Don Pensack

It helps to remember the three "C"s:

--Collimation.  what tools are you using for collimation?  how are you doing it and in what sequence?  Do you check the results in a star image?

Remember, it will have to be done every time you set the scope up.

--Cooling.  Are you running the fan on the mirror all the time you observe?  it can take a large heavy mirror like yours a few hours to cool down to the ambient temperature,

and until it is at ambient temperature, the images will be poorer, especially at high powers.  Put the scope out at sunset and let the fan run.

when you start observing later, the images will be much better than if you just set it up and zoom to high powers immediately.

--Conditions.  The steadiness of the atmosphere is all-important to get clear and sharp high power images.  This will vary from night to night.  First, reduce the "local" seeing problems by

setting up on grass or dirt instead of concrete or asphalt.  Heat will rise from the hard surfaces all night and ruin the high power views.  Don't look at a planet right above a rooftop.

Roofs release daytime heat most of the night and cause turbulence in the air.  Don't look at a planet below 30° altitude if possible--the air is twice as thick at 30° as it is straight up

and it is 10x as thick at the horizon.  If you must look at something low in the atmosphere, look at it when it crosses the N-S meridian in the sky, where it will be highest. And be aware 

that when you look through a lot of air, you will also be looking at a lot of dust, smog, and water vapor, not to mention a lot more atmospheric turbulence.  Use a shroud on the scope to keep

your body heat from drifting into the optical path of the scope.  Start with low powers and slowly work up to the maximum power that yields a clean sharp image, above which the image becomes blurrier.

That point will be different from night to night and even from hour to hour.  In most places, the seeing settles down after midnight, though that is too late for Jupiter and Saturn.

But it will be ideal for Mars.  and Mars, being farther north in the sky, will rise much higher.

i think it sounds a lot like the atmosphere just wasn't steady enough for high powers.

On your scope, low powers are 48-120x (32-13mm eyepieces), medium powers are 120-240x (12-7mm eyepieces), and high powers are 240-360x (6-4mm eyepieces), and above that "thar be dragons", i.e. the number of nights you will be able to use and magnification up to the theoretical maximum of 720x will likely not exceed 1 or 2 per year.

6 hours ago, Trentend said:

Really enjoying the view through my PVS7 NV goggles which have a long rubber eyeguard that completely blocks out all surrounding light, useful in my light polluted back yard. Is there something similar I can buy to go on the end of a panoptic 24mm eyepiece (x2) to be used in my Binotron? I know Televue sell an extender but not sure it will block as much, plus £33 a pop.

Maybe something like this style B

 

https://www.edmundoptics.co.uk/f/rubber-eyeguards/12476/

You don't need an eyeguard extender with the 24mm Panoptics--it would sacrifice too much eye relief.

You just want a longer rubber eyecup.

Like this, perhaps?:

https://www.edmundoptics.com/f/rubber-eyeguards/12476/

There are other retailers that sell similar eyecups.

https://inspectusa.com/eye-guard-accordion-style-eye-cup-125inch-pveg1-fits-std-borescope-p-392.html

or maybe something here would work:

https://www.google.com/search?q=rubber+eyepiece+eyeguards&client=opera&hs=XdK&source=lnms&tbm=isch&sa=X&ved=2ahUKEwithPjAsKrsAhXUpZ4KHSAMD4QQ_AUoAnoECAwQBA&biw=1880&bih=970

And there is always the option of making your own by cutting out a short section from a bicycle inner tube and stretching it over the eyepiece and folding it over to make it whatever length you want.

You could get a hundred eyecups from one inner tube.

8 hours ago, alan potts said:

One of the 100 degree TeleVue's I choose to keep, I did find it needed the Paracorr with this though in my F4.3 Dob, I personally don't see the point in paying 800 quid and then settling for coma, the trouble is the Paracorr is another 400. I did see a difference in the TeleVue Paracorrs between the new Mk2 and the old Mk 1 ( I have a feeling there was a model before what I call the Mk 1) The new current model is the only one that gave me perfect results.

Great eyepiece though.

Alan

The Paracorr II has optimized positions for the 21mm Ethos, the 17mm Ethos and the 31mm Nagler, which the Paracorr I did not.

There were at least 3 different versions of the Paracorr I and versions before it.

As long as they are in the case when not in use, I see no reason for heating the eyepieces.  They won't fog up in the case.

If it's just because they fog up when in use at the telescope then:

--when you walk away from the scope to consult maps, put a cap on the eyepiece

--if it fogs because you breathe on it, don't breathe on it--learn to breathe from the corner of your mouth away from the eyepiece and not through your nose by the eyepiece

--if it fogs simply because your eye is close and your eye is warm and moist, then use the eyepiece with the rubber eyecup removed (which allows air to circulate in between the eye and the eyepiece)

--if it fogs because you accidentally breathed on it, wave your hand at the eyepiece or wave a piece of paper at it--the fog will evaporate.

I've observed at sites where the dew was so heavy you could hear it dripping from nearby scopes, your garments became wet and a table with a lip at the edge filled up with water like a lake.

Yet fogging of the eyepieces was not a problem with unheated eyepieces.

3 hours ago, horseheadnebula said:

I have Orion XT10 intelliscope (1200 mm focal length / 254 mm mirror / f 4,72) with two Orion Sirius plossls (10 mm and 25 mm) which came with the telescope and Televue Delos 8 mm eyepieces. I also have Lumicon UCH 1.25" filter but so far haven't found any use for it. Besides these eyepiece I only have tried Baader Aspheric but I was really surpised about it's poor image quality (astigmatism) specially considered it's price. So for my first eyepiece I wanted more quality and bought Delos. I'm wearing glasses so I would need long eye relief eyepieces. My 10 mm plossls is useless for me. I'm practically blind without glasses so I would like to use glasses all the time instead wearing them on and off with high magnification.

I would need help to decided next eyepieces. My budget is somewhere 600-700 €. Problem is that because I only have experience about mentioned eyepieces, I don't know what I actually want. Moon and Messier 13 have been my favourite targets. I never would have guessed Moon would be so nice with telescope. So perhaps another eyepiece could be with more magnification to see more details from Moon and to see topical Mars as a larger. I have read positive feedback about Baader Morpheus but I'm not sure is eyerelief too tight with 6.5 mm and is that focal length too close to 8 mm Delos. If eyerelief is not enough there would be Vixen SLV but is it's apparent field of view too tiny with non motorized dobson?

With other eyepiece I would like to enlarge my hobby to more deep sky objects. I don't even know what would be ideal focal length but I have understand it could be somewhere between 12-20 mm. If I'll buy cheaper higher magnification eyepiece (like Morpheus or SLV) I would stay on budget with Explore Scientific 92 or another Delos. Is that ES eyepiece too heavy so that can my focuser handle it? Is this right plan to concentrate more money in this focal length area?

Then I read from Televue's choosing eyepiece guide that it would be nice to have eyepiece for low-power viewing of large objects. (Generally I didn't understand guide's section how to choosing eyepiece based on field stop sizes.) This eyepiece would be about 30 mm focal length. Though I have understood from other 'help to decide eyepiece' topics that this probably is not must have focal length area. For this I have looked 30 mm APM ultra flat field but I'm not sure about eyerelief. I have also looked APM hi-fw 12.5 mm for dso but again I have read mixed reports of APM's eyerelief sufficiency for glasses.

For that f/ratio and focal length, I'd go with 24mm, 12mm, 8mm, 6mm, 4.7mm

Those focal lengths can be +/- of course, to suit your choices.

Given the scope and the need for glasses, I'd recommend (I wear glasses and find all these fine with glasses):

Baader Morpheus 17.5mm to 9mm

Explore Scientific 92° in 17mm, 12mm

TeleVue Delite in 3mm to 18.2mm

TeleVue Delos in 3.5mm to 17.3mm

TeleVue Apollo 11

TeleVue Panoptic in 27mm to 41mm

Pentax XW in 3.5mm to 40mm

APM Ultra Flat Field in 18mm to 30mm

APM HiFW 12.5mm ( I wear glasses and find it fine for glasses--the eyecup rolls down but it can be pressed down even farther until flat on top, yielding another mm of eye relief)

Noblex/Docter 12.5mm

For your UHC filter, a maximum of 100x is used, and that means eyepieces of 12mm or longer.

As for field size, if apparent fields are identical in all your eyepieces, and you'd like each shorter focal length to reduce the field size by 50% in AREA, then each focal length should be x/1.414 where X is the next longer focal length,

i.e. 30mm, 21.2mm, 15.0mm, 10.6mm, 7.5mm, 5.3mm.  This results in a 50% smaller field by area in each shorter focal length.  The"rounded off" rule is 1.4x, or 30mm, 21.4mm, 15.3mm, 10.9mm, 7.8mm, 5.6mm

Personally, I prefer even "steps" of magnification.  On your 10", 50x/100x/150x/200x/250x.  This results in the % differences getting smaller as the magnifications increase, which is desirable when bumping up against the seeing conditions.

My earlier suggestions in focal lengths were based on that.  I also find a difference of 30x about the smallest noticeable jump and 75x a bit too much on an 8" or 10" scope.  So, a 50x jump between eyepieces.

50x is a good low power, 100x will be a "most-used" magnification, 150x will always be usable, 200x will be more affected by seeing, but usable most of the time, 250x is a reasonable high power (25x/inch).  If your seeing conditions allow higher powers, I advise getting a Barlow and magnifying some lower-power eyepieces because the ultra high powers will be useful much less of the time.

16 hours ago, globular said:

Even with the long eye relief requirement met it seems to be EPs with wider AFOV that have more mixed opinions about glasses suitability. I guess this makes sense, after all there are similar mixed opinions about the ease of use of wide verses narrower AFOV EPs amongst non glasses wearers too?

I notice you settled on the APM UFF for your 30mm EP, Don, not the ES 82. And the Morpheus rather than the ES 92 at 17mm. Is their slightly narrower AFOV part of the reason?

No, not really.

I found the APM 30 had a "wide-enough" true field in my scope (1.2°) to be fine as a lowest-power eyepiece I don't use all that often, and found its lighter weight and smaller size than the 31mm Nagler (my other choice, at 1.3°, as I think the ES has too much astigmatism in the outer field and too much scattered light).  But the real important reason was in "presentation".  The Nagler was sharp to the edge and displayed no astigmatism, but the field appeared to be curved as if I were looking at stars on the interior surface of a bowl.  The APM was dead flat and made me think I was looking at a star map.  I really liked that presentation, so I ended up choosing it over the 31mm Nagler or the 30mm XW.  I was also impressed with the contrast.  It is truly an under-priced eyepiece (I hope Markus doesn't read that).  My most-used low power eyepiece, though, is the 22mm Nagler (83x, 0.98°), an eyepiece I mistakenly sold once, but never again.

I would gladly have picked 82-85° eyepieces over the Morpheus eyepieces in the 14mm and 17.5mm range but such eyepieces suitable for glasses don't exist.  The 17mm T4 Nagler has some optical issues I didn't like, so that wasn't an option.  The ES 92s are overly large and heavy, and require additional counterweights on my scope, and though I think they are fine eyepieces, that obese nature just ruled them out.  The 12mm was a possibility, but I own and use a superb 11mm eyepiece (the Apollo 11) that would have duplicated the 12mm ES (plus, the Apollo is a LOT lighter).  I thought the Delos, as fine as they are, are just too narrow for that scope (I use Delites in my 'frac), as are the Pentax XWs.  I prefer 80°+ if I can get it.  So the Morpheus were the closest I could get to a glasses-friendly 80° eyepiece (the 14mm tests at 78°, the 17.5mm at 74°)  with a relatively light weight, small size, and freedom from over-abundant edge of field astigmatism.  In fact, my first full night with both, I purposely used all my eyepieces and I thought the 14mm and 17.5mm Morpheus were both excellent.  The 14, especially (my wife even commented about how sharp it was, and I agreed).  Note that this is at f/5 with a Paracorr II, so really f/5.75, and there is not much field curvature when the focal length is 1826mm.  I even find the notoriously-curved field of the 14mm XW to be acceptably flat.

Still, my experience with the other focal lengths of Morpheus eyepieces is short, so I cannot give you a full rundown of optical characteristics, though I thought all of them felt pretty much the same.  I didn't use the 4.5mm extensively--just a few minutes--because the seeing didn't allow that power (406x) to be used for long, so for criticisms of that focal length, I defer to others.  The eye relief gets tighter as the focal lengths shorten, so the 9mm may be the shortest focal length glasses users will find comfortable.  

Sorry to be so long winded.  Probably TMI.

I didn't find it marginal,  Like the 31mm Nagler, I found it usable with glasses.

Did I press the lens of my glasses against the rubber?  Yeah, just like I do with nearly every eyepiece that is glasses-compatible.

I don't think any eyepiece with 20mm of eye relief has a true 20mm of effective eye relief from the rubber eyecup (folded down) up.

I think you have to have 23-24mm of eye relief to get a true 20mm effective eye relief.

The 17.5mm Morpheus has 24mm of eye relief, and that's just about the only eyepiece I've tried where, with glasses on, I can actually get close enough to see blackouts (!)

If maximum contrast is desired in a narrowband UHC-type filter, the obvious candidates are the TeleVue Bandmate-II Nebustar (26nm bandwidth, zero red transmission)

or the Lumicon UHC (27nm bandwidth, zero red transmission).  If observing in severe light pollution the H-II nebulae, removing red might help.

My sample of the DGM NPB had a 21nm bandwidth in the blue green, but had the same two peak orange and red transmission shown in post by Globular (BTW, the two peaks correspond to

no wavelength of emission for the shorter wavelength, and H-α for the longer wavelength peak, so no homologue to the photographic filter mentioned by Louis. The OPT Triad is not a visual filter and only picks up the 500.7nm O-III line).

Gerry's point about nominal specs is apropos--filters vary a bit from one sample to the next.  Doveryai no proveryai, trust, but verify.

The view of M8, M20, M17, M16, M42 are all better with a UHC than an O-III.

That's because these nebulae pass a LOT of hydrogen AND oxygen light.

Using either an H-ß or an O-III filter on these large H-II gas clouds merely reduces their sizes and darkens them appreciably.

On O-III targets, the narrower bandpass of the O-III filter helps improve contrast a lot.

12 hours ago, AstroTim said:

Hi @Don Pensack,

Out of interest, how did you calculate that approximation? I have a C8 and have also been trying to work out the effect of various barlows and a Binoviewer. 

Given that you have to adjust the focus when adding a barlow (not sure if it’s inward focus or not) and that this in turn will alter the focal length of the scope (due to the mirror moving?), does that mean that a 2x barlow will not actually give a 2x magnification when used in a C8? I think I’ve also observed a difference between a nosepiece barlow vs the same magnification normal barlow, which I wasn’t really expecting, but maybe one of them is poorly specified.

Regards,

Tim

 

The C8 adds 31mm to the focal length for every addition 10mm of back focus distance.

UHC-type like NPB--passes H-ß and O-III and is a universal filter for emission nebulae of all kinds.

O-III passes two O-III lines in the spectrum and creates great contrast on objects that emit more energy in O-III than in Hydrogen emission, like supernova remnants, planetary nebulae, Wolf-Rayet Excitation nebulae.

H-ß  passes only the H-ß line and maximally enhances contrast for large, faint hydrogen-only emission nebulae.  Almost all of these objects have very low surface brightnesses, like IC434, the nebula behind the HorseHead (B33).

If you get one, get a narrowband UHC-type.

Examples:

TeleVue BandMate II Nebustar*

Astronomik UHC**

Lumicon Gen.3 UHC**

DGM NPB*

Orion Ultrablock#

Thousand Oaks LP2

and so forth

* transmits no red, stars are blue green

** transmits red as well as blue green Stars have red in them.

#varies in quality, but mostly are good.

My TO wasn't good at all.

Brands to avoid: Explore Scientific, Optolong, StarGuy, Celestron UHC/LPR, Baader UHC-S, Astronomik UHC-E, DGM VHT, or anything with a bandwidth > 30nm.

17 hours ago, Pixies said:

Hi John,

How would the NBP compare with an Oiii with something like the Veil Nebula?

I'm not John, but I can tell you that while the NPB does a good job on the Veil, it is not the equal of a good 2 line O-III filter, which will show you more and with better contrast.

Narrowing the bandwidth in the blue green from 21-22nm to 12nm has a strong effect on contrast.

a maksutov's f/ratio increases with back focus distance.  Adding a binoviewer adds a substantial optical back focus length.  In your case, it looks like it added 15% to your focal length.

This is not unusual.  it isn't the binoviewer that added the magnification, it's the back focus light path length.  If you added an extension tube, it would go up even more.

Very approximately, the focal length goes up by 10% for every 2 additional inches of back focus in that scope, so it looks like you added about 3" of additional back focus over the diagonal.

Compatible in both scopes: 1.25"

Widest possible field of view in the scope (all these have the same TRUE field of view):

40mm 40° Plössl

32mm 50° Plössl

24mm 68° widefield

Formula to compute true field:

True Field in degrees= (field stop of eyepiece ÷ focal length of telescope) x 57.296

The eyepieces above all have a 27mm field stop, the approximate size of the inside of the barrel.

44 minutes ago, John said:

My 31mm Nagler gets used a lot less than my 21mm Ethos and the 40mm Aero ED much less than either.

If I observed regularly under very dark skies perhaps the result would be different perhaps ?

It could be you are expressing a preference for a darker background in the eyepiece, but it is equally possible you are expressing a desire for a higher magnification.

I had the 31 Nagler and 21 Ethos for a few years, but found I only reached for the 31 a few times in that period, so I sold it.  After moving away from the 100° fields of the Ethos eyepieces at longer focal lengths

due to astigmatism and needing glasses at lower powers,  I found that narrowing the fields brought back a need for the longer focal length again.  If limited to 76-82°, I find I can use a smaller gap between eyepieces.

It's not obvious that having 100° eyepieces makes possible a wider spread between magnifications, but it seems to be the case.

As Al Nagler explains the "majesty factor" (unfortunate name), if the higher power eyepiece has the same field size, most people will prefer it because the background will be darker and the apparent field less bounded.

Those 3 eyepieces have true fields of a 10 : 8.3 : 6.2 ratio, but a magnification ratio of 25 : 32 : 48, so the field area decreases by 38% while the magnification increases by 92%.  That makes the higher power feel as if it has not narrowed in keeping with the magnification increase, giving more of a feeling of a huge expanse of sky.  The 21mm Ethos is narrower in field stop than the 31mm Nagler, but the impression of the field size, contrast, and sharpness makes the 21 more impressive to look through.  And that would be true in dark skies as well as brighter ones.

1 hour ago, John said:

I expect it up to a point with O-III and UHC filters but, for me, the NBP just took it a little too far. The effect of the filter on nebulosity though was really nice so I'm in two minds whether I should have held onto it. Maybe I'll get a new one and see if the latest coating tech / glass polishing has reduced the effect ?

 

The DGM NPB has a nearly unrestricted red-orange peak and a red peak after that.

It has pretty close to the narrowest of all UHC-type filters in the Blue-green (mine was 21nm)

Because the blue-green bandwidth is so narrow, and the red bandwidth so wide, stars will appear red.  This annoys some people, but not all.

But if it is nebulae you are looking for and at, the DGM is an excellent filter.

If you get a good one.  They seem to vary a bit in bandwidth placement in the spectrum, which seems to result in a variation in the % of transmission at the 500.7nm O-III line.  This variation doesn't render the filter ineffective, however.

Why the red when filters like the TeleVue Nebustar II and Lumicon UHC have none?

Astronomik aims to be useful for imaging too, by having a high red output at H-α, S-II and N-II wavelengths, but the red starts so deep into the red there is just a trace of red in the star images.

But the DGM starts its red transmission at a lower wavelength and covers a lot more visible reddish wavelengths.

Dan McShane explains it this way:

Every nebula's brightness is a combination of its intrinsic emission AND the brightness of the sky overlaying it.  Reducing the brightness of the background will increase contrast between the nebula and the sky.

So keeping the bandwidth narrow in the range of maximum nighttime sensitivity of the eye (~450-550nm) is important.

But eliminating the red wavelengths, where the nebulae emit a lot of energy (maybe MOST energy), when our eye is relatively insensitive to those colors, doesn't make sense.

Plus, there is brightness from the night sky in those long wavelengths, making the nebula even brighter.  Yes, it sacrifices a bit of contrast by allowing so much light to come through the filter.

But it is at wavelengths we see only dimly if at all, and those wavelengths make the nebula appear larger and a bit brighter.

Is this true, i.e. does it work?  

Well, visually, and used at truly dark sites, I can say yes, it does work.  On the super-bright nebulae like M42/43, it reveals reds in the nebula you might not see in another filter.

It also makes nebulae like M8, M17, and M16 appear larger than any other UHC filter I've tried.  I would credit that to the narrowness of the blue-green bandwidth (it even outperforms some O-III filters on O-III targets)

but for the fact it allows me to see some reds in M8, M20, M17, M42, and even M27 that other filters do not.

But, comparing the TV, the Astronomik, the Lumicon, and 3 others on M17, the DGM was simply the most amazing of the bunch, where the "Swan" was maybe 10% of the visible nebula (which went way outside

the 45' field), and nebulosity was traceable all the way to M16, verifying that M16 and M17 are merely the brightest points in a very large nebula several degrees wide.  and it revealed, one especially transparent night,

a pink color across much of the nebula.

So, new or old, the DGM NPB will show reds in stars instead of the blue-green color of the Lumicon or TeleVue.

There is a slowdown in production recently due to a huge increase in demand and a couple hurried batches that ended up not passing QC.

Personally, I found a place for it in my kit along with a Lumicon UHC as they perform differently on different nebulae and sometimes you may want the maximum contrast without the red transmission.

I think the jury is still out on the TeleVue and Astronomik for me.  Like Johnny 5, I need more input (obscure '80s reference).

No difference.  I was using the 3mm Delite comfortably the other night.

3 minutes ago, martinl said:

Yes, absolutely. The only downside of the 24mm Pan is that it is a bit too short on eye relief to use with glasses. If I didn’t wear glasses to observe I would still have mine. 

Same here, so I converted to the 24mm APM UFF, and, so far, I'm pleased with the eyepiece.

21 hours ago, Barry-W-Fenner said:

Sorry to sound like a lemon Don. But do you mean you rate the 4.5 and 17.5mm morphs or the whole range, 4.5 through to17.5?

Cheers

I should have said "all", or 4.5mm through 17.5mm.  The 4.5mm and 6.5mm are "tight" with glasses on, but the other focal lengths are easy.

14 minutes ago, Connor brad said:

Would the 24mm Panoptic work well on a 200pds skywatcher explorer? 

Yes.

On 24/09/2020 at 09:51, globular said:

I'm trying to get glasses friendly EPs at all focal lengths too. 
Can I be cheeky and ask you to cast your eye over the them in my thread?
https://stargazerslounge.com/topic/362724-perfect-set/
(Very cheeky but I'm lovely with it 😇).

Some obvious candidates for glasses use:

Baader Hyperion 5-24mm (OK for longer focal ratios), but not the 31mm or 36mm (you can do better).

*Baader Morpheus 4.5-17.5mm

*Explore Scientific 92° series 12,17mm

Explore Scientific 82° 30mm

Explore Scientific 68° 40,34mm

Explore Scientific 62° 40,32,26mm

Explore Scientific 52° 40,30mm

*TeleVue Delite 3-18.2mm

*TeleVue Delos 3.5-17.3mm

*TeleVue Apollo 11

*TeleVue Nagler 31, 22

TeleVue Panoptic 41,35,*27mm

*Pentax XW 3.5-40mm

*APM/Altair/Orion UFF 30mm, 24mm, 18mm

Orion LHD 4-20mm

Vixen SLV 50° 2.5-25mm

I've put stars by my favorites in the group.  I haven't used the Orion LHDs

21 hours ago, Louis D said:

According to Ernest in Russia who tests many eyepieces on his optical test bench, the 35mm falls somewhere between the 40mm and 30mm.  You can look on his summary page for United Optics, ED toward the bottom of the table.  I've tried to repeat it below.  The numbers reflect the size of the blur spot of an artificial star at center/70%/98% to the field stop using an F4 and an F10 lens.  He moves the eyepiece to center the area of interest over the center of the lens image to eliminate lens aberrations influencing the results.  The actual full report page is here.  Try using Chrome browser to translate them.

	FL	AFOV	F4	F4	F4	F10	F10	F10	List of
Eyepiece	mm	°/deg.	centre	zone	edge	centre	zone	edge	rest aberrations

United Optics, ED	40	64	5	18	25	<5	12	20	Ast.,FC
United Optics, ED	35	70	5	20	35	<4	12	20	Ast.,FC
United Optics, ED	30	66	5	20	40	<4	11	22	Ast.,FC

Oof.  That is poor edge performance even at f/10.  His measurements are in arc-minutes.  The predominant aberration is astigmatism.

These are not well-designed eyepieces, IMO.

32 minutes ago, John said:

For me, either no filter or a good UHC such as the DGM NBP. I've used the O-III and H-Beta filters on Messier 42 to see the effects but on balance either no filtration or a UHC are my preference.

I'll be interested in Don's opinion as well of course

Pretty much agree.  I either use no filter or the DGM NPB on that one, though the Baader UHC-S adds just a bit of contrast enhancement and makes the image a tad better than no filter at all.

I don't disagree with LDW1--the Baader UHC-S is the only broadband in my filter box, and in dark skies it is my go-to filter for M20 because it doesn't kill the reflection nebula like the narrowbands do.

Normally, in dark skies, M42/43 is so bright it damages my night vision.  It's hard to see that a filter is needed, which is why turning up the contrast just a tad with the broadband works well.

When a nebula is as bright as M42/43, maximal contrast might not be needed.

The choice of filter can be an aesthetic choice instead of maximum contrast, even on the fainter stuff.  It depends.

Though a narrow O-III filter really is what is needed on NGC2359 (Thor's Helmet), I often prefer the view in the Baader UHC-S because the nebula sits in an incredibly rich area of the Milky Way.

Seeing the nebula seemingly hanging in space in front of thousands of background stars is a wonderful view, even if I pop in a narrow O-III to actually study striae in the bubble.

Different views require different filters.  I've whittled my filter collection down from 52 to only 13 now, but it's getting hard for me to decide which of the remaining ones have to go.

Yeah.  I hear you.

If not at the scope, I use progressives and I like them a lot, but they do not work at the scope.

I thought about single vision glasses with readers hung around my neck, but it is always cold at the altitude I observe, so I am always wearing a hood.

I use the glasses over the hood, held in place by a tightenable lanyard behind my head (otherwise, they'd fall right off), so changing glasses back and forth

would not be practical.  Fortunately, I can just let the glasses hang when using a 10mm eyepiece or shorter, but then I have to put the glasses back on to read my notes

and DSC.

I think I may be in a transition phase to all glasses-friendly eyepieces at all focal lengths for convenience.

13 hours ago, LDW1 said:

Don’t forget the Baader / Celestron UHC its a great filter that shows more back ground stars if you aren’t into the darker, back ground blocking filters

The Baader UHC-S, reportedly the same as the Celestron UHC/LPR filter, has too wide a bandwidth to be a great nebula-enhancement filter.

If you don't want as dark a field, the filters with a 30-45nm bandwidth (usually also labeled UHC) would be better.

Don't get me wrong, as the Baader UHC-S is a great broadband filter.  I thought it was a bit better than my "gold standard" Lumicon Deep-Sky.

It works great on bright nebulae in truly dark skies.

But if the purpose is to enhance nebulae and the LP conditions are less than perfect, a narrower filter would work better.