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swap out 2 delites for one delos?

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#1 Brian Schmidt

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Posted 27 March 2023 - 08:51 PM

Thinking of swapping our my 9 and 7 Delites for an 8 Delos.  I have had this thought before when the planets sink from view before, but have had some superb views of the planets through my 9 and 7 deletes and have liked the flexibility of having the 9 and 7 in 8-inch f/6 eq.  I also have a 12-inch f/5 dob and DSOs get really cramped at the viewing when I want more juice. I've read a bunch of articles that seem to state that the planetary performance is consistent across both lines, so the only difference would be the added bulk of the 8, but would have the benefit of not being as cramped for DSOs.   

 

My other medium power eyepieces are 17.3 and 12 delos.  I guess that would just leave me with the 5 delite only, although I have a GSO 2 inch Barlow for the higher powers on the rare nights that they seem to be usable in this part of the country.  

 

Am I missing anything?  



#2 SeattleScott

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Posted 27 March 2023 - 09:05 PM

I don’t think you are missing anything, other than other alternatives, if you want the AFOV without the bulk of the Delos, there are ways to get there. Getting the focal lengths to line up could be a problem though. Just not a lot of 8mm premium eyepieces out there. So yeah, assuming you want the ER of Delos instead of 7 and 9 Naglers, probably the 8 Delos is the obvious alternative. It does make your jumps a bit bigger, but that’s not necessarily bad, as it also simplifies swapping eyepieces.

#3 russell23

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Posted 27 March 2023 - 09:51 PM

In terms of TFOV, the 9mm DeLite and the 8mm Delos are almost identical.  The 9mm has a 9.6mm field stop and the 8mm has a 9.9mm field stop.  

 

So from a TFOV perspective you really aren’t gaining anything.  


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#4 SeattleScott

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Posted 28 March 2023 - 12:56 AM

Yeah if the issue is really that the view is getting cramped, it seems like he needs to go wider. 62 to 72 isn’t that big of a deal. Morpheus or Nagler would open things up more. But perhaps he is happy with his other 72 AFOV Delos and just finds the 62 AFOV Delite a little tight by comparison? It might not be a TFOV issue as much as AFOV issue. If another 10 degrees would make him happy, then the Delos makes sense.

#5 Brian Schmidt

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Posted 28 March 2023 - 04:45 PM

Correct.  It's the soda straw view and for some reason, I seem to have an easier time viewing through the Delos.  I have been viewing for many decades and completely understand how to adjust the eyecup.  



#6 SeattleScott

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Posted 28 March 2023 - 07:22 PM

Ok so it's the AFOV, 72 is fine, 62 feels a little tight. Nikon SW gives the AFOV without the bulk of Delos, but no 8mm. Of course there is 9 and 6.7 Morpheus if you want to keep your flexibility of focal length options but with wider AFOV, and a bit lighter than Delos. Nagler has a 9 and 7 with the AFOV and without the bulk but not the long ER. Or there is the 8 Delos since you like those, and it would simplify your lineup a little, even if 8 to 5 is a bit of a gap. I think those are your main options.

 

Scott



#7 GGK

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Posted 28 March 2023 - 08:08 PM

Correct.  It's the soda straw view and for some reason, I seem to have an easier time viewing through the Delos.  I have been viewing for many decades and completely understand how to adjust the eyecup.  

I use the 7 and 9 Delites and also the 6, 8 and 10 Delos.  I observe without glasses and am more comfortable with the Delos because of the large eye lens and large eye guard opening. Rather than hovering above the iris like I do with the Delite, the Delos allows me to move my face closer with the eye guard out around my eye and eye lashes.  It is for this reason that I'm also more comfortable with the Pentax XWs than the Delites. The XWs are an option if 70o AFoV is acceptable.

 

The 8mm Ethos might be the best option if the shorter eye relief is acceptable.  It is slightly lighter and only slightly taller than the Delos and has a huge 13.9mm field stop diameter vs. 9.9mm for the Delos. I don't know your focuser so it's best to confirm it would reach focus if using in 1-1/4 mode.

 

The Delites, Delos and Ethos are all superb with minimal image difference within comparable fields of view.  It comes down to AFoV preference, user comfort and cost. I am using these eyepieces in small refractors and a SCT at f/5.4, through f/10.

 

Gary



#8 CeleNoptic

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Posted 28 March 2023 - 08:58 PM

IMO, 17.3 mm - 12mm - 8mm looks like an ideal line for the 8" F/6 reflector. Plus, you've got the 2" 2x GSO Barlow which has a removable nosepiece. If you screw the Barlow nosepiece into the bottom of your reflector 2"/1.25 adapter it'll give ~1.4x magnification factor. How do I know? I had tried this combination on my 8" F/6 Dob before I sold my 2" AT Barlow (rebranded GSO). I didn't have a 12mm Delos at that time, but checked magnification e.g. with my 8.8mm and 14mm Meade 5K UWAs by star drifting and it was close to 1.4x. I sometimes use my 12mm Delos with all 1.25" Barlows I have (1.5x, 2x, 3x) with good results, but of course, a dedicated eyepiece(s) would be a much more convenient option. So, you can try your 12mm Delos with the Barlow cell attached to 2"/1.25" adapter for virtual ~8.6mm Delos before buying the 8mm.



#9 Brian Schmidt

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Posted 29 March 2023 - 08:54 PM

Just got back in from viewing the moon, and definitely feel claustrophobic at 62 degrees.  I like the option to wear glasses if possible.  For some reason the tradeoff to go from 82 to 72 seems worth it.  Appreciate the honorable mention for the 8 Ethos.  Been considering that one too, but think I'm going to get the 10 Ethos to make a minimalist wide field set with my 26 Nagler.  So it looks like I will be going with the 8 Delos when I return from this trip. 

 

Also--never thought of using the Barlow that way.  



#10 Chad7531

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Posted 29 March 2023 - 08:59 PM

I had XWs before I had my current Delos. I would probably choose the XWs and may go back to them for my shorter focal lengths. I haven’t seen anything compare to Ethos though in the focal lengths I have. You can sell both of your Delites and invest another $100 for an 8 Ethos. That would be nice unless you wear glasses. But that puts you in a rabbit hole of needing more Ethos.

Edited by Chad7531, 29 March 2023 - 09:03 PM.


#11 RAKing

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Posted 31 March 2023 - 01:22 PM

As long as you don't miss (or need) the extra magnification bump you get from the 7mm DeLite, then your swap sounds like a good idea to me.  You will have the same actual FOV of the 9mm with a slightly stronger (and more contrasty) view.

 

I did a similar thing last year when I decided that I liked the view with a 6mm Ethos better than my 7T6 Nagler.  The tight eye relief of the little T6 was giving me trouble and the 15mm eye relief of the Ethos felt more comfortable.  Add the slightly higher magnification and better contrast... and I have been very happy with the result.

 

Cheers,

 

Ron


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#12 Centaurius

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Posted 31 March 2023 - 11:37 PM

Yeah if the issue is really that the view is getting cramped, it seems like he needs to go wider. 62 to 72 isn’t that big of a deal. Morpheus or Nagler would open things up more. But perhaps he is happy with his other 72 AFOV Delos and just finds the 62 AFOV Delite a little tight by comparison? It might not be a TFOV issue as much as AFOV issue. If another 10 degrees would make him happy, then the Delos makes sense.


62° to 72° is quite noticeable.... For me.


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