Tele Vue Optics: Calculator

Calculator

Eyepiece Calculator

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Input Box

Follow the steps below to see the eyepiece table.

(1) Enter any 2 of the 3 parameters for your telescope

Focal Length

Aperture

Focal Ratio (f/#)

... or Recall a Stored Run

(2a) Choose telescope eyepiece preferences

Does your telescope accept 2" eyepieces?

Are you using a Tele Vue Paracorr?

Limit to eyepieces that accept DIOPTRX astigmatism correctors?

(2b) Limit to these eyepieces

Current: Ethos Nagler Delos Panoptic DeLite Plössl
Discontinued: Nagler (+zoom) Panoptic Wide Field Radian Plössl Click Stop Zoom Apollo

(3) Enter optional run name and select table presentation order

Run Name

Sort

True Field: Listed from wide to narrow. Eps with same field sort higher mag first.
Magnification: Listed from low to high. Eps with same mag sort wider field first.
Design: Listed from narrow to wide field designs and zooms last.
Note: Zooms sort based on low-power specification.

(4) Calculate Results

Initial Conditions

Focal Length:	2,400.0mm
Aperture:	150.0mm
Focal Ratio:	16.0
Include 2-inch data:	True
Table corrected for Paracorr:	False
List only DIOPTRX eyepieces:	False
Max recommended mag. for aperture:	350x

d:150mm, f:2400mm, w/2in

Design	Focal Length (mm)	Apparent Field (°)	Eye Rel. (mm)	Barrel Size	Mag. (x)	Exit Pupil (mm)	True Field (°)	Star Drift Time (sec)	True Field @ 1000 yards (feet)	Mag. w/2x Barlow (2x)	Mag. w/2x Big Barlow or Power- mate (2x)	Mag. w/2.5x Power- mate (2.5x)	Mag. w/3x Barlow (3x)	Mag. w/4x Power- mate (4x)	Mag. w/5x Power- mate (5x)
Plössl	55	50	38	2"	43.6	3.4	1.1	263	57.5	--	87.3	--	--	174.5	--
Panoptic	41	68	27	2"	58.5	2.6	1.1	263	57.5	--	117.1	--	--	234.1	--
Plössl	40	43	28	1¼"	60.0	2.5	0.64	154	33.8	120.0	120.0	150.0	180.0	240.0	300.0
Panoptic	35	68	24	2"	68.6	2.2	0.92	221	48.4	--	137.1	--	--	274.3	--
Plössl	32	50	22	1¼"	75.0	2.0	0.64	154	33.8	150.0	150.0	187.5	225.0	300.0	375.0†
Nagler 5	31	82	19	2"	77.4	1.9	1.0	240	52.5	--	154.8	--	--	309.7	--
Panoptic	27	68	19	2"	88.9	1.7	0.73	174	38.1	--	177.8	--	--	355.6†	--
Plössl (disc)	26	50	18	1¼"	92.3	1.6	0.53	126	27.6	184.6	184.6	230.8	276.9	369.2†	461.5†
Plössl	25	50	17	1¼"	96.0	1.6	0.51	121	26.5	192.0	192.0	240.0	288.0	384.0†	480.0†
Panoptic	24	68	15	1¼"	100.0	1.5	0.64	154	33.8	200.0	200.0	250.0	300.0	400.0†	500.0†
Nagler 4	22	82	19	2"	109.1	1.4	0.74	178	38.9	--	218.2	--	--	436.4†	--
Panoptic (disc)	22	68	15	2" & 1¼"	109.1	1.4	0.60	143	31.3	218.2	218.2	272.7	327.3	436.4†	545.5†
Ethos	21	100	15	2"	114.3	1.3	0.86	207	45.3	--	228.6	--	--	457.1†	--
Plössl (disc)	21	50	14	1¼"	114.3	1.3	0.43	103	22.6	228.6	228.6	285.7	342.9	457.1†	571.4†
Plössl	20	50	14	1¼"	120.0	1.3	0.41	98	21.4	240.0	240.0	300.0	360.0†	480.0†	600.0†
Panoptic	19	68	13	1¼"	126.3	1.2	0.51	122	26.6	252.6	252.6	315.8	378.9†	505.3†	631.6†
DeLite	18.2	62	20	1¼"	131.9	1.1	0.46	109	23.9	263.7	263.7	329.7	395.6†	527.5†	659.3†
Radian (disc)	18	60	20	1¼"	133.3	1.1	0.44	105	22.9	266.7	266.7	333.3	400.0†	533.3†	666.7†
Delos	17.3	72	20	1¼"	138.7	1.1	0.51	121	26.5	277.5	277.5	346.8	416.2†	554.9†	693.6†
Ethos	17	100	15	2"	141.2	1.1	0.71	169	37.0	--	282.4	--	--	564.7†	--
Plössl (disc)	17	50	12	1¼"	141.2	1.1	0.34	82	17.9	282.4	282.4	352.9†	423.5†	564.7†	705.9†
Nagler 5	16	82	10	1¼"	150.0	1.0	0.53	126	27.6	300.0	300.0	375.0†	450.0†	600.0†	750.0†
Panoptic (disc)	15	68	10	1¼"	160.0	0.94	0.41	98	21.4	320.0	320.0	400.0†	480.0†	640.0†	800.0†
DeLite	15	62	20	1¼"	160.0	0.94	0.38	91	20.0	320.0	320.0	400.0†	480.0†	640.0†	800.0†
Plössl	15	50	10	1¼"	160.0	0.94	0.30	72	15.8	320.0	320.0	400.0†	480.0†	640.0†	800.0†
Delos	14	72	20	1¼"	171.4	0.88	0.41	99	21.6	342.9	342.9	428.6†	514.3†	685.7†	857.1†
Radian (disc)	14	60	20	1¼"	171.4	0.88	0.34	82	18.0	342.9	342.9	428.6†	514.3†	685.7†	857.1†
Ethos	13	100	15	2" & 1¼"	184.6	0.81	0.53	127	27.9	369.2†	369.2†	461.5†	553.8†	738.5†	923.1†
Nagler 6	13	82	12	1¼"	184.6	0.81	0.42	101	22.0	369.2†	369.2†	461.5†	553.8†	738.5†	923.1†
DeLite	13	62	20	1¼"	184.6	0.81	0.33	79	17.3	369.2†	369.2†	461.5†	553.8†	738.5†	923.1†
Plössl (disc)	13	50	9	1¼"	184.6	0.81	0.26	62	13.6	369.2†	369.2†	461.5†	553.8†	738.5†	923.1†
Delos	12	72	20	1¼"	200.0	0.75	0.36	86	18.8	400.0†	400.0†	500.0†	600.0†	800.0†	1,000.0†
Radian (disc)	12	60	20	1¼"	200.0	0.75	0.30	72	15.8	400.0†	400.0†	500.0†	600.0†	800.0†	1,000.0†
Apollo (disc)	11	85	18	2" & 1¼"	218.2	0.69	0.39	93	20.3	436.4†	436.4†	545.5†	654.5†	872.7†	1,090.9†
DeLite	11	62	20	1¼"	218.2	0.69	0.28	67	14.6	436.4†	436.4†	545.5†	654.5†	872.7†	1,090.9†
Plössl	11	50	8	1¼"	218.2	0.69	0.22	52	11.4	436.4†	436.4†	545.5†	654.5†	872.7†	1,090.9†
Plössl (disc)	10.5	50	7	1¼"	228.6	0.66	0.21	50	10.9	457.1†	457.1†	571.4†	685.7†	914.3†	1,142.9†
Ethos	10	100	15	2" & 1¼"	240.0	0.63	0.42	101	22.1	480.0†	480.0†	600.0†	720.0†	960.0†	1,200.0†
Delos	10	72	20	1¼"	240.0	0.63	0.30	73	15.9	480.0†	480.0†	600.0†	720.0†	960.0†	1,200.0†
Radian (disc)	10	60	20	1¼"	240.0	0.63	0.25	60	13.1	480.0†	480.0†	600.0†	720.0†	960.0†	1,200.0†
Nagler 6	9	82	12	1¼"	266.7	0.56	0.30	71	15.5	533.3†	533.3†	666.7†	800.0†	1,066.7†	1,333.3†
DeLite	9	62	20	1¼"	266.7	0.56	0.23	55	12.0	533.3†	533.3†	666.7†	800.0†	1,066.7†	1,333.3†
Ethos	8	100	15	2" & 1¼"	300.0	0.50	0.33	79	17.4	600.0†	600.0†	750.0†	900.0†	1,200.0†	1,500.0†
Delos	8	72	20	1¼"	300.0	0.50	0.24	57	12.4	600.0†	600.0†	750.0†	900.0†	1,200.0†	1,500.0†
Radian (disc)	8	60	20	1¼"	300.0	0.50	0.20	47	10.4	600.0†	600.0†	750.0†	900.0†	1,200.0†	1,500.0†
Plössl	8	50	6	1¼"	300.0	0.50	0.16	37	8.1	600.0†	600.0†	750.0†	900.0†	1,200.0†	1,500.0†
Plössl (disc)	7.4	50	5	1¼"	324.3	0.46	0.15	35	7.8	648.6†	648.6†	810.8†	973.0†	1,297.3†	1,621.6†
Nagler 6	7	82	12	1¼"	342.9	0.44	0.23	55	12.1	685.7†	685.7†	857.1†	1,028.6†	1,371.4†	1,714.3†
DeLite	7	62	20	1¼"	342.9	0.44	0.18	43	9.4	685.7†	685.7†	857.1†	1,028.6†	1,371.4†	1,714.3†
Ethos	6	100	15	2" & 1¼"	400.0†	0.38*	0.25	59	13.0	800.0†	800.0†	1,000.0†	1,200.0†	1,600.0†	2,000.0†
Delos	6	72	20	1¼"	400.0†	0.38*	0.18	43	9.5	800.0†	800.0†	1,000.0†	1,200.0†	1,600.0†	2,000.0†
Radian (disc)	6	60	20	1¼"	400.0†	0.38*	0.15	36	7.9	800.0†	800.0†	1,000.0†	1,200.0†	1,600.0†	2,000.0†
Nagler Zoom	6 - 3	50	10	1¼"	400.0† - 800.0†	0.38* - 0.19*	0.12 - 0.06	29 - 15	6.4 - 3.3	800.0† - 1,600.0†	800.0† - 1,600.0†	1,000.0† - 2,000.0†	1,200.0† - 2,400.0†	1,600.0† - 3,200.0†	2,000.0† - 4,000.0†
Nagler 6	5	82	12	1¼"	480.0†	0.31*	0.17	40	8.8	960.0†	960.0†	1,200.0†	1,440.0†	1,920.0†	2,400.0†
DeLite	5	62	20	1¼"	480.0†	0.31*	0.13	30	6.6	960.0†	960.0†	1,200.0†	1,440.0†	1,920.0†	2,400.0†
Radian (disc)	5	60	20	1¼"	480.0†	0.31*	0.13	30	6.6	960.0†	960.0†	1,200.0†	1,440.0†	1,920.0†	2,400.0†
Ethos SX	4.7	110	15	2" & 1¼"	510.6†	0.29*	0.21	51	11.2	1,021.3†	1,021.3†	1,276.6†	1,531.9†	2,042.6†	2,553.2†
Delos	4.5	72	20	1¼"	533.3†	0.28*	0.13	32	7.0	1,066.7†	1,066.7†	1,333.3†	1,600.0†	2,133.3†	2,666.7†
DeLite	4	62	20	1¼"	600.0†	0.25*	0.10	25	5.4	1,200.0†	1,200.0†	1,500.0†	1,800.0†	2,400.0†	3,000.0†
Radian (disc)	4	60	20	1¼"	600.0†	0.25*	0.10	24	5.3	1,200.0†	1,200.0†	1,500.0†	1,800.0†	2,400.0†	3,000.0†
Ethos SX	3.7	110	15	2" & 1¼"	648.6†	0.23*	0.17	40	8.8	1,297.3†	1,297.3†	1,621.6†	1,945.9†	2,594.6†	3,243.2†
Nagler 6	3.5	82	12	1¼"	685.7†	0.22*	0.11	27	6.0	1,371.4†	1,371.4†	1,714.3†	2,057.1†	2,742.9†	3,428.6†
Delos	3.5	72	20	1¼"	685.7†	0.22*	0.11	25	5.5	1,371.4†	1,371.4†	1,714.3†	2,057.1†	2,742.9†	3,428.6†
Radian (disc)	3	60	20	1¼"	800.0†	0.19*	0.08	19	4.1	1,600.0†	1,600.0†	2,000.0†	2,400.0†	3,200.0†	4,000.0†
DeLite	3	62	20	1¼"	800.0†	0.19*	0.08	18	4.0	1,600.0†	1,600.0†	2,000.0†	2,400.0†	3,200.0†	4,000.0†
Design	Focal Length (mm)	Apparent Field (°)	Eye Rel. (mm)	Barrel Size	Mag. (x)	Exit Pupil (mm)	True Field (°)	Star Drift Time (sec)	True Field @ 1000 yards (feet)	Mag. w/2x Barlow (2x)	Mag. w/2x Big Barlow or Power- mate (2x)	Mag. w/2.5x Power- mate (2.5x)	Mag. w/3x Barlow (3x)	Mag. w/4x Power- mate (4x)	Mag. w/5x Power- mate (5x)

Table Notes

For further reading, see Eyepieces Advice.

†Tele Vue recommends maximum magnification of 60x / inch (2.5x / mm) of telescope aperture and 350x maximum regardless of aperture.

*An exit pupil greater than 7.5-mm may be too big for a telescope with central obstruction (most reflectors). Conversely, small exit pupils may reveal eyesight defects such as floaters. Consider binocular viewing to diminish the effect of an eye having floaters.