... Don: Thanks! I've been doing some checking and am thinking about going with Discovery Optics for my diagonal. Several people have recommended them to me...
... Your likelihood of getting a very good mirror will be better at F/6. They are easier to make, even for the masters. More likely to have a smooth surface...
... My personal preferences - I'd rather have more "top end" in terms of magnification than wide field. Nice wide views are nice, but I don't use really low...
... be ... Well, assuming we're talking about a large aperture scope--a big Dob, I can't think of a reason to go with anything faster than than f/5 for a...
So last night, I was looking at Mars. Then I plugged in an old 3x barlow and took another look. To me, it didn't look dimmer...just the same light spread...
Brightness per unit area diminishes by the square of the magnification--i. e. in your case, the image was 1/9th as bright per unit area. If you have a larger...
Hi Steve, Yes, you got it - the light is spread out over 9 times the area, so it's the square of the magnification factor. Paul ... From: "stevereecy"...
... so it's the ... Cool. So with my 12" mirror and a 4x barlow, the image will drop to 1/16th the light density, which would be as bright as I would expect ...
A 0.5x barlow is called a "reducer" and they can be bought, typically for imaging. The 0.63 reducer/corrector is a standard among sct users. But you can get...
Now and then an opportunity presents itself that one simply cannot resist. For sometime now, I have been in possession of a 14.5" F4.3 ZOC mirror that I was...
Pretty much, A "negative barlow" that gives a magnification under 1x (eg. 0.66x, 0.33x) is called a focal reducer. These are commonly used with slow scopes...
... All I can say is, after looking through this ... Hi Mike... A friend told me last week that he had received an Ed Stevens mirror (I believe this was a...
Mike, Me thinks you were talking about my Stevens Optical 12.5" f/5. I have also owned a bunch of lovely ZOC mirrors (every one of them was a winner). Well, my...
There are a few problems with this plan. First, when you use lower power, the light density ("surface brightness") increases, but the same thing happens to the...
It looks like Meade hasn't given up on Dobs. I don't see anything on Meade's website yet, but I believe Stephen Hamilton was a beta tester for Meade's DSI ...
John, Check out Astronomics they have them on their web site, Rick Runcie John Mahony <jmmahony@...> wrote: It looks like Meade hasn't given up on Dobs....
Well I hope the new Meade truss tubes have 1/2 wave mirrors, bad spiders, and wobbly focusers. Many Meade enthusiasts will go into severe shock followed by...
This isn't specifically a DOB question, but perhaps someone can point me towards some advice on filters. Was out tonight hoping to get a look at Mars- I did,...
For you lovers of big dobs with superb aperture. I have a loaded 20" f/4.5 NightSky with Argo Navis and ServoCat GOTO/tracking and Feathertouch focuser. The...
Am a new member from Simpsonville SC and have noticed quite a bit of chat about F/6 mirrors. I have not seen any "advertised" large mirror dobs of this focal...
Right now, Mars is at opposition, so it _is_ like looking at a full moon. The sunlight is hitting it from nearly the same angle we're viewing it from. But ...
Greg - I agree with you on the bad focusers, and in some cases the bad spiders. The optics on the other hand, have usually been good to excellent. Karl...
All, Just looked at the Meade website. Really impressive to see them building a truss dob similar to the ones I was building circa 1988. But, guess this is a...
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