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TV Ethos 3.7 vs Delos 3.5


darkseadiver

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Has anyone tried both TV Ethos 3.7 vs Delos 3.5 on an APO 80 or 100 refractor? 

I have an Ethos 3.7 and 6mm. Also Have 4.5, 8, 14, 17.3 Delos - and several Naglers & Radians.

I didn't believe anything could beat the Ethos, ...until I tried a Delos, I was amazed - for me Delos beats Ethos ...I have Old eyes, 60 yrs now / astigmatism on low mag

( That only shows up on 14mm & up - I use the TV DIOPTRIX on & above 14mm, they are awesome for me ...but don't make any diff below 14mm for me).

I know the Ethos vs Delos specs, Ethos should be superior but for some reason Delos works better for me IDK why.

So - Has anyone tried Delos 3.5 (70) against an Ethos 3.7 SX (110)?  I'm wondering other than apparent field of view, how they stack up.

at 3.5mm or 3.7mm the depth of field is minimal - I get it.  However I seem to get a tad more depth out of a 3.5 Nager than I get out of a 3.7 Ethos ...wondering about the 3.5 Delos.

I thought I would buy one used (Kinda hard to find), if no difference other that FOV I'll keep the 3.7SX, but I thought someone may have some insight out there ...maybe the 3.7SX is as good as it gets for sharpness & huge FOV.

I'm just not that enamoured with my Ethos 3.7, wondering if the Delos may be a better fit for me & my aging eyes.

Any related experience anyone could share??

JC

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I think the Delos is as good as the Ethos in terms of sharpness and contrast, but personally I found the 110 degree field of view too much on the Ethos 3.7SX. I think because the eye relief is relatively shorter, maybe related to the exit lens being concave, I seemed to spend as much time looking at my eye lashes as the target if I got close enough to see the whole field.

The Delos is a smidge better than the Nagler, and very comfortable to use due to the 20mm eye relief.

I still find it amazing that they can fit 82 degrees afov into the Nagler though, the 3.5mm type 6 is relatively tiny and compact compared with either of the others.

In summary, I suspect you would enjoy the Delos more.

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I had full sets of both a while back and spent a very long time comparing like for like matches on a all my scope, these include a 115mm APO. I have to say my findings were Delos were slightly better in terms of how deep they see, a galaxy was just that tiny bit better. However i would say differences were subtle and nowhere near black and white. In terms of sharpness my findings were they were much the same. But on my 18 inch Dob Ethos shone due to the wide field of view.

Both superb eyepieces in my view designed to do different jobs.

Alan

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I had the Ethos 4.7 and 3.7 for quite a while and compared them extensively with the Pentax XW 5mm and 3.5mm. Much as I love the hyper wide field, I found that the XW's were just a little better in terms of sharpness (on and off axis) and light scatter control so eventually and with some twinges of the regret I let the Ethos SX's go to new homes. I suspect the results of a Delos - Ethos SX comparison might be very similar.

I currently have the Delos 17.3 and 14mm as part of my 1.25 inch set and they are excellent. I chose them over the Pentax 20mm and 14mm XW's because I was not keen on the field curvature that those focal length XW's posess. I'm very happy with the 10, 7, 5 and 3.5mm XW's though.

 

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Wow, as this was my 1st post - Big THANK YOU! to all those who replied!

I suspect the Delos 3.5 will be the EP I prefer, certainly a subjective choice, but it sounds as if many of you have had similar experiences with Delos.

I believe TV has a winner in that EP, I kick myself for waiting so long to try one and purchasing Naglers & Radians. I shunned them primarily because of "specs" the stated 70 AFOV - which frankly to me "seems" to have more FOV edge to edge than Naglers. Just goes to show you - you really just have to look through the glass - not the specs!  I'm sure that has to do with a magical mix of eye relief and exit pupil.

Thank you all again - I really appreciate the input!!

John

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It's worth remembering that the Delos (and the later Delite) were developed on the back of the work that went into the Ethos so the performance of these 3 ranges has a lot in common apart from the apparent field of view and eye relief.  The Pentax XW's have been around for a long while and replaced the also excellent Pentax XL's. To some extent Pentax were beating Tele Vue in the 68-82 something degree field niche until Tele Vue launched the Delos. From my experience the Delos and XW's are very, very similar in optical performance and overall quality. It's worth bearing in mind that the 17.3 and 14mm Delos are not par-focal with the other Delos focal lengths by around 8mm but they are close to the XW's which is one of the reasons that I use those focal length Delos to compliment my shorter focal length XW's.

Another "quite interesting" factoid is that the 6mm and 8mm Delos are actually a touch heavier than the Ethos of the same focal lengths.

Good luck with your seach for a nice used 3.5 Delos :smiley:

 

 

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The Delos also have less glass to that may add in for the extar sharpness. I think the choice may depend on what your interests are and whether you have an undriven scope.

 

Owen

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Thanks John, I did know that they Ethos/Delos/De-lite have that commonality, at the time I purchased the 3.7SX I figured it would be the best choice for that reason, and FOV of 110 it would be easier to catch a target if my gotos were off a bit - or on the porta-II or Dob.  However, I'm not sold on the 110 degree FOV so much now, GOTOs have been good and I usually use 17mm, then 6-8mm and finally drill down to Hi-mag depending on the scope ...so I'm very close anyway.

I'll find a 3.5 Delos, and update my experience ...but I'm pretty sure how that'll go :)

JC

 

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Hi Owen, yes I have a few of each, Driven, GOTO & Undriven. 

I did choose the wider FOV for that reason.  It's nice but I don't think I "need" it. 

The internal element count / i.e. glass aspect is a good point as it should relate to differences in contrast /sharpness.

Thanks, JC

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