No no....it's not illogical. And Debash, show us the funny!
The calculations are based on a few assumptions:
The weight of the lens assembly and focuser/eyepiece assemply is the same: 500g.
The length along the tube from mounting ring to CG of lens is 0.5m. Same for the length from mounting rings to CG of focuser.
Design of the tube has ID 113mm and OD 115mm.
Of course, this numbers may change due to tube length/geometry. This just serves to give us an idea on how much errors due to flexing can be reduced.
My RX80-L Refractor
- harlequin2902
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- Joined: Tue Sep 30, 2003 11:04 am
- Location: Singapore, Sengkang
Managed to take the RX80-L out to Toa Payoh Park on Monday evening. Though there was a full moon and the sky was very cloudy, I still managed to test it on Jupiter (it was nearly overhead and somehow in a totally cloud free zone ), Sirius and M42. It had already passed the test on Saturn 2 weeks ago.
The image of Jupiter was quite pleasing at 140x with a barlowed 10mm Zeiss Ortho - the bands appeared sharp and contrasty, and a couple of small dark blotches on the bands could be resolved too. Chromatic aberration only started to become a pain when the magnification was brought closer to 200x with a single 4mm eyepiece. At 150x and below, it was still ok. Jupiter through the RX80-L was also noted to be not as yellowish as seen from other Chinese made 80mm short tube achromats.
Orion was beginning to set behind a building, but I could just manage to get M42 in the view. Low power, wide field views of the M42 region was also ok. No gross distortions of stars near the edges. All 4 trapezium stars were also nicely resolved at 30x.
Star test on Sirius was also ok : no serious inherent optical defects detected, only showing just a bit of off-collimation which can be fixed easily.
Hm, overall I'm quite satisfied with it, so I guess it's time to put the "QC Passed" sticker on
RX80-L at the park
The image of Jupiter was quite pleasing at 140x with a barlowed 10mm Zeiss Ortho - the bands appeared sharp and contrasty, and a couple of small dark blotches on the bands could be resolved too. Chromatic aberration only started to become a pain when the magnification was brought closer to 200x with a single 4mm eyepiece. At 150x and below, it was still ok. Jupiter through the RX80-L was also noted to be not as yellowish as seen from other Chinese made 80mm short tube achromats.
Orion was beginning to set behind a building, but I could just manage to get M42 in the view. Low power, wide field views of the M42 region was also ok. No gross distortions of stars near the edges. All 4 trapezium stars were also nicely resolved at 30x.
Star test on Sirius was also ok : no serious inherent optical defects detected, only showing just a bit of off-collimation which can be fixed easily.
Hm, overall I'm quite satisfied with it, so I guess it's time to put the "QC Passed" sticker on
RX80-L at the park
Samuel Ng
- zong
- Administrator
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- Favourite scope: 1x7 binoculars (my eyes)
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Yay, not to mention I was there too! Haha, really wanted to test the scope, when i called Samuel the sky was all right, when we met the sky got totally covered in clouds.. Yuck. Lucky the clouds cleared a bit, and we did test it on quite some objects.
Oh, just for the fun we tested it on the moon too, and it showed little softness in detail even at 175x, so given that the moon was covered with a layer of clouds the scope did very well.
As to the calculations part, you gave me the numbers, but I still can't figure out how to link them together. sorry! But I am quite convinced though, from the above numbers, that you assumed quite an ideal situation, which is not really applicable. Also, the error difference will not be really discernable to the eye, if I am not wrong.
Oh, just for the fun we tested it on the moon too, and it showed little softness in detail even at 175x, so given that the moon was covered with a layer of clouds the scope did very well.
As to the calculations part, you gave me the numbers, but I still can't figure out how to link them together. sorry! But I am quite convinced though, from the above numbers, that you assumed quite an ideal situation, which is not really applicable. Also, the error difference will not be really discernable to the eye, if I am not wrong.
- harlequin2902
- Posts: 744
- Joined: Tue Sep 30, 2003 11:04 am
- Location: Singapore, Sengkang
I'm looking forward to doing more deep sky with it to see how deep it can really go. May bring it down for another session sometime on Sunday. Coming ?Yay, not to mention I was there too! Haha, really wanted to test the scope, when i called Samuel the sky was all right, when we met the sky got totally covered in clouds.. Yuck. Lucky the clouds cleared a bit, and we did test it on quite some objects.
Oh, just for the fun we tested it on the moon too, and it showed little softness in detail even at 175x, so given that the moon was covered with a layer of clouds the scope did very well.
Samuel Ng
- harlequin2902
- Posts: 744
- Joined: Tue Sep 30, 2003 11:04 am
- Location: Singapore, Sengkang
It's still just for fun right now. I don't really intend to seriously try selling any self branded scopes at the moment. I'm exploring different ideas, (cheap) lenses of different origin etc...congrats on ur new scope, guess that's the start of harlequin telescopes any chance u going to play with the tmb 100/8 objective?
~MooEy~
I don't think my tubes are worthy of TMB objectives at the moment
Samuel Ng