Explore scientific 24mm 68 degree?

[John]

1 hour ago, lee g said:

It really is a treat to look through though it is probably the least used mostly because of it size.

when I first bought the ES 82s I purchased the 30mm, 18mm, 11mm and 8.8mm as well as a 1.25” Barlow.

I have the Nagler 31mm and it is my least used eyepiece for that reason and also that my moderate light pollution generally means that I get better views of fainter targets with a 21mm eyepiece.

I'm still glad to have the 82 / 31mm for when I want to go as wide as possible though 🙂

[lee g]

7 hours ago, John said:

I'm still glad to have the 82 / 31mm for when I want to go as wide as possible though

I totally agree even though my 30mm is the least used I wouldn’t be without it.

[lee g]

After careful consideration I think I’ll be saving my pennies for now until a reasonably priced used ES24mm 82 degree becomes available after reading the replies to this post I don’t feel that an ES24mm 68 degree could bring enough to the table to justify its price 

nevertheless it’s been interesting reading and goes to show it’s never as straightforward as first thought 

[Don Pensack]

21 hours ago, PeterC65 said:

I think that's referring to both eyes, operating unaided.

The maximum apparent field of view that is visible will vary from person to person, just like exit pupil size, but it is around 68 degrees. What I mean by the maximum apparent field of view is when opposite edges of the field stop can just be seen at the same time. With the ES 68 24mm I can see opposite edges, with any of my ES 82 degree eyepieces I cannot. I can see right to any one edge by swivelling my eye, but I can't see the opposite edge at the same time. It might feel like you are seeing both edges but in fact you're seeing one field stop edge and the edge of your own vision. You can check this by swivelling your eye towards that edge and you will then see more sky appearing.

Wide apparent field of view eyepieces are often recommended for people using manual Dobsonians as objects can be allowed to drift further and yet still be visible by swivelling your eye.

Personally I find my vision is best when I'm looking straight on through the eyepiece and I struggle a bit when swivelled, so for me 68 degrees is enough.

 

If you stare at the center of the field, no one with normal vision would have a problem seeing the edge of a 100 or 110° eyepiece in peripheral vision.

Each eye has about a 145° lateral and 125° vertical field of vision.

But, you are generally correct about 68-70° fields when you want to look at one edge and still see the other edge with peripheral vision.

Turning you head on your neck to look directly at the edge becomes second nature when you do it for quite a few years.  The fact peripheral vision cannot see the opposite edge 100° away never bothered me one iota.

It's like having a stage too wide for the spotlight to see it all at one time.  It's still nice to have the rest of the stage there when you want to look at it.

[Louis D]

What about getting a 20mm 100 degree eyepiece instead of the ES 24mm 82 degree?  It should have similar TFOV and eye relief but at a slightly higher magnification.  The various Lunt/APM HW rebrandings here in the US tend to be cheaper than the similar focal length ES 82 degree offerings.

Edited November 2, 2023 by Louis D

[John]

6 minutes ago, Louis D said:

What about getting a 20mm 100 degree eyepiece instead of the ES 24mm 82 degree?  It should have similar TFOV and eye relief but at a slightly higher magnification.  The various Lunt/APM HW rebrandings here in the US tend to be cheaper than the similar focal length ES 82 degree offerings.

I was thinking just that, earlier.

This UK vendor seems to have stock and reasonable pricing:

APM 20mm XWA 100 Degree AFOV Eyepiece (astrograph.net)

Edited November 2, 2023 by John

[lee g]

2 hours ago, Louis D said:

What about getting a 20mm 100 degree eyepiece instead of the ES 24mm 82 degree?  It should have similar TFOV and eye relief but at a slightly higher magnification.  The various Lunt/APM HW rebrandings here in the US tend to be cheaper than the similar focal length ES 82 degree offerings.

Noooo just as I thought I had it all figured out 😂

[Franklin]

Talking of FOV size I had a face off the other week between an LVW3.5 65deg, an SSW3.5 83deg and a HR3.4mm 42deg. Of course these short fl eyepieces gave silly high magnification in the ED102S F9, so I wasn't looking at large vistas but at the planet Saturn. They all gave a nice view when the seeing cooperated but what I felt about the FOV difference was that the LVW was the most comfortable to look through (maybe that's the longer eye-relief), the SSW gave the most drift time but I could see the whole field at once and the HR, which compared to the other two was like looking through a straw gave easily the best view, such high contrast, even at 270x.

[bingevader]

I find, at most, I only need to move my eye to see the whole field of view in an 82° ep.

However, if you needed any further justification for buying low mag, wide fov eye pieces, that would appear to be not too dissimilar in magnification or field of view!

I've found that (if you don't own a filter wheel) swapping between a non filtered and filtered ep of similar mag and fov when locating nebulae makes a world of difference.

Star hop with the one and then swap to the other.