M13 at 374X

On Thursday night 24th July at about 11pm, Valerie and I spent some time checking out the Great Globular in Hercules. The cluster is very high at that time. There was no wind in Dublin, and those wispy clouds that were prevalent earlier had disappeared soon after sunset. I was amazed to find myself pushing the magnification beyond 225X on M13. I could see all the stars and the dark lanes at this power, and there was no turbulence at all. So we pushed it up to 280X, and again to 320X. No sweat to the 6.2" apo. So we have 1 more eyepiece: a 3mm Radian. I rarely use it. It only gives me 25 minutes field of view and M13 is 23 minutes wide -but what a sight! At 374X, it completely filled the field of view, and there was still no turbulence at this power!

I wonder if I should get a more powerful eyepiece. Would anyone recommend one? And preferably one with a good field of view. By the way, I have heard of Dave Lillis using 600X on Saturn a few years ago. That must have been something else!

Aubrey.

Hi Aubrey,
On a small number of occasions I've used a 5mm t6 nagler on the obsessionator. Being a 20" F5, this gives me 500x. More often then not, the 7mm gives a better view (357x), but on a rare night when the conditions are right, the 500x works on high altitude planets and globulars well..

It would be nice to have a 6mm eyepiece, to fill the gap between 357x and 500x.

I'd recommend the t6 naglers to anyone looking for a high power set of eyepieces and the 82 degree fov is nice. Televue also have a very high power zoom eyepiece, 3-6mm, I wouldn't normally mention zoom eyepieces as they're usually rubbish, but this is apparently a good one and its specifically made for short focal length scopes. It's pricey though and you might be able to get a small set of specific planetary short focal length eyepieces for a similar price.

Whoops! It is my 8mm eyepiece that gives me 25 minutes true field of view. My 3mm Radian gives me only 9.5 minutes.
Anyway, I have found that Televue have introduced at 2.5mm Nagler. It is a T6, Dave. This would give me 448X and 11 minutes true field of view. Views of planets would be astounding under very calm conditions through this eyepiece. I have been on Google trying to get a review; but no joy on that. It seems perhaps that no one in the world has bought one of these. Amateurs on one website were greatly discouraging anyone from using more than 200X -which I think is ridiculous. I have lost count of how many times I have used my 5mm Nagler.
I have used 320X on many occasions also; most recently on Mars -and M13 too. Tight doubles like 32 Orionis, 52 Orionis and Lambda Cygni need my 3.5mm Nagler to split. I notice that last Thursday night was my 1st time this year to use the 3mm Radian.

Aubrey.

Less then 200x ? Maybe if you have poor optics, collimating or bad seeing or a small aperture. I'd be willing to bet that the 2.5mm is a good eyepiece as it's a televue. There aren't many reviews as it probably wouldn't be a common eyepiece in most peoples eyepiece cases, it's too high a power for any SCT, most Newts (it would be 1000x in my scope !) and most refractors could be hitting a resolution wall with this eyepiece given that most refractors have small apertures, but not all

It never fails to amaze me how many people on other websites claim never to view above 200x. I just don't understand this at all.

To be fair, it is not very often that it can be done, especially in Ireland, but I always take every opportunity to do so.

Could I recommend two excellent high power eyepieces. The first is the Explore Scientific 4.7mm 82 degree. I owned this until recently, before passing it on to Simon, another NIAAS member. He has a 14" Skywatcher Flextube go-to, and one night at Bragan, he used this eyepiece on both the Eskimo nebula and M5. The views of both were jaw-dropping, especially the Eskimo.

The reason I passed on the ES was because I came into possession of a Meade 5000 UWA 5.5mm, which is also an 82 degree eyepiece. This eyepiece gives somewhere in the region of 220x in my 10" dob, and the view of M13 on a good night is superb. I was using it just last night in my Nexstar 6se to view both Uranus and Neptune, as well as several doubles, including Izar (Epsilon Bootes), which it splits beautifully
In fact, it is so good that I soon picked up the 8.8mm, which I am not yet totally convinced by, and then the 14mm, which is now my favourite eyepiece. The 14mm also works brilliantly with my TAL 2x barlow

The Televue zoom mentioned by Dave is also an excellent eyepiece. I borrowed Neil's one night down at Bragan to view Saturn with the 10" dob. The views at both 6mm and 5mm were excellent, and 4mm was not too bad either. At 3mm, the planet shot through the field of view very quickly, but it was pretty clear even with that.
Televue also have a 2-4mm zoom, but I have never seen or used one.

To be honest, I would think that spending money on something like a 2.5mm eyepiece would be a waste. The opportunities to use it would be so few and far between that it would be difficult to justify.

Thank you, Stevie, for your exquisite report. It has been some years since I observed the Eskimo Nebula. But I have been observing M5 and, even before sunset, finding Izar split in 2 at 112X. (See the adjoining blog).

I am only considering a 2.5mm Nagler at present. It is simply because I had no problem magnifying M13 up to 374X the other night. I just wonder what other objects would look like at 448X. I would only use it when the 3mm Radian is seeing a planet or a tight double star in most favourable circumstances.

Thank you for your other pieces of advice. Let us keep pushing the boundaries. The rewards can be superb.

I do own a William Optics 158 mm Apochromatic Refractor F/7. Its focal length is 1121mm. And I have had it for 4 years. And yes, field of view is very important to me.
My 5mm Nagler gives me 225X, a TMB 4mm gives 280X, and a 3.5mm Nagler provides 320X. Plus I do have extra space for 1 more eyepiece in my travelling case.

Aubrey.