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Do I have this straight?

Started by explore, 09/26/2003 07:21PM
Posted 09/26/2003 07:21PM Opening Post
I have a 10" dob and I'm looking to get a Denk II with 2" OCS. Assuming I get two 24mm Pans and two 16mm Naglers, I will have(using the 1.3x and 2.5x for the OCS):

24mm Pans - 18.5mm(1.3x) and 9.6mm(2.5x)

16mm Naglers - 12.3mm(1.3x) and 6.4mm(2.5x)

So my focal lengths will be 18.5mm, 12.3mm, 9.6mm, and 6.4mm, correct?

What about wide-field low power views(say around 26mm-32mm focal length ep's), is this possible with binoviewers? Or am I going to have to go mono-view for low power wide-field views?
Posted 09/26/2003 07:38PM #1
Chris,what is your focal length on your scope.
Posted 09/27/2003 06:00AM #2
Chris,

You have it correct, sir.

The only thing I will add is that swapping power modes on the 2" OCS at night is not as simple as it is in the garage or den. The logistics of unscrewing it, finding a place to put the binoviewers, reconfiguring the OCS and then screwing it back on the binoviewers is no simple feat. In the meantime, your target of interest has drifted well outside the FOV. Unless your 10" tracks, and even then the OTA may be off balance because you had to remove 2 lbs plus of stuff from the front end. Been there, done that. I've resigned myself to buying more pairs of ep's rather than using the high power mode of the OCS. That's my opinion, btw.

For wide field, the 24 Pans will be your widest possible true field of view. They have a field stop of 27mm. A 32mm ep has a field stop of 27mm, so it won't provide any larger FOV, just a lower magnification. The 20mm KK Widescan III has a reported field stop of 29.5mm, but I'm not sure how they do that. I didn't buy a pair of them because they were reported as poor performers at f/5. Even though I do all of my viewing with binoviewers (which equates to f/6 or so), I want my ep's to be able to perform in my f/4.7 dob in mono mode as well.

Clear skies,

Tom