Louis D

4 hours ago, Don Pensack said:

That's not a "simple" eyepiece, i.e. an all-positive design with the field stop below the field element.

Field stops in 2" all-positive designs max out at ~46.5mm.

What do you mean by "bare upper section?  Did you remove the field lens?

ES says the field stop int he 12mm ES92 is 19.6mm, i.e. the eyepiece has a "virtual" field stop that can't be measured by measuring an internal stop.

I recollect it came from Telescope Warehouse originally.  The owner, Bill Vorce, seems to get a lot of surplussed ES equipment.  This particular eyepiece (the 12mm ES-92) has no Smyth lens group, only the upper, positive section.  I'm guessing it was an abused return.  Without the lower section, it has a 28.5mm focal length with an exposed field stop below the lenses.  I removed the lower section's empty tube and added two step rings to adapt the original 2" nosepiece directly to the upper section.  This reduced the required in-focus from 40mm to 21mm.

It's third from the left in the group shot below.  In the second image, you can see it has such a wide true field of view that I had to add a second yardstick to measure it.  The slightly dark line near the left edge of the ES-92 29mm "full view" is where they push against each other.  None of my other eyepieces, even my 40mm Pentax XW, are this wide in TFOV.  If ES could reign in the extreme chromatic aberrations with a compensating prismatic, but zero power, lower element, it would make an awesome eyepiece.  Even as it is, I love scanning rich star fields with it.  It is what the Kasai Super Wide View 30mm 90° should have been.

The only Panoptic I have is the 27mm, and I've never noticed any SAEP with it.  I just can't stand its tight eye relief while wearing eyeglasses.

The 12mm and 17mm Nagler T4s are loaded with SAEP.  It's so bad, I can't hold the entire FOV once the field stop becomes visible as I move closer to the eye lens.

I tried the original Radians side-by-side with the Pentax XLs in the daytime at a shop back in the late 90s.  I couldn't hold the FOV in the Radians at all, but had no problems with the XLs, so I ended up going with the XLs.  I didn't notice any "coffee" tone in the Radian.

My lone Vixen, a 9mm LV, views darker than my other 9mm eyepieces.  I can't say that it doesn't go as deep as a result, but it sure seems dim by comparison.  I wonder if it is due to the Lanthanum element introducing a coffee tone that suppresses blue hues to some extent?  I don't see a coffee tone in the daytime with it, though.  Perhaps I should try a fixed color balance photo through it to find out.

I recall seeing one of the Celestron long FL lineup in a photography store glass case back in the mid-90s.  It was impressively large for the day, and expensive.

4 hours ago, Mr Spock said:

I was in Austria 

Absolutely loved the scenery and the people when the wife and I vacationed there 30 years ago.  Hopefully, nothing has changed for the worse.

3 hours ago, Don Pensack said:

Without distortion, the apparent field at 80mm and a 46mm field stop would be 32.1°.  Field stops in simple eyepieces don't exceed 46-46.5mm in a 2" eyepiece.

Add a typical 4% distortion and you get about a 33-1/2° field.

Sure they do when they're above the shoulder.  There's some vignetting and lots of in-focus is required, but it does work.  I've got the bare upper section of a 12mm ES-92 with a 51mm physical field stop that actually measures in use to be 48.4mm, probably due to cutoff from the internal shoulder step.  Chromatic aberration is so bad toward the edge that I've never noticed vignetting.

1 hour ago, Mr Spock said:

As you can see July was a poor month to take a holiday 

Or a great month to take a holiday somewhere else with better weather.  I usually vacation in the Mountain West during the heat of summer here.

5 hours ago, F15Rules said:

Nice photo..

..but what's that clear bluish coloured area running along the top of the photo from middle to the right?? I know it sounds ludicrous, but it almost looks like, er, cloudless sky??🤦‍♂️🫣😲

Dave

We do get a lot of blue skies in this part of Texas.  In fact, it was clear here for the entirety between Christmas and New Years.  It's cloudy and drizzling right now, though.  We need the rain.  We were over 10 inches behind average (32 to 34 inches around here) for 2023.

Of course, the further west you go in Texas, the more clear days you get because it gets more and more arid moving away from the Gulf of Mexico and toward the Desert Southwest.

This map of average annual rainfall pretty closely tracks clear sky days.  Less rainfall equals more sunshine:

Moving from east to west across Texas, you go from Cypress swamps to high desert.  I don't know of any European country that can say that.  Australia is most similar to Texas in this and many other respects, though.

2 hours ago, Second Time Around said:

Unfortunately, Gary Russell doesn't sell to the UK.  It may be that, like some other US companies, he doesn't have an export license.

It's probably the whole change to making the international seller collect VAT instead of the courier/buyer collecting/paying VAT.  It creates a huge amount of paperwork to collect it for each and every possible taxing jurisdiction and then remit it.  I think that's what Don P.  ran into with his recently shuttered store.  He only had to collect sales tax for California sales because he didn't exceed $500,000 in sales to any other state.  That really simplifies paperwork.

I also know Gary is 80 miles from the nearest post office from which to get the proper export paperwork to fill out and file, so he doesn't want to deal with that headache.

The US market is large enough that most sole proprietorships don't feel like they're giving up much in sales to stick with US-only sales.

They are highly sought after in the US, show up infrequently, and command high prices for what is a basically a Plossl.  I think Gary Russell or Harry Siebert could cobble together something similar if asked.

13 minutes ago, Mr Spock said:

The water has no where to drain to. Next door, which is lower, has a proper drain fitted. My flooding seems to have occurred only since they built a new wooden 'wall' and fitted decking. I suspect they have blocked off the water draining from the top of my garden hence why it is all coming down to the patio.

I have a plan for that... wait until the summer then did a trench up to the fence so when it rain the water goes where it used to 

Sounds like my neighbor who put in 2 foot high metal edging along the fence on their side.  This effectively created a dam and violated Texas law about blocking the natural flow of water and causing it to flood neighboring properties.  Rather than take them to court, I waited until they moved out and listed the home for sale.  When no one was around, I went over to their yard and ripped out all the metal edging to allow water to flow naturally again.  That was 20 years ago, and no new owners have ever tried blocking the flow again.

On 27/12/2023 at 17:40, GrumpiusMaximus said:

Councils really need to start thinking about water run-off better when approving housing.

Our part of Texas is quite particular about limiting runoff from impervious cover.  Developers have to build large catch basins with elevated outlets to retain most of the runoff and allow it to soak into the ground rather than run off into a stream, creek, or river.  This also limits the spread of pollutants from oil spills on pavement.

Here's one near my house with a little bit of water still in it just behind the spillway to the far right:

That whole open area can fill with water after a rainstorm like a temporary pond.  If it rains more than it can hold, the excess goes over the spillway.

A shorty Barlow tends to be any Barlow that seats all the way into a diagonal.  They have deeper curves in the lens group to diverge the light rays in a shorter distance to get to the same magnification factor that traditional long Barlows get to over a longer distance.

Here are some images I found illustrating the difference.

Shorty Barlows next to a PowerMate:

Long Barlows next to a PowerMate:

1 hour ago, Second Time Around said:

That's interesting, Louis. You learn something new every day.  Can you give any specific examples please?

IIRC, it happens with simple positive-only eyepieces like Plossls and shorty Barlows with rapidly diverging light cones.  I think it's what is causing SAEP in the 6mm and 9mm 66 degree "UWA" eyepieces as well.  Eyepieces with a well designed Smyth lens group tend to tame down the incoming diverging light rays pretty well.

Unless you're using a super slow scope like an f/15 Mak and want a large exit pupil for narrow band nebula filters, I can't think of a particularly good reason to have a long focal length Plossl.

I've found Barlows can also create SAEP (kidney-beaning) where none existed before.

I was in a similar situation with my 15" truss Dob 23 years ago after a violent car accident tore up my back.  While my back healed up most of the way, I've never really gotten back to 100%.  However, I've kept the Dob with the high hopes of putting it in a dark sky vacation home's shed where it could be wheeled out as needed.  Because of where I have to store it (back of a deep coat closet) and its largest indivisible component (mirror box at 65 pounds), I can't really use it at my current house any longer.

I also had a double inguinal hernia operation 10 years ago.  It took about 6 months to heal up to about 85% of where I used to be able lifting-wise.  I say give yourself time to heal before selling your scope.  I'm able to lift 50 to 60 pounds again despite the bad back, hernias, and advancing age.  As a result, my 8" Dob is not a problem to pick up and move.  Just lift with your legs, take it slowly, and listen to all parts of your body.  Most importantly, give your body time to heal, or you'll tear something and have to start all over.

4 hours ago, John said:

it needed more inwards focuser travel in that mode than I wanted to use.

I had forgotten the 1.25" in-focus issue as another reason I didn't buy it.  My primary use of zooms is with my old ST80 which is 1.25" only and has limited in-focus available.  The APM SZ would have been unusable in that scope to replace my Celestron Regal 8-24mm zoom.  I take that scope and zoom on the road to chase solar eclipses because if my car is broken into while on the road and my equipment gets stolen, I'm not out a whole lot of money.  Eclipses don't always happen in the nicest of places, and neither are the places I sometimes have to stay on the road there or back.

6 hours ago, Jaymoon said:

So does anyone have any recommendations on good 3mm eyepieces that aren’t eye watering high in price? 

You could look into the TMB Planetary clones.  I picked up a 2.5mm for $35 off of ebay last year (2022), and it is surprisingly well corrected for the price and power.  There's a 3.2mm as well, but sometimes it's actually a 2.5mm instead.  There's also 4mm and 4.5mm versions you could try.  Here's a post with my findings about it followed by one with a comparison image taken through it:

6 hours ago, Jaymoon said:

being able to make out Jupiters rings is blowing my mind.

Considering even professional observatories missed Jupiter's rings for centuries, that is quite an achievement.  Well done!

8 hours ago, Second Time Around said:

Rather than the Svbony zoom I use the APM zoom plus a Barlow as that gives more eye relief and a wider FOV.  The Barlow also makes the APM more parfocal.

I had thought about recommending that, but I was unsure what magnification factor a Barlow would yield in 1.25" mode given that the SZ's focal plane is 32mm above the 1.25" shoulder.  By my way of thinking, it would be larger than the rated magnification.  Thus, if used with a 2x Barlow, you would skip some of the 6mm to 8mm range in all likelihood.

I thought about buying one of Don's SZ's at his closeout pricing as a Christmas present, but I just didn't think it would have enough eye relief for me and my eyeglasses.

After a few years of taking a few crappy snaps, I realized that I'm more than happy looking at the hundreds to thousands of images being churned out by amateurs worldwide on a weekly to monthly basis.  I let them spend their money and time on capturing and processing them.

2 hours ago, bosun21 said:

I’ve only owned one achromat  and that was a 120 f9.

I've had an ST80 for 20+ years, and never really cared for it.

I came across a used KUO 152mm f/5.9 under the Astro Telescopes brand recently for a decent price, so I bought it to see if 6" of unobstructed aperture could make up for its enormous amount of false color at both ends of the spectrum and some SA.  So far, I'd say no.  My 6" f/5 GSO Newt and 90mm TS APO FPL-53 Triplet both walk circles around it.  I haven't given up on it, though.  Thus, my tinkering with various filter combinations.  See some of my experimentation starting at the post below:

1 hour ago, bosun21 said:

I actually prefer observing Jupiter unfiltered. I will increase or decrease the magnification until I get the best image for the seeing conditions and then settle down to spend some time on it. 

Try doing that in a fast achromat.  I've found with my 6" f/5.9 achromat that I need to filter everything below about 470nm to above about 625nm to get a reasonably sharp image.  Basically, a yellow-blue/green filter.  The problem is, no one makes such a beast for unknown reasons, so I've been assembling my own by stacking various shortpass and longpass dielectric filters to determine the widest passband possible at the best image sharpness.

When using an APO, Mak, or Newt, I would agree about going unfiltered, but I would add using binoviewers helps to really bring out details.

4 hours ago, Neutrinosoup said:

Considering 1 or 2 for a small travel case when I visit my parents, Delos are big…..and I only have the 24mm panoptic 

Option 1 = Get the Baader zoom….

Option 2 = Take my Panoptic 24, and buy Delite 11/13 and Delite 5/7

(For use with a 72mm apo, focal length 430)

For travel compactness, you might consider getting the APM Superzoom as it would cover 7.7mm to 15.4mm with better correction and wider field at the long end than the BHZ.  At the short end, the Svbony 3-8mm might work for you despite its short eye relief.  Just some more options for you to consider.

11 hours ago, Manoah said:

Thank you they are a 1,25 inch eyepeace but i will look for a polarising filter

Check ebay for low cost 1.25" filters, such as variable polarizing sets.

10 hours ago, RT65CB-SWL said:

Another filter you may find useful is the Baader Neodymium. It is one of my most used filters. I often refer to it or call it my ‘Swiss-army knife’ filter.

Again, the low cost Moon & Skyglow filters from ebay are basically the same as the BN filter for less than 10% of the cost:

Any of the mid-strength blue filters (#80C, #80B or #80A) work well on Jupiter.  Unfortunately, I've only been able to find #80C and #80B in 2" (48mm photographic) size.  The #80A is readily available in 1.25" size, but a bit dark for my taste.