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Eyepieces for 6" to 10" Dobsonians with 1,200mm Focal Lengths
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Advice
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TeleVue.com: Advice Article List > Eyepieces for 6" to 10" Dobsonians with 1,200mm Focal Lengths |
CEO, Tele Vue Optics
Tele Vue eyepieces are ideal for maximizing the performance of 6", 8", and 10" Dobsonian telescopes with 2" focusers. The fast focal ratios of these telescopes place an extra burden on eyepiece performance. Because all Tele Vue eyepieces are designed for excellent sharpness over wide fields when used with fast telescopes, you'll get the most spectacular "spacewalk" viewing experiences using Ethos, Nagler, Delos and Panoptic eyepieces. If you must wear glasses to correct astigmatism and know the astigmatism value, it's best to call Tele Vue for specific advice. For a full explanation on how to choose eyepieces and an eyepiece calculator, you can check out Choosing Eyepieces.
Our 100° Ethos and 82° Naglers, in particular, will not only give you the widest, sharpest images, but very long viewing times as objects traverse the field. You won't have to constantly shift the scope to place the image in the "sweet spot," and of course, the whole "spacewalk" view is your "sweet spot."
I believe you only need three or four eyepieces to cover the full range, from low-power, wide true field, to high-power for planetary viewing. Since many 6", 8", and 10" models all have the same focal lengths (1,200-mm), the magnifications and field sizes will be the same for each eyepiece recommended (I assume you have a 2" focuser):
| Power | Field | ||
| 1. Low Power, Wide Field |
Either 35mm Panoptic or 31mm Nagler Type 5 or 21mm Ethos |
34x 39x 57x |
1.85° 2.00° 1.73° |
| 2. Low Medium Power |
Either 18.2 DeLite or 17.3mm Delos or 17mm Ethos |
66x 69x 71x |
0.91° 1.01° 1.41° |
| 3. Medium Power |
Either 15mm DeLite or 14mm Delos or 13mm Ethos or 13mm Nagler Type 6 or 13mm DeLite |
80x 86x 92x 92x 92x |
0.76° 0.83° 1.06° 0.84° 0.66° |
| 4. Medium High Power |
Either 8mm Ethos or 8mm Delos or 7mm Nagler Type 6 or 7mm DeLite |
150x 150x 171x 171x |
0.66° 0.47° 0.46° 0.36° |
| 5. High Power |
Either 6mm Ethos or 6mm Delos or 5mm Nagler Type 6 or 5mm Delite or 4.7mm Ethos SX or 4.5mm Delos |
200x 200x 240x 240x 255x 267x |
0.50° 0.36° 0.33° 0.25° 0.43° 0.27° |
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6. Alternative "Spacewalk Supreme" Ethos-only set |
21mm Ethos 13mm Ethos 8mm Ethos 6mm Ethos |
57x 92x 150x 200x |
1.73° 1.06° 0.66° 0.50° |
Note: using a Paracorr to eliminate the mirror's coma, will increase the power, and decrease the field of each eyepiece by 15%.
The above selection should give you great experiences for most viewing situations, although both a little more field and a little more power are possible using a total of four or more eyepiece choices. Also, if your scope is f/5 or faster, consider Paracorr coma corrector to get the full field sharpness your eyepieces can deliver.
