16 replies to this topic

[vicuna]

i have read 30 threads on this. I don't know why it's not sinking in to my brain so sorry to repeat.

 

how do I calculate the FOV with eyepieces bino-viewing?

 

is there some sort of max?

 

is it even worth it to have Naglers where there is an 82 degree and you have to move your eyes around? will you see the entire field?

 

let's leave out vignetting due to field stop for low powers...I pretty much get that part get that part.

 

so for example let's say you use the APM super zooms all the way zoomed in at 7.7mm it's 67 degrees. vs a Nagler 7mm with 82 degree FOV

 

thank you so much for anyone who talks to me like i'm a 4th grader

 

ETA: i have Denis' CZAS for moderate to high power views.

main scope will be 140 f6.5 refractor (910 focal length) that is binoviewer friendly

Edited by vicuna, 21 May 2024 - 02:00 PM.

[ubcastro]

I've used a variety of apparent FOV eyepieces when I'm binoviewing, including Naglers (82 degree), Panoptics (68 degree), Plossls (50 degree), and Fujiyama Orthos (42 degree). When binoviewing, I find that the apparent field of view looks larger than when I'm mono-viewing. Although the Naglers were a fun novelty initially (especially on the moon with my SCT, feels like you're looking at the moon out of a spacecraft in orbit), for critical observing I find that the larger FOV is more distracting than helpful, and I gravitate to eyepieces that have superb centre resolution/contrast at the expense of a large AFOV like orthos or Leica/Zeiss microscope eyepieces. 

 

It really depends on what you're observing. If you want to fit large nebula/galaxies in the field of view, it makes sense to go with the largest AFOV eyepiece you can fit between your IPD, but for critically observing planets/moon/sun when you're focused on one small part of the FOV at a time, a pair of orthos will serve you well. 

[bsturges]

You should mention exactly which model you have so folks with comparative binoculars can suggest what they are using. I've found that the choice of eyepieces has been one of the most uncertain questions I've had about the equipment I've used over the years. There are just so many to choose from, and I've wished there was a local place I could rent from.

[vicuna]

i have Denis' CZAS for moderate to high power views.

 

main scope will be 140 f6.5 refractor (910 focal length) that is binoviewer friendly

 

this is what i'm most confused about...with an 82 degree field of view, you can't really use it all, right? like if you look right, won't you not be able to merge the images at some point? so is the point of getting the naglers just to have a more immersive view? (other than the quality of the glass)

Edited by vicuna, 21 May 2024 - 02:00 PM.

[MisterDan]

The "point" is subjective.

 

Some people love ultra-wide fields of view (even if the entire field is not "discernible" at a given instant; it IS visible - just maybe not "usable" or "fully discerned" or...).

 

Other people shrug their shoulders and think, "Meh. That extra umpteen degrees doesn't impress my eyes at all."

 

Similar subjectivity is EVERYWHERE in our lives.  This car versus that car.  This stereo...that one.  Brian Regan or Mike Birbiglia...

 

Cheers and best wishes.

Dan

[betacygni]

The problem with very wide AFOV is normally to examine the edges of AFOV in mono you have to move your head slightly to keep the exit pupil centered on your eye. But with two eyed viewing moving your head will cut off the exit pupil in the other eye. So essentially binoviewing you have to keep your gaze roughly centered. Past about 60 degrees AFOV give or take I can’t view the edges directly without losing an exit pupil.

Now that said a wide AFOV can still provide peripheral vision and a greater sense of “expanse” to the view, but it’s very challenging if not impossible to really directly observe those edges.

[Eddgie]

i have read 30 threads on this. I don't know why it's not sinking in to my brain so sorry to repeat.

 

how do I calculate the FOV with eyepieces bino-viewing?

 

is there some sort of max?

 

is it even worth it to have Naglers where there is an 82 degree and you have to move your eyes around? will you see the entire field?

 

let's leave out vignetting due to field stop for low powers...I pretty much get that part get that part.

 

so for example let's say you use the APM super zooms all the way zoomed in at 7.7mm it's 67 degrees. vs a Nagler 7mm with 82 degree FOV

 

thank you so much for anyone who talks to me like i'm a 4th grader

 

ETA: i have Denis' CZAS for moderate to high power views.

main scope will be 140 f6.5 refractor (910 focal length) that is binoviewer friendly

It is the same with binoviewers as it is without.  Divide the field stop of the eyepiece by the focal length of the scope and multiply by 57.3.

 

For the 7mm Nagler, the field stop is 9.7mm, so the true field would be 7 / 910 x 57.3 or .44076923076 degrees. 

 

I don't know the field stop size of the zoom, but if you can find that, you do the same thing.  

 

Of course if you  are using a Barlow or GPC or other amplifier, you would find the new effective focal length of the system and use that. 

 

As to the 82 degree field, some report that they can take it in by simply rolling their eyes up/down/left/right, and others report that they cannot. You usually can't tilt your head when using eyepieces or you will lose the exit pupil or have spherical aberration of the exit pupil (kidney bean/blackout) so the answer can only be known if you try it out.  

Edited by Eddgie, 22 May 2024 - 08:18 AM.

[noisejammer]

My experience is that I can comfortably observe an apparent field of 70 degrees.

 

I use orthoscopics (usually 10 & 16), Delos (6 / 10 / 14), Vixen LVW (22), Pentax XW (5) and Docter clones (12.5). The Nagler 16T5 is among my favourites. It really doesn't matter as long as your binoviewers hold them square to the optical axis, you set the IPD correctly, your focuser can cope with the weight and they are comfortable.

 

In terms of true field of view, this is more complicated because the aperture of the binoviewer can constrict the field of view. The widest true field I can achieve is about 2.2 degrees using my 115/805, Mk V binoviewers and 35 mm Masuyama eyepieces. I think the OP's scope / binoviewer combination is more likely to be limited to around 1.6-1.7 degrees.

[vicuna]

 

I use orthoscopics (usually 10 & 16), Delos (6 / 10 / 14), Vixen LVW (22), Pentax XW (5) and Docter clones (12.5). The Nagler 16T5 is among my favourites. It really doesn't matter as long as your binoviewers hold them square to the optical axis, you set the IPD correctly, your focuser can cope with the weight and they are comfortable.

 

nice thank you.

 

how do you decide between the ortho at 16mm, delos at 14mm, and nagler 16. aren't they all super similar? even the Vixen 22 seems super close. what makes you pick one over the other?

[noisejammer]

nice thank you.

 

how do you decide between the ortho at 16mm, delos at 14mm, and nagler 16. aren't they all super similar? even the Vixen 22 seems super close. what makes you pick one over the other?

Short answer - I'm just loopy. I drove a very old car which meant my toy budget was excessive.

 

To be honest, I don't really like the 14 Delos. I can't really say why but it's really between the 16's and my Docter clones. I use my orthoscopics (ZAO II) when I'm looking at the moon (using a Barlow + GPC) or I'm trying for deep objects at my scope's limit. They have essentially no scatter and allow my TOA150 to achieve everything a 6" can achieve.

 

I use the 16T5 a lot although I've recently found my APM 12.5-alphabet-soup spends more time in the scopes. It's more comfortable to use.** I switch between the 1.7x (really 1.5x) and 1.25x GPC. These give me 1.5 & 1.4 mm exit pupils which is so close to not matter at all.

 

On the 22 LVW .. that's because I really dislike the 24 Panoptic (pin cushion distortion) and the old 22 Pan is not very sharp. The 22 LVW is about the best eyepiece ever made in this focal length. They give me a 3.0.  2.4 or 2.0 mm exit pupils (GPC choice) which is about as good as it gets.

 

** This eyepiece has had a lot written about EOFB. Don & I have discussed it at length & I find it comes & goes. It's weird.

[faackanders2]

i have read 30 threads on this. I don't know why it's not sinking in to my brain so sorry to repeat.

 

how do I calculate the FOV with eyepieces bino-viewing?

 

is there some sort of max?

 

is it even worth it to have Naglers where there is an 82 degree and you have to move your eyes around? will you see the entire field?

 

let's leave out vignetting due to field stop for low powers...I pretty much get that part get that part.

 

so for example let's say you use the APM super zooms all the way zoomed in at 7.7mm it's 67 degrees. vs a Nagler 7mm with 82 degree FOV

 

thank you so much for anyone who talks to me like i'm a 4th grader

 

ETA: i have Denis' CZAS for moderate to high power views.

main scope will be 140 f6.5 refractor (910 focal length) that is binoviewer friendly

Yes you can see 82afov with 2 eyes, but not full 100afov with both eyes.

[ABQJeff]

I can use 82 degree EPs fine in BVs, and ignoring vignetting (which is applicable if BV clear aperture is close to or larger than the EP field stop), max field of view is same as without BVs.  BVs do make objects and scenes appear larger.

 

Jeff

Edited by ABQJeff, 05 June 2024 - 08:03 PM.

[slavicek]

Again, you CAN use Naglers in binoviewers and have no vigneting. I use CZAS, Baader Mark V and TV binoviewers with Naglers and have no problem with them. 

[Kutno]

 

is it even worth it to have Naglers where there is an 82 degree and you have to move your eyes around? will you see the entire field?

 

 

 

I agree with slavicek about using Naglers in binoviewers and having "no problem with them." 

 

My eyes are more relaxed using Naglers in binoviewers vis-à-vis Plossls.  Eye movement contributes to the more relaxing experience with Naglers.  When I use Plossls, I feel more constrained to stiffly hold my head when viewing.  Naglers facilitate a more natural movement of eyes and neck with their ample field of view.  

[Kutno]

this is what i'm most confused about...with an 82 degree field of view, you can't really use it all, right? like if you look right, won't you not be able to merge the images at some point? so is the point of getting the naglers just to have a more immersive view? 

 

You sure can use all of the Nagler's 82° field of view.  Merging is not an issue at all with any of the Type 6s or the 16mm Type 5.  Getting immersed in their ample fields of view is one of the charms of Naglers, in addition to their sharpness, contrast, and scatter control. 

[wolfli]

it's kind of weird but definitely true.

 

when I observe with the Quark chromosphere with a 90mm f/6, I can't see the full disk at all if I just use a TV 32mm plossl with no binoviewer. The field stop was a fussy black line and I can't see the sun's boundary when the sun is centered.

 

But when I use that same eyepiece with the denk binotron 27, I can see the full disk, albeit less bright at the boundary. But the boundary of the sun is visible, clear and sharp. I can even see proms all around at once.

 

The simple theory says that the TFOV in this case is determined by the small field stop of the Quark. So with or without binoviewer shouldn't make any diff. I don't understand how this can happen at all.

Edited by wolfli, 06 June 2024 - 09:59 PM.

[Brollen]

I find this site helpful when trying to understand FOV and other characteristics of my optical setup:

 

https://skyandtelesc...ope-calculator/

 

Enter the characteristics of your optical train and press calculate, you will a number of attributes.

 

Hopefully it is correct! But comparatively speaking, I have found it to be very useful in comparing my different scopes and then validating through the eyepiece(s).

 

Clear skies!