At the limit

[Piero]

I had some fun this evening with my new Delos 8mm. Needless to say the field is perfectly sharp until the field stop. It's a great eyepiece to me. Unfortunately, I observed from a different location where Jupiter was still hidden by trees and could not observe this at 112x (Delos 8mm + PM2.5x). It was still interesting to try to go deep with known targets and compare the views between Delos and Vixen SLV. As far as I can see, apart from the field of view, the mechanics and the weight, these two eyepieces are very close in terms of image quality. It would be nice to read a comparison between Vixen SLV and Pentax XW's.

In summary, I haven't been able to spot differences between the views obtained with the Delos or the Vixen SLV (apart from the field of view of course). Instead to me they both outperform the Naglers T6, mostly in terms of colour neutrality and "pin-point" stars. Now, I don't know, optically speaking, what are the features to describe "more pin-point stars" or "stars seem smaller and sharper", but this is how I see and this is quite obvious. Possibly I am biased as I am using a very short refractor and these sort of telescopes generate larger Airy discs. So it could be that on my telescope, this difference is larger. In any case, I believe that this increase in "detail sharpness" is the reason why these eyepieces are able to go a bit "deeper" and work wonderfully on planetary targets (Sun included!).

 

 

 

Date 04/03/2016
Time 20:20-22:00
Location Cambridge, UK
Altitude 12m
Lunar Phase Waning crescent 18%
Temperature 2C (NNE 3 km/h)
Seeing 2 - Slight undulations
Transparency 4 - Partly clear
Telescopes Tele Vue 60 F6
Eyepieces Delos 12, Delos 8, Vixen 5 SLV, PM2.5x

M42 Ori Neb 30x, 45x, 72x, 75x, 112x, 180x
The Great Orion Nebula. The nebula showed a nice extension even without filter and was visible with all the magnifications. Tonight, my test was to try to spot E and F stars in the trapezium with the Delos and Vixen SLV. To avoid biasing the result, I did not look at the positions of these two stars. Although some time I had the impression to see something near C (there is F near C), I doubt this impression was reliable as I could not spot any trace of a potential E, which is easier than F. The four stars were clear and distinct with all the magnifications. With this target under this average sky, I could not spot any difference between the image quality produced by the Vixen SLV 5mm (72x) and the Delos 12mm+PM2.5x (75x). Using both these eyepieces, stars are noticeable more "pin-points" than when observed with a Nagler T6 (7mm and 3.5mm) to my eye. I believe that this reduced Airy disc is the reason why these eyepieces give slightly more details on planetary targets. Although the powermate 2.5x works extremely well with the Delos eyepieces, the combo is quite heavy and long for the TV60. After seeing the great performance of the Vixen SLV compared to the Delos, I am even more convinced to get a Vixen SLV 9mm and use this for solar and planetary targets together with the powermate 2.5x. This gives 3.6mm f.l., 0.6mm e.p., and 100x.

Sigma Ori Mlt Star 45x
Nice multiple system. Six stars were easily visible. Not really surprised as these were also visible at 30x with the Delos 12mm. Still a gorgeous view though.

NGC869/884 Cas Opn CL 45x, 72x, 75x, 112x
Double Cluster. To me, this is a target were the Delos 8mm makes a difference compared to a Nagler T6. In particular NGC869 revealed many faint / very faint stars that I do not remember to have seen them with the Nagler T6 7mm. This could be partially explained by an increase in exit pupil, although some of these stars were also visible with the Vixen SLV 5mm with a bit of difficulty. I counted about 20-25 of these stars, some of them were visible via averted vision. With 1.6 degree fov the view with the Delos 8mm was really spectacular. Pin-point stars, great contrast, the two clusters in the same fov and overall lovely colours. Egonomically, these eyepieces are very comfortable to use to me during night time. During day time I think the Vixen SLV are considerably easier to use than the Delos regarding eye placement.

[John]

Nice report Piero

I felt that the SLV's performed as well as Pentax XW's which seems to mirror your findings in comparing them to the Delos.

I reckon the SLV is probably the best eyepiece that I've ever used bearing Vixen's branding.

 

 

[jetstream]

Great report Piero! Many members such as mod John and member Shaun (Pig) hold the SLV in high regard. I'm interested in hearing more reports on these and with your 8" dob. My Delos had nice rich colors on Jupiter and would like your opinion on planetary/lunar between the 2 eyepieces.

[estwing]

You certainly seem happy with it Piero,a super read again clear skies!

[Stu]

Great report Piero. I always really enjoyed my Delos eyepieces when I had them, Ethos like qualities from a contrast and sharpness point of view, just the reduced FOV compensated by the better eye relief.

I do fancy giving the SLV's a go at some point, nice lightweight option without giving up any quality.

I could spend ages just picking out the tiny stars on the limit of visibility in the DC, it's lovely stuff.

[Special K]

Fantastic results, Piero, and I envy your move into the Delos range!  I should do the same. 

NGC869 is an interesting voyage of discovery what lies in the background using different optics.  When I first used my Nag31 on it I was stunned by the stardust in the background of the DC. And again when I viewed 869 in the 6" refractor, those very faint delicate companions really come out. So aside from always being a joy to view, it's an effective test of optics!  

[Paul73]

Great session & writeup Piero.

Sigma Orionis is a favourite. I think that, strictly speaking, it is only the left hand grouping that counts as the Sigma Orion system but it the two groups do make a striking view. Did you catch any colour? Or, the fourth star in the group?

Paul

[Piero]

1 hour ago, Paul73 said:

Great session & writeup Piero.

Sigma Orionis is a favourite. I think that, strictly speaking, it is only the left hand grouping that counts as the Sigma Orion system but it the two groups do make a striking view. Did you catch any colour? Or, the fourth star in the group?

Paul

Thanks Paul  

Good questions! It seemed to me that the brightest two were slightly more blue-ish whereas the third was more grey. However, the position of Orion in the sky from the location I observed was not the best, meaning that there was a bit of light pollution, which can affect the colours I detected. I could not detect the 4-th star in the left-hand group. I think you mean C. According to the image below, the ones I saw were A, D, and E. For the other group, A, B, C. 

(source: http://homepage.univie.ac.at/peter.wienerroither/pwafods/ )

[YKSE]

Nice report Piero.

For some reason, F has been easier than E for me too. It's kind of like a little bulge from the bright C.

I'm glad that Delos and SLV performs very well, I think I see the on-axis sharpness difference among different EPs, not big, but certainly noticeable.

[alan potts]

Very nice report Piero there are a couple of target you looked at the I want to look at in greater depth if I ever feel like going to a scope again, can't shake this illness off and the weather isn't playing ball.

I always have problems when comparing eyepieces with say  50 degree FOV and a 70 degree FOV, it is so much harder I would have thought to plull off the Delos trick with the extra size, which is why they cost more I am sure. I remember doing a review with a 13mm Ethos in and I removed it half way through as to me there was no point in the end. Now i try to compare as near as I can like for like but it would appear surplies have dried up.

Alan 

[laudropb]

Very nice report Piero.