SLAP Observer --- TMB130SS, SV102V(LOMO Lens), SV80ED Deluxe "The only thing necessary for the triumph of evil is for good men to do nothing." -- Edmund Burke. "People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf." -- George Orwell "The measure of a man’s greatness is not determined by what he accomplishes for himself, but by what he accomplishes for others.” -- Some Bald Guy
“I am the only person to ever ace a 1951 USAF resolution test. My 'to observe' list says 'done'. I do not use charts or atlases when I starhop; men do not use maps. One of my sketches won an SBIG deep sky imaging contest. I am the life of star parties I have never attended. I never say anything looks like a faint fuzzy - not even a faint fuzzy. Pilots aim green laser pointers at me. Don Pensack proofreads my CN forum posts.” - The Most Interesting Astronomer in the Universe
Webster D18 f/4 ServoCat w/Argo Navis & SkyFi Ceravolo HD-216 Ceravolo HD-145 Nagler 31mm T5, 26mm T5 Nikon NAV 17mm HW, 12.5mm HW, Panoptic 27mm Pentax XW: 20mm,14mm, 10mm, 7mm, 5mm, 3.5mm
Ray Teeter 18" f/3.5 Dob D&G 5.375" f/20(?) refractor 天体観測にも威力を発揮する、本格仕様の大口径双眼望遠鏡です。 興和ハイランダー
Clear skies - Jim Crazy PNW imager !
A-P Mach1 on 12" concrete pier - ROR structure.
Tak FSQ85-EDX, Tak FS-128. Orion 8" f/3.9 w/MoonLite motorized - MPCC MkIII CCD:
SBIG 8300M/FW8, Astrodon 36mm LRGB, 5nm Ha, 3nm SII, OIII - Canon EOS 6D unmod SSI3, SSAG,
Skytools3pro, MaxImDLpro, PSCS5, PSPpro, TheSkyX, TheSky6, BYE, StarTools
Orion XX14g -for visual- diags, ep's, accy tubes, Binocs .
Quote:Very enjoyable read, thank you.
If I had to choose between the two, Id pick the refractor due to confortable eyepiece position only.
Quote:For pictures go to Tamiji Homma's site
"You're not afraid of the dark, are you?" - Riddick "The best scientists are humble. They seek to understand, not to ensure their legacy, but merely to understand." - Mori
The opinions expressed herein are solely mine as an amateur astronomer hobbyist & consumer. Information herein was correlated from experience, discussions with others, & research from multiple sources freely available at time of posting. All reasonable care & skill was used, but no warranty is made as to accuracy, & liability cannot be accepted for errors/omissions. This is for information only and not intended nor implied to be a substitute for professional advice.
Ed "You have to grow old, you don't have to grow up."
Quote:Tammy - did you find that basket at the bottom of a rainbow?
NP-101 on a DM-6
Teeter 11" STS/Waite Mirror
Zeiss, Fujinon, Nikon, Vixen binoculars
Astronomy educator/Sidewalk astronomer
Owner of Astronomy Delight franchise
18 inch f4.42 Dob on eq platform w ST120 f/5 finder
12 inch Zhumell Dob
8 inch f/6.9 home made Dob with Seevers optics
William Optics red 10th Anniversary 80mm FD
C8 XLT on Vixen GPDX
26lb eyepiece box
Cernan Space Center astronomer
Member of Northwest Suburban Astronomers
14.5" Starmaster with ServoCat and Argo Navis 1966 Unitron 4" Model 152 EQ Tec 140 TV NP101 f/5.4 APO Telvue .8 Focal Reducer FLI ML8300 and CFW-2-7 filter wheel Astrodon Gen2 RGBL 2" filters Baader 2" Narrow Band Filters Borg 50mm Guide Scope/ATIK Titan Guide Camera AstroPhysics AP900 Losmandy GM-8 Gemini
Quote:All these issues are reasons that I have been advocating the use of MTF test charts for testing telecopes.With refractors, you can basically elimiate the diagonal to remove it from the equeation.And the difference in focal lenght in totally unimportant because you can move the test target closer or further as necessary to get to the maximum spacial frequence to make the comparison.This eliminates all of the variables. There is no turbulance to deal with , no diagonal, no worry about magnification diffrences, and so on.It is to me the only way to get a reliable result. This page presents a nice overview of the process:http://www.normankoren.com/Tutorials/MTF.htmlHere is a link to charts that can be printed:http://www.normankoren.com/Tutorials/MTF5.htmlThese charts off a superb way to compare optical quality. You can basically use the chart to measure the lowest spacial frequency that the scope is capable of resolving vs the theoretical limit.It will also show mid-frequency falloff that will occur when there are abberations like spherical abberation or chromatic abberation, or a central obstruction.I have mentioned this many many times, but for some reason, people seem to trust under the stars shootouts. It would seem to me to be much easier to simply set up a controlled test using MTF charts.The MTF tests don't lie. That is why it is the standard for camera lens testing.Also useful for comparing eyepieces. Again, it doesn't matter that the focal lenght is different. You simply move the target further or closer to get the same number of lines per millimeter at the focal plane into the field of each eyepeice. Using this, you can compare a 10mm to a 20mm using the same telescope if you desire.Again, I don't know why people resist this kind of testing. It has far fewer variables and is easily repeatable.
Quote:What I think what all this shows is how close the two scopeswere to each other in performance. As long as they tooklooking at the objects, that little difference shown couldeasily be the differences in eyepieces or the effects ofthe diagonal. I've done comparisons between several highend eyepieces (Pentax SMC Orthos, Zeiss Abbe Orthos, andTMB Supermonos) of the same focal length on the same scopeon the same night. All were at such a level that thereshould have been essentially no difference, yet there weresubtle differences to my eye, no less than those shown inthis comparison. I think this was an excellent point tobring out.Tom