Explore scientific 24mm 68 degree?

[lee g]

I already own Explore Scientific 30mm and 18mm 82 degrees and always fancied filling the gap with a 24mm 82 degree but due to the high price I am now considering a 24mm 68 degree ep.

Do you all feel this is a worthwhile purchase or should I make do? 
 

 

[inedible_hulk]

Admittedly it depends to some degree on your scope, but I doubt there’s enough difference to make it worthwhile. This is the field of view in mine:

red: 24 82 - Yellow: 24 68 - Green: 18 82

[lee g]

14 minutes ago, inedible_hulk said:

Admittedly it depends to some degree on your scope, but I doubt there’s enough difference to make it worthwhile. This is the field of view in mine:

red: 24 82 - Yellow: 24 68 - Green: 18 82

Wow when you put it like that it hardly seems worth it .

 Scopes I would use it with would be an 8”sct and a 120mm f5 refractor 

The 30mm 82 degree is a bit heavy for the f5 refractor 

[Franklin]

1 hour ago, lee g said:

Do you all feel this is a worthwhile purchase

As above, splitting hairs really. Having eyepiece focal lengths close together when they are short can be useful but at the longer focal lengths it's not that much of a difference.

With a C8.

 

Edited October 31, 2023 by Franklin

[John]

To fill the gap, such as there is, you should really be considering a 24mm 82 degree eyepiece. The 24mm 68 is too close to the true field that the 18mm 82 gives to be worth the investment. 

Edited October 31, 2023 by John

[Franklin]

C8 is a 2m fl scope, with your current eyepieces the jump from 30mm to 18mm is fine, I'd be looking to go the other way and try to get a larger exit pupil for those tricky DSO's. Your ES30/82 gives a 3mmEP, a budget 50mm 2" even though in comparison will be like looking through a straw, will give you a 5mmEP which will help when using filters on elusive targets like the Veil.

Edited October 31, 2023 by Franklin

[PeterC65]

I have the ES 68 24mm and it is my most used eyepiece. I also have the ES 82 14mm and recently bought a StellaLyra 30mm. I find all three useful. I don't think the field of view of the ES 82 18mm and ES 68 24mm are too close because you won't be able to see all of the field in one go with the 18mm whereas you will with the 24mm.

 

[John]

12 hours ago, PeterC65 said:

..... you won't be able to see all of the field in one go with the 18mm whereas you will with the 24mm.

 

Is that because of the tight eye relief with the ES 18mm 82 ?

Edited November 1, 2023 by John

[PeterC65]

19 minutes ago, John said:

Is that because of the tight eye relief with the ES 18mm 82 ?

No, it's because your eyes can only take in 68 degrees, any more than this and you have to roll your eye around the available field of view only seeing part of it at any time.

One of the claims to fame of a 68 degree 24mm eyepiece is that it has the maximum true field of view possible with a 1.25" barrel while also filling the maximum field of view of your eye.

 

[globular]

"Humans have slightly over 210-degree forward-facing horizontal arc of their visual field (i.e. without eye movements)"
https://en.wikipedia.org/wiki/Field_of_view

Nearly all of my eyepieces are over 68 degrees - the widest 92 degrees - and I can assure you it's all there in one go to my eyes.
I agree the centre tends to dominate and the wider field is more like an averted vision presence - but it being there really helps to frame the view, and with slight movement of the eye (eye, not head) you can focus on other parts of the field.  Indeed, moving your eyes around when observing really helps to tease out details as movement is required to trigger some parts of the eye.

I think the 82/24 will be a better long term EP to fill your gap (given you're already using 82 ones) - but agree the 68/24 will provide benefits with your C8 if you can't stretch to the 82.

I would add that you should really fill gaps when you notice you have a gap while observing (i.e. "I could do with more magnification" or "I need a bigger exit pupil") rather than looking at the EPs specs and "wanting" to have all the bases covered.

HTH, YMMV

[johnturley]

16 hours ago, lee g said:

 

The 30mm 82 degree is a bit heavy for the f5 refractor 

I don't think that the 24mm ES 82 degrees is a lot lighter than the 30mm.

It was partly due to the weight that I sold my ES 24mm and replaced it with a 24mm Panoptic, also because the 24mm Panoptic is parfocal with my Type 6 Naglers.

John  

Edited November 1, 2023 by johnturley

[bosun21]

The 24mm SL UFF 70 degrees  is another good eyepiece at this focal length. No good of course if you want only ES in your collection.

[globular]

23 minutes ago, bosun21 said:

The 24mm SL UFF 70 degrees  is another good eyepiece at this focal length. No good of course if you want only ES in your collection.

I have a pair of these for my Binoviewer. I think they're more like 66 degrees, but work very well indeed.  Like you, I got the impression the OP has a preference for ES as he was specifically asking about them..

[Coco]

I have a Maxvision 24mm 82 degrees (same as ES24 )  and its awful in my Celestron 102 f6.5 achro, the last 20% stars look like rice, it needs a coma corrector in my Newtonian, that said in the newt its fantastic! pin sharp.

[Zermelo]

The Opticstar version of the 24/82 is quite a bit cheaper than ES.

They don't do a version of the 24/68.

[Scosmico]

I have the ES 24/82. on my f5 dob it sits on the limit of the coma annoyance. It is a great eyepiece for rich field. I use it a lot.

Edited November 1, 2023 by Scosmico

[PeterC65]

3 hours ago, globular said:

"Humans have slightly over 210-degree forward-facing horizontal arc of their visual field (i.e. without eye movements)"
https://en.wikipedia.org/wiki/Field_of_view

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.

 

[John]

4 hours ago, PeterC65 said:

No, it's because your eyes can only take in 68 degrees, any more than this and you have to roll your eye around the available field of view only seeing part of it at any time.

One of the claims to fame of a 68 degree 24mm eyepiece is that it has the maximum true field of view possible with a 1.25" barrel while also filling the maximum field of view of your eye.

 

I seem to get on quite well with eyepieces up to 110 degrees AFoV but I guess I've had a lot of experience using them so know the technique. 

 

 

[johnturley]

37 minutes ago, PeterC65 said:

 

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.

 

I prefer 65-75 degree (including17.5 mm Morpheus) eyepieces to 80 degree plus eyepieces for low power rich field viewing, and in addition they are not so big, bulky and heavy

John 

[John]

8 minutes ago, johnturley said:

I prefer 65-75 degree (including17.5 mm Morpheus) eyepieces to 80 degree plus eyepieces for low power rich field viewing, and in addition they are not so big, bulky and heavy

John 

We all have our preferences in eyepieces. @PeterC65 said that a person cannot take in a field of view of more than 68 degrees which is simply not my experience. To be fair though he did later quality this in that those are his preferences rather than a blanket statement applying to all.

 

 

 

[PeterC65]

4 minutes ago, John said:

We all have our preferences in eyepieces. @PeterC65 said that a person cannot take in a field of view of more than 68 degrees which is simply not my experience. To be fair though he did later quality this in that those are his preferences rather than a blanket statement applying to all.

My understanding is that most people can generally only take in about 70 degrees at once. Putting that another way, most people will only be able to see a portion of the view through, say, a 100 degree eyepiece at any time. That's not to say people can't make use of all 100 degrees. It just needs you to swivel your eye around to take in different portions of the image. This is certainly my experience of using the ES 68 degree and 83 degree eyepieces.

 

[John]

10 minutes ago, PeterC65 said:

My understanding is that most people can generally only take in about 70 degrees at once. Putting that another way, most people will only be able to see a portion of the view through, say, a 100 degree eyepiece at any time. That's not to say people can't make use of all 100 degrees. It just needs you to swivel your eye around to take in different portions of the image. This is certainly my experience of using the ES 68 degree and 83 degree eyepieces.

 

Each time I read this (you are not the only one who says it) I get out some of my 100 degree AFoV eyepieces and check that I can still see the whole of the field of view without conscious head turning or eyeball rolling or swivelling. As of 15 minutes ago, I still can 🙂

The whole point of ultra and hyper wide eyepieces though is that the edge of the field of view is not really apparent to the observer. As Alan Dyer says in his review of several 100 degree mid-focal length eyepieces "....that’s more or less the point — the eyepiece gets out of the way so you no longer have the sense you are looking through a round porthole or window....."

On the whole, field stops are not terribly interesting to observe in my opinion. It is the space in between them where the fascinating stuff lies 🙂

Edited November 1, 2023 by John

[globular]

5 hours ago, globular said:

I can assure you it's all there in one go to my eyes

There are two of us at least John.

[inedible_hulk]

23 hours ago, lee g said:

The 30mm 82 degree is a bit heavy for the f5 refractor 

Sorry to go off topic, but do you get much use out of the 30mm? It’s the only 82 I don’t own, but I have been put off by its size and perceived (to me) usefulness. I do like these eyepieces and I’m surprised they’re not more popular.

[lee g]

4 minutes ago, inedible_hulk said:

Sorry to go off topic, but do you get much use out of the 30mm? It’s the only 82 I don’t own, but I have been put off by its size and perceived (to me) usefulness. I do like these eyepieces and I’m surprised they’re not more popular.

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.