39 replies to this topic

[Echolight]

CeleNoptic, on 01 Nov 2024 - 10:07 PM, said:


No surprise there. I suspect variation in human vision physiology is responsible for that. Some see, some don't. E.g., Ernest thinks that EOFB is just a figment of impressionable observers . Even though it was documented/pictured well enough in this forum. I clearly see it in the same eyepieces (especially in zooms, but not only) the other folks sensitive to EOFB report it. It's impossible to predict so I'd take all recommendations from others with a big grain of salt. If one never saw it is a good sign that s/he will never see it at all. Otherwise, only firsthand experience with certain eyepiece can help, IMO.

Seems like a result of eye placement.

[Jon Isaacs]

Seems like a result of eye placement.

 

I think it is more complicated that that.

 

My thinking is that EoFB is in part, a matter of awareness. It's something we probably mostly ignore as part of the observing experience.

 

15 years ago, it was not something commonly discussed in this forum. The term EOFB had not been invented yet.

 

I first really became aware of it because I had a 16 mm Type 2 Nagler and a 13 mm Orion Stratus, same as the 23 mm Hyperion. These were both 1.25"-2" eyepieces very similar in size and weight. Sometimes I would grab the 16 mm Nagler, thinking I had the 13 mm Stratus and sometimes I would grab the Stratus thinking I had the Nagler.

 

When I had the Nagler thinking it was the Stratus, my immediate thought was that the Stratus was really a much better eyepiece than I thought, not only was it sharp to the edge but the bright ring at the edge was not there. In a few seconds, I again realized I was looking through the 16 mm Nagler.

 

At the time, I posted about the bright ring with the Stratus and others mentioned they saw it too.

 

With time, the bright ring at the edge of the field became a frequent topic of discussion and it was given the acronym, EoFB for Edge of Field Brightness.

 

Some eyepieces are pretty bad in this regard. The 23 mm Celestron Luminos is probably the worst I've seen.

 

These days, my eyepieces are pretty good in this regard and I just ignore whatever small EoFB I see.

 

Jon

[Echolight]

I think it is more complicated that that.

 

My thinking is that EoFB is in part, a matter of awareness. It's something we probably mostly ignore as part of the observing experience.

 

15 years ago, it was not something commonly discussed in this forum. The term EOFB had not been invented yet.

 

I first really became aware of it because I had a 16 mm Type 2 Nagler and a 13 mm Orion Stratus, same as the 23 mm Hyperion. These were both 1.25"-2" eyepieces very similar in size and weight. Sometimes I would grab the 16 mm Nagler, thinking I had the 13 mm Stratus and sometimes I would grab the Stratus thinking I had the Nagler.

 

When I had the Nagler thinking it was the Stratus, my immediate thought was that the Stratus was really a much better eyepiece than I thought, not only was it sharp to the edge but the bright ring at the edge was not there. In a few seconds, I again realized I was looking through the 16 mm Nagler.

 

At the time, I posted about the bright ring with the Stratus and others mentioned they saw it too.

 

With time, the bright ring at the edge of the field became a frequent topic of discussion and it was given the acronym, EoFB for Edge of Field Brightness.

 

Some eyepieces are pretty bad in this regard. The 23 mm Celestron Luminos is probably the worst I've seen.

 

These days, my eyepieces are pretty good in this regard and I just ignore whatever small EoFB I see.

 

Jon

I was aware that I didn't see it in the 14 until I placed my eye too far away.

Something that might be more common if I wore glasses.

[Jon Isaacs]

I was aware that I didn't see it in the 14 until I placed my eye too far away.

Something that might be more common if I wore glasses.

 

I don't wear glasses..

 

Find a 23 mm Luminos.

 

Jon

[Echolight]

I don't wear glasses..

 

Find a 23 mm Luminos.

 

Jon

I don't need a 23 Luminos 

I already have an APM 20 XWA and 28 PWA. And have come to the conclusion that they are "good enough".

 

I thought about a 20 LHD when FLO was blowing out the Marvels. But I didn't have a spare 1.85 rubber eyecup, and Agena's been out for years.

[Jon Isaacs]

I don't need a 23 Luminos 

I already have an APM 20 XWA and 28 PWA. And have come to the conclusion that they are "good enough".

 

I thought about a 20 LHD when FLO was blowing out the Marvels. But I didn't have a spare 1.85 rubber eyecup, and Agena's been out for years.

 

I agree, they are good enough, I am using them, .  The reason to purchase a Celestron 23mm Luminos is have a good example of an eyepiece that exhibits a great deal of EoFB.. 

 

Jon

[triplemon]

All those that complain so badly about EOFB could well place a carefully sized baffle at the end of the eyepiece barrel and create vigneting that exactly counteracts it.

Heck, you could even make these with filter threads and sell them as separate accesories. Since the spacing and diameter would depend a little bit on f-ratio, you could expand that product line with spacers, make apps to calculate all the "optimal" parameters for any given one eyepiece. And count on that not many are like Jon (or me) that just say - so what 

Edited by triplemon, 07 November 2024 - 01:26 PM.

[Starman1]

I've switched from 12 inch f/5 UC dob to a 355mm f/4.8 sturdy one, that handles heavier EPs with ease and is balanced (with P2). My current set at the moment using with it includes (so this is a total of 1960mm with P2 and f/5.5):

 

40 Paragon (Hbeta only)

30mm UFF

17.3 Delos

13 T6

10 Ethos

8 Ethos

6 Ethos

5 T6 

3.5 T6

 

I left out Pan 24 because it is 'neither here nor there' compared to the others and somehow never feels right. 13T6 is sort a bit of a disruptor in feel of the line. 10-8-6 progression is fantastic. 5 and 3.5 T6 are there 'just in case' the seeing permits.

Two questions.

First, would 30- 20- 13 - 10 progression have more sense in this scope than 30-17-10? This is 65-116-196, so the last jump is huge.

Second, should I go for XWA5, or is T6, long term, sufficient for those fleeting moments of good seeing on planetaries? Too bad I can only use PM2.5 on my 8mm in P2, but that is already 600x.

What follows would be my recommendations, and seeing how it works with your scope.

First, what you have:

30mm UFF 65x

17.3mm Delos 113x

13mm T6  151x

10mm Ethos  196x

8mm Ethos 245x

6mm Ethos 327x

5mm T6 392x

3.5mm T6 560x

Or, a difference of 48x, 38x, 45x, 49x, 82x, 65x, 168x

 

I could live with that set.

Let's start with the 30mm and increase by 40% between eyepieces.  Note: this is common, but results in big jumps at high powers:

30mm...21mm...15mm...11mm...8mm...5.5mm...4mm

Instead, let's start with 65x and increase magnifications by 50x between eyepieces, which makes the high end jumps closer together, %-wise, to bump up against the Seeing ceiling more gradually:

30mm...17mm...12mm...9mm...7.5mm...6mm...5.5mm...4.7mm...4.0mm

What you have:

30mm..17.3mm..13mm..10mm..8mm..6mm..5mm..3.5mm

 

It looks like you're OK on eyepieces, though you might be able to use one in between the 3.5mm and 5mm, like maybe a 4.5mm Delos (436x)

And your jump from 8mm to 6mm is a bit wide, and a 6.7-7.0mm could fit in there.  Interesting.  I felt the jump from 8mm to 6mm was a bit too large and I put the 7mm XWA in between, to discover that

I always jumped the 8mm and went straight to the 7mm, so I sold the 8mm.  However, I had a 9mm I really liked, so 9..8..7..6 was probably a bit too close in terms of a spread.  9..7..6 made more sense.

Whether you feel you need an eyepiece in between 245x and 327x is up to you.  If you rarely go above 245x, maybe not.

 

Your eyepiece set is pretty solid.  I might add the 4.7mm Ethos SX or 4.8mm XWA and sell the 5mm T6, or add the 4.5mm Delos.

Then add a 6.7mm (labeled 6.5mm) Morpheus or a 7.0mm XWA for the in-between 8mm and 6mm.

 

Or not.  I could live with the set you have as long as you definitely don't wear glasses.

Edited by Starman1, 07 November 2024 - 05:02 PM.

[BGazing]

What follows would be my recommendations, and seeing how it works with your scope.

First, what you have:

30mm UFF 65x

17.3mm Delos 113x

13mm T6  151x

10mm Ethos  196x

8mm Ethos 245x

6mm Ethos 327x

5mm T6 392x

3.5mm T6 560x

Or, a difference of 48x, 38x, 45x, 49x, 82x, 65x, 168x

 

I could live with that set.

Let's start with the 30mm and increase by 40% between eyepieces.  Note: this is common, but results in big jumps at high powers:

30mm...21mm...15mm...11mm...8mm...5.5mm...4mm

Instead, let's start with 65x and increase magnifications by 50x between eyepieces, which makes the high end jumps closer together, %-wise, to bump up against the Seeing ceiling more gradually:

30mm...17mm...12mm...9mm...7.5mm...6mm...5.5mm...4.7mm...4.0mm

What you have:

30mm..17.3mm..13mm..10mm..8mm..6mm..5mm..3.5mm

 

It looks like you're OK on eyepieces, though you might be able to use one in between the 3.5mm and 5mm, like maybe a 4.5mm Delos (436x)

And your jump from 8mm to 6mm is a bit wide, and a 6.7-7.0mm could fit in there.  Interesting.  I felt the jump from 8mm to 6mm was a bit too large and I put the 7mm XWA in between, to discover that

I always jumped the 8mm and went straight to the 7mm, so I sold the 8mm.  However, I had a 9mm I really liked, so 9..8..7..6 was probably a bit too close in terms of a spread.  9..7..6 made more sense.

Whether you feel you need an eyepiece in between 245x and 327x is up to you.  If you rarely go above 245x, maybe not.

 

Your eyepiece set is pretty solid.  I might add the 4.7mm Ethos SX or 4.8mm XWA and sell the 5mm T6, ot add the 4.5mm Delos.

Then add a 6.7mm (labeled 6.5mm) Morpheus or a 7.0mm XWA for the in-between 8mm and 6mm.

 

Or not.  I could live with the set you have as long as you definitely don't wear glasses.

Yes, it is one of the possible progressions, although 13mm is a bit off in weight and 'feel' (UFF is almost like a 30mm Delos in use). Not sure I should go for SX in 4.7 and 3.7, as they get limited (but lovely use). E8 takes PM2.5 to 3.2 effectively, which is the upper limit, I guess...too bad 10E cannot be used with PM 2.5 in PII.

In all honestly, 6E is probably the upper seeing limit here on 95 percent of the nights (325x), probably also on PNs and not on planets only. I feel like PNs can take more mag meaningfully. 

I was always intrigued how you dropped 4.7 out of your line-up and went straight to 3.7, fairly interesting.

[Starman1]

Yes, it is one of the possible progressions, although 13mm is a bit off in weight and 'feel' (UFF is almost like a 30mm Delos in use). Not sure I should go for SX in 4.7 and 3.7, as they get limited (but lovely use). E8 takes PM2.5 to 3.2 effectively, which is the upper limit, I guess...too bad 10E cannot be used with PM 2.5 in PII.

In all honestly, 6E is probably the upper seeing limit here on 95 percent of the nights (325x), probably also on PNs and not on planets only. I feel like PNs can take more mag meaningfully. 

I was always intrigued how you dropped 4.7 out of your line-up and went straight to 3.7, fairly interesting.

I do have the 4.5mm Morpheus, which is really 4.8mm.

But, often, if the seeing is good enough for a 6mm eyepiece, it's also good enough for a 3.7mm eyepiece, and planetaries are better in the 3.7mm than they are at lower powers.

I just don't always get to that high a power, alas.

[Jon Isaacs]

All those that complain so badly about EOFB could well place a carefully sized baffle at the end of the eyepiece barrel and create vigneting that exactly counteracts it.

Heck, you could even make these with filter threads and sell them as separate accesories. Since the spacing and diameter would depend a little bit on f-ratio, you could expand that product line with spacers, make apps to calculate all the "optimal" andparameters for any given one eyepiece. And count on that not many are like Jon (or me) that just say - so what 

 

EoFB is not a complaint, it's an observation. It's something that is worth understanding.

 

Jon

[BGazing]

What follows would be my recommendations, and seeing how it works with your scope.

First, what you have:

30mm UFF 65x

17.3mm Delos 113x

13mm T6  151x

10mm Ethos  196x

8mm Ethos 245x

6mm Ethos 327x

5mm T6 392x

3.5mm T6 560x

Or, a difference of 48x, 38x, 45x, 49x, 82x, 65x, 168x

 

I could live with that set.

Let's start with the 30mm and increase by 40% between eyepieces.  Note: this is common, but results in big jumps at high powers:

30mm...21mm...15mm...11mm...8mm...5.5mm...4mm

Instead, let's start with 65x and increase magnifications by 50x between eyepieces, which makes the high end jumps closer together, %-wise, to bump up against the Seeing ceiling more gradually:

30mm...17mm...12mm...9mm...7.5mm...6mm...5.5mm...4.7mm...4.0mm

What you have:

30mm..17.3mm..13mm..10mm..8mm..6mm..5mm..3.5mm

 

It looks like you're OK on eyepieces, though you might be able to use one in between the 3.5mm and 5mm, like maybe a 4.5mm Delos (436x)

And your jump from 8mm to 6mm is a bit wide, and a 6.7-7.0mm could fit in there.  Interesting.  I felt the jump from 8mm to 6mm was a bit too large and I put the 7mm XWA in between, to discover that

I always jumped the 8mm and went straight to the 7mm, so I sold the 8mm.  However, I had a 9mm I really liked, so 9..8..7..6 was probably a bit too close in terms of a spread.  9..7..6 made more sense.

Whether you feel you need an eyepiece in between 245x and 327x is up to you.  If you rarely go above 245x, maybe not.

 

Your eyepiece set is pretty solid.  I might add the 4.7mm Ethos SX or 4.8mm XWA and sell the 5mm T6, or add the 4.5mm Delos.

Then add a 6.7mm (labeled 6.5mm) Morpheus or a 7.0mm XWA for the in-between 8mm and 6mm.

 

Or not.  I could live with the set you have as long as you definitely don't wear glasses.

Well, decided to add 4.7E (CN classfields), but I still feel the 17D-10E jump too wide, and inserting 13E inbetween might be too close.

 

Perhaps a 30UFF-19N7-13E-10E would be a better progression?

Magnification 65x-102x-150x-195x

Exit pupil 5.5-3.5-2.4-1.8

17-13 gap is much closer 112x-150x and 3.0-2.4 exit pupil.

Your thoughts?

[SeattleScott]

Seems pretty good to me.

[Jon Isaacs]

Well, decided to add 4.7E (CN classfields), but I still feel the 17D-10E jump too wide, and inserting 13E inbetween might be too close.

 

Perhaps a 30UFF-19N7-13E-10E would be a better progression?

Magnification 65x-102x-150x-195x

Exit pupil 5.5-3.5-2.4-1.8

17-13 gap is much closer 112x-150x and 3.0-2.4 exit pupil.

Your thoughts?

 

I use the 20mm -13mm -10mm -8mm in my F/4.4 Dobs = F/5.06 with a Paracorr.  I would like to have a 17mm but it would have to be a 100 degree.  Fine tuning exit pupils around 2mm is useful for galaxies and smaller DSOs.  

 

Jon

[BGazing]

I use the 20mm -13mm -10mm -8mm in my F/4.4 Dobs = F/5.06 with a Paracorr.  I would like to have a 17mm but it would have to be a 100 degree.  Fine tuning exit pupils around 2mm is useful for galaxies and smaller DSOs.  

 

Jon

Thanks, that is very usefu to know and matches my experience.

17mm in that scope comes out exactly the same pupil as 19mm in mine.

But yours are even bigger, if I remember, although magnification steps with your 16 are almost the same as my 14.