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91
ATM, Optics and DIY Forum / Re: Plans for a Portable a 6" F/8?
« Last post by ricoperte on February 09, 2018, 11:09:04 AM »
Quote
Maybe...for a reflector forum...And it is an old site.Why are you keep this OT going.
You might want to review the OP's original post.....he is looking for ideas on a new lighter setup for his 6" f/8. Would what we are talking about not fit as a consideration using T-SLOT to construct an OTA? It would be collapsible for transport, only require a couple or one short piece of 8" tube etc....ie a metal version of "scope on a stick".So I am not sure why you would be calling it OT.....you just feeling contrary today?
92
Reflectors Telescopes Forum / Re: Plan:Boundary fan suspended over 16" mirror.
« Last post by maogrinjorli on February 09, 2018, 11:08:21 AM »
I dunno if this is relevant or not, but it's related I guess...This guy has several demonstration videos of this tube current stuff..

https://www.youtube....h?v=UbH4AS-0ViE
93
Eyepieces Questions & Recommendations / Re: Eyepiece question
« Last post by juskemenbo on February 09, 2018, 11:07:31 AM »
OK, let me explain about eyepieces as afocal devices.

As you move your eye back from the eyepiece, the field gets smaller, but stays in focus.
That's because, once the focal plane of the eyepiece is coincident with the focal plane of the scope, the eyepiece is essentially afocal.
No matter what distance you are from the eyepiece, the field is in focus.

Nonetheless, as you back away from the eyepiece, the pupil of your eye becomes smaller than the size of the image
formed by the eyepiece (which becomes wider). You see less of the field because the edge of the eyepiece barrel is literally occulting the image.
You can move your eye back and forth laterally and see different parts of the image, and it stays in focus.
But the body of the eyepiece itself occults the edge of the field.
This sounds suspiciously similar to your description of drifting back and forth and having the edge of the field get occulted.

This only occurs when you are too far from the eyepiece, however, to see the actual field stop completely all the way around
(which occurs at the exit pupil).

Now, if you are at the exit pupil, you see the entire field to the field stop and, if the exit pupil is smaller than your eye's pupil, all the light from the eyepiece goes into the eye.

If you are too close, however, the light from the eyepiece becomes larger than the pupil of the eye and your iris starts occulting the image.
If you move back and forth, first one side, then the other, blacks out as the rays are intercepted by the iris and you get what are termed "black-outs".
This happens a lot with long eye relief eyepieces used by non-glasses wearers, or people who stand to observe or even just when you drift a bit too close to
an eyepiece. I can induce the blackouts on nearly every eyepiece that's made unless the eyepiece has such a short eye relief I automatically hold back
to preserve my eye.

So what it looks like at the eyepiece is dependent on where your eye is relative to the exit pupil.

If the eyepiece has spherical aberration of the exit pupil, however, then the exit pupil itself is not all at the same distance from the eyepiece, and moving in toward the eyepiece may make either the
center or edges of the field black out in an alternating way that resembles large kidney-bean-shaped shadows in the outer parts of the field. This is termed "kidney bean blackouts" or simply
"kidney-beaning". It is found in (primarily) widefield eyepieces without a flat exit pupil. This doesn't have to be severe (like the original 13mm Nagler)--it can be slight, but still result in an eyepiece
being sensitive to eye placement. I have run into many of these over the years.
http://www.handprint...O/ae4.html#SAEP

So, traditional "blackouts" are caused by the observer's eye position relative to the exit pupil.
"Kidney bean blackouts" are caused by SAEP in the eyepiece.
Other than cataracts or macular degeneration, those are the two sources of blackouts in eyepieces as I understand it.

The "walking past a keyhole" look simply indicates the observer is farther away from the eyepiece than the exit pupil.
94
Reflectors Telescopes Forum / Re: Focal ratio and Coma.
« Last post by consmagestma on February 09, 2018, 11:06:45 AM »
Quote
Jeff's descriptive term "convenient medium aperture " perfectly describes what I was thinking. I am looking for the "CMP" scope that has "refractor like" stars. Thank you for the input. I am leaning towards the dobs, I have had a 8SE and an 8CPC I don't think of them as convenient.

Bill:

This one is really calling out to me:

http://www.astromart...ified_id=937983

It's set up for photo and visual and could be easily converted to Dob use. But the second-to-last-thing-in-the-world I need right now is another scope!

Do you use bino-viewers?

Jeff
95
Mounts Questions & Expirience / Re: Tak mounts
« Last post by urinhatmo on February 09, 2018, 11:06:06 AM »
Jesus Christ! Aint that a beauty
96
Mounts Questions & Expirience / Re: Skywatcher AZ GTi mount
« Last post by plethenofin on February 09, 2018, 11:05:25 AM »
Can hardly wait for this mount. Keep talking myself out of ordering it from overseas.
97
Eyepieces Questions & Recommendations / Re: Replacing undercut chrome barrels
« Last post by Stanley Elliott on February 09, 2018, 11:04:17 AM »
My solution is to use Baader ClickLocks for all visual backs and eyepiece adapters and TV Binovues for two-eyed viewing.
The only time I now have the issue is with the N31T5 in the FTF 2015BRC-LW on my dob....
98
Quote
Just bought the Orion XX12G,I think it's better than the SW, the base does come apart ,it comes with a fan ,duel speed focuser,and has closed loop Electronics so once you align it won't get loss if you want to push it around ,,think you should check it out

Greetings and thanks for your comment.

I've spent the last 2 hours reading up on the Orion XX12G--it seems very similar and comparable indeed to the SW version. The SW has the same feature, fyi, in that you can push it around after alignment without losing your alignment. So the differences seems to be the dual speed focuser (the lack of which I've heard only mild complaints from purchasers of the SW), the inclusion of a fan (one less things to worry about!), and, importantly, the collapsable base. I've heard from about 80% of the respondents that a cumbersome and unwieldy base is a drawback of the SW's.

BTW, do you know if theOrion XX12G is compatible with SkyFi? I believe it would be but am not certain.

Now I'm thinking of posting and asking folks for the theOrion XX12G vs. the SW 12" go-to. The difference in price right now is not much.

I'm really torn over which one to get. Any further comments and insights are very welcome!

Thanks again,
Lem
99
Mounts Questions & Expirience / Re: PEC Recording with a CGX mount.
« Last post by Elijah York on February 09, 2018, 11:02:43 AM »
Quote
Thanks ran it in Win7 compatiblity and that worked.

Let me see if I got this straight.

1.) I have to set up guiding through phd2 via the ST4 port?
2.) I do not need an imaging camera running, just the guide camera?

Then just get the program to 'talk' with the hand controller. Start the mount guiding, then start the pectool?

If it's possible for you to guide through the st4 port then I would go ahead and use the pectool since you have it installed.

But if it's a problem setting up st4 guiding then I would do what Rod suggests and just record PEC with the handcontrol - while autoguiding with ascom or whatever you normally use. That will record one worm period and tell you when it's done.

One worm period may be ok but it depends on how the cgx-l is geared. Some mounts have multiple frequencies in the PE graph and you get a big benefit by averaging many. But other mounts don't have that problem and one curve would do pretty well. I haven't seen a multi-period guide curve from cgx-l so I can't tell. CGE's and CGE-Pro's benefit from averaging many curves - which the PECTool can do.

No matter how you record PEC you need to find the worm index first - so be prepared for the mount to warn you that it needs to seek the index - which means moving away in RA for a degree or so.

If you use the hc to record PEC just follow its instructions after finding the index and guiding well on a star.

If you use the PECTool then do the same, and then set it up for batch training with up to 8 periods or so. It will do multiple curves in succession and save them to individual files - then at the end it will ask if you want to average them and load them into the mount. It makes it all very easy.

There is another option that I think would work that lets you use PECTool and averaging - but without needing st4 - but it would be more trouble. You could use the hc to record a curve, then use PECTool to download the curve from the mount and save to file. If you did that several times you could then use PECTool to average them and load them back.

But the simplest of all, which may be perfectly adequate, is just to record one period with the hc and see how well it works.

Frank
100
Reflectors Telescopes Forum / Re: intelliscope warp factor way off
« Last post by laycacdownsell on February 09, 2018, 11:01:58 AM »
It is.  Many times, if the object falls just outside the fov after alignment is to center the third object, press the FNC button, and press enter twice.  You should get a "new" warp factor.  This is, in essence, a "Third" alignment star.....
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