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Topics - Rob Freeman

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I have a 10in f4.66 that will be converted to a dob, and the new carbon fibre 10in f4 will be used as my main deep sky imaging scope and I will also use it viewing rich fields.I do have some coma correctors ,>> the old Lumicon CCFF is attached to my 48mm Lumicon EzyGuider>> a Baader MFCC>> a Tele Vue 2" tuneable top Paracorr ... a recent acquisition>> also have a 2in Tele Vue 2x PowerMate .... a recent acquisitionI'm thinking either Vixen SSW eyepieces (5mm, 10mm, 14mm these are all 1.25in) and maybe NLVW 30mm (2in)orPentax SMC in similar fls 5mm to 15mm as 1.25in eyepieces.I don't mind spending to get very good quality in my eyepieces which will have to do me out , it's taken me years to get to this point.I will likely want to try eyepiece projection once the scope and ROR observatory is installed.Til now my best eyepieces have been RKEs, these may be OK using the Paracorr on the f4.66 dob but I have my doubts about using these even with the Paracorr on the f4.Comments on my eyepiece choices for the f4 Newtonian would be greatly appreciated.

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Sorry for the long title but I wondered if anyone can confirm that this is true:
Comparing  a 6 inch F5 with a 80mm f7.5, the 80mm would require 8x more time to gather the same amount of light assuming they're both being used for astrophotography.
This is from dividing this ((6x24.5)^2/80^2) by this 5^2/7.5^2
Thanks
Ryan

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ATM, Optics and DIY Forum / 152.4mm f/15 apo doublet
« on: January 01, 2018, 05:46:46 AM »
Even with other scopes I have or will be making next year after retirement, I would love to make and/or have this telescope as well. 6" f/15, but color correction way better than conventional achromats. 0.7º (28mm) circular field of view, diffraction limited on axis (yes, for real) over the 0.435-0.700µm spectrum, and over a -10º to +40ºC temperature range with refocusing. Equal internal radii, good glasses, adequate but not overkill on aspect ratio. Maximum incidence/exitance angles do not exceed 20º at each surface, which allows multilayer AR coatings to perform even better.

If the surfaces are made well and within tolerances (which I'll work up if anyone else is interested in this lens), visual star images through this refractor would essentially be perfect, like an equivalent Newtonian without the spider and diagonal blockage and diffraction, and tube currents, limited only by atmospheric turbulence and dispersion.
Richard Whalen started a 130mm f/15 apo thread below but it's getting kind of long, and I thought I'd bring this up to the surface to be noticed more easily.

Comments?
MikeAttached ThumbnailsAttached Files<li class="attachment">


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Beginners Forum / $ eye pieces
« on: December 27, 2017, 09:41:10 PM »
I'm getting a lot of information on eye pieces for my se 8. Thanks !Everyone is right about wantingmore stuff. I want to do it right the first time on eye pieces. Not sure about my limits on lens. How high or low. I would like to get a good set of lens and filters that I can use with this and other scopes I may get in the future. So far I've read thatyou don't want anything higher than 70 degrees. 68 degrees seems fine. Thinking of going with Explore sciencelens. 31mm 85 degree. But rule of thumb says not over 70 degrees.Thinking a15mm 68 degree 5.5 mm 68 degree. Can buy singles if best. Maybe a Pentex.Waiting to get my scope to see what's what with the Celestron package lens first. But it would be nice to hear what others withthe se 8 scopethink first. I want at least 3 good lens and a couple of nice filters. Also thinking ofonesun eyepiece and filter. Camera will be way later on.So let me here your thoughts. Please.

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Reflectors Telescopes Forum / Orion XT Classic mods
« on: December 27, 2017, 12:22:21 PM »
I made quite a few mods to my XT8 Classic over the last 5 years (See sig) many of which I am sure would not be considered cost effective, but I'm not planning on selling it any time soon.  There is a pic of my scope on the Astrogoods/ First Base home page (thanks Mark)One mod that I have not made is putting ebony star laminate on the 5 inch plastic alt bearings.  I am getting good results with the plastic riding on virgin teflon bearings, and I was concerned that ebony star would make the alt motions TOO SMOOTH, and cause balance issues when changing eyepieces for example.I know that some of you have made the alt ebony star mod, and I would be interested in your opinions.Thanks

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General Astronomy & Observing / Eclipse traffic horror stories?
« on: December 26, 2017, 11:08:31 PM »
Anyone have a story to tell?

My sister-in-law drove down in the Milwaukee area to where we were set up to observe the eclipse.  About 40 miles SW of St. Louis.  The drive down took her the regular 5??1/2 hours.  Against our guidance she chose to push back after the eclipse, leaving about 2:30.  She did not make it back until nearly 2am!  Aside from the bad traffic she conducted into: Gas channels empty of all but premium fuel (huge lines to fill up).  An Arby's that had run out of meat.  A McDonalds that took her 30 minutes to get into the restroom.  Two big thunder boomers.  Traffic reports that signaled all clear ahead (many times she might have taken another) but were completely wrong.  Numerous fender benders and stalled vehicles.

The fantastic part of the....she said seeing the eclipse (her first) was worth every hour spent in traffic.  That is what I like to listen.

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Reflectors Telescopes Forum / .4 magnitude worth $700?
« on: December 26, 2017, 07:53:43 PM »
I've determined that my birthday present to myself will be a big dob.  I'm especially looking at the Orion xx12i, or it's bigger brother the 14i.  My question is that, is .4 magnitudes really worth the additional $700?  And of course the additional hassle.  It must be noted that my primary observing area (my backyard) is a orange, borderline red zone, my "dark" website is a green zone.  I have a 8 inch SCT that I love but it can't quite solve some of those fainter DSO's.  I have a few weeks to pick yet, so no hurry.

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General Astronomy & Observing / How long has Mars been out?
« on: December 26, 2017, 07:25:09 PM »
I was thinking the other night whilst looking at the Mars conjunction, it sure was out quite a while since last year in the night's sky.  Seems it's been at the nighttime sky for nearly a year now?  I looked at a map from last July and Jupiter was at the west compared to Mars was almost due south with Saturn to the east at Scorpio.

They have gone from the nighttime skies, long past and Mars is still out and does not set until near 10 pm.  Must have something to this retrograde motion I read about?

I visit Jupiter has gone full circle and is outside now about 9:30 where I live....and Mars is still up!

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ATM, Optics and DIY Forum / how much should a 16" blank cost
« on: December 24, 2017, 06:41:42 PM »
Hi!

My EL Panel flatfield screen just broke accidentaly.  I Need to Make another one, but I find EL panels too delicate for that purpose and they suffer some disadvantages such as :
- special voltage (high frequency high pressure)
- very little Assortment of luminosity modification
- undependable light spectrum (depends on the maker, changes with temperature), quite feeble in the Ha bandwidth

I found that a few acrylic glass manufacturers have made a substance that would reflect light when lit with hot white LED strips on the edges.  Here would be for exemple a few datasheets from two opponents :
- Altuglas Elit 3 : http://www.qsv.gr/wp...t-III-specs.pdf
- Plexiglass EndLightning : https://www.plexigla...lighting-en.pdf

There are some benefits :
- routine 12V DC supply
- potential to adjust the luminosity with LED dimmers
- really robust
- stable and reproductible light spectrum inclusive Ha/SII bandwidths(see red line in the picture)

Did someone already attempted to make a flatfield screen with that type of material ?  This seems to be a powerful, reliable and cheap alternative to EL panels like Aurora Flatfield.

Fred

Edit -- I ordered a sample (20x30cm x 6mm) of Plexiglass EndLightning and will observe how it functions.  I will keep you informed.

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Beginners Forum / Mount for 130 SLT OTA
« on: December 24, 2017, 03:38:12 PM »
Ok so I've requested this around in a group on facebookso in case you visit it for the second time please do not shout at me.  Just want to get some insight.
I have recently acquireda 130 SLT OTA Newt but no bracket.  And a travel scope 70 that has a dovetail bracket on it.  I've looked up the SLT Computerizedmounts and they are not easy to come by used.  Celestron has it new for $310 however, the 90 SLT Mak is $330 on Amazon.  My question is, even if I'm going to spring up and get the SLT bracket for this, it could be a no brainer to get the 90 SLT instead.  My question is when I am going that far should I choose the 102 SLT refractorinstead.  Or only bump up to the 4SE that's a sturdiermount from what I read.  I really don't have the budget to go more than that and I will not have the ability to get it straight away.
Or should I hold out and get the AVX bracket, and hope to grab a deal with one that has a scope.  I have a 127eq electricity seeker that I am using the bracket from right now but it's shaky to say the least.

I am looking at a few low-endcameras like the neximageand neximage5 and asio34mc.  Should I just go with the 90 SLT Mak and utilize the otherwise spent money on the camera or choose the more expensive scope and continue to utilize my iPhone.

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Light Pollution Topics / Massive windfarm could hit dark skies
« on: December 24, 2017, 09:24:03 AM »
"The Scottish Dark Sky Observatory is composing a Reaction to the South Kyle wind farm consultation voicing concerns about light pollution, which could spoil precious Celebrity views. " http://www.troontime...-massive-win...

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