6 replies to this topic

[Gregory Gross]

Last night I was curious to know if anyone had started a thread for discussing which non-Questar eyepieces come to focus when used with the 3.5-inch Questar in finder mode. By means of an internet search, I found a page entitled "Finder Eyepiece Compatibility" on Rob Pettengill's website. He does a great job indicating the information sources for this list (thanks much, Rob).

 

Tele Vue also has a table on this page indicating which of their eyepieces also work in finder mode.

 

Considering that eyepieces appear and disappear from the market all the time, are there any other non-Questar (i.e., non-Brandon) eyepieces that folks like to use with their Questar that come to focus in finder mode?

[cbwerner]

Rob's got a great site - lots of valuable information there.

[RobertPettengill]

Thanks!  I had not noticed that TeleVue had updated their Questar finder focus compatibility table.  They added a couple of Delos and a bunch of DeLite eyepieces.  It's good to get confirmation on the DeLites.   I've added these to the table at my site.

 

When I originally put this together I was not able to test every eyepiece myself.  I found some discrepancies between reports from others and my own experience.  I finally realized there there are two obvious explanations for these:

 

1. Vision correction.  It's easy to adjust telescope focus to correct for simple near and far sightedness.  The finder focus has a much smaller range.  Results can vary depending on the vision of the user and whether or not they use corrective glasses with the eyepiece.

 

2. Questar has made more than one version of its diopter adapter.  TeleVue also makes a diopter adapter that allows the use of standard 1 1/4" eyepieces.  I expect that there is variability in finder focus depending on the model of diopter adapter used.

 

None of the sources I found, documented either of these possible causes of variation in reports of finder focus compatibility for the Questar.  As a result, YMMV (boy am I old?).  Take any report of compatibility with a grain of salt until you can verity it with your own eyes and equipment.

 

I'm happy to add new information.  I like to the original sources I used so that anyone can check for updates.  Please let me know of any changes or corrections and I'll update the table.  Here is my updated compilation:

 

http://astronomy.rob...inderFocus.html

 

;rob

 

[munirocks]

In your "Out" category (those eyepieces that focus if pulled some way out of the eyepiece holder and then secured at that height) you can add these:

 

B&L 30 mm A.S.P (Achromatic Symmetrical Plössl)

B&L 18 mm A.S.P (Achromatic Symmetrical Plössl)

B&L 12.7 mm A.S.P (Achromatic Symmetrical Plössl)

 

I quite like the eyepieces in the "Out" category, such as the B&Ls. Because you can push or pull the eyepieces in both directions, you get a gigantic focus range so they will come to focus in the finder no matter what your prescription is -- something that the big finders on my big scopes can't even do.

 

The B&Ls are compact, indestructible, very sharp, and work very well with the Questar.

[davidmcgo]

My old mushroom top University professional series 10.2 and 6.8 Orthos will focus slid out partway.  The 10.2 is really sweet in the Q for Jupiter.  Wish there was a 10mm Brandon!

 

Dave

[RobertPettengill]

Thanks for the updates.  I'm adding those now.

[Darkskyaz]

My old mushroom top University professional series 10.2 and 6.8 Orthos will focus slid out partway.  The 10.2 is really sweet in the Q for Jupiter.  Wish there was a 10mm Brandon!

 

Dave

I used my 8mm Brandon on Mars this morning and it was fantastic. Also, my wife gave me a 19mm Panoptic for my birthday this month. That is as fantastic an eyepiece for the 3.5" Questar as everyone says it is. It focuses in the finder just fine, when using my contacts or glasses. I've also found that the Televue 32mm Plossl comes to focus in the viewfinder, again, as long as I'm using my contacts or glasses. As a nearsighted person these eyepieces don't go in far enough if I'm not using glasses or contacts. These results are with using the Questar adaptor on a 1969 version. 

Edited by Darkskyaz, 31 August 2020 - 06:34 PM.