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Do you find 2" eyepieces more engaging? 

Last week I used my 1.25" EP set with my tak. Despite the similar apparent field of view of some eyepieces (e.g. 24 Pan Vs 30 UFF), the 2" offered a more attractive view to my eye.

I'm not talking about the actual field of view, exit pupil difference, or eye relief, so I guess it was down to the larger top lens in the 2" ep. I will try this again next time.

What are your thoughts on this?

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Posted (edited)

I often think about this subject as I have a collection of 100 degree eyepieces and a collection of orthos. For general observing I prefer the widefields, there’s so much to see. However, if I’m searching for something faint then I nearly always switch to orthos. This happens the most with my 9mm EPs. The Lunt XWA gives way to the Baader Genuine Ortho. The Ortho has better contrast and transmission but a much, much smaller FOV. I can see faint galaxies with it that are lost in the Lunt. I think the smaller FOV can actually help with this too. My honest conclusion is that it’s the right tool for the job. I wouldn’t want to be without either EP. I would like to try a 10mm Ethos though just to see if the TV quality gives performance closer to the BGO than the Lunt. 

Edited by Littleguy80
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Posted (edited)

The diameter of the eye lens is set by the apparent field of view and the eye relief, so the combination of these two must determine your viewing satisfaction?

 

comfort.png.d0b20d77ac514b63aecbefece858fda6.png


Left:      tan (afov / 2) = (diam. eye lens /2) / (eye relief)   =>  diam. eye lens = 2 * (eye relief) * tan (afov /2) 

Right:   actually the eye lens should be a little wider to fully illuminate the exit pupil

 

 

 

Edited by Ruud
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3 hours ago, Littleguy80 said:

For general observing I prefer the widefields, there’s so much to see.

Hi Neil & Piero, I also love the widefields and have just bought a couple of 100 degree eyepieces (at IAS), but have not had chance to try them yet.  However, I also love the convenience of 1.25" ep's, especially my Pan 24mm, which gives a great view of the sky.

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I had a set of Ethos EPs -8mm, 13mm and the 21mm and I sold them and switched to the ES82 range. After a period I regretted that decision so I bought the 20mm and 9mm Myraid and then another 13mm Ethos. I just prefer the 100 degree view.

I also seem to like the ES68 range and have both the 24mm and 16mm but they are mainly for my Heritage 130P which only has a 1.25" focuser.

At the moment to gain higher magnification I use a 1.6x and 2.25x barlows although I would like a new EP in the 5mm/6mm area but I accept unless I can obtain a 5mm Myraid it will be a 1.25" variety.

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For my 12 dob I find my Ethos / Nagler set irresistible. For my refractors I generally find the Delos / XWs / Nagler zoom seem more appropriate. Don't really know why this is - all the refractors (bar the little TV Ranger) will take the 2 inch eyepieces and maintaining the 2 sets does involve some investment duplication :dontknow:

Perhaps all these great eyepiece options are driving us a little crazy ? :tongue:

Oh for the days when the choice was kellner, ortho, plossl or erfle !

 

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My set spans 2" (31T5, 17E), to 1.25" (10E/8E/6E)... and no notable change in experience at the EP that I've noticed at least, other than mag, etc!

Man I love the wide afov - started with plossls and don't personally like the narrow afov.  Was very happy with 82° Naglers ...until I looked through a 20ES100 ?

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Thanks for all your replies, gentlemen!

My ideal AFOV is between 70 and 80 deg, although I enjoy the rest too. 

My TV60 only supports 1.25" eyepieces, so no choice there. As John said, I also prefer 2" eyepieces with my 8 " dob. ..and I very much doubt that this will change with the coming 12"! The Tak Is in between I have to say. Its a bit easier to use with 1.25" EPs, but gosh when the 20mm Lunt or the docter are stuck into the focuser, the views are superb, particularly when scanning Cygnus and Aquila...

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I've decided to get a baader 2.25x Barlow for my Nikon zoom and a baader clamp for attaching the TV60 to the other arm of my Ayo II/Uni19 tripod. Doing so, the TV60 + 32 plossl will work as a finder (11.25x60, 5.3mm e.p., and 4.3deg FOV) for the Tak. The new barlow will cover the range up to the HR 3.4mm.

If used with 1.25" EPs, the Tak could start with the 24 Pan, which works well with that scope. 

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Posted (edited)

Personally I am happy with the smaller FOV, the widest I have is 72 degrees, and I have one 2 inch 68 degree Maxvision which I have used a lot (more at darker sites).   My policy has been to optimise transmission and FOV and avoid big towers and barlows with extra optical elements and an overall heavy kit . In my case my decision was also driven by having a good quality performance across the entire FOV. At f4.7  I would really want a coma corrector for the ultra wide 2 inch eyepieces to do them justice , and that is extra baggage I rather live without. 

My mantra has been to keep it simple, keep it light, that way I don't need counter weights, the standard focussers in both of my scopes handle that setup well. 

Edited by AlexB67

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I need one low mag 2” wide eyepiece. Wider the better. After that, 70°ish works a treat. I believe that at wider than  72°, compromises start to creep in. You can’ne change the laws of physics (although you can get really close if you throw enough money at it ??).

Paul

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24 minutes ago, AlexB67 said:

Personally I am happy with the smaller FOV, the widest I have is 72 degrees,

Delos per-chance?

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4 minutes ago, Paul73 said:

Delos per-chance?

Correct ? 14mm. 

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My set spans both too.

However, I'm a bit confused if we're not actually talking FOV, but just 2"?

On 01/04/2019 at 08:22, Piero said:

I'm not talking about the actual field of view, exit pupil difference, or eye relief, so I guess it was down to the larger top lens in the 2" ep. I will try this again next time.

What are your thoughts on this?

I have an adapter that turns all my 1.25" EPs into 2"! ;)

I'm currently looking at the possibility of an 82° 4mm EP that is most definitely 1.25".

Doesn't the wider FOV necessitate a larger top lens, or am I missing something?

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43 minutes ago, bingevader said:

...Doesn't the wider FOV necessitate a larger top lens, or am I missing something?

Not necessarily. I've had 50 degree eyepieces with massive top lenses, eg: Celestron Ultima 35mm and 82 degree eyepieces with quite small eye lenses, eg: 20mm Nagler Type 5.

I think having a very wide field of view AND long eye relief does require a really large eye lens though.

Don Pensack explains here:

https://www.cloudynights.com/topic/601763-why-does-long-eye-relief-and-a-wide-field-of-view-require-so-much-extra-glass/?p=8270576

 

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Ok, thanks for that John.

Although, that doesn't help with the confusion.

I do prefer a larger lens top, but it doesn't necessarily mean it will have a larger FOV or be 2"?

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2 hours ago, bingevader said:

Ok, thanks for that John.

Although, that doesn't help with the confusion.

I do prefer a larger lens top, but it doesn't necessarily mean it will have a larger FOV or be 2"?

You are right Ben. I enjoy large eye lenses too. The Pentax XW's and Delos have whoppers for 1.25" ~70 degree EP's and are lovely to observe with :smiley:

I have a couple of orthos which are very good optical performers but increasingly I can't be doing with their tiny eye lenses.

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I also prefer large lenses on top of the eyepiece. Just a feeling of comfort.

When I observe I tend to stick with 1 set, instead of mixing between 1.25" and 2" eyepieces. All my medium size eyepieces work in 2" mode with baader adaptors. This is particularly handy with the docter and Zeiss zoom as I can screw the VIP via T2 thread. This gives me a "super high power docter" or a zoom eyepiece that goes down to 2.7mm. The VIP too works in 2" mode only. It is nearly unrecognisable. Love that Lego toy!

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