7 replies to this topic

[k.darwin]

Lots of CN folks poo-poo the 6x30 straight finder, but I find it very useful for putting the moon or planets into the FoV during daylight hours.  You know, those times when the are no other celestial things to use to align the fancy go-to mount, and the sky is too bright for a red dot to work.

 

I bend down (what a pain) and look through the finder with both eyes open.  Manually move the scope until the planet / moon are in the finder FoV then switch to the hand controller to get it on the cross hairs and in the eyepiece.  This does not work with the right angle finder.  Has to be straight.

 

BUT there may be some other method I'm missing.  So, please, educate me and show me the better way.  Quick, before I buy another 6x30 finder for my newly acquired scope.  :-)

[TOMDEY]

Hint: >>> For dim stuff use a polarizing filter to darken the sky. It will darken the target too, but the sky darkens a lot more, so the target's contrast goes way up... especially if it is in the neighborhood of 90^o from the sun. You rotate the filter so its electric pass vector is pointing along the ecliptic toward the sun. (I know, I know... very few linear polarizers have the polarization vector tagged. But you can figure that out.)    Tom

 

[I researched that kinda stuff in the jungles of Panama over half a century ago. This resulted in such best sellers as my "Polariazation sensitivity of the compound eye of hymenoptera bombus."]

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Edited by TOMDEY, 18 March 2025 - 12:00 PM.

[jimr2]

darwin,

 

Hi, I guess I don't understand why your system of using a 6x30 finder-scope in the daytime, wouldn't work w/ a right-angled 6x30 (or other mag.) finder? RACI finders are all I use on my various scopes, in order to prevent the "pain" of having to contort your body in to see thru a straight-thru finder, whether used in the daytime or at night. But again, don't see why a rt-angled finder wouldn't work for finding things in the daytime sky?? Anyhow, good luck!

 

-jim-

[k.darwin]

Jim

 

My daylight technique is to use the finder like a red dot:

1. Manually move the scope to point it close to the moon/planet.  Eyeball down the scope tube side.  This puts me maybe within 15 degrees.  I'm in the neighborhood but the object is not in the finder scope yet.
2. With BOTH EYES OPEN, look through the finder.  One eye will see the blue sky and the moon/planet.  The other, looking through the finder will see blue sky with the cross hairs.
3. With both eyes open, use the cross hairs as a guide to manually move the scope so the moon/planet appears in the finder scope.
4. Close the non-finder eye and finish moving the scope to put the object in the center.

With a right angle finder, step 2 has one eye looking through the finder at blank blue sky and the other looking at the side of your scope.

[triplemon]

BUT there may be some other method I'm missing.  So, please, educate me and show me the better way.  Quick, before I buy another 6x30 finder for my newly acquired scope.  :-)

Mount a piece of plain second-surface bathroom mirror next to or all around the finder ? Then you can do the usual coarse vs fine eyeballing much more conveniently. Or point the entire straight through finder at such a mirror. In which case the extra ghost reflection would likely suck a bit more, so you might have to put up with a first surface mirror then.

 

I just chopped a surplus 6x30, glued on a equally surplus 0.965 prism diagonal and the bathroom mirror piece wasn't exactly new, either. The mirror needs to be an inch wider on all sides than the backside of the mirror diagonal - you glue it directly to the backside of it, so it is properly oriented.

That gets you a truely complete "all sideways finder system".

Edited by triplemon, 18 March 2025 - 03:57 PM.

[zizzapnia]

Mount a piece of plain second-surface bathroom mirror next to or all around the finder ? Then you can do the usual coarse vs fine eyeballing much more conveniently. Or point the entire straight through finder at such a mirror. In which case the extra ghost reflection would likely suck a bit more, so you might have to put up with a first surface mirror then.

 

I just chopped a surplus 6x30, glued on a equally surplus 0.965 prism diagonal and the bathroom mirror piece wasn't exactly new, either. The mirror needs to be an inch wider on all sides than the backside of the mirror diagonal - you glue it directly to the backside of it, so it is properly oriented.

That gets you a truely complete "all sideways finder system".

A picture of this would be cool if you have one!

[jimr2]

darwin,

 

OK, understand now what you're doing in the daytime--using your OTA as a sight-tube in essence! Still think you could do that with a rt-angled finder too, maybe just a little more time-comsuming, but might be easier on your body....

[Jon Isaacs]

A technique I use to find Venus in the twilight before it is visible naked eye is to use a digital level. I mount the level on the OTA. Digital levels are accurate to about 0.1 degrees so I put a wide field eyepiece in the scope, use one several techniques to focus.  Then I look up the altitude of Venus using SkySafari.  Set the OTA to the proper altitude and then slowly scan the region by sweeping back and forth.  

 

The other night, Venus was 10.7 degrees from the sun and less than 2% illuminated.  The sky was very bright but using this method, I was able to spot Venus a few minutes before the sunset.  Venus was at 8.4 degrees.  

 

When observing a planet so close to the sun, it is important to be in a shadow of a large building or something that ensures you will not accidentally glance the sun.

 

This is the one I use, it is $20 and reads out to 0.05 degrees.  The important thing is that the illumination is white on a black background so when using it at night, I can tape some red film of the screen to protect my night vision.

 

https://www.amazon.c...2627102&sr=8-31

 

Jon

Edited by Jon Isaacs, 22 March 2025 - 02:07 AM.