Advice on a 12mm Delos

[Teal Rain]

Hello all

I'm been toying with the idea of getting a 12mm delos for use in a varierty of scopes, one of which is a Lunt 60 B1200 PT. Would I be right in assuming that the FOV yielded by the delos would be a bit wasted in the Lunt given the blocking filter?

Any advice welcome!

Thanks

Mark

[Pig]

The FOV is the FOV, does the filter have this effect on any other eyepieces you have ?

[Stargazer_00]

A blocking filter can act like a field stop, so it limits the maximum field stop diameter of eyepieces which have a greater field stop diameter, is what I think the OP was getting at.

In this instance, you need to find the field stop diameter of the Delos (which Televue are awfully good at publishing) and then find the size of the blocking filter diameter.

After that it's simple maths i'd expect.

[bingevader]

(which Televue are awfully good at publishing)

Aren't they!

That'd be 15mm for a 12mm Delos!

I wish all EP manufacturers would publish the field stop.

I know, My pipe dream/soap box at the moment.

Cheers

[John]

Explore Scientific publish their field stop sizes, eg: here are the 82 degree ones:

http://www.explorescientific.com/eyepieces/82_degree_series1.html

[bingevader]

Oooh, nice one John, thanks for that!

I've only ever looked at the European dealer's sites.

Cheers

[michael.h.f.wilkinson]

I use a 10mm XW and 12mm Nagler in my LS35 regularly (also equipped with a B1200 blocking filter). The field stops of both are on the large side (let alone the 27mm field stop of the 24mm MaxVision I use very much in the LS35), but that is hardly a problem. Of course you could get a narrower FOV ep, but the quality of the view in the XW and Nagler is just great. Besides, they have long eye relief. If you want to save some money, you might consider the Pentax XF12. I do not have that particular one, but my XF8.5 performs very nicely in the LS35.

[NGC 1502]

Posts #1 and #7 are using the B1200 blocking filter, so will benefit from a wider field eyepiece.

Those like me who have the Lunt LS35 with the B400 blocking filter will not gain from a wide field eyepiece because of the restriction of the B400.

I use Vixen LV (original series) eyepieces, the 50 degree field is more than enough with the B400, the 20mm eyerelief is great, and I can bury my eye in the long rubber eyecup to exclude all light except that coming from the scope. The 25mm, 15mm and 9mm LVs work a treat.

Regards, Ed.

[Teal Rain]

Hello all

Sorry for the late reply! Many thanks to all who replied and please excuse my lack of knowledge and use of incorrect terminology!   - I was referring to the blocking filter reducing the apparent FOV.

Thanks for your post Michael, I'm seriously thinking about the 12mm Nagler now. At the moment I don't have any really good eyepieces, save the 18mm BGO so I'm looking forward to getting the best out of my scopes when I get the Nagler.

Cheers

Mark

[Pig]

The 12mm Delos is an excellent eyepiece, I am not sure how it will perform in a Solar scope but the performance in my scope is spot on in every way 

I have only had the chance to use 12m once since I bought my Solar filter a week or so ago and I must say it produced great definition with Sun spots

[Stargazer_00]

I dont think it'll work very well if im honest.  I find the Delos suffer from black out when used on a solar scope.  I have an 8 and 10 only though.  They also have exceptionally large eye glass portals which look fantastic but present a very extant problem with other light sources reflecting and tarnishing the image quality.

I prefer to use something with a little tigher eye relief and smaller eye glass portal for solar viewing.  A TV Plossl would probably be best In my opinion.   My dad has a range of BSTs he uses on his PST and these work quite well, too.

[alanjgreen]

The 12mm delos is my most used eyepiece in my lunt60

The main issue is getting your eye exactly in the center of the eyepiece (I have the 1200 blocking filter so the sun is "only in the center"). With practice you learn where to put your eye as second nature.

Howver, the most important thing is "the view" & the sun looks great through the Delos & the contrast. of sun to black background really helps with prominences.

Alan

[John]

I used to use my Ethos 13mm with a PST and that seemed to work very well. It looked rather comical stuck out of the side of the PST though !

Mind you I found the views though much less expensive eyepieces just as good in terms of detail and contrast so maybe H-Alpha scopes are less fussy about eyepiece choice ?

[Stargazer_00]

The pst is f10 so it would follow that is kind in eyepieces I guess

[NGC 1502]

I used to use my Ethos 13mm with a PST and that seemed to work very well. It looked rather comical stuck out of the side of the PST though !

Mind you I found the views though much less expensive eyepieces just as good in terms of detail and contrast so maybe H-Alpha scopes are less fussy about eyepiece choice ?

That's just what I've found too.   On good clear transparent days, I've been very pleasantly surprised how my basic Lunt 35 / B400 performs, but the views are just as good through a cheapie zoom eyepiece, as with TV Radians and Vixen LVs.   That zoom is awful with my 10" F4.8 Dob.............

Regards, Ed.