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14 Delos edge performance?

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#1 Tank

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Posted 18 June 2013 - 09:24 AM

Just wondering as far as the edge performance of 14 Delos in a faster scope say F4.5-F5.
Any experiences
Also the eye placement is it similar to the 17.3mm?

#2 Starman1

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Posted 18 June 2013 - 09:36 AM

The 14 and 17.3 are parfocal and identical in visual characteristics.
Both are very sharp in that f/ratio.
You will see coma in the mirror, of course, which would be eliminated with a Paracorr, but the eyepieces themselves reveal only what's there.
Note that both the 14 and 17.3 require close to a 1/2" of additional inward focuser travel compared to many 1.25" eyepieces.
If that is an issue, TeleVue makes a 1.25" adapter with an actual step down, called the "In-Travel Adapter" with about 1/8" of drop down from the top of the focuser.
Astrosystems and ScopeStuff make adapters with even more in-travel, so even if you have very little in-travel left in your focuser, the correct choice of adapter will likely allow you to bring these eyepieces to focus within normal focuser travel.

#3 Phillip Creed

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Posted 18 June 2013 - 11:39 AM

I have the 14mm Delos. I've used it in my 8" and 12" scopes, both at f/4.9. I don't use a Paracorr, though careful examination of the edges will reveal coma in all but the highest powers (25X / inch on up).

I previously tried the T4 Naglers, and I just couldn't get myself to like them. With a Paracorr? Outstanding. Without? Not that great; distortion from about 60% on out. In fact, I don't think I've ever seen a more dramatic "night-and-day" difference between an eyepiece with and without a coma corrector than I did with both the 12T4 and the 17T4. I also didn't care for the finicky eye placement required to see the full FOV.

I've also used the 14mm Pentax XW, and it's great with a Paracorr, but I could easily see field curvature w/o PC. Maybe it's because my eyes are really sensitive to field curvature, but the 14XW was a bit disappointing in that regard. Again, good with Paracorr--and comfortable with eye placement--but not so good w/o coma correction.

Enter the 14mm Delos. This is a godsend if you don't have a Paracorr and need eyeglasses for an f/5-ish scope. The un-Paracorr'ed performance is impressive. Long story short, it's like having the same true field of view, image scale and edge sharpness as the 13T6, with, oh, by the way, gobs of eye relief, if you need it. Eye placement is more sensitive than the 14XW, but significantly less than the 12T4 or 17T4. You'll see coma, but edge aberrations are nowhere near what they are in the T4's. If you don't already have a Paracorr, the 14mm Delos isn't going to compel you go run out and buy one. I didn't see any field curvature in my 8" f/4.9. I only have this and the 10mm in the Delos set, but the contrast in both is incredible.

Edge-performance-wise, it's an Ethos stopped down to 72-deg. Contrast- and transmission-wise, it's a premium ortho opened up to 72-deg. Highly recommended if you've got the budget.

Clear Skies,
Phil

#4 Starman81

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Posted 18 June 2013 - 12:30 PM

I have the 14mm Delos. I've used it in my 8" and 12" scopes, both at f/4.9. I don't use a Paracorr, though careful examination of the edges will reveal coma in all but the highest powers (25X / inch on up).

I previously tried the T4 Naglers, and I just couldn't get myself to like them. With a Paracorr? Outstanding. Without? Not that great; distortion from about 60% on out. In fact, I don't think I've ever seen a more dramatic "night-and-day" difference between an eyepiece with and without a coma corrector than I did with both the 12T4 and the 17T4. I also didn't care for the finicky eye placement required to see the full FOV.

I've also used the 14mm Pentax XW, and it's great with a Paracorr, but I could easily see field curvature w/o PC. Maybe it's because my eyes are really sensitive to field curvature, but the 14XW was a bit disappointing in that regard. Again, good with Paracorr--and comfortable with eye placement--but not so good w/o coma correction.

Enter the 14mm Delos. This is a godsend if you don't have a Paracorr and need eyeglasses for an f/5-ish scope. The un-Paracorr'ed performance is impressive. Long story short, it's like having the same true field of view, image scale and edge sharpness as the 13T6, with, oh, by the way, gobs of eye relief, if you need it. Eye placement is more sensitive than the 14XW, but significantly less than the 12T4 or 17T4. You'll see coma, but edge aberrations are nowhere near what they are in the T4's. If you don't already have a Paracorr, the 14mm Delos isn't going to compel you go run out and buy one. I didn't see any field curvature in my 8" f/4.9. I only have this and the 10mm in the Delos set, but the contrast in both is incredible.

Edge-performance-wise, it's an Ethos stopped down to 72-deg. Contrast- and transmission-wise, it's a premium ortho opened up to 72-deg. Highly recommended if you've got the budget.

Clear Skies,
Phil


Thanks Phil, that's the best mini-review of the 14mm Delos that I've seen anywhere yet. I was tempted by the 14mm as I know it would be an improvement over the XW 14 (and still tempted due to the current Delos summer sale), but instead I opted for a Paracorr since I can use that for field flattening in the XW 14 and 20 (and other eyepieces, of course).

#5 SteveG

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Posted 18 June 2013 - 01:47 PM

I have the 14mm Delos. I've used it in my 8" and 12" scopes, both at f/4.9. I don't use a Paracorr, though careful examination of the edges will reveal coma in all but the highest powers (25X / inch on up).

I previously tried the T4 Naglers, and I just couldn't get myself to like them. With a Paracorr? Outstanding. Without? Not that great; distortion from about 60% on out. In fact, I don't think I've ever seen a more dramatic "night-and-day" difference between an eyepiece with and without a coma corrector than I did with both the 12T4 and the 17T4. I also didn't care for the finicky eye placement required to see the full FOV.

I've also used the 14mm Pentax XW, and it's great with a Paracorr, but I could easily see field curvature w/o PC. Maybe it's because my eyes are really sensitive to field curvature, but the 14XW was a bit disappointing in that regard. Again, good with Paracorr--and comfortable with eye placement--but not so good w/o coma correction.

Enter the 14mm Delos. This is a godsend if you don't have a Paracorr and need eyeglasses for an f/5-ish scope. The un-Paracorr'ed performance is impressive. Long story short, it's like having the same true field of view, image scale and edge sharpness as the 13T6, with, oh, by the way, gobs of eye relief, if you need it. Eye placement is more sensitive than the 14XW, but significantly less than the 12T4 or 17T4. You'll see coma, but edge aberrations are nowhere near what they are in the T4's. If you don't already have a Paracorr, the 14mm Delos isn't going to compel you go run out and buy one. I didn't see any field curvature in my 8" f/4.9. I only have this and the 10mm in the Delos set, but the contrast in both is incredible.

Edge-performance-wise, it's an Ethos stopped down to 72-deg. Contrast- and transmission-wise, it's a premium ortho opened up to 72-deg. Highly recommended if you've got the budget.

Clear Skies,
Phil


Excellent report Phil - thanks!

#6 russell23

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Posted 18 June 2013 - 03:34 PM

Has anyone compared the 14mm Delos to both the 10mm and the 17.3mm Delos? I loved the 10mm Delos but was very disatisfied with the 17.3mm Delos. I did not think the edge of the field in the 17.3mm Delos was nearly as good as the 10mm Delos. There was a noticeable falloff in sharpness that I did not see with the 10mm Delos as well as some EOFB that was not evident at all in the 10mm Delos. Since the 14mm sits between them I have to wonder if it is more like the 17.3mm or more like the 10mm.

Dave

#7 Phillip Creed

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Posted 18 June 2013 - 03:42 PM

I've got both the 14mm and 10mm Delos. The 10mm is sharper at the edges, though I suspect it's because I'm seeing less coma at that power than I am with the 14mm. Much in the same way that, w/o a Paracorr, a 7T6 or 9T6 will look sharper at the edge than a 13T6 due the difference in field stop size.

Bear in mind, only the central 2.6mm in the field will be coma-free in an f/4.9 scope. Beyond that, the observer's sensitivity to coma plays a role as to how wide the eyepiece's field stop has to be before it encompasses enough for the coma to be noticeable/objectionable.

I was looking for astigmatism, field curvature, contrast issues and edge brightening with the 14mm Delos. If it's there, I'm not seeing it.

Clear Skies,
Phil

#8 russell23

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Posted 18 June 2013 - 03:54 PM

I've got both the 14mm and 10mm Delos. The 10mm is sharper at the edges, though I suspect it's because I'm seeing less coma at that power than I am with the 14mm. Much in the same way that, w/o a Paracorr, a 7T6 or 9T6 will look sharper at the edge than a 13T6 due the difference in field stop size.

Bear in mind, only the central 2.6mm in the field will be coma-free in an f/4.9 scope. Beyond that, the observer's sensitivity to coma plays a role as to how wide the eyepiece's field stop has to be before it encompasses enough for the coma to be noticeable/objectionable.

I was looking for astigmatism, field curvature, contrast issues and edge brightening with the 14mm Delos. If it's there, I'm not seeing it.

Clear Skies,
Phil


Thanks Phil!

A 14mm Delos would be nice for me because I could barlow it to several different magnifications and therefore get more bang for the $315 investment. Perhaps I'll give one a try while it is on sale this summer. I use a Petzval refractor so Coma is not an issue.

Dave

#9 Starman81

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Posted 18 June 2013 - 04:19 PM

I've got both the 14mm and 10mm Delos. The 10mm is sharper at the edges, though I suspect it's because I'm seeing less coma at that power than I am with the 14mm. Much in the same way that, w/o a Paracorr, a 7T6 or 9T6 will look sharper at the edge than a 13T6 due the difference in field stop size.

Bear in mind, only the central 2.6mm in the field will be coma-free in an f/4.9 scope. Beyond that, the observer's sensitivity to coma plays a role as to how wide the eyepiece's field stop has to be before it encompasses enough for the coma to be noticeable/objectionable.

I was looking for astigmatism, field curvature, contrast issues and edge brightening with the 14mm Delos. If it's there, I'm not seeing it.

Clear Skies,
Phil


Thanks Phil!

A 14mm Delos would be nice for me because I could barlow it to several different magnifications and therefore get more bang for the $315 investment. Perhaps I'll give one a try while it is on sale this summer. I use a Petzval refractor so Coma is not an issue.

Dave


Dave, I think you would have to thin the herd at 20mm first!

;)

#10 russell23

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Posted 18 June 2013 - 04:47 PM

I've got both the 14mm and 10mm Delos. The 10mm is sharper at the edges, though I suspect it's because I'm seeing less coma at that power than I am with the 14mm. Much in the same way that, w/o a Paracorr, a 7T6 or 9T6 will look sharper at the edge than a 13T6 due the difference in field stop size.

Bear in mind, only the central 2.6mm in the field will be coma-free in an f/4.9 scope. Beyond that, the observer's sensitivity to coma plays a role as to how wide the eyepiece's field stop has to be before it encompasses enough for the coma to be noticeable/objectionable.

I was looking for astigmatism, field curvature, contrast issues and edge brightening with the 14mm Delos. If it's there, I'm not seeing it.

Clear Skies,
Phil


Thanks Phil!

A 14mm Delos would be nice for me because I could barlow it to several different magnifications and therefore get more bang for the $315 investment. Perhaps I'll give one a try while it is on sale this summer. I use a Petzval refractor so Coma is not an issue.

Dave


Dave, I think you would have to thin the herd at 20mm first!

;)


Yes - that is probably my ultimate goal. But I figure since I have the three 20mm widefields I might as well do a review of them this summer. I'm considering throwing a 19mm Pan and 20mm T5 Nagler into the mix as well.

Dave

#11 Phillip Creed

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Posted 18 June 2013 - 05:41 PM

I was tempted by the 14mm as I know it would be an improvement over the XW 14 (and still tempted due to the current Delos summer sale), but instead I opted for a Paracorr since I can use that for field flattening in the XW 14 and 20 (and other eyepieces, of course).


Yeah, if you've already got the Paracorr, you're not really gaining much in going to the 14mm Delos if you've already got the 14XW. The field curvature was an issue for me with the 14XW, but everything else was beautiful. In fact, the eye placement was among the most comfortable I've ever seen in any ocular.

The nice thing about the Delos and XW's is that the series can not only peacefully co-exist in one's eyepiece case, they also complement one another being so similar in AFOV and eye relief. Got a hole between the 14XW and 20XW? Get the 17.3mm Delos. Don't like that gap between the 8mm and 6mm Delos? Grab a 7XW.

Clear Skies,
Phil

#12 dscarpa

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Posted 18 June 2013 - 09:16 PM

I find that to be true with my 2 XWs and 2 Delos. Edge performance of my 12 and 17.3 Delos is the same and excellent in my cats and F/7 refractor. There's just a bit of lateral color at the very edge on bright planets. An advantage of the Delos over the XWs as to lateral color is that they're less sensitive to eye position. David

#13 ibase

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Posted 18 June 2013 - 09:29 PM

Don't like that gap between the 8mm and 6mm Delos? Grab a 7XW.


Exactly how I got my 6mm Delos (reversed) - traded for it the 7XW that I used to own. The Delos field stop is sharp but with a blue fringe at the extreme edge:

Posted Image
Afocal shot of a billboard ad through the Delos 6mm

It's similar to the field stop of the 100-deg. Explore Scientific 14mm. In comparison, the Nagler 5mm T6 has lighter and very slight aqua color fringe that's hardly noticeable.

Posted Image
L-R: Televue's Nagler 5mm T6 and Delos 6mm; Explore Scientific 14mm 100-deg.

Best,

#14 Tank

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Posted 19 June 2013 - 12:09 PM

Thanks for all the info. guys

Phillip Creed great mini review sounds like the 14 maybe in my case one day. I've looked thru the 12 and the 17.3 Delos so far and they feel similar viewing thru them. Eye placement does seem more critical than the XWs but not a huge issues I feel.

#15 Mr Magoo

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Posted 19 June 2013 - 12:26 PM

Has anyone here used the 14mm Delos in a 16" LB at f4.5? I'm wondering if you were able to achieve enough in focus travel without an adapter. Thank you.

#16 Starman1

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Posted 19 June 2013 - 01:08 PM

Has anyone here used the 14mm Delos in a 16" LB at f4.5? I'm wondering if you were able to achieve enough in focus travel without an adapter. Thank you.

No two 16" Lightbridges focus at exactly the same point, which is why Meade has often packed the scope with an extension tube for the focuser.
They allow a range of focal points in the mirror.
So, it will be easy to see whether the scope has enough in-focus.
I presume you have other 1.25" eyepieces. Note how much additional infocus travel you have when those eyepieces are in focus.
You will need about 1/2" (similar to most barlows, by the way) additional in-travel to accommodate the 14's focus position.
If you have that, cool--don't worry.
If you don't, look into getting another 1.25" adapter that allows more in-travel than your current 1.25" adapter. If yours is the stock GSO adapter, you will gain quite a bit of in-travel with the TeleVue In-travel adapter, more with the Astrosystems, and even more with the Scopestuff.
Even if your other 1.25" eyepieces focused with the focuser all the way in, that last one would probably still work with the 14 Delos.
So don't worry about focusing; just be aware you may need another 1.25" adapter.

#17 GeneT

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Posted 19 June 2013 - 10:44 PM

Here's my take. I love the Delos line of eyepieces. I own the 14, 10, 8 and 6. Moving into the high power range of 10 and shorter focal lengths, along with the Pentax XW 7 and 5, I like the look and feel of these eyepieces. In the high power range, I am looking at the moon planets, globulars, double/multiple stars and nebula/galaxies, and the 72/70 is fine. However, I did not like my 14. It was not due to the infocus issue, although I had barely enough. At the mid to low power realm, I like more AFOV than 72. I liked the AFOV of my Nagler 12. Unfortunately, it does not come in a 14.

I just received my Ethos 13. I won't be able to try it out for a few days, but I believe that its 100 AFOV will be just what I need, although its 15 mm of eye relief, although generous, is about 2mm short of what I prefer. The 13 Ethos will frame the view I prefer far better than the 14 Delos. What these things come down to are largely personal preferences.

#18 vkhastro1

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Posted 19 June 2013 - 11:30 PM

Just in from a field test in my 13.1" f/4.5 Dobsonian with a refigured Norman
Fullum mirror. Tried a 17.3mm, 14mm, 12mm & 10mm Delos with and without a Paracorr (first version - not a tuneable top). The Deloi are very
impressive eyepieces but coma is definitely visible in the outer 15 -20% of the field (no Paracorr). Put in the Paracorr and it really cleans up the coma to the point you really have to look for it - an amazing transformation. A Paracorr with Delos eyepieces in a fast reflector is definitely recommended !

#19 Mr Magoo

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Posted 20 June 2013 - 10:57 AM

Thanks Don. My LB has a JMI EV-1 focuser on it. I would also be using a type 1 Paracorr. Not sure how that all figures in. Looks like I need to do some testing.

#20 Starman1

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Posted 20 June 2013 - 12:45 PM

Thanks Don. My LB has a JMI EV-1 focuser on it. I would also be using a type 1 Paracorr. Not sure how that all figures in. Looks like I need to do some testing.

The Paracorr essentially parfocalizes all your eyepieces. But since the Paracorr 1 has a flat-topped adapter only 1cm tall, you will need an adapter with the 14 that allows the eyepiece to drop below the top of the Paracorr in order to make it parfocal with your other eyepieces (i.e. to focus using the tunable top). Since the Paracorr 1 doesn't allow the eyepiece to move as close to the lens as the Paracorr 2 does, and since the 14 needs additional In Travel in the Paracorr 2, you will need an adapter that allows you to lower the eyepiece into the Paracorr to a point below the top.
I recommend the Astrosystems adapter. See:
http://www.astrosyst...ieceadapter.htm on the left.
The TeleVue In-Travel adapter works best with the Paracorr 2. You may even find you don't need to lower it all the way into the adapter.

Here's what you do:
--adjust the Paracorr to the correct setting for another of your 1.25" eyepieces. Focus that eyepiece.
--remove the eyepiece and the adapter from the Paracorr.
--Pre-adjust the setscrew in the adapter so the eyepiece slides in with some pressure required. I like to set it so the eyepiece can be "rotated" in, but not pushed in easily.
--Install the AS drop-in adapter into the Paracorr and set the Paracorr in its lowest possible setting.
--put the eyepiece into the adapter and rotate it in until it is in perfect focus.
--remove the eyepiece and the adapter and tighten the setscrew in the adapter at that point. Leave the adapter attached to the eyepiece so you won't have to refocus much when it is reinserted and the Paracorr is in its lowest setting.

Now, what if the 14 moves all the way in and it's still not quite in focus? No biggie. You're still very close to the perfect Paracorr setting for the 14.
In that case, you don't necessarily have to leave the adapter attached to the eyepiece because the next time you use it, you'll just push the eyepiece in until it bottoms, then focus slightly using the focuser.
[Note: even though the Paracorr parfocalizes all your eyepieces, you still have to adjust the focuser a tiny bit, even if all the eyepieces have optimum settings. Even on the Paracorr 2 I focus 1-2mm back and forth with different eyepieces.]






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