Louis D

Also good for flocking the rear baffle tube of Maks and SCTs.

16 hours ago, markse68 said:

From what I understand they work with rollers and can have issues where the rollers twist out of parallel and can jam when there is an undercut or worse the tapered barrels on some eps. But I've never had a close look at one though might do soon although they are rather pricey!

Mark

I've had this problem with brass compression rings becoming distorted on undercuts and then coming up and out of their groove and jamming the eyepiece in the holder when trying to pull it up and out.  It took a lot of coaxing to get the ring to drop back down in the groove so the eyepiece would release.

Okay, then the ability to overtighten is a design flaw that needs fixed in a future release.  They could design it to use a torque sensing release that just clicks and rotates once it reaches the proper tension.  The gas caps on my cars have worked this way for years without any problems.

6 hours ago, Zermelo said:

(c) In the UK at least, the legislation now makes shining a laser at a plane (or other vehicles) a strict liability offence, i.e. they don't need to prove that you did it deliberately to ensure a conviction.

I'm guessing much lower violent crime rates in the UK allow the police to investigate laser violations there.  We had a case here where it took police 2.5 hours to respond to a DUI/DWI vehicular accident involving injuries because they prioritize homicide investigations much more highly.

7 hours ago, alacant said:

Also, based purely on words overheard at the eyepìece, the susceptibility to being sensitive to purple fringing seems to be age dependent. Older observers may well benefit financially, filter-wise!

I've heard of that as well.  Older eyes tend to filter violet light.

From a quick internet search on the topic:

Apparently, age 70 is about the starting point.  The eye's lens starts to yellow, filtering violet and some blue light.  It can also mess up distinguishing green from yellow-green.  Cataract surgery that replaces the natural lens can fix this issue as a side benefit.

Be conscious of the weight of 2" 82 degree eyepieces.  The 30mm ES-82 and 31mm Nagler T5 are both quite heavy in particular.

3 hours ago, alacant said:

The purest stars we've seen is with a Bessel V.

Agreed.  They're basically the same as the Green X1 filter just with higher transmission which doesn't really matter on bright stars, planets, the moon, and the sun:

Bessel V curve:

Or Johnson-Cousins V curve (the green one):

Hoya (Rokunar) Green X1:

I looked for an affordable V filter, but couldn't find one.  I'm happy with the X1 for now.

1 hour ago, John said:

It would be wonderful if the Svbony 3-8 zoom were to match the optical performance of the Nagler zoom plus deliver a larger range, a slightly wider AFoV and a bit more eye relief as well. At the price they are, they would simply fly off the shelves - I would certainly buy one 🙂

I've yet to see a detailed comparison between them though. Bill Paolini has one of the Svbony 3-8's so might oblige in due course. 

By one account on that other forum, they're pretty close with the NZ being better across the zoom range, especially at the short end.

Despite having the means to purchase a NZ, I could never justify the cost and limited use cases for my preferred styles of observing.  The price/performance ratio of the SZ is such that I had no issues picking one up for my travel kit.  I've been quite happy with it.

2 hours ago, Ags said:

Made obsolete by the Svbony SV215 3-8 Zoom?

Perhaps for BV usage.  Eddgie, the BV guru over on that other forum, has been gushing over his recently acquired pair for BV usage.

1 hour ago, powerlord said:

that's a good point - I've found on low voltage the asiair will stay up, but the network won't (ethernet or wifi connected).

You are fine with a battery if fully charged (13.5v), but if the voltage drops below 12v it starts to get dodgy. At about 11.5v it starts dropping out and doing weird stuff.

If going down a battery route ,something around 15-16v is better, as it will continue running it till more or less flat. e.g, 4s lipo.

Sounds like there needs to be a buck-boost constant output voltage regulator between the battery and the device.

This thread got me interested in revisiting fast achromats a bit more, so I recently picked up a used Astro Telescopes 6" f5.9 first generation KUO achromat for a good price.  It's basically the same optically as the current Starwave 152mm F5.9 V3 and TS-Optics RFT 6" f/5.9.  My first impression is how much heavier it is than a 6" f/5 GSO Newt (about 10 pounds heavier).  I mounted the two on either side of my DSV-2B mount.  Surprisingly, it didn't have any motion issues with the two once well balanced.

Going back and forth, I would have to recommend the Newt as the better all around scope for most folks.  It's lighter, cheaper, color free, and the eyepiece is in an easier to view from position (at least for me being a Dob guy).  That being said, it's pretty special viewing bright objects with no spider diffraction spikes in the achro frac.  However, you have to filter the view in the frac to get a sharp view which brings this post back to the subject of this thread.

I also picked up a Baader Semi APO filter for a good price recently.  All I can say is, it cuts maybe 50% of visible violet fringing while trying to maintain a neutral color balance by cutting yellow and orange spectrum using Neodymium glass.  It cuts violet by using violet reflective coatings instead of yellow glass.  As such, this filter is probably more appropriate for daytime use where such things matter more.  I'm just glad I didn't pay full price for it.  Pairing it with either the Hirsch Yellow #12A or Rokunar Yellow K2 eliminated all residual violet fringing at the cost of a bit more yellow cast.

Much more cost effective are my two recent purchases detailed in my previous post: the Rokunar Yellow K2/#8 and Rokunar Green X1/#11.  Both are high quality Japanese made photography filters in 48mm mounts, so they can be used as 2" astro filters.  On bright objects (above magnitude 2), the Yellow K2 cut all violet while introducing just a slight yellow cast and adding very little to no additional scatter.  Sirius looked more pleasing without spikes in the achro than it did with spikes in the Newt.  I did not attempt to see the Pup in either, though.  However, there was residual red fringing which made Sirius sort of orange depending on how I refocused with the filter.  Thus, in went the Rokunar Green X1 filter.  All violet and red fringing was gone with just a slight green cast added to the star.  It yielded a distinctly sharper view.  Basically as sharp as the Newt, but with less scatter because of a lack of central obstruction and spider vanes in the frac.  The 50% transmission of this filter was not an issue on such a bright object.  If anything, it made it easier to view.

Overall, I'm very pleased with these two vintage photography filters.  I'd love for GSO to bring them back in 1.25" size.  Right now, their Yellow #8 is more like a Wratten Yellow #3/#4 and their Yellow-Green #11 is more like a Hoya Green X0 which has no Wratten equivalent that I can find:

The Hoya Green X0 (GSO #11) passes way too much orange and red to be useful at blocking residual red fringing once violet fringing has been blocked.  That, and it's not quite aggressive enough at blocking violet fringing.  It's very similar to my Hirsch Light Green #11, which I've found to be ineffective at completely blocking either violet or red fringing on bright objects.

The Rokunar Green X1 was definitely sharper and caused less scatter than my home-brew R89 Moss Green film mounted in a 1.25" Meade #8 Yellow filter or 2" Skylight 1A filter.  I'm glad I was able to locate an optical glass equivalent to the R89 film.

The Rokunar Yellow K2 was just slightly more aggressive than my Hirsch Yellow #12A at cutting violet/blue wavelengths.  I would consider either acceptable for cutting violet fringing on bright objects.  Both are way better than either a modern GSO Yellow #8 (too weak) or GSO Yellow #12 (too strong).  The cheap Chinese made Yellow filters come closest, but with more scatter.

The biggest surprise of the night was that violet fringing was all but invisible at magnitude 2 and dimmer.  Thus, the Orion belt stars and Collinder 70 looked just as good in the frac as in the Newt.  The same goes for the Orion nebula and nearby open clusters.  It's hard to say if they looked better in the frac to justify the weight, cost, and color fringing issues on brighter objects.  I just enjoyed discovering that large, fast KUO achromats are almost indistinguishable at moderate powers from a Newtonian.  I'll keep the 6" f/5.9 achro for a while to see if it grows on me.

I discovered another plus for the laser sight last night.  I had both my 6" Newt and 6" frac on either side of my alt-az mount.  The two sides aren't quite perfectly aligned.  So, I put the laser on the Newt (and aligned it) and the RACI on the frac.  I would find a dim object scanning the sky with the Newt (shorter focal length makes it easier) and observe it for a bit.  Then, to center it in the frac for comparison purposes, I would light up the laser while looking through the RACI which was aligned with the frac.  I would note where it was pointing on the sky in the RACI FOV, quench the laser, and move the RACI crosshairs to where the laser had just been pointing.  BOOM!  The frac is centered on the same object in seconds.  It's much quicker, easier, and more accurate than jumping between two RDFs on two scopes to do the same.  Yes, I need to work on getting the two sides of the mount aligned better, but this was a great workaround.

Having owned some Tele Vue eyepieces, I can attest that they are not perfect and can be improved upon.  I retired my 27mm Panoptic in favor of my 30mm APM UFF, my 12mm NT4 for my 12.5mm APM Hi-FW and 12mm ES-92, and my 17mm NT4 for my 17mm ES-92.  I'm on the hunt for a 22mm NT4 replacement with greater eye relief and/or AFOV while being at least as sharp across the field with less SAEP.  The 23mm Pentax XW 85° might be that eyepiece.  I'm just not willing to drop $500 on one until I know for certain it is comfortable to use with eyeglasses (at least 17mm of usable eye relief in my case).  It seems to tick the other criteria (greater AFOV, sharp across the field, and less SAEP).

Read up on SkEye DSC star alignment.  The key is to mount the phone to the scope and then use one of two alignment options: 1) select an alignment object in Indirect mode and slew to it and confirm or 2) point to a well known object and then drag the screen to the object and confirm it when centered.  I generally use the second method.

9 minutes ago, Steve said:

Don, @John is a moderator for Cloudy Nights, so he is familiar with your posts there 🙂

I think John is looking for opinions from UK/SGL owners. 

Although I wonder how much effect observing locale or clientele has on the optical properties of a widely available eyepiece.  I could see where power supply impressions might vary greatly between US/UK given the power grid differences.

Just look and listen for aircraft when using lasers.  The ones getting arrested are lasing police helicopters or landing aircraft from the end of the runway.

I've switched over from Telrad/QuikFinder (I have both) to laser sight (check on ebay) as my neck and back have gotten stiffer and more painful to contort.  I can be on target with a laser sight in under 5 seconds if bright stars or planets are nearby.

From there, I generally rely on a wide field 2" eyepiece to center the object.  I have a RACI, but don't find myself using it much.

For times when the sky is washed out, I'll use SkEye on my mounted smartphone to get to scope within a few degrees of a target.

This image shows my RACI, GLF, and QF setup.

While this image shows my RACI, SkEye, QF setup.

The filter material is probably stressed in some manner.  It may also be too thick to be optically transparent.  Baader Solar Film is really thin and mounted unstressed.  Wrinkles or wobbles in the surface don't matter.  I've been using BSF in homemade cells since it first came out over 20 years ago to good effect.

3 hours ago, ONIKKINEN said:

Apply only a small amount of the fluid.

To the cleaning cloth.  This was seemingly left out.  Never put cleaning fluid directly on a lens, ever, at least while they're still in their lens cell.

Windex or other ammonia/detergent based glass cleaners work very well in my experience to get stuck-on grime off.  Just don't scrub.  Unseen micro-grit can scratch the lens coatings.  Instead, leave a damp cleaning cloth on the lens for a bit of time if needed to loosen grime, then lightly wipe again.

You can finish up with dedicated lens cleaning solutions.

If the lenses are still grubby, you could get a lens wrench/spanner and remove the retaining ring holding it in the lens cell.  Next, put a small dowel or similar up into the cell to support the lenses.  Finally, lift off the lens cell and clasp the lenses.  Set the lenses down carefully on a folded towel and note their orientation.  You could even mark the edges with a dark permanent marker showing alignment and which way is up along with the stacking order.  Now you can put a folded towel in a plastic tub in the kitchen sink and fill it with soapy dish detergent water.  Let the lenses soak for a bit and then repeat the cleaning steps, except using running water and your soapy finger tips to immediately flush away any unseen grit that works loose.  I've salvaged some pretty grimy lenses this way.

Again, finish with lens cleaning solution if you see any remaining streaks or water spots when viewing reflections from a bright light at an angle to the lens.

3 hours ago, malftobe said:

Have you had any difficulty with the airlines when flying with the Lithium batteries?  I used to have nightmares about having to check my carry on bag full of all camera gear or having to throw away my spare camera batteries when I used to travel!

The FAA (US) prohibits all spare (uninstalled) lithium batteries from traveling in checked baggage:

Spare (uninstalled) lithium metal batteries and lithium ion batteries, electronic cigarettes and vaping devices are prohibited in checked baggage. They must be carried with the passenger in carry-on baggage.

I'm planning on traveling toward Uvalde for the eclipse despite its recent infamy.  The farther south and west you get in Texas, the higher the probability of clear skies on any given day/night.  It's marked with the cyan dot.  You could go all the way to Eagle Pass (gold dot), but I'm not keen on being that close to the Mexican border.  Really, though, anywhere in the red outlined area should give you the highest probability of clear weather along the path of totality.  Once you get east of I-35 or north of I-20, the weather is generally cloudier and more humid due to the proximity to the Gulf or because of jet stream propelled storm systems.  Simply pull up a map of the US and turn on satellite view to see for yourself.  Where it's greener is where there is more rain.  Where there is more rain, there are more cloudy days/nights.

Another possibility is that SAEP is so strong that once you get close enough to see the entire FOV, you start fighting kidney bean blackouts.  I get this quite strongly with the 12mm and 17mm NT4s along with the 20mm Meade 5000 UWA and 26mm Meade MWA.  It almost feels like the eyepiece is fighting back and doesn't want to cooperate with your eye.

I have never looked through a 13mm NT6 given the short eye relief, so I have no idea if it has any SAEP like its predecessor the 13mm NT1 or kinfolk 12mm NT4, but that might account for difficulty seeing the entire field at once.

2 hours ago, Pixies said:

So - now having tried a Delos and an Ethos (too wide for me) - should I just bite the bullet and get a 13mm Nagler? Anyone here have experience with the 12mm Delos and 13mm Nagler (T6)? How do they compare in use?

Here are some other wide field options at 12mm/12.5mm:

• The discontinued 12mm Nagler T4 which I have and don't really care for.  It does have an 83° AFOV.
• The 12.5mm Morpheus as others have said.  It supposedly has a 78°AFOV, so not that far behind the 13mm NT6.  The longish eye relief might put you off, though.
• The 12.5mm Noblex which supposedly restarted production and is supposed to be superb across its 84° AFOV.
• The 12.5mm APM Hi-FW which I have and like quite a lot. Given the longish eye relief, you might not like it, though.  It has an 80° AFOV.
• The 12mm ES-92 which I also have.  It's huge and 2"-only, but a joy to use with its 92° AFOV.

The TFOV is roughly the same between those last two thanks to opposite types of edge distortion.

I've had trouble with heavy eyepiece/diagonal combos causing my AT72ED focuser to slip downward when used near zenith.  It didn't matter how much I tightened up the central tension screw or roughed up the tube flat (rack).  I eventually bought a 90mm APO with a helical R&P focuser for use with heavy eyepieces or a binoviewer.  It will still unravel if I loosen off on the tube tension, but not otherwise.

I had to buy an 8" dovetail bar and mount the clamp just about even with focuser knobs to reach balance on the AT72ED.  I never had any balance or load issues even with my old DSV-1 mount and certainly none with my DSV-2B mount.  I would think your scopes should be long enough that this won't be such an issue.

You'll just have to try it out and see how it behaves in each focuser.  If you can get the Terminagler for about $525 or less (USD equivalent), then you'll be right in line with typical US used prices and should be able to resell it for no loss.

Or $175 shipped to the US (no additional taxes for us).  If I didn't already have a 22mm NT4, I'd probably order one.

13 hours ago, Don Pensack said:

I didn't see any noticeable SAEP in the 14mm (unlike the 14mm Vixen SSW, which had it in abundance), but I did notice EOFB (edge of field brightening).

Right, but I was referring to the 9mm and below focal lengths.  It wouldn't be unprecendented for the shorter focal lengths to diverge in quality from the longer ones.  The Redline 70 degree eyepieces are supposed to be pretty bad at 8mm and below despite the 22mm being excellent and the 17mm pretty good.