From 8 mm to 7 mm, would I even notice the difference?

[The Lapwing]

I probably know the answer to this already, but you know how it is, you  need to hear it from someone else sometimes.

I have, as you can see a minimalist set of astro kit and like to keep everything as simple as I can in the field. Everything is 1.25 as I hate changing over to 2 inch eyepieces and have same dislike of barlows. 

Anyway I digress a little. I was thinking about a move to a 7 mm Delite from a 8 mm Radian, but would I notice the difference. I have no complaints about the Radian btw, I have always liked them.

 

Edited July 10, 2023 by The Lapwing
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[oldfruit]

If you have a TV 102 with a focal length of 880mm then the 8mm will give 110x. The 7mm will give you 125x, so there will be a small increase in magnification, however not enough to justify the purchase in my opinion.

[NGC 1502]

I’m a Radian fan as well.

I’m thinking the shift from 8mm to 7mm is not worth worrying about.  I’ve tried a clubmates 9mm Delite, best part is the lightweight design compared with the Radian.  The Delites have well documented and deserved approval in many reviews.

I’m also a minimalist by nature……..unfortunately I’ve not kept to that in practice😁

[John]

Personally I would probably make that move for the optical quality rather than the focal length, but whether I would notice the difference, I don't know because I have not yet used a Delite. I have owned some Radian eyepieces and enjoyed them. I did notice the difference in optical quality between the Naglers and Ethos when I (over some time) made that move. I thought that the Delos were a subtle improvement over the Radian's as well and the Delites are reported to be at least Delos good, if not a touch better.

Whatever you do, the differences will only be slight and what you have is already a pretty darn decent eyepiece set 🙂

 

Edited July 9, 2023 by John

[Don Pensack]

2 hours ago, The Lapwing said:

I probably know the answer to this already, but you know how it is, you  need to hear it from someone else to say it sometimes so you can move on....

I have, as you can see a minimalist set of astro kit and like to keep everything as simple as I can in the field. Everything is 1.25 as I hate changing over to 2 inch eyepieces and have same dislike of barlows. 

Anyway I digress a little. I was thinking about a move to a 7 mm Delite from a 8 mm Radian, but would I notice the difference. I have no complaints about the Radian btw, I have always liked them.

 

Not worth it for such a slight difference.

It would be worth it if moving from the Radian to, say, an APM 7mm XWA 100° eyepiece (which is also 1.25"), where the field would be 2.78x as large in area and 1.67x as wide.

But, if the intention is to have small, lightweight, eyepieces in 1.25", and you use glasses at the eyepiece, then stick with what you have.

Another, wider, small, lightweight, 1.25" eyepiece would be the 7mm TeleVue Nagler Type 6.  In that case 1.87x as much area of true field and 1.37x as wide.  Like the XWA, not glasses-compatible.

[Louis D]

Pick up a Svbony 3-8mm zoom and try the different magnifications yourself to see if you are missing any "in between" fixed focal lengths.

[The Lapwing]

Thanks for your replies folks, much appreciated. Sometimes you just have to go through the process of elimination don't you? I will stick with my current kit, I can't see me changing anything now.
 

However I should buy a cheap zoom for outreach this autumn, suggestions welcome 

Edited July 10, 2023 by The Lapwing
Predictive text nightmare

[The Lapwing]

15 hours ago, John said:

Personally I would probably make that move for the optical quality rather than the focal length, but whether I would notice the difference, I don't know because I have not yet used a Delite. I have owned some Radian eyepieces and enjoyed them. I did notice the difference in optical quality between the Naglers and Ethos when I (over some time) made that move. I thought that the Delos were a subtle improvement over the Radian's as well and the Delites are reported to be at least Delos good, if not a touch better.

Whatever you do, the differences will only be slight and what you have is already a pretty darn decent eyepiece set 🙂

 

Thanks John, appreciated 

[John]

4 hours ago, The Lapwing said:

Thanks for your relies folks, much appreciated. Sometimes you just have to go through the process of elimination don't you? I will stick with my current kit, I can't see me changing anything now.
 

However I should buy a cheap zoom for outreach this autumn, suggestions welcome 

I currently have 3 zooms. The Nagler 2-4mm is not one that I would suggest for outreach but the Hyperflex 7.2mm - 21.5mm and the Baader 8-24mm Mk IV (a recent acquisition) would seem suitable for this purpose. They are easy to use and reasonably comfortable with regards to eye positioning. People who have not used scopes before find the zoom capability very interesting and it helps the flow of an outreach session not having to change eyepieces.

The only slight drawback that I have found with the Baader zoom is that it is not par-focal and the focus needs some adjustment (perhaps more than I expected ?) after changing the focal length. The field of view that the Baader offers is appreciably larger than the Hyperflex throughout the focal length range although the latter is a pretty sharp eyepiece for it's cost.

I have used the Hyperflex for outreach in the past quite a bit but I'll try the Baader this summer (solar outreach) and see what the punters think of it 🙂

Edited July 10, 2023 by John

[The Lapwing]

8 hours ago, John said:

I currently have 3 zooms. The Nagler 2-4mm is not one that I would suggest for outreach but the Hyperflex 7.2mm - 21.5mm and the Baader 8-24mm Mk IV (a recent acquisition) would seem suitable for this purpose. They are easy to use and reasonably comfortable with regards to eye positioning. People who have not used scopes before find the zoom capability very interesting and it helps the flow of an outreach session not having to change eyepieces.

The only slight drawback that I have found with the Baader zoom is that it is not par-focal and the focus needs some adjustment (perhaps more than I expected ?) after changing the focal length. The field of view that the Baader offers is appreciably larger than the Hyperflex throughout the focal length range although the latter is a pretty sharp eyepiece for it's cost.

I have used the Hyperflex for outreach in the past quite a bit but I'll try the Baader this summer (solar outreach) and see what the punters think of it 🙂

I had a Baader years ago, but it fell apart (honestly) and so it went back to FLO and I never bought another. I might have a look at the Hyperflex instead 

[John]

1 hour ago, The Lapwing said:

I had a Baader years ago, but it fell apart (honestly) and so it went back to FLO and I never bought another. I might have a look at the Hyperflex instead 

I had the Baader MkIII a few years back and it did seem a bit flimsy. The MkIV seems better put together. Hopefully it will stay in 1 piece long enough for me to see how it fares !

 

 

[Alan White]

I think you have made the correct call on the Radian and DeLite, I have used both and optically very little if any difference.

The 8 to 7 step is too small I think.

The only advantage is a weight saving with the DeLites.

But I think you already knew this and needed positive confirmation from us all, which is most sensible indeed.

Amazed no one’s tried to encourage a purchase though

Edited July 11, 2023 by Alan White

[John]

5 minutes ago, Alan White said:

But I think you already knew this and needed positive confirmation from us all......

 

Well, not quite all 

[michael.h.f.wilkinson]

Just to give a dissenting opinion: I have a series of planetary eyepieces, quite closely spaced to adjust to the seeing In my C8 the Pentax XW 10mm gives me 203x,  the Delos 8mm (made par-focal with the XWs) gives 254x, the XW 7mm gives 290x. I also have a Vixen SLV 9mm (226x) in my travel kit, which I am tempted to use to bridge the gap between 10 and 8 mm. In rare cases of superb seeing, and then only on Moon and Mars, I might even use the Delos 6mm 338x, or the XW 5mm 406x. I use the latter EPs in my 80mm F/6 triplet and 6" F/5 Schmidt-Newton a lot more.

[Mr Spock]

6 minutes ago, michael.h.f.wilkinson said:

Just to give a dissenting opinion: I have a series of planetary eyepieces, quite closely spaced to adjust to the seeing In my C8 the Pentax XW 10mm gives me 203x,  the Delos 8mm (made par-focal with the XWs) gives 254x, the XW 7mm gives 290x. I also have a Vixen SLV 9mm (226x) in my travel kit, which I am tempted to use to bridge the gap between 10 and 8 mm. In rare cases of superb seeing, and then only on Moon and Mars, I might even use the Delos 6mm 338x, or the XW 5mm 406x. I use the latter EPs in my 80mm F/6 triplet and 6" F/5 Schmidt-Newton a lot more.

Same here. With the C9.25 I had 12mm, 10mm, 9mm and 8mm; with the 100mm apo I have 4mm, 3.3mm and 2.5mm; with the 12" I have 7mm, 6mm, 5mm and 4mm. When doing planetary work small increments are the best way to get the most out of the seeing conditions.

[John]

I agree. With my refractors my most used 1.25 inch set goes 24mm, 14mm, 10mm, 7mm, 5mm, 4mm and then .5 mm steps down to 2mm. All but the 2mm get plenty of use.

That's why the short focal length zooms can be so useful - you get the FL's between the click stops as well !

 

 

[Saganite]

When I had my 5" f15 refractor I would very definitely  have had an 8mm and a 7mm they giving a difference in mag  of 34x, but now I don't consider it necessary, so my 1.25" eyepieces are 32mm, 24mm, 18mm, 13mm, 10.5mm, 8.5mm  and 6.3mm, with a decent zoom lens for double stars. 

[IB20]

3 hours ago, Mr Spock said:

When doing planetary work small increments are the best way to get the most out of the seeing conditions.

Agree 100% with this. Also, you can never have enough EPs. 😁

[Don Pensack]

The planet/seeing issue is why a constant magnification increase makes more sense than a constant % change.

Pentax and Baader use constant % changes and this results in too-large magnification changes at high powers and too-small magnification changes at low power.

Example:

8" SCT with 2032mm focal length:

Constant magnification: 50/100/150/200/250/300x.  By % change it is +100%, +50%, +33.3%, +25%, +20%.

Constant % change (using 40%, a common increase): 50/70/98/137/192/269/376x, or increases of 20x, 28x, 39x, 55x, 77x, 107x

 

If bumping up against the seeing conditions, the first makes more sense than the latter.

 

One exception, however, could be a person whose interest is mostly deep sky with a side interest in planets.

In my 12.5", for example, I keep magnification increases modest until 300x, and when the seeing is good enough that 300x is sharp and steady, jumping to 400x and 500x above that seems fine for the objects that are typically viewed at such high powers.

I don't feel the need for small magnification changes at low powers or the highest powers, only in the middle range where I spend most of my observing time.

Hence the "U" shaped magnification regime, where magnifications slowly increase or decrease on either side of a most-used magnification and get larger the farther the choice is away from that magnification.

At low powers, large jumps in magnification are required to make an appreciable difference in the views.  At high powers, if a certain magnification isn't enough, a large jump will get you to the power you need.

This protocol works fine as long as you observe at a site with good seeing, but wouldn't work for a planet observer in mediocre seeing.

There, the best idea seems to be to creep up on the maximum by having higher powers closer together.

Edited July 12, 2023 by Don Pensack

[Mr Spock]

Same here. With the 12" I start at x217, if the seeing is excellent I jump straight to x461 (when observing the moon).

[John]

1 hour ago, Mr Spock said:

Same here. With the 12" I start at x217, if the seeing is excellent I jump straight to x461 (when observing the moon).

Sounds like cracking optics in your 12" Michael 🙂

 

[Mr Spock]

28 minutes ago, John said:

Sounds like cracking optics in your 12" Michael 

In excellent seeing, at those magnifications, it's razor sharp. I can see fine rilles, split the double craterlets h and p in Plato, plus see others smaller than those. But, only when the seeing is good enough.

The other part of the equation is collimation. It needs to be spot on - near enough isn't good enough.

[Stu]

38 minutes ago, Mr Spock said:

split the double craterlets h and p in Plato

Not seen these, but are they both double craters? They look well separated so more a case of seeing them than splitting them perhaps? I normally fail to split C and D in the 4”, when I can see them that is 🤪

[John]

On the best lunar night I can remember I managed to see 11 Plato craterlets with my 12 inch OO dob. The illumination was spot on and I was getting them as tiny pits with an illuminated rampart during the moments of best seeing. I recall my Pentax XW 5mm being "the one" on that night so that was 318x. Good memories 🙂

[Stu]

10 minutes ago, John said:

On the best lunar night I can remember I managed to see 11 Plato craterlets with my 12 inch OO dob. The illumination was spot on and I was getting them as tiny pits with an illuminated rampart during the moments of best seeing. I recall my Pentax XW 5mm being "the one" on that night so that was 318x. Good memories 🙂

I must get my 12” finished off for this kind of view, I have a lovely Nichol Mirror just waiting to go in it!