Orion Starblast 4.5 inch reflector
Rokinon 8x42 Binos
Nikon Aculon 7x35 Binos
The Mass of Uranus is 86,810,300,000,000,000,000,000,000 kg
12" Harden Optical "Bubba"
16" Meade Lightbridge "Beached Whale"
70mm ETX-AT "Peashooter"
& a slew of EPs
...It is better to know the value of your equipment than the price of your equipment.
Quote:I'm in the process of building a 70mm f4.5 finder scope and will be using a 1.25" 26mm Erfle. It throws a bright,sharp view 68* image with an edge that is crisp and doesn't have any lateral color to it at all. I also like it's light weight and lack of internal reflections. It's no Nagler, but it works for me.----Dave
10" F/4.7 Modified Skywatcher Reflector 38mm Orion Q70, 17mm Modded Ultima LX 10mm TeleVue Delos, 7mm Pentax XL
Quote:I miss the old Edmund 7x50mm finder that had a big 2" military surplus Erfle. Those had about a 10 degree field.Dave
Quote:F50?Is that a F/3.5, Don?I have heard that one of those SV finders is really hell on eyepieces!
Quote:My StellarVue F50 finder came with a 1.25" 23mm 50 degree crosshair eyepiece.
I put in a 24mm TeleVue Panoptic, and the field of view was 7.7 degrees and reasonably sharp at 8X. No crosshairs, though, but it didn't matter. It was still easy to estimate the center of the field.
That finder was a nice right angle finder, too. Helical focuser.
It was a nice complement to a Telrad.
Time spent looking at the stars is added to your life Bashful, Misty, and little Ralphie - my heavenly stars
A-P 105 Traveler ~ TEC 140 ED ~ TEC 6 MCT ~ XT10 (Zambuto) A-P Mach1 GTO ~ Losmandy GM-8 ~ TV Gibraltar
Refractors Reflectors Two Cats A few eyepieces
Quote:I don't really understand an F4orF3.5 finder. Images are *BLEEP* compared to an F5 or F6. The longer FL EP on the F5-6 gives you more ER. My best 50mm finders are F5 and F6.
C10NGT, Z8, 150 Rumak, XLT 150, C6, C5, SW5 Newt, 4.5 Ball, C102GT, C90, ST80, A70LF; 15x70, 25x100; Burgess BV; Paracorr II; T6 2.5, XO 2.58/5.1, Ethos-SX 3.7, Delos 4.5, TV Plossl 7.4-26, BCO 10, Hutech HC 12.5, Sterling 12.5-25, ES100 14, CZJ H 16/25, CZJ O 16, M5k UWA 24, T5 31, Ultrascopic 35, Titan-II 40; Bino Pairs M5k UWA 6.7, Baader Zoom 8-24, M5k SWA 24, TV Plossl 26, RKE 28.7; Zooms NZ 2-4, NZ 3-6, Leica ASPH 8.9-17.8, Baader 8-24; Baader Zoom Barlow, VIP Barlow
Classic refractors; visual observer, old school.
"Toto, I have a feeling we're not in Kansas anymore."
Quote:I miss the old Edmund 7x50mm finder that had a big 2" military surplus Erfle. Those had about a 10 degree field.
Inventor of the Herschel Wedgie. Watch your back.
Astronomy - The World's Second-Oldest Profession.
"You don't know Swift from Astrola." -C.H.-
Quote:These small scopes have a limited function, and that is to help find things, and for this, a wide apparent field is not so important.
Quote:The point is that for the same size true field a wide field type eyepeice would be so badly out of focus that fianter stars would be impossible to see, and the astigamatism would further aggrevate the condition given that a give star will be magnified even more with the wide field than with a standard eyepiece.
Quote:And why would he manufacturer want to spend extra money on an Erfle when a lower power inexpensive eyepeice will serve the same function purpose.
Quote:Better to use as standard 80mm air spaced doublet if your desire is to actually look through the scope for anthing other than just finding, which is in the end, why they call them Finders to begin with.
Quote:For my 10" f/4.8 Dob, that happens to be an Orion Multi-Use 70mm f/3.9 achromat with a true RACI diagonal and Orion 20mm illuminated-reticle eyepiece. IME, reticles or crosshairs are very important for aligning the finder closely to the main scope and for accurate star hopping. If you do that right, you don't really need a "finder eyepiece" in the main scope. I wouldn't have an eyepiece in a finder without crosshairs or a reticle. And for a dark site, illumination is a virtual necessity. I'd only consider a Pan or other high-end eyepiece if I could backfit it with an illuminated reticle or crosshairs.Mike
Quote:That's what I used to think, too.But then I used a non-crosshair eyepiece in the finder and found the finder was just as useful, and that I had no trouble aligning the finder with the scope using a bright star and centering it first in the scope, then centering it in the field of the finder. It was easy to estimate the center of the field in the finder, the same as it was easy to estimate the center of the field in the scope's eyepiece.
Quote:And, once I realized that, it enabled me to use a sharper eyepiece with a wider field and have a more useful finder scope (7.7 degrees at 8X) for, well, finding stuff.
Quote: Fully multi-coated objective: This color-free, high contrast ED lens has extreme broadband multi-coatings on all four lens surfaces. These coatings transmit light above and below the visual spectrum, which is important to minimize reflections.
Quote:The only other finder I've found as useful (and, admittedly, it does depend on the length of your scope as to how ergonomic you'd find it) is the Explore Scientific Correct image/straight-through 8x50mm. It has a nice big field of view (>6 degrees) and the images match finder charts because they're correct. And, because it's straight through, a Telrad isn't necessary to point it in the right direction first. The illuminator is way too bright, though, and needs to be heavily dimmed.
Quote:That's why I made the disclaimer about telescope length.
I find it usable on my 12.5" f/5 (and I can sit everywhere the scope points), but on a 10? Probably not, unless it's f/6.5+.
Quote:Ditto a Telrad. Straight-through finders require the ability to get behind them.
Seeing one on nearly any refractor, mounted near the eyepiece, just makes me laugh.
Quote:That's why I made the disclaimer about telescope length.I find it usable on my 12.5" f/5 (and I can sit everywhere the scope points), but on a 10? Probably not, unless it's f/6.5+. Ditto a Telrad. Straight-through finders require the ability to get behind them.
Quote: I bought one the ES 50mm Straight through finders. It's on the shelf, I am just too used to non-correct image finders.
Quote:Mine's on the shelf, too. But not because of the correct image. I like that. I tried to make straight-through work for me on my 10" f/4.8 Dob, but it's just not for me. Mike
Quote:You know I have an adjustable stool. The range is 14" to 19".
Quote:I bought one of these ES straight-through finders last year with the intention that it would replace both a RACI optical finder and a Telrad on my 10" f/4.8 Dob. In practice, though, it did not work out for me. I have my 10" Dob set as low as possible so I can sit at all positions of the OTA. This fact made it very uncomfortable for me to view for more than a few seconds through the ES straight-through finder. A straight-through design is OK for the Telrad, because I only need to look through that for a few seconds to get in the neighborhood of an object before star hopping with a RACI optical finder. Also, the ES finder has inconveniently short eye-relief, which makes for an uncomfortable star hop, at least for me.So for these reasons I put the ES finder away in my closet after only one trial at the dark site. Maybe if I acquire a telescope on which I can mount the ES finder farther above the ground, it would work out better for me. But I doubt that, because I like to have my scopes set low-low. I don't like standing to observe and I don't like being perched on a tall chair.So far my experience is telling me that I just do not like any straight-through finder for star hopping. Not gonna happen. Give me a RACI any night over a straight-through finder! This is also a main reason why I detest the Telrad for more than getting in the general vicinity of an object.The illumination on the ES finder is too bright, but that is easy to remedy with red touch-up paint or nail polish. That was by far the least of the problems with the finder.Mike
Quote:Quote: I bought one the ES 50mm Straight through finders. It's on the shelf, I am just too used to non-correct image finders.Jon Mine's on the shelf, too. But not because of the correct image. I like that. I tried to make straight-through work for me on my 10" f/4.8 Dob, but it's just not for me. Mike
Quote: I bought one the ES 50mm Straight through finders. It's on the shelf, I am just too used to non-correct image finders.Jon
Orion XT12i with Swayze-refigured primary/Protostar secondary
Televue NP101 refractor
William Optics Megrez 90 refractor
Universal Astronomics Deluxe Mounts