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Pleiades M 45 with the Pleiades 68

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finder piece EP ?

Started by Midnight Sun, 01/30/2007 11:45PM
Posted 01/30/2007 11:45PM Opening Post
Before I sold my Panoptic 35mm. it is what I used as my initial "finder" prior to X higher... in it's place is a earlier 32mm. 2" TeleVue Widefield with a (I believe a 62º fov) my question is; how would the older Celestron 36mm. Ortho 1.25" perform comparatively to the TV WF ? as an example, trying to fit the double cluster PER. in the field... thank you, John Meiners

Posted 01/30/2007 11:59PM #1
10" f/5 scope
36mm 40° FOV 1.2° Ortho
35mm 68° FOV 1.98° Panoptic
32mm 62° FOV 1.65° Wide Field

[SIZE="Large"][/SIZE][COLOR="Blue"][/COLOR] Floyd Blue grin
Amateur Imager
Posted 01/31/2007 02:14AM | Edited 01/31/2007 02:16AM #2
For Widefield EP's, most of which have significant distortion, the simple assumption that TFOV=FOV/magnification can be quite bit off. When calculated useing the real fieldstop diameter the numbers are:
35mm pan = 38.7mm fieldstop = 1.75deg TFOV
32mm WF = 34.6mm fieldstop = 1.53deg TFOV
For the ortho the simple formula FOV/mag is likely very close, as the name orthoscopic just means it has no field distortion, so its some 1.2deg TFOV at best.
Which puts the ortho not that much behind the widefield.
On the question with the double cluster - its 1.5 degrees across both parts.

Michael
P.S. I use a GSO 42mm superview as a finder - 46mm fieldstop !