September 2006 - Utah-Astronomy - mailman.xmission.com

Re: [Utah-astronomy] Re: 25x100 binos for sale
by Wayne Sumner 25 Sep '06

25 Sep '06

I believe they are from Orion, but I'll check tonight to be sure. Wayne A. Sumner Math/Physics/Astronomy/Engineering Boy's Tennis Coach Northridge High School Davis School District (801) 402-8610 >>> chuckhards(a)yahoo.com 09/25/06 1:21 PM >>> What brand of 20x80mm do you own, Wayne? --- Wayne Sumner <wsumner(a)dsdmail.net> wrote: > Sounds like the eye > relief is better than > on my 20x80's. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.utahastronomy.com

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Re: [Utah-astronomy] Pupil envy
by Michael Carnes 25 Sep '06

25 Sep '06

Chuck sed-- >Taken to extremes, the limit with >Newtonians anyway, is when the shadow of the secondary >mirror gets large enough to completely fill your >pupil- then you see nothing at all, on-axis! That's the problem I have when the exit pupil gets too large for my pupil. The secondary takes a larger and larger portion of the image reaching the eye, and it can be quite difficult to hold an image. For me anyway, long eye-relief makes it even trickier, since you have to keep your head in a perfect position. Even though there might be higher resolution in the image, it's hard for me to deal with that odd blind spot bobbing around out there. Just goes to show you how personal the match may be between observer and equipment. I've often gotten a so-so view with an eyepiece someone else is raving about--even when it's obvious that eyepiece is really showing them a lot. This is why you have to be cautious about recommendations.

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Re: [Utah-astronomy] Pupil envy
by Michael Carnes 25 Sep '06

25 Sep '06

You can sure save a bunch on eyepieces too. No point in getting a short F/L 2" eyepiece since most of the light won't make it through the pupil. >A diminishing pupil diameter with age is the trend, >although by no means does it happen to absolutely >everyone- thus the need for the gauge. > > >If it helps, Rich, think of it this way: The older >you get, the more efficient your eyes get, so the >fewer photons you need to achieve the same level of >sensitivity... ;o)

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RE: [Utah-astronomy] Image processing, cont.
by Tyler Allred 25 Sep '06

25 Sep '06

Kurt, I had to go back to the original subframes to extract the detail from the core. Somewhere along the line the core area had been pushed to pure white. When that happens it is impossible to recover the data. Pure white is pure white! Cheers, Tyler Kurt said: <Replicating your image histogram brightening <enhancements to bring out more detail in the disk <using AIP4WIN was straightforward. But I was unable <to do anything with the central core. What kind of <filters did you use in Photoshop to recover detail out <of the disk? - Kurt

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Re: 10x70mm binos & pupil dia.
by Chuck Hards 25 Sep '06

25 Sep '06

Some details on choosing a binocular. The 10x70mm Harbor Frieght binos aren't a bad binocular, especially at the $40 price- but you need to know a bit about yourself before you spend your money. Specifically, how wide will your pupils open at night? If your pupils only open to 5mm, then about half the light-gathering power of the 10x70mm binos is going to waste. Your eye won't open enough to accommodate the entire Airy disk of the bino. If your pupils open to 6mm, then you can use about 75% of what the 10x70mm offers. Binocular model exit pupil dia (approx.) 10x50mm 5mm 10x70mm 7mm 11x70mm 6.4mm 15x70mm 4.7mm 20x80mm 4mm 25x100mm 4mm Knowing your dark-adapted pupil diameter will help you choose the best binocular for your own eyes. S&T used to sell a pupil gauge, and I think it was printed in a monthly issue some years ago. I was unable to find it on Sky Publishing's on-line catalog today, however. If someone can search for the issue it was published in and post it, I'd sure appreciate it. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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9-25-2006 LPOD
by Canopus56 25 Sep '06

25 Sep '06

Not to toot my own horn, by today's (9-25-2006) LPOD http://www.lpod.org/ is about one of my charting projects in an off-handed kind of a way. - Kurt __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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Re: 25x100 binos for sale
by Chuck Hards 24 Sep '06

24 Sep '06

As a recap, this bino is the Apogee/Fotar/Celestron 25x100mm model. I measure the eye-relief at about 12-13mm, as measured from the glass surface to the Airy disk projected on a piece of wax paper. The rubber eyeguards fold-down. With my eyeglasses on and the guards folded, I can just see the entire FOV with the eyeglass lenses touching the rubber eyeguard. However, since my astigmatism correction is very small, I typically remove my glasses at the eyepiece and re-focus accordingly. And about focusing, this binocular has individual-eyepiece focusing, so each side must be focused independantly. Makes it tough on group observing. A heavy-duty tripod or parallelogram is required due to the sheer mass of the unit. A terrific deep-sky binocular, and Patrick's price is pretty darn good, Wayne. I love mine. --- Patrick Wiggins <paw(a)wirelessbeehive.com> wrote: > I don't know and am not sure how to measure it. > However, I think Chuck > said he had the same binos so I'm sending this on to > him to see if he knows. > > Wayne Sumner wrote: > > > Hi Patrick, > > Do you know how many millimeters of eye relief the > 25x100's have? __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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Autumnal equinox at the Gallivan Center sundial
by Canopus56 23 Sep '06

23 Sep '06

Sundial gnomons only trace a straight line between 10 and 4 on equinoxes, here animated between Sept. 23, 2006 between 12:24MDT and 2:01MDT: http://www.utahastronomy.com/view_photo.php?set_albumName=album40&id=200609… (234kb) in http://www.utahastronomy.com/view_album.php?set_albumName=kurt __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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Happy equinox to all
by Canopus56 23 Sep '06

23 Sep '06

Began Sept 23 04:03 UTC Local SLC equinox is 13:21 MDT - Kurt __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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RE: [Utah-astronomy] New Pretty Picture of NGC7380 details?
by Tyler Allred 23 Sep '06

23 Sep '06

Patrick wrote: <You are using a smaller chip than I am and your pixels are bigger and <yet your stars are sharply focused, tiny pinpoints as opposed to the <ugly splotches the stars form in my pictures. That is what Takahashi is all about! :) Seriously, the most likely reason for star bloat is poor tracking, but with your mount I don't think that is likely. It could also be focusing, but I assume you are getting your focus right (MaxIm is great for that). It is more likely to be a result of your processing. If you are lowering the white point to bring out detail in your image (which I suspect), then you will be causing your stars to bloat. You will also be causing portions of the image that once had detail to become washed out. Perhaps you could email one of your fits files to me so I could examine it. A dark subtracted version would be even better. I can easily tell if that is the issue leading to bigger stars. I would love to get together some night to take a pretty picture or two using your equipment. We could do a session of processing in Photoshop and MaxIm as well. <What is the effective focal length of your system? I'm running at about <1,800 mm. This image was taken with the Tak Epsilon 160 at F/3.3, for 528mm, so I am using a much shorter focal length than you. I also image with my Tak CN-212 at F/4 and F/10. My mount has trouble at F/10 and my stars show the tracking difficulties when I use it. <You note that your exposures are "Ha 10x1200s RGB 6x300s each". From <that I'm guessing you mean the Ha is a combination of ten 1,200 second <(20 minute) exposures and then you made an additional six 300 second (5 <minute) exposures for each of red, green and blue. <So that would be a total of 290 minutes or nearly 5 hours of exposures. < Have I got all that right? Yes, that is right. Lots of data makes for smoother images, so I collect as much as possible. <Also, for your 1,200 second luminance exposures did you also make 1,200 <second darks? <If so, did you make a series of 1,200 second darks and then combine them <into a master dark? If so, how many in the series? <How's about 300 second darks for the 300 second color exposures? More <than one and, if so, how many? I have a library of dark frames that I captured during the daytime when I couldn't image. I just make sure that the camera can cool to the temp I plan to use, and then start the camera taking darks. For the most part, I use 20 dark frames at each exposure length. I have created "Master Darks" for exposures of 1s, 5s, 10s, 20s, 30s, 60s, 120s, 180s, 300s, 600s, 900s, 1200s, and 1800s. It sounds like a lot of work, but I just use MaxIm to take a series of darks and let the camera work on its own all day. I also use bias frames (one Master for each resolution only), and I try to shoot a series of flats while I am imaging. I use a projector screen for that. <Would you be willing to email me one of those ten 1,200 second raw, <unprocessed FITS images you used to make your NGC 7380 picture? I'd <really like to see how your stars look before they've been dark <subtracted, flat fielded or PhotoShopped. I'll send one off ASAP. <Carpe Noctem! Same to you! Cheers, Tyler Tyler Allred President Allred Restoration, Inc. 670 W 1725 N Orem, UT 84057 801-358-1868 cell tylerallred(a)earthlink.net pw _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.utahastronomy.com

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