Louis D

45 minutes ago, Ags said:

I use a Wratten #8 when viewing planets at lower elevations - it significantly reduces atmospheric dispersion.

When viewing Venus at low elevations, I found my Meade Green interference filter worked best in my achromat by squashing all spurious red and blue, both from the scope and the atmosphere.  I then tried it in my 72ED, and it did the same for atmospheric smearing, leaving a nice and sharp view of the planet in brilliant green.

The 3.5mm XW is probably the finest of the XW line.  No edge astigmatism, chromatism, or field curvature at f/5 to f/6 in my scopes.  It is sharp and contrasty across the field of view.  The problem for me is with the resultant tiny exit pupil and my floaters getting in the way of enjoying the view.  Eye relief is excellent for relaxed, extended viewing.

I went ahead and added the Meade Yellow #8 spectrograph image to the rest of the minus violet spectrograph images above.  The Yellow #8 cuts just the tiniest bit more violet than the Minus Violet.  I have no idea why they strayed so far from the Wratten Yellow #8 spec, which is much closer to the Cheap Yellow or Yellow #12A below.  I've got a vintage 48mm Yellow #8 (also known as Y, K2, Y48, or 022 by other filter specs) camera filter on the way to use on 2" eyepieces.  I'll run it through the spectrograph once I have it to see where it falls on the "spectrum" of minus violet (yellow) filters.  I'm really curious because it looks way more yellow than the Meade #8 Yellow in its photos.

Since I have such strong astigmatism in my eyes (2.0+ diopters), I need to wear eyeglasses even at 1mm exit pupils, so that rules out short focal length orthoscopics.  I did buy a 25mm Edscorp Abbe orthoscopic (volcano top) just to what they're like.  I didn't care for it at all.  It has terrible correction across the field in my fast scopes.  I even disassembled it, clean everything (not that hard, just a singlet and a triplet), and tried every combination of flipping each of the two elements (there's just 4 possibilities), but the way it was delivered yielded the best images, so it's just the design itself that can't handle fast scopes.  It does better in my 127 Mak at f/12, but that's a pretty limited application.

I prefer my Pentax XLs and XWs for short focal lengths.  Nice and sharp across the field with excellent contrast.

For critical planetary observing, I use my binoviewer with a pair of vintage microscope eyepieces adapted to 1.25" or a pair of Svbony UWA 20mm eyepieces.  I use the nosepiece of a vintage Meade 140 2x Barlow to reach focus, boost power by 3x, and to slow down the light cone to f/15 to f/18 so the eyepieces perform at their best.  I also have a pair of Celestron Regal 8-24mm zooms that I sometimes use, but they tend to make my BV rig quite heavy requiring rebalancing.

For long focal lengths at lower powers, I prefer 2" eyepieces.  My favorites are my 40mm Meade 5000 SWA decloaked, 30mm APM UFF, and 22mm Nagler Type 4.  In the mid range, I prefer my 17mm and 12mm Explore Scientific 92 degree eyepieces.  At high-mid power, I really like my 10mm Delos and 9mm Morpheus.  If I'm using 1.25" eyepieces only, I'll substitute my 12.5mm APM Hi-FW for the 12mm ES-92, 14mm Morpheus or Pentax XL for the 17mm ES-92, and 24mm APM UFF for the 22mm NT4.

10 minutes ago, Skipjack said:

Wow Louis! That's quite a big collection. Impressive! 

That's just a small sample of my eyepiece collection.  Check this thread for more:

I've added couple more since this photo was taken.

Probably a travel Dob would give the most aperture per kg.

They must have changed the rubber formula, then.  The eye cups flip up and down quite easily on my set of 6 of them.

Up:

Down:

If you want to talk about stiff, the eye cups on my Astro-Tech AF70s can't be flipped at all.  I have to unscrew and remove them to use them with eyeglasses.  The 22mm version is second from the right below while the 18mm HD-60 is on the far left.

Without running your Orion Ultrablock filter through a spectrograph or optical spectrum analyzer, it's hard to say what's wrong with it.  My guess based on your latest comparison is that it is left shifted and is only passing H-Beta and no OIII bands where M42 is brightest.

My cheap Svbony UHC has a wider passband than my 1990s Lumicon UHC, but the view of M42 is surprisingly similar under Bortle 6/7 skies.  M42 has enhanced contrast with both filters without unduly dimming nearby stars.  For under $20, the Svbony UHC comes highly recommended for those on a tight budget.

I picked up a Japanese made Meade #8 Yellow for comparison since they are so often recommended as a cheap minus-violet filter.  Through my spectrograph, it is nearly indistinguishable from my vintage minus-violet filter shown in my comparison images posted above.  It is indeed way off from Kodak's Wratten specification for a #8 Yellow and closer to a Wratten #4 Yellow.  The #12A Yellow is closer to the Wratten #8 Yellow specification.  It's too bad the closest modern equivalents are the cheap yellow filters coming out of China that show a bit of scatter.

Last night I had super clear and steady skies after a front moved through the day before.  I compared the various Yellow, Yellow-Green, and Green filters through my ST80 f/5 achromat.  I even combined a few of them with the M&SG filter.

Venus required the heaviest filtration:

• The #8 Yellow left noticeable violet flaring ruining the view.  No yellow cast could be detected.  Venus looked about the same with or without this filter.
• The #12A Yellow removed all violet fringing leaving a slight yellow hue, but the red fringing then overwhelmed the view.
• The #12 Yellow left a deep yellow color cast that when combined with the residual red fringing created an orange hue.
• The Hirsch #11 Light Green needed combined with the #12A to block enough violet to be usable.  It still leaked a fair amount red, but it was an improvement.
• The R89 Moss Green completely eliminated all violet and red fringing while still showing a bit of blue and yellow hues.  Venus was a sharply defined disk.  The brightness needed cut down a bit, though, for better contrast.
• The Cheap Green showed a purely green view that was darker and slightly sharper.
• The Meade Green (interference) showed hints of yellow shades and despite the brighter view due to high transmission still showed excellent contrast.

Jupiter required a noticeable step down in filtration:

• The #8 Yellow left barely noticeable violet flaring.  A barely noticeable yellow cast could be detected.  Adding the M&SG filter cut most of the yellow cast, leaving an odd color cast (pale magenta?)
• The #12A Yellow removed all violet fringing leaving a noticeable, but subdued, yellow hue.  The red fringing was all but unnoticeable unlike with Venus.  Adding the M&SG didn't cut the yellow color cast much at all.
• The #12 Yellow left a deep yellow color cast that overwhelmed the view.  The belts were a bit sharper, though.
• The Hirsch #11 Light Green did a decent job.  Moving it in and out of the light cone, it did cut some of the unfocused red while imparting a light yellow-green hue that was unobtrusive.
• The R89 Moss Green completely eliminated all violet and red fringing while imparting a blue-green-yellow color cast.  It was probably overkill for Jupiter, though.
• The Cheap Green showed a purely green view that was darker and slightly sharper.  It seemed like overkill.
• The Meade Green (interference) showed excellent contrast, but with a strong green-yellow color cast.

The Moon, being a greatly extended, but very bright object, was somewhere between Jupiter and Venus in filtration needs.

• The #8 Yellow left noticeable violet flaring and a violet wash all gray areas.  A barely noticeable yellow cast could be detected.  Adding the M&SG filter cut most of the yellow cast, leaving an odd color cast (pale magenta?)
• The #12A Yellow removed all violet fringing leaving a noticeable, but subdued, yellow hue.  The red fringing was unnoticeable unlike with Venus.  Adding the M&SG created an odd color cast (pale magenta?) on the gray areas.
• The #12 Yellow left a deep yellow color cast that overwhelmed the view revealing greenish tints to shadows.
• The Hirsch #11 Light Green needed combined with the #12A to block enough violet to be usable.  It was a slight improvement over the #12A alone.
• The R89 Moss Green completely eliminated all violet and red fringing while imparting a strong blue-green-yellow color cast.  Details were nice and sharp without fringing.
• The Cheap Green showed a purely green view that was darker, but not any sharper.  It seemed like overkill.
• The Meade Green (interference) showed excellent contrast, but with a strong green-yellow color cast.
• The Meade Red (interference) showed excellent contrast once refocused for red.  It left a strong red-orange color cast.
• The Meade Blue (interference) revealed strong violet blurring on high contrast details.  It needed combined with the #12A to create a teal-blue filter that showed excellent contrast once refocused for blue.
• I could see using the above Meade color separation filters in a filter wheel with the #12A on the front of the diagonal as a pre-filter to cut violet for the blue filter for all bright objects.  The #12A has no effect on the green and red filters (verified with blinking it in and out).  That way, the observer could get sharp views in teal-blue, green-yellow, and red-orange after refocusing for each filter's passband.  It's just too bad the human mind can't combine RGB channels sequentially in time.  I suppose if the filters and focus could be changed rapidly enough it might work.  Alternatively, use three achromats filtered in RGB and use relay lenses to send the outputs to a combiner prism and view the result.  3-CCD video cameras do the reverse, so I know it can be done.

Orion nebula and star clusters:

• The #8 Yellow barely helped with bright star fringing.  Violet was subdued but still obvious, as was red flaring.
• The  #12A Yellow was a better choice for violet flaring, but left red flaring on bright stars.
• The Hirsch #11 Light Green was just about the best choice, possibly combined with the #12A Yellow to eliminate the residual violet flaring.  Without the #12A, violet and red flaring was still slightly visible, but not too intrusive.  Overall, probably the best choice.  The nebula was still visible, but contrast wasn't really improved any.
• The R89 Moss Green gave sharp views with no flaring, but was a bit dark.  The faintest component of the Trapezium was all but eliminated.  However, the nebula stood out a bit better by squashing some light pollution.
• The green filters eliminated flaring (good) and the nebula (bad), so not appropriate for this view.

It became clear to me that there is no one filter that is best for all objects in an achromat.  You want to apply the lightest touch possible to get to a sharp view.

The #8 Yellow is barely useful.  I think it was useful only on Jupiter, but not much else.

The #12A Yellow filter, being halfway between the modern #8 and #12 filters, desperately needs reintroduced as the Goldilocks of minus-violet filters.  It cuts all violet fringing on all objects without cutting too heavily into the useful blue spectrum, thereby leaving a light yellow cast instead of a heavy yellow cast as with the #12 Yellow.  Until then, either pick up a cheap yellow filter from China or cut your own from Rosco's R11 Light Straw material.

There needs to be an interference filter with a similar passband to the R89 Moss Green filter to improve transmission.  The blue end needs to cut on at around 570nm to cleanly get H-B emissions at 586nm and cut off at around 610nm to eliminate red flaring while leaving the yellow and orange-red spectrum that focuses fairly closely to green.  This filter could act as a jack of all trades to sharpen up achromat views of bright planets, the moon, and bright stars and star clusters while still allowing nebula to be seen in context.

9 hours ago, Moonlit Knight said:

A couple of years ago I was doing an outreach, loads of astronomers there too, some of whom brought their scopes with them. While I was locating a target a couple of the group made a comment something like "Oh, he's one of those blokes who knows where everything is " like taking the time to learn the night was a bad thing, showing off even.

I've done that too, simply sighting along people's scopes that they brought, shooting from the hip, so to speak, to put them on target.  If you don't know the sky and the scope doesn't have goto, DSCs, setting circles, or even a decent sighting device, what other choice does one have?

1 hour ago, AstroKeith said:

How many professional astronomers now push their telescopes. None unless they are using a heritage instrument.

Most professional astronomers request time on large scopes by submitting imaging proposals that are graded and either approved or rejected or perhaps tabled.  The imaging request is then added to the telescope's imaging schedule if approved.  Sometime in the future, the data is gathered and sent in raw format to the astronomer who then processes it (or possibly sends it to a processing expert).  Regardless, the professional astronomer never actually travels to the telescope.  Almost no professional astronomers own their own equipment these days.

I only use DSCs when I'm trying to track down unfamiliar targets or moving targets like Uranus and Neptune.  Most of the time lately, I've been comparing equipment and experimenting, so I look at mostly showpiece objects that I'm very familiar with.

In my younger days, I spent a lot of time using DSCs to track things down.  Once I knew where they were on the sky, I needed them less and less.  Uranus, Neptune, and comets don't fit that model very well, so I tend to still use DSCs sometimes for them if I'm having difficulty tracking them down.  I was able to find C/2022 E3 (ZTF) several times without DSCs thanks to it being fairly bright, high in the sky, and near bright stars/Mars.

Where have you been @John?  Miss us?

On 20/02/2023 at 07:37, Gfamily said:

I feel very cheapskate, but it works for me. Eyepieces in the caddy tray, other accessories below. 

I've been using a Popular Mechanics plastic toolbox since the late 90s to hold many of my non-eyepiece bits and pieces like collimation tools, solar finder, laser sight, filter wallets, allen wrenches, Rosco gel swatchbook, small counterweights, observing eyeglasses (in a case), various photography adapters, smartphone mount, tri-finder mount, alternate diagonal noses, focal reducers, folded nightsky map, etc.  A few things like my filter wheel, spare 2" diagonal, and Herschel wedge still get their own small cases/boxes outside of it.

OMG, my last post on this thread was 6.5 years ago.  Apparently, people really do go back through the archives and read these musty old threads.

17 hours ago, Don Pensack said:

But negative positive designs max out with a field stop that is smaller than the inside diameter of the barrel because the field lens expands the image after passage through the lens.

You should qualify that with effective field stop for negative-positive designs.

I know for a fact that the physical field stop of the 12mm ES-92 is 51mm in diameter because I measured it with a micrometer in my surplussed version of it that lacks its Smyth group.  Due to vignetting or some other artifact, it measures out as a 48.4mm field stop diameter photographically when used in a scope, however.  It requires about 21mm extra in focus relative to its shoulder to reach focus because the field stop is so far above the shoulder.

If its off-axis chromatic aberrations could be reigned in with an appropriate corrector lens, it would make for a fantastic widest field eyepiece.  I was just out last night quite happily cruising the Orion constellation with it in a 6" f/5 GSO Newt.  If you look straight on axis, the chromatic aberrations are all but undetectable in peripheral vision.  Eye relief is fantastic and the enormous 92 degree AFOV is easy to hold thanks to very little SAEP with the Smyth group gone.  The higher magnification and slightly wider TFOV than my 40mm Meade 5000 SWA or 40mm Pentax XW-R make the view much more engaging than either of those 40mm options.

13 hours ago, Mike Q said:

More area for more light light to come through.  It works with rifles scopes and binoculars and it makes sense that the same would hold true with eyepieces.

You're mixing up objective lens diameter which does indeed collect more light the larger they get with eyepiece field stop diameter which simply controls the extent of the projected image circle visible in the apparent field of view (AFOV) which then equates to the true field of view (TFOV).

A 2" eyepiece may or may not show more TFOV than a 1.25" eyepiece of the same focal length.  It depends on the diameter of the field stop.  It also depends on the size of the eyepiece's field lens (the bottom-most one) to a lesser extent.  An oversized field lens has no effect on TFOV, but an undersized field lens can lead to edge vignetting.

In general, a 2" eyepiece will indeed have a larger AFOV than a 1.25" eyepiece given the same eyepiece focal length, but not always.  Sometimes, the designer(s) chose to package the eyepiece in a 2" barrel simply due to weight and bulk concerns overwhelming a 1.25" focuser and/or diagonal.  Sometimes the choice was made because there would have been some vignetting if they hadn't.

The classic example of this choice is the 17mm Nagler T4 in a 2" barrel versus the 18mm Meade 5000 UWA in a 1.25" package.  Both are/were 82 degree AFOV eyepieces, but the latter suffers from edge vignetting while the former does not.

6 hours ago, paulastro said:

 Where actually was it that you met my wife Louis? 🙂

At a summer internship.  She doesn't take kindly to being slighted.

13 hours ago, paulastro said:

My wife?  😊

Ouch!!!  Watch out for a frying pan to the backside of your head. 😂

It looks to be from the same family of scopes as the Orion SkyQuest XT Classic Dobsonians.

If you're not looking for eye astigmatism artifacts, you might not notice them.  It's the same for coma from the primary mirror.

2 minutes ago, Don Pensack said:

There are better-corrected eyepieces at those focal lengths.

And prices.  It's absurd what Baader charges for the BHAs.

4 hours ago, HonestGazer said:

Explore Scientific are looking like a good option.

They were a good budget option 5+ years ago, then their prices climbed into near Tele Vue territory even pre-pandemic, at least here in the US.  There's a bit of a sale on ES-82s here right now; but even then, the Nirvana ES are a much better value.

1 hour ago, Cornelius Varley said:

Carports and detached garages are not normally covered by building regs or require planning permission but certain rules need to be met, non of which include construction methods.

In the US within most city limits, if a concrete pad is poured under the structure, it may be classified as permanent and needs permits/inspections and will be taxed as real estate property depending on size or other considerations.  Many US counties outside of city limits don't have such rules about permits/inspections, but you will still probably be property taxed on it if they find out it exists.  Homeowners insurance will generally cover damage to such structures.

If there was no concrete pad under it that it will be attached to, it is generally considered a portable structure, and generally won't be permitted/inspected/taxed unless it is over certain size limits.  Homeowners insurance generally covers damage to these types of structures and their contents as well.  They are covered under the "other structures" portion and may have different limits than structures attached to the main house.  Contents may be covered at cash value rather than replacement value, depending on the policy.

So, was the carport attached to the main house?  Was it permanently attached to a concrete slab?  How big was it?  Is it in the property tax appraisal roles?  The answers to these questions may help to determine the classification of the structure and insurance coverage limits.

Either way, it may be worth discussing with your insurance company because they might cover the damage and go after the other homeowner for reimbursement via subrogation.

1 hour ago, Captain Scarlet said:

YES! Well done … my proprietary Porro setup. It works! And as far as I could tell, no vignetting with 18.2 DeLite inserted. 😁😁

I remember trying that with a pair of surplus prisms cemented at 90 degrees in a home brew finder scope in the late 90s.  IIRC, it does work, but you have to stand at 90 degrees to the OTA, facing the hypotenuse side of the eyepiece holding diagonal to get the image in the right orientation.  Otherwise, it's rotated 90 degrees if you stand behind your OTA.