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My friend(s) just received his/her Ethos 3.7mm with a 110º apparent field of view doing side-by-side A/B Test. We are going to compared with the expensive APM80/480 versus cheap Equinox 80/500.
We are going to focus on some leaves at the top of the mountain that APM is totally worth for that. Beside the colour resolution of the APM is much more sharper than Equinox and also it can't see any observable violet edge on APM.
Finally, we can concluded that the price is one of the factor to control the quality of telescope.

During the test, we found that other "Ethos" 10mm is still a little bit colour gradient change from centre to edge, those green colour becomes pale yellowish-green. Maybe we need to re-test again

This is very much consistent with what we found earlier in the artificial star tests on these two scopes earlier.
viewtopic.php?f=14&t=763

For example, under blue 'star', the Equinox shows a halo rather than clear airy disk and diffraction ring(s). This shows that the equinox is very poorly corrected in blue. However, the APM80/480 still shows a nice airy disk plus a very dim first diffraction ring.

Lewis 寫:We are going to focus on some leaves at the top of the mountain that APM is totally worth for that. Beside the colour resolution of the APM is much more sharper than Equinox and also it can't see any observable violet edge on APM.
Finally, we can concluded that the price is one of the factor to control the quality of telescope.

我的個人經驗，從天文觀測上，Sky Watcher Equinox 80這類優秀的ED鏡，跟頂級APO折射鏡APM 80/480的表現，分界線就在每mm口徑2x這傳統指標上。

例如兩鏡都是80mm口徑，特別是100x以下，很多人都會滿足其表現。但推上在160x以上，你會看到Equinox比APM的成像稍為柔化。

當付出5000元買一台80ED折射鏡，能在每mm口徑2x這傳統指標以內表現理想的，生產商已做足功夫，用戶也覺實物有所值了。

而頂級APO是設計作超指標工作的，例如我的203APO，是不時可以推上406x以上，跟David的18"UC競賽的，我們不時說18"UC的影像亮些，但不一定能反映那5x集光力的差距，而且就算在極理想的視寧度下，兩鏡的解像度也沒有很大分別。

問題是，APM 80/480的價格是Equinox 80的三倍以上，是否"totally worth"，是見仁見智了。至少我經常跟人家說，對絶大多數人來說，是不應該考慮我的203APO的，反而一台100至130級APO，另加一台400級的牛反(Dobsonian或加個Equatorial platform都可以)，應已足夠大多數用途。

Lewis 寫:My friend(s) just received his/her Ethos 3.7mm with a 110º apparent field of view doing side-by-side A/B Test. We are going to compared with the expensive APM80/480 versus cheap Equinox 80/500.
We are going to focus on some leaves at the top of the mountain that APM is totally worth for that. Beside the colour resolution of the APM is much more sharper than Equinox and also it can't see any observable violet edge on APM.
Finally, we can concluded that the price is one of the factor to control the quality of telescope.

During the test, we found that other "Ethos" 10mm is still a little bit colour gradient change from centre to edge, those green colour becomes pale yellowish-green. Maybe we need to re-test again

I learnt a lot from Equinox 80ED. It led me from novice to beginner.
http://willisao.blogspot.com/2010/11/my-first-m42.html
http://willisao.blogspot.com/2009/11/lunar-x.html
http://willisao.blogspot.com/2009/07/pl ... aging.html
http://willisao.blogspot.com/2009/07/bu ... n-day.html
I've seen many China made refractors of similar size. At this price level, Equinox is a good choice for sure. Certainly it cannot be compared with wrold class refractors. But u get more than what u paid. u know how I learn in the past two years as u go stargazing with me. So I wish u can utilize this good scope.

"During the test, we found that other "Ethos" 10mm is still a little bit colour gradient change from centre to edge, those green colour becomes pale yellowish-green. Maybe we need to re-test again"


Is that mean Ethos 10mm is less good than 3.7?

噢，原來Lewis是Equinox 80新物主。

這鏡保值能力不俗，最近有一枝，用了近兩年轉了兩手，才從新價的4980跌至3800元。

Lewis 寫:During the test, we found that other "Ethos" 10mm is still a little bit colour gradient change from centre to edge, those green colour becomes pale yellowish-green. Maybe we need to re-test again

Lewis, I think u made a mistake. The one with some color is Ethos 3.7mm, not Ethos 10mm. There is a bit yellow gradient towards the edge. However, if one shifts the head a bit, the color will disappear. In addition, there is blue at the extreme edge and this will not go away even shifting one's head. I guess it is hard to observe the color if one do the observation in dark skies. We were doing bright terrestrial observation that day.

willis 寫:Lewis, I think u made a mistake. The one with some color is Ethos 3.7mm, not Ethos 10mm. There is a bit yellow gradient towards the edge. However, if one shifts the head a bit, the color will disappear. In addition, there is blue at the extreme edge and this will not go away even shifting one's head. I guess it is hard to observe the color if one do the observation in dark skies. We were doing bright terrestrial observation that day.

I think I saw this colour gradient also with my 3.7 when observing the moon. I also notice the blue at the very extreme edge as mentioned here:
viewtopic.php?f=16&t=999

So all three 3.7mm showed similar phenomena. It is inherited in 3.7mm

對，我前晚看月亮也有這個情況。哈哈，不過用來看H-alpha太陽伯伯就不會出現了。
今早趁上課前偷偷地看了一會，600/3.7 = 162倍的日珥好靚呀~~~

willis 寫:So all three 3.7mm showed similar phenomena. It is inherited in 3.7mm

It also appears in my ethos 8mm but I am ok with that