Unexpected performance of APM-LOMO 80/480

[willis]

Today I did solar observations two times, Ha in the morning & white light in the afternoon. The proms were big in the morning. In the afternoon, I used the Equinox 120ED to do high power magnification. I plugged the Ethos 3.7mm into it and resulting a magnification of 900/3.7=243x. The view was quite good. One of sudden I want to see the limit of my APM-LOMO 80/480. I tried the 3.7mm on 80/480, the image is good. However when I added an 2.5x Powermate on it, the magnification was 480/3.7x2.5=324x, the image was bad. After that I tried the Ethos 10mm and 5x Powermate on 80/480, the magnification was 480/10x5=240x, the image is better than that of 120ED & 3.7mm despite of a dimmer image!

[社長]

you mean unexpected or expected performance of your 2nd hand heavily used APM 80/480?

[willis]

you mean unexpected or expected performance of your 2nd hand heavily used APM 80/480?

I mean how come a 80mm refractor beats a 120mm refractor.... In order to be scientific, I need to do a side by side test. But I don't have two Herschel Wedge!

[社長]

實事求是，你說的"較好"是很主觀的，須要更深入的描述。

正如在路邊天文，我發現要讓路人有認為影像"較好"，用上較大視場的目鏡，較長的eye relief，可以容下整個月面及預留一些空間的倍率，影像稍亮便可以，跟口徑及解像度無關的。

[sharkfin]

next time let us compare ethos 10 + 5x powermate and 2-4 nagler zoom using 80/480
and also compare ethos 3.7 and the 2-4 nagler zoom

[Robin]

實事求是，你說的"較好"是很主觀的，須要更深入的描述。

正如在路邊天文，我發現要讓路人有認為影像"較好"，用上較大視場的目鏡，較長的eye relief，可以容下整個月面及預留一些空間的倍率，影像稍亮便可以，跟口徑及解像度無關的。

对，而且大众通常不会停留太久，那个initial impression就要通过大视场和高亮度的物体来刺激出来。像是那些要观测一阵子才能欣赏的暗天体大众就不懂得欣赏了。