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Posts Made By: Ed Zarenski

July 23, 2002 11:55 AM Forum: Deep Sky Observing

Re: Milky Way from my backyard!

Posted By Ed Zarenski

There were two nights last week when the Milky Way through Cygnus / Vul area was naked eye in Rhode Island. It got cold those two nights and around midnight the daytime slight haze broke to show a glowing sky with the great rift just standing out easily. Through binoculars the area was swarms of stars and it was difficult to distinguish some of the clusters in the area from the background. But the sky was so clear that Objects like the Dumbell-M57 and M71 in Sagitta easily stood out in binoculars. I followed Milky Way through the sky with my binoculars down to my visible southern limit and easily saw M16,M17,M18,M24,M25,M23 all down near the Oph,Scu,Sag border and nearly all in the same view.

August 16, 2002 08:04 AM Forum: Eyepieces

0.965" eyepieces from Orion

Posted By Ed Zarenski

This thread started over in the Equipment Forum.

About a year ago Orion must have been cleaning house of it's 0.965 plossls. I bought 3 on sale since I have a few old scopes that use this size. (One of these is the Orion Sirius 17mm plossl, one of the sharpest plossl eyepieces I've seen in this midrange. Sharpness to the edge better than 16Konig and 18SWA, just not as wide a field, but much better eye relief.)

Much to my surprise, the 0.965 Orion Sirius plossl is exactly the same as the 1 1/4" Sirius plossl eyepiece, (I own a couple duplicates of the 1 1/4"), but instead of the 1 1/4" sleeve it has a 0.965 adapter/sleeve screwed on. This adapter sleeve can be unscrewed from the Orion barrels and screwed onto almost every other 1 1/4" eyepiece in my box, turning them into 0.965 format. So for every eyepiece, up to about a 21mm field stop without vignetting, I can now use them in my 0.965 scopes. If you can get your hands on one of Orions 0.965 plossls, you'll only need one to increase the number of eps you can use in the 0.965 format by ten fold. The adapter fits my Celestron Ultimas, Celestron Plossls, Meade 4000s, UO orthos, UO Konigs and Meade SWA. Does not fit 30mm Ultima, Meade UWA, TV plossls or TV Radians.

September 6, 2002 08:22 AM Forum: Astro Binoculars

Pentax 12 x 50, Orion 10x50, Oberwerk 15x70

Posted By Ed Zarenski

I picked up a used 12 x 50 PCF binocular last week on the mart. These Pentax are the sharpest binoculars I have looked thru. I haven't looked thru Fujinon. I set up the other night with my Orion Ultraview 10x50 on one side and my Oberwerk 15x70's on the other side for a comparison. I viewed Albierio to test for poor image, the point at which I could no longer see it split. I noted star patterns at the limit of fov to find true fov size and I viewed the oc IC4665 in Oph for a wide range of faint stars to test how deep each binocular could see.

The Orions have a 6* measured fov but can't begin to compare to the sharpness of the Pentax. Orions are sharp only out to 60% of field, between 70-80% out the image becomes un-useable, leaving only about a 4.5* clean view. In the Orions favor, the wider fov does make it easier to initially find objects and at 32oz. they can easily be handheld.

The Oberwerks measure the full 4.4* fov as advertised with a good sharp image out to 60-70% of field. The image doesn't become poor until about 90% out giving a fairly good sized viewable field of 4*. The Oberwerks have the edge on power, allowing to see deeper into every cluster I tried but need to be mounted for best results.

The Pentax measured a hair less than their stated 4.2* fov and are sharp across 70% of the field, with a fairly sharp view all the way out to 90%+! This gives the Pentax just under 4* clearly useable fov. The Pentax have the best eye relief - 20mm, the best focus mechanism, and at 12x they saw almost every faint star seen in the 15x Oberwerks, although a few were harder to see. I think they also have the best color. And they only weigh about as much as the Orion 10x50, they can be hand held.

Previously I had tested the Oberwerks against Orion Giant 16x80 and the Oberwerks had wider fov and more of it sharply focused. These Pentax were proving equal to or better than the Oberwerk in every way except image size, 12x vs. 15x, and the ability that magnification gives you to see fainter stars. If you're looking for a great astro binocular try out the Pentax 12x50. Not for wide field views, but sharp across the field they provide. And they do it in a package that appears to be very high quality and is nicely sized.

edz.

September 18, 2002 07:22 PM Forum: Deep Sky Observing

Saturn's Moons

Posted By Ed Zarenski

Last Friday night, I left my 5” SCT out to acclimate and planned to get up at 4am to view Saturn. The sky I awoke too was a sky most people never see. It was brilliant. The winds had died down and the temp was just under 50.

I started out with a wide-field ep viewing a few clusters in Auriga. I easily saw NGC1907 as a diffuse hazy glow that looked like a nebula in the same field as M38. After stopping at M36, then M37, I settled on M35 and could see the faint NGC 2158 close-by.

Then I turned the scope to Saturn. Too my surprise, right away I noticed a few moons. I was using my 9mm UO ortho at 152x. I’m sure I could have gone higher, the seeing was so good, but I had the focus nats on and the view was so pleasing I didn’t want to take the eyepiece out, so I stuck with it. Turned out to be very productive as I did a nice sketch and plotted the moons I saw. I labeled the moons as b1= pa195 2ringL, f1=pa15,3/4ringL, f2=pa255,1diskD, suspected f3=pa165,1diskD.

Afterwards the key would be to verify if those were moons and which moons they were. You can do this by projecting the curved lines from the chart in S&T magazine up to the ellipses in the diagram at the top of the chart. Go to the curved lines chart, figure your correct UT and at that point, for each curved line project a parallel line up to the ellipse diagram. The point at which you hit the ellipse for that moon is the spot it is at in it’s orbit. See the dots S&T has placed for the example time as an indicator for whether you should be in front of or behind the disk.

Within 10*pa and at the correct distances, I had plotted b1=Titan mag8.4, f1=Rhea mag9.7, f2=Dione mag10.4 and suspected f3=Enceladus mag11.8. Tethys mag 10.3, as it turns out was pretty close to Dione and I missed it.

Last night again I left a scope out, this time my CR150. Similar conditions this morning led to similar results, I noticed 3 moons right away with a 17mmNagler at 71x. In fact the moons showed up easier with the 17mm than they did at any other higher power I used. I recorded many notes on the disk and rings, notably seeing Cassini all the way around except where the disk hid it and seeing the C ring especially at the north where it passed in front of the disk. The disk appeared as 3 dimensional and the A ring appeared as stripes. The best view of the disk and rings was with a 6mm UO ortho at 200x, but the best view of the moons was with the 17mm nagler at 70x. I verified that I saw Rhea, Tethys and Dione. Titan was 5 ring lengths to the east in starfields and Enceladus was very close to Dione, I missed it.

Looking back thru my old notebooks, all I had ever recorded was spotting Titan and one other moon in closer. Not a bad two nights for identifying Saturn’s moons. Somewhere it was said recently, part of the enjoyment is doing your homework. I really believe in that.

edz

November 20, 2002 05:06 AM Forum: Deep Sky Observing

Venus Cresent

Posted By Ed Zarenski

If you haven't looked lately, catch Venus in the morning before sunrise. This morning I put the 20x80 bionocs on it and it looked as big as I can ever remember seeing it. The cresent is maybe 15% to 20% lit and it literally looked so large it was like looking at the moon. the phase will increase rapidly throughout the coming weeks. Watch the illumination increase. Enjoy, edz.

November 20, 2002 05:10 AM Forum: Solar System Observing

Venus Cresent

Posted By Ed Zarenski

Venus, this morning thru 20x80 binoculars was an outstanding sight. The cresent is maybe 15%-20% lit and the disk is so large its like looking at the moon. Illumination will rapidly increase in the coming weeks, although with that change comes a decrease in disk size. Catch it now and follow the phase change. edz.

November 22, 2002 06:47 AM Forum: Astro Binoculars

Turning Prism Tilt Screws is Not ??? Collimating

Posted By Ed Zarenski

I’m amazed the general user population hasn’t figured this out yet. Binoculars are a more complex optical instrument than a telescope simply because there are two optical paths with more optical surfaces that must by critically aligned.

edited 11-26-02
If images are not aligned, but you are starting with nice round exit pupils, you can tilt the prisms to merge the out-of-collimation images, but you might then be moving the prisms out of alignment.

True collimation is the aligning of all the optical elements along the binocular optical axis. No optical element should be tilted from the optical axis.

I must admit that I own binoculars that needed serious alignment and I achieved making these binoculars usable by turning the prism tilt screws to merge the images.

Tilting binocular prisms can have the dramatic affect of considerably reducing the amount of light through the binocular optics. The shape of the binocular exit pupil image can be observed to directly assess the amount of light being lost. Perfectly round exit pupil images should be observed for a binocular to pass 100% of the light. Binoculars that have tilted prisms will exhibit a pointed oval shape to the exit pupil image indicating a light loss thru the binocular.

Ignore, for sake of this discussion, the sometimes seen squared off edges in the exit pupil image caused by undersized prisms. Unless grossly undersized, this vignetting will not impart as significant a loss of light as might be induced by tilting the prisms.

Precise measurement of exit pupil images with a micrometer is required to calculate the amount of light loss induced by tilted prisms. The results of one example calculation are given here. A pair of 20x80 binoculars that should have a fully round exit pupil of 4mm was adjusted to acquire a merged image. The exit pupil measured still a full 4mm in one dimension, but only 3.2mm in the narrowed dimension. An accurate calculation of the area obscured by the tilted prism proves that nearly 26% of the area is lost.

Simplified A=pi r2, 80mm lenses, if passing 100% of the light would pass 80x80= 6400 sq. mm. of light. Reduced by 26%, the same lenses pass only 6400 x 74% = 4736 sq. mm of light. The square root of 4736 gives the resultant of the equivalent diameter objective lens as 68.8mm. Therefore, 80mm binoculars with tilted prisms resulting in an exit pupil image narrowed by 20% in one dimension are effectively reduced to the equivalent of 69mm binoculars.

If you have tilted the prisms in only one barrel of your binoculars and they exhibit these symptoms, try using the same eye to compare the images thru both barrels of your binoculars. The light loss should be readily apparent.

I have written more on this subject and I would encourage discussion. You may refer to this article for more information. edz
http://www.cloudynights.com/howtos2/binoc-collimatin.htm

December 13, 2002 08:34 AM Forum: Deep Sky Observing

Christmas View

Posted By Ed Zarenski

I opened my mail to see what's the chatter,
and what did I find, all questions that matter.
So fingers to keys, I set out to reply,
I put down these words in answer to why.

The scopes are how long in comparison to wide,
this gives us the f, it's true and it's tried.
The longer they are, the narrower they see,
you'll hear wider is better, just like an SUV.
We like to use power so we can see small,
there is no one scope that can capture it all.

To test out our numbers we give it a go,
your 880 by 102 gives f8.6 we know.
My 1200 by 150 at f8 is my pride,
but 750 by 150 at f5 is my wide.

We put in the eyepiece and easily get power,
it's F scope by f eyepiece and changes each hour,
for how often do you keep to only a few,
if you're like me with eyepieces, you'll use a whole slew.

And here we take note of F big and f small
F big is how long, f small how it all
meets up with your eye and dishes it out,
as long or as wide is what it's about.

So now that we know the mag that we get,
we figure the view by some math to learn yet.
Eyepieces all come with an apparent view stated,
it's the angle your eye scans inside that it's rated.
Take power and divide by the angle they say,
gives True field of view with which you can play.

A common reference we see is max 50 per inch,
but the 880's so good 60 to 70 is a cinch.
At 102 it’s 4 inches, so crunch the numbers,
at 60 to 70 you'll see more high power wonders.

The closer you get to the eyepiece you bump,
so eye relief saves you the inevitable lump.
The best er is a comfortable spot,
without crunching the eyepiece, you see the whole lot.

Some who wear glasses and can't see without,
need most eye relief, too short, and then they're put out.
The higher the power, the less er matters.
At hi mag many eyepieces correct lots of abbers.

So much of this stuff is a jumble to you,
what really counts is how much you view.

We all want to know what's under the tree,
will Santa bring that Nagler for me?

Clear skies, and if not Cloudy Nights too you all,
for if you can't see then read, till asleep you do fall.

Merry Christmas, edz. 12/02

I got inspired by my friend, George Strayer's questions.

December 16, 2002 09:49 AM Forum: Eyepieces

Re: .965 to 1.25 adapter Q

Posted By Ed Zarenski

Are you not using a diagonal?
Is this for straight thru viewing?

If it's diagonal viewing, screw the filter into the diagonal.

January 6, 2003 08:22 AM Forum: Equipment Talk

Re: I have a scope with that KD stamp

Posted By Ed Zarenski

I have an old white tube 60mm F415 (f6.9) refractor with that exact same stamp. It's a 0.965 focuser scope probably 60's or early 70's vintage. Works pretty good. It has a doublet objective with a thin clear plastic washer spacer to separate the two lenses. Seems to be single coated. Does not appear to be an expensive piece of equipment.

I always thought it was an E for Edmund. Now that you mention it, it sure does look like a K. Any more info would be appreciated.

edz