Another EP choice question!

[Markinaboat]

Recently acquired my first newt (Orion XT8i push to) and building up a collection of decent EP's for visual only. Have bought used an ES 30mm 82deg, TV Nagler 22mm Type 4 and a Delos 10mm.

Now considering a Delos 17.3 or 14mm. Whilst the 14mm magnification sits between the 22mm and 10mm, and given that I'm mostly into DSO, which one may be the best option for the time being? I do realise it's often subjective but all views most welcome (no pun intended!)

I'll also be looking for a high mag for planets and small DSO's (on a very dark night) but whilst I don't wear my specs for observing, am not sure this will remain so over the next year or two so eye relief is a consideration. As I'm manual/push to, TFOV is also a consideration but not sure I want to dive into the 100 deg arena yet.

My current short list for the high mag is as follows but constantly evolves:

Delos 4.5mm 76 deg (er 20) 

Pentax XW 5mm 70 deg (er 20)

ES 4.7mm 82deg (er 13.6)

Nagler 5mm 82 deg (er 12)

 

Thanks for taking the time to read this!

[Piero]

With that telescope, I'd add only a 6mm, but not 14mm or 17mm.

I add the ES 30mm 82 and it's a good match.  The only reason why I sold it was its weight. 

Enjoy the sky!

[Markinaboat]

4 minutes ago, Piero said:

With that telescope, I'd add only a 6mm, but not 14mm or 17mm.

I add the ES 30mm 82 and it's a good match.  The only reason why I sold it was its weight. 

Enjoy the sky!

Thanks for your feedback Piero. You could be saving me money! I wasn't sure if the 30mm would be too heavy but it worked just fine on first light with it!

[Ricochet]

I go 28-14-10 and then use a 2x barlow for 7 and 5. I think the 10-14 "gap" is ideal when it comes to DSOs.

[Piero]

44 minutes ago, Markinaboat said:

Thanks for your feedback Piero. You could be saving me money! I wasn't sure if the 30mm would be too heavy but it worked just fine on first light with it!

30mm gives you 5mm exit pupil and 2deg fov on that scope.

A 12-10mm eyepiece gives you something between 1.5mm and 2mm exit pupil, which works well as middle power. 

A 6mm gives you 1mm exit pupil which is a great high power considering the seeing in the UK. 

I'd keep it simple and focus on the views rather than on the number of eyepieces.

 

I prefer Barlows with a zooms rather than single focal length eyepieces. 

[Piero]

If the 30mm is too heavy for you, alternatives could be APM uff 30mm, nagler 26, 35 panoptic.

For televue, I'd look at the second hand market. The UFF 30 is a great eyepiece in my opinion and in the same weight class as your Delos.

[Markinaboat]

Thanks for the tips guys! Have read a Barlow will increase ER with the Deloise 20mm ER? Could a TV Powermate (x 2.5) be a better option and worth saving for? 

[John]

38 minutes ago, Markinaboat said:

Thanks for the tips guys! Have read a Barlow will increase ER with the Deloise 20mm ER? Could a TV Powermate (x 2.5) be a better option and worth saving for? 

Barlows do increase eye relief - the sliding eye cup section of the Delos might be able to cope with it though ???

Powermates are optically wonderful and don't have this effect but they are pricey. The Explore Scientific 2x Focal Extender does pretty much the same as a Powermate at quite a bit less cost if you can find one.

 

 

[Markinaboat]

3 minutes ago, John said:

Barlows do increase eye relief - the sliding eye cup section of the Delos might be able to cope with it though ???

Powermates are optically wonderful and don't have this effect but they are pricey. The Explore Scientific 2x Focal Extender does pretty much the same as a Powermate at quite a bit less cost if you can find one.

 

 

Good point on reducing the Delos .. it's been a long day! Interestingly, there is a 2.5x powermate on ABS.n This would go well with the Delos 14 giving around 5.6 but just for the one ep? Or hold out for used Delos 14 and 6..decisions!

[Louis D]

Remember that the 14mm and 17.3mm Delos require 1/2" more infocus than the 12mm and below focal lengths.  Make sure you have that much infocus left or you'll need to buy a special adapter to submerge the eyepiece shoulder below the level of the 2" focuser.

By most accounts, the 17.5mm Morpheus is about equal to the 17.3mm Delos.  The same is not true of the 14mm offerings.  The Delos is definitely better than the Morpheus.  I have the 14mm Morpheus and Pentax XL.  Field curvature is visible in both, but the Pentax is sharp to the edge once refocused while the Morpheus is astigmatic at the edge.  The 14mm Delos is reportedly flat of field and sharp to the edge.

I would get a 4.5mm to 6.5mm eyepiece before getting something between 10mm and 22mm.  It will be nice for planets, luna, globular clusters, and planetary nebula.

Do you have a coma corrector yet?  The 30mm ES-82 and 22mm Nagler will both definitely benefit from it.  Both clean up nicely to the edge with it.  I use a GSO/Revelation CC with a 25mm extension between the eyepiece holder and the optics section.  My 10mm Delos shows no difference with or without a CC.  At high powers, you'll want to remove it due to slight spherical aberration that lightly blurs low contrast planetary details.

[John]

48 minutes ago, Markinaboat said:

Good point on reducing the Delos .. it's been a long day! Interestingly, there is a 2.5x powermate on ABS.n This would go well with the Delos 14 giving around 5.6 but just for the one ep? Or hold out for used Delos 14 and 6..decisions!

Louis is correct re: the additional infocus - it's worth bearing in mind especially if a barlow means you need even more.

Another downside about using a barlow or Powermate with an already large / tall eyepiece is that the stack sticking out of the focuser gets pretty long:

 

[Paz]

With my 350mm f4.6 newtonian my eyepiece set was originally

31mm and 22mm Naglers and 17.3mm, 12mm, 8mm, 6mm, 4.5mm, and 3.5mm Delos.

I found over time I often felt I could do with something in between 12mm and 8mm but I never felt the need to fill the gap between 17.3mm and 12mm.

I eventually got a 10mm Delos and never got a 14mm but have been content ever since.

[Louis D]

28 minutes ago, John said:

Another downside about using a barlow or Powermate with an already large / tall eyepiece is that the stack sticking out of the focuser gets pretty long:

Add a coma corrector to the stack for even more length, though I generally remove mine when using a barlow.

[Piero]

Personally, I don't feel the need of a coma corrector at F6, particularly with 70 Deg afov eyepieces.

[Markinaboat]

1 hour ago, Louis D said:

Remember that the 14mm and 17.3mm Delos require 1/2" more infocus than the 12mm and below focal lengths.  Make sure you have that much infocus left or you'll need to buy a special adapter to submerge the eyepiece shoulder below the level of the 2" focuser.

By most accounts, the 17.5mm Morpheus is about equal to the 17.3mm Delos.  The same is not true of the 14mm offerings.  The Delos is definitely better than the Morpheus.  I have the 14mm Morpheus and Pentax XL.  Field curvature is visible in both, but the Pentax is sharp to the edge once refocused while the Morpheus is astigmatic at the edge.  The 14mm Delos is reportedly flat of field and sharp to the edge.

I would get a 4.5mm to 6.5mm eyepiece before getting something between 10mm and 22mm.  It will be nice for planets, luna, globular clusters, and planetary nebula.

Do you have a coma corrector yet?  The 30mm ES-82 and 22mm Nagler will both definitely benefit from it.  Both clean up nicely to the edge with it.  I use a GSO/Revelation CC with a 25mm extension between the eyepiece holder and the optics section.  My 10mm Delos shows no difference with or without a CC.  At high powers, you'll want to remove it due to slight spherical aberration that lightly blurs low contrast planetary details.

How would I go about checking the 'infocus'? I' assuming you mean that a Delos of 12mm or below might not have enough travel  inwards (or outwards)?

[Markinaboat]

1 hour ago, John said:

Louis is correct re: the additional infocus - it's worth bearing in mind especially if a barlow means you need even more.

Another downside about using a barlow or Powermate with an already large / tall eyepiece is that the stack sticking out of the focuser gets pretty long:

 

Yes, that has occurred to me John. I do like to keep things simple so perhaps would shy away from this.

[Markinaboat]

1 hour ago, Paz said:

With my 350mm f4.6 newtonian my eyepiece set was originally

31mm and 22mm Naglers and 17.3mm, 12mm, 8mm, 6mm, 4.5mm, and 3.5mm Delos.

I found over time I often felt I could do with something in between 12mm and 8mm but I never felt the need to fill the gap between 17.3mm and 12mm.

I eventually got a 10mm Delos and never got a 14mm but have been content ever since.

Interesting and useful!

[Markinaboat]

1 hour ago, Louis D said:

Add a coma corrector to the stack for even more length, though I generally remove mine when using a barlow.

maybe sometime in the future! At the moment, I'm impressed with the views I have but I'm sure given time ....

[BGazing]

Given that your scope is 1200mm, I would not bother with 17 or 14 and would go around 5 or 6mm for planets and the Moon.

You do not have a tracking system so wide field is useful. T6 then, unless you can spring for an Ethos.

[John]

The core set I use with my 12 inch F/5.3 dob (no coma corrector used !) is:

21mm, 13mm, 8mm and 6mm

I do have a 31mm and also shorter focal length options but most of the time the above 4 focal lengths cover the observing situations / targets that I come across.

[Piero]

Mark,

Telescopes and eyepieces work together. You need to consider the focal ratio (in your case F6). For instance a 30mm in your telescope works well, in an f4 doesn't unless one observes under really dark skies. 

Don't rush and buy lots of eyepieces just because they 'might' turn useful. The reason why there are many eyepieces is because there are many types of telescopes and observers.

[Markinaboat]

43 minutes ago, BGazing said:

Given that your scope is 1200mm, I would not bother with 17 or 14 and would go around 5 or 6mm for planets and the Moon.

You do not have a tracking system so wide field is useful. T6 then, unless you can spring for an Ethos.

Thanks. Would an 82 deg make a big difference over the 76 deg of the Delos for keeping in view? Especially when the Delos offers 20mm of ER compared to 12mm. Not sure how I'd get on with 100  deg from the countless research I've done and certainly not Ethos due to the cost. The ES 5.5mm 100 deg only has 11.6 ER.

[John]

The Delos has a 72 degree apparent field of view (AFoV). I don't find a massive difference tracking with a 72 vs an 82 degree field. 100 degrees does make a difference IMHO but not everybody likes those. Baader Morpheus are 76 degrees AFoV.

With my dob, tracking involves putting the target on one side of the field and then letting it drift across observing as it drifts, then moving it back across again, and repeating. The wider the AFoV, the longer the drift / observation phase can be. I don't try and keep an object right in the centre of the field of view at high power - I'd go nuts trying to do that I think !

You can and do adjust to whatever field of view you have available though - I have observed with orthos with just 40 degree AFoV's at 300x plus with my dob - you have to concentrate more but it can be done.

 

 

[Markinaboat]

27 minutes ago, Piero said:

Mark,

Telescopes and eyepieces work together. You need to consider the focal ratio (in your case F6). For instance a 30mm in your telescope works well, in an f4 doesn't unless one observes under really dark skies. 

Don't rush and buy lots of eyepieces just because they 'might' turn useful. The reason why there are many eyepieces is because there are many types of telescopes and observers.

Thanks Piero. I do understand the basics (mostly). That's why I got the ES 30mm and the (eagerly awaited) TV 22mm T4. Also kept the scope to an 8" for now but if I get on with the newt, then may add either a 12 or 14" next year. Just wanted to get a basic toolkit together and so far, this thread has been very useful. I'm thinking mayne jst a 5 or 6mm for now. Just to decide on which one taking into account a safe amount of ER for future proofing my eyes!

[Markinaboat]

2 minutes ago, John said:

The Delos has a 72 degree apparent field of view (AFoV). I don't find a massive difference tracking with a 72 vs an 82 degree field. 100 degrees does make a difference IMHO but not everybody likes those. Baader Morpheus are 76 degrees AFoV.

With my dob, tracking involves putting the target on one side of the field and then letting it drift across observing as it drifts, then moving it back across again, and repeating. The wider the AFoV, the longer the drift / observation phase can be. I don't try and keep an object right in the centre of the field of view at high power - I'd go nuts trying to do that I think !

You can and do adjust to whatever field of view you have available though - I have observed with orthos with just 40 degree AFoV's at 300x plus with my dob - you have to concentrate more but it can be done.

 

 

Yeah, I've been getting the hang of it with my 10mm. Thought I might struggle but took to it comfortably very quickly. 76 deg was typo (now am experienced with those!)