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Messages - Christopher Hess

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Indeed you can! I have mine set up to approximately 240x with a combination of a barlow and eyepieces.

A binoviewer uses regular astronomical eyepieces  And can be used on any scope, but usually you need a barlow or OCA (optical corrector assembly - a fancy word for barlows for binoviewers) to reach focus as well as clean up some aberrations in the system.

Ah, so I would need two identical barlows too? I might have those but it'll take awhile to find them in the mess I call my "observing parts room!"

Or do I just need one barlow and put it in front of the binoviewer in the viewing train? I can use my 2x shorty barlow

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Beginners Forum / Re: Thoughts on 10 yr old Orion intelliscope dob
« on: February 09, 2018, 05:18:04 AM »
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Is this a push-to scope, meaning it does not use motors to automatically track objects?
If so, the extra field of view offered by an 82 degree eyepiece vs a 50 degree eyepiece, for example, would be a welcome plus.
I enjoy my Dob, but without my wide field eyepieces (about 70 degrees), it would be bothersome. Just my thoughts.

Thanks, Jason. What about the Meade 5000 ultra wide angle series? https://www.astronom...ice_p19428.aspx

Are there others in the $100+/- range you would reccomend? I like how I just stated in my previous post that I'm trying to stay in the $75 range and now I've bumped it up for the wide angle EP. This could be a slippery slope.

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<p class="citation">QuoteHm... I would not consider 100 degree eyepiece as comfortable especially in comparison to ortho. Eye relief is quite short (11-13 mm), AFOV is extra large. So you can not see stars at edge by direct vision without cut off more then 50% FOV. Observing in even short focal Ortho looks for me more comfortable.

I think this is a personal preference. An ortho has a 40 degree AFoV and in the focal lengths we are discussing, the eye relief will be approximately 4mm...

limited AFOV of ortho lets observer to place his pupil more distant from EP than exact eye relief without any loss in FOV
eye_relief.PNG

So for adapted (fully open) pupil real eye relief of Ortho can be extended +10 mm (depends from level of adaptation to darkness) becoming comparable to ER of Ethos and 100ES
My point is this:

The eye lens of the 20mm ES 100 degree is 30mm in diameter. This implies the eye relief is about 12.5mm. But if I am OK with only viewing an 80 degree AFoV, double that of the ortho, I can be back about 18mm..

Jon

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Beginners Forum / Re: Question about green lasers
« on: February 08, 2018, 07:28:42 PM »
Thanks, Jayhall; I like to hear about real, verified "in the field" tests.

So it appears that despite the DPSS design's inherent weakness at cold temperatures, it doesn't mean they are all created equal as far as cold performance is concerned.

Have you any experience with 520nm direct laser diodes that don't use the DPSS design? My understanding is that direct lasers have a better immunity to cold than DPSS lasers but it seems that the blue frequency models are becoming available but not so much the green as yet.

Edit: I've got one of those Z-Bolt "Astro 10 Emerald" 123 lithium lasers as well as a newer Laserglow model from Canada that appears outwardly very similar. The Laserglow, with a new, single use 123 battery at 0° put out a very faint (useless) green beam which increased to full output at around 20°F. The similar Z-Bolt was more sensitive and needed to be closer to 30° before its output became bright enough to be useful. I use chemical warmer packs and some foam insulation for winter use because of this.

Rich

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General Astronomy & Observing / Re: What's your favorite Astro Vehicle?
« on: February 04, 2018, 01:19:31 PM »
My Ford F-350 carries all my gear and my travel trailer up the sides of mountains to get to the dark sites.  The diesel engine does not even know there is a trailer behind it.

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Reflectors Telescopes Forum / Re: Dobsonian advice - late 2016
« on: February 02, 2018, 11:09:11 PM »
Dusty99, I think you've chosen wisely. I prefer the Z8 to the SW8 (own them both). The optics may or may not be as good, but the mechanicals of the Z8 are definitely better. Having a small refractor for grab 'n go widefield viewing is nice, too. Enjoy your scopes!

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ATM, Optics and DIY Forum / Re: Oversized Secondary Mirror
« on: February 02, 2018, 07:55:56 PM »
As is often stated, a reason to oversize the secondary is to eliminate the extreme edge in the light path. The edge of most optical surfaces is often hard to get exact, and the full rated p-v wavelength tolerance of secondary might be in just that edge zone. Best to oversize it a bit to cut that edge out of the picture.

Our Meade 16s have 4" secondaries...a 3.5" would be better. They're very flat across the central area, but the edges are not great. Unless we want to buy or make a really excellent 3.5", we're happy with these.

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Beginners Forum / Re: Reducing Chromatic Aberration
« on: February 02, 2018, 05:04:19 PM »
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Dave, please post a link to the thread withyour images and work here with the various filters...


It took me a while to find it ... but here it is:

http://www.cloudynig...uction-filters/

The pictures are posted are on pages 3&amp;4. The pictures posted by skyguy are excellent!

Dave

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Darryl, I think you would benefit from forgetting about the aperture masks and actually use the scope's full available resolving power which is at full aperture unless the optics of your scope are such that the chromatic aberration blur makes high power use pointless. There is no point magnifying past a certain point, a less magnified sharp image is better than an over-magnified blurry disc.
By stopping down the aperture you will not get to see the details that your scope is capable of resolving. Planet killer scopes have aperture, they are not something that has been stopped down to 4, 3 or 2 inches no matter what the focal ratio...

The most detail I have ever seen on Jupiter has been with my 18" F5.6 Newtonian which on a good night was pushed 587x and later that night to 652x.... I don't know what vegetable that translates to....

I always get a sharp crisp image. I once pushed things to far. I think it was masked into a f20 for Saturn. The image was puffy and dark. A 3" mask gives me a f/13 scope, for a sharp image of Saturn's Cassini division. That is only a few times. Saturn was kinda low. I think pollution and heat from houses have a negative effect on the view.

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Reflectors Telescopes Forum / Re: Visited Zambuto Optical Company
« on: February 02, 2018, 02:11:47 PM »
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I take it there's a serious risk of drool damage then, Bob?

Mark,
ROFLMAO, I was thinking that exact thing when I posted his suggestion for wearing a mask but Carl was actually referring to the fact that we tend to send out spittle when we speak, somewhat unknowingly, and that the saliva would affect the fresh coatings. However, I did notice that when I was closely inspecting the coatings with the said supplied mask that the inside of the mask was becoming somewhat moist from my drooling over the perfection of the coatings

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Light Pollution Topics / Re: Please welcome new Moderators!
« on: January 31, 2018, 01:00:43 PM »
Martin.

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General Astronomy & Observing / Re: mounts at fault?
« on: January 31, 2018, 12:11:30 PM »
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Binoculars are easily aimed, and the larger FOV is a lot easier to keep it in the view. But looking at a star field with hand held binoculars at 7X does not come close to the pain of trying to see a planet at 100X with a shaky mount. As far as a noob, I would think that I stated the first scope, which would include mainly kids, with no experience with fixing problems with mounts, not grown ups. Grown ups probably would not purchase these dept store scopes to begin with.

While a seven year old would not be able to figure out what to do to fix the mount, a twelve year old might and a fourteen year old almost certainly could. IF they are interested and resourceful.

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Beginners Forum / Re: Astronomy noob looking for a quality telescope
« on: January 31, 2018, 12:04:33 PM »
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Also if you are a techie by any means you'll quickly want something with an electronic aid for finding items.

I'm not sure that being a techie has much to do with this -- that could cut both ways. I love finding my own way by star-hopping, without electronic aids, and the part of me that loves star-hopping (and is good at it) is quite obviously related to the part that makes me a good techie.

I think a really good test for this is using GPS in a car. If you're 100% happy with having GPS tell you how to get to new destinations -- no questions asked, no further information desired or needed -- then Go To telescopes are likely going to suit you very well.

I have recently started using GPS in my car, but in almost all cases, I will consult a map before going somewhere new even if I'm 100% sure that the GPS will get me there. If I follow a GPS blindly, I always wonder the following things:

1. Did the GPS really choose the best route? Are there other alternatives -- perhaps even a bit slower -- that would have been more scenic or more enjoyable in other ways?

2. Where am I, anyway? Knowing how to get somewhere isn't the same thing as knowing how my starting point and destination are connected in 2-dimensional space. What lies between us? Would there have been interesting places to stop en route?

3. Suppose my GPS were to break. Would I be able to get back all on my own?

For me, the real value of GPS is that it leaves me more free than ever before to navigate on my own initiative. I hardly ever follow the GPS's advice; instead I go down odd alleys and roads that seem to be going in the right direction, confident that if I get really, deeply lost, the GPS can get me unlost a lot faster than I could manage with conventional maps.

Go To scopes can be mighty handy. I but never really feel that I own a deep-sky object until I'm sure that I can get there just by pointing my scope to the right spot in the sky.

The other big indication for or against Go To, besides the user's temperament, is light pollution. Star-hopping is really easy under dark skies. It's much harder in cities and bright suburbs, because the light pollution hurts you two ways: it leaves you far fewer stars to navigate by, and it makes your targets much harder to see.

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Beginners Forum / Re: Orion SkyQuest XT8 vs Sky-Watcher 8"
« on: January 31, 2018, 11:41:22 AM »
glee, too many roots? Stones in the yard? Larger wheels can handle much of that!

Wouldn't it be better to view with a larger scope?!

I do know what you mean about trips and motions; it would get tiring if one had to keep taking the OTA off and on many times per session.

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Beginners Forum / Re: Dob not working out for me, what should I try?
« on: January 31, 2018, 11:11:20 AM »
I used one of the degree circle templates mentioned above and printed it out onto transparency film using my inkjet printer. I cut out the pieces and taped them down to my 12" Lightbridge base using double sided tape. I made an adjustable pointer out of some computer case knockouts and a little hot melt glue. The pointer is thin and just slides in between the top an bottom part of the base when I zero it for the night. I invested the $30.00 in the Wixey angle finder for the altitude. I used it last night for the first time and I must say it was the best experience I have had yet with my dob.

I agree with everyone else here though about finding some darker skies.....

--Jon

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