minimally sound insulated wall.  I also have an 8 lane tollway 1/4 mile from my house that motorcycles race up and down at night with minimal muffling of their engines.  On top of that, there are the occasional emergency responder sirens, train horns, dogs barking, etc.  Unless you're living in a seriously rural area, that neighbor shouldn't have any expectations of absolute silence at night.  The clack of a DSLR mirror is pretty minor compared to all these other nighttime noises.  You can put a camera blimp around them to muffle the sound, but it would increase the image noise because the camera couldn't cool itself very well inside it.  I seriously doubt that mirror clack violates any sound ordinance, though.

Resolution is dependent on primary diameter regardless of central obstruction.  That's why very long baseline interferometry works.

You can read up on the effects of central obstructions here.

4 hours ago, Ags said:

I jsut realised I typed Delta Cygni when I meant Delta Cephei. Three times.

At least you're consistent. 😉

4 hours ago, Sargares said:

Skywatcher does a coma corrector for their f5 reflectors I presume wouldn’t need a spacer. Would that work? 

It probably would work, but I've read nothing about it's use visually.  The problem becomes getting the spacing correct for the majority of your eyepiece collection as with the GSO.  I also don't know if it has any field flattening effects as does the GSO and Paracorr, or what its in-focus requirement is.  I also don't know how much spherical aberration it introduces at higher powers.  I remove my GSO CC at high powers to get sharper images because of SA not visible at lower powers.  Users of the Paracorr T2 claim it does not have SA and can be left in the focuser at all powers.

4 hours ago, Don Pensack said:

I don't know where he got 14mm as the effective eye relief of the 22mm Nagler type 4.

I need at least 17.5mm of effective eye relief to see the field stop of an eyepiece with glasses on with that apparent field, and I have no problem whatsoever with that eyepiece with the eyecup in the down position and the eyeguard

in its maximum inward position.  My glasses touch the rubber, but they don't press hard against the rubber, and the edge of the field is easily seen in peripheral vision.  I'd put the effective eye relief at or about 17.5mm.

 

Ditto the 30mm APM UFF, which is even easier to use than the 22mm Nagler.  I barely have to touch lens to rubber to use that one.

My personal experiences with most of the eyepieces on that list differs by only about a mm from his figures, but a few are way off, differing by 4mm or more from his figure.

He has the 17mm Astrotech AF70 at 17mm, for instance.  On my sample, the rubber eyecup could not be flipped down, and when it was at its minimum height it put the effective eye relief around 10mm--it was completely unusable with glasses, and only the central 50-60% of the field was visible.

So how was the Effective eye relief figure derived?  Glasses use?  Or subtracting the depth from the top of the eyecup from the mfr's quoted eye relief figure?

 

One thing occurs to me: You may not need as much eye relief to see a narrower field of view.  A 10mm Design eye relief on a 16mm 82° eyepiece, for instance, was so tight that seeing the field stop was very difficult.

A 10mm Design eye relief on a 50° eyepiece, however, seemed comfortable and easy.  So perhaps glasses-friendly eye relief will vary according to the apparent field of the eyepiece.

If that is the case, then using ones glasses to gauge effective eye relief may not be an accurate way to measure the effective eye relief.  Alas, if that is the case, it also means that knowing both Design eye relief and Effective eye relief may

not tell you if the eyepiece is glasses-compatible.

 

 

I used the projection method of shining a bright flashlight into my AT72ED with an eyepiece in the diagonal and measuring the distance from the top of the folded down rubber eye guard to the point where the exit pupil was smallest in diameter when projected onto parallel card stock.  Sometimes with SAEP and CAEP, this covered an entire range of distances (as with the 30mm ES-82), so I use the middle of this range.

For eyepieces with stiff rubber eye cups that are easily removable like AF70s and Aspheric 62, I measure the distance with them removed since that is how I tend to use them with eyeglasses.  I haven't scratched an eyeglass on any of them yet.  If you don't push in hard, you won't scratch your eyeglasses.  I did scratch an eyeglass on the top retaining ring of the TV Panoptic 27mm despite leaving the flipped down rubber eye cup in place by pressing in hard, so leaving the eye cup in place is no guarantee of scratch-proofness if you wear front surface convex lensed eyeglasses.

Yes, some of the numbers don't match up with "feels like" eye relief, and I can't explain it.  I have remeasured multiple of these eyepieces, sometimes just shining a distant flashlight straight into the bottom of them with the same result.  Obviously, there's more to eye relief distance than the point at which the exit pupil is smallest in diameter.  Not being a trained optical designer (I'm a computer chip designer by education and trade), I can't offer any further insights into it.  I agree, the 22mm NT4 has more usable eye relief than the hard numbers would show.  Go ahead and repeat my testing with your setup on such eyepieces and see what numbers you get.  I guarantee a few will surprise you.  Feels like and measured ER sometimes disagree.

I agree that narrow AFOV eyepieces are sometimes fairly easy to use with eyeglasses.  I have little trouble with my short ER Kellners and such with just a bit of head bobbing from side to side.

An alternate method to measure effective eye relief depends on measuring the distance to a phone camera lens once the camera is at the exact position the field stop pops into view while viewing an actual, distant test target.  This seems more accurate because the incoming light actually forms an image.  The distances will need an offset added to them to account for the location of the camera's entrance pupil location with its lens, but it will be a constant.  It can be derived by comparing the two measured ER distances and arriving at mean value that most eyepieces agree on.  This measurement might provide more insight into "feels like" ER distance because the camera is acting like an eye and may need a different distance than the point at which the exit pupil is narrowest in diameter.  This is how I arrived at the 10mm value for the 26mm Meade MWA due to its massive SAEP.  It refers to the ER to see the field stop.  I may work on adding a cardboard wrap around the eyepiece and push it down with the phone body and then measure the distance to the top of the cardboard from the top of the eyepiece once the camera is removed.  All I need is more free time to repeat this dozens of times.  I'd start with the ones that have an obvious disconnect between feels like and measured ER, though.

The ES-62's are basically 5 element super Plossls (the older Meade 5000 Plossl line reintroduced).  As such, they are fine in the inner 50% of the field, and gradually fall off with astigmatism to the edge.  The polish and coatings are quite good.

You'll want a coma corrector for that Dob.  The GSO (Revelation, TPO, etc) CC is quite good once you add a 25mm M48 spacer ring between the eyepiece holder and the optical section.  Of course the Paracorr T2 is better, but vastly more expensive.

If you don't need to wear eyeglasses, you can get away with using eyepieces with 12mm of usable eye relief or more.  Below that, it starts to get a bit uncomfortable for extended viewing sessions.  Ask on here about usable eye relief before buying.  ES in particular likes to recess their eye lenses and quote design eye relief.  This disappoints many buyers because the usable eye relief is generally much less.

The BST Starguiders are a good step up eyepiece range.  They have 12mm of usable eye relief from 18mm on down, no noticeable kidney beaning, and are quite sharp for the money spent.

The Baader Morpheus would be a good choice to step up to premium level performance at a reasonable price.  The 9mm in particular compares very favorably to the 10mm Delos.

I would get the 30mm APM UFF for a near widest field eyepiece.  It is very well corrected and should work well in your Dob.

You could also look into Abbe Orthos for high power, planetary eyepieces since you don't need to wear eyeglasses.  However, the narrow field of view can be a pain when manually tracking at high powers because you don't get much dwell time with each nudge.

It's also dependent on your nose bridge to eye socket depth and eyeglass style.  Technically, you could get away with wearing a monocle wedged into your eye socket to use low eye relief eyepieces.

To answer your question, I need 18mm of measured eye relief to avoid touching the top of the eyepiece, 17mm when touching, 16mm when pushing in slightly, 15mm when really pushing in, and 14mm when cramming my eye in to the point of hurting my eye socket with my eyeglass frame.

I say measured eye relief above because manufacturers claimed eye relief is rarely the usable eye relief.

Here are my measured usable eye relief figures for my eyepiece collection:

15 hours ago, Stardaze said:

Got royally caught with this, shipping a filter  from the US. Customs duty and processing fee was £20, which when added to VAT and a poor PayPal exchange rate, meant I lost out. Annoying!

If you sell it on to someone in the US, can you reclaim that VAT tax at that time from the guv'mint?

FLO's 10mm Astro Essentials Super Plossl Eyepiece is only £20 and in stock.  It should work fine as a direct replacement.

If budget isn't an issue, I highly recommend the 10mm TV Delos at £336 from FLO.  Mine is essentially flawless even in fast scopes.

I would guess you'd have to try them back to back to see which works better under your skies.  I could see the narrower band pass photographic filter pulling ahead in heavily light polluted skies where a 10% loss in transmission of one line and complete loss of the other line is more than offset by increased contrast against background skyglow.

12 hours ago, Chefgage said:

Would this one work? I you search on this site for Geoptik bags there are.some hard case and padded cases of different sizes up to12".

https://www.rothervalleyoptics.co.uk/geoptik-padded-case-for-925-10-sctrc.html

Seems to be little more than a large soft sided cooler.

2 hours ago, Shimrod said:

I would think the fact it is mount and OTA would provide a challenge getting an appropriate sized bag. I have a Meade LX90 8" and I just wrap mine in an old duvet and fasten it in the back of the car with the seat belts.

Possibly you could look for a large storage box and use some foam to pad the inside-  the challenge may be finding one deep enough - this might be a starting point   large storage case

That's a good idea if it will be packed in with hard, shifting objects.  Again, wrap it in bubble wrap or a camping ground pad and place it in the case.  You don't want it bouncing around inside the hard sided case.

If you've got the spare cash lying around, and you've done due diligence with the seller, why not?  You just want to avoid any as-is sales on such high dollar items in case they're trying to pass off a damaged item with undisclosed defects.  ebay is pretty good about protecting buyers in non-as-is sales, so no worries there.

Generally, if you wrap the OTA in several inches of bubble wrap and put it in a duffel bag, you should be okay for personal transport.  Just make sure the corrector end is sturdily capped.

The mount should be fine when taken down to pieces and transported similarly.  In fact, the tripod legs will be fine with a camping ground pad wrapped around them to prevent dings and scratches.

Transport by airline or common carrier is a whole 'nother matter.

1 hour ago, Stu said:

Lucky you! Replace the $ with a £ and you are thereabouts our new price.

There is a hidden 20% VAT now that I think about it in UK pricing absent from US pricing.  Since sale tax varies state by state, county by county, and city by city, it would be impossible to quote it in prices online here.  It comes down to £552.63 without VAT, which is still $772.  I suppose the rest of the difference (~$100) is import tariffs and importer markup.