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
Meade LS8 ACF Meade 2" Diagonal Apetura 10" Tweakers Package Meade ETX-125, ETX-90 for Solar Celestron 80mm APO PST Meade SWA - 34mm,28mm,24mm,20mm Brandon 32mm, 16mm Vernonscope 40mm Erfle 2" ES 14mm,11mm,6.7mm 8.8 Nagler 13mm T6, Pan 19mm Meade 12.4 Pl,9.7mm, 15mm SP Meade 2x Shorty Barlow Powermate 2.5x WO Bino Viewer, 20mm 66* pair Denkmier 2 Super System Meade Nebula Filters Meade 9x60 Bino Vivitar S1 8x42 Bino Canon T2i, 18-55mm, 50mm 1.8, 55-250mm
"Coffee leads men to trifle away their time, scald their chops, and spend their money, all for a little base, black, thick, nasty, bitter, stinking nauseous puddle water." ~The Women's Petition Against Coffee, 1674If it ain't broke, fix it 'til it is.
Quote:I loved it in the Dob and I think the lower profile focuser would only make it better.
Orion ED80 - AT Voyager with TNT,pier ext.,Vixon steel tray and Manny's mod.
Omni 120 cg4 with Orion pier ext. and RA drive, Binotron-27 (25mm & 17mm Sterlings)
Orion XT10(Original F/5) SkyStopper Equatorial Platform
Jason Constellation Model 311(Modified with 1.25"Crawford Machine focuser & rings)
Quote:Because the binoviewers greatly limit your true field, the coma is a lot less of an issue than you may realize.
Suppose that you use a Denk with D21 eyepieces.
If your scope is 1220mm focal length, then with the low power arm, it will be like the scope is going to be more like 1590mm focal length.
This means that if you were to use a pair of D21s, the power would be around 73x.
And remember, the D21s are only 65 degree apparent field.
Now suppose you were to duplicate this power in your scope at native focal length. That would be like using a 16mm wide field (something like the ES 16/68).
Because you are limited to relatively high powers, most of the bad coma simply is not going to be in the field.
I used the Binotron in a 12" f/4.9 dob with a pair of 20/68 ES eyepeices, and honestly coma was not really much of an issue.
In essence, you are going to be using only the center 50% of the mirror.
Quote:Just a newbie in the world of BV and have been mainly using my Denk2 P/S in my 8" SCT. But recently bought a 10" Dob to see what all the fuss is about on CN with so many members using them.I bought an OCS for the Denk's and I must say they are pretty neet. I have not looked at a planet yet as Jupiter rises late here, but looking forward to doing so in this scope. The stars in the double star cluster look really sharp and contrasty with the reducer arm in, get both of them in the EP. The moon is dazzingly in the BV in all 3 modes. I'm using a pair of 20mm SWA and a 26mm SP.With the OCS I'm working at f/1600, f/2800 and f/3800 in the 10" Dob.Bob
Quote:I loved it [the Binotron] in the Dob and I think the lower profile focuser would only make it better.
Quote:Haven't used one, but in the S&T review they said the power switch did introduce a little aberration.
Quote:I recently upgraded to a 1.5" low-profile Moonlite, so I should be good to go.
Quote:I am still not settled as to how important coma correction really is to planet/lunar observation.
Quote: Quote:I recently upgraded to a 1.5" low-profile Moonlite, so I should be good to go. I don't think you will be able to reach focus in the high power mode of the binotron with a 1.5" tube without having to pull it out of the focuser at least 1/2".Eric
Quote:Now if I do get a Binotron, maybe I can stack it in the filter wheel and be able to come to focus at all settings. IMO, that would be an excellent outcome!
Quote:Use a 2.1" focuser tube.
Quote:This is the way the Binotron is going to work. You are going to have to rack all the way in to get the low power arm to focus.When you go straight though, you are going to have to rack out quite a bit, and when you go high, you have to rack out even more.The solution is simply. Set up the focuser with the lowest profile you can.Use a 2.1" focuser tube.
Quote:Ignore the fact that in low power, the tube is going to extend into the light path. At low power, it really doesn't do enough damage to the image to make it possible to detect. It simply does not matter.
Quote:Quote:I am still not settled as to how important coma correction really is to planet/lunar observation. For planets, coma may not be a factor if you're using a driven scope and can keep the planet centered. For Lunar, I prefer coma correction across the entire field. I don't own a scope with coma but I do have an eyepiece pair which is bad in this department and I can't stand to use them on the moon.Tanveer.
Quote:No, the lowest profile I can have is a 1.5" focuser tube. That's what I have now. If I went any longer I'd probably not be able to come to focus with the filter wheels in some of my eyepieces
Quote: the more you would have to extend the newtonian spacer to still achieve focus at low power thus marginally reducing the FOV the more it is extended.
Quote:I am using a Binotron with a 10" home-built f/6.5 newt. I asked Russ if a Paracorr would be useable and he said it was not needed--even at shorter f-ratios. I suspect that this may have to do with the OCS. However, the magnification effect of the OCS alone would not affect coma correction as coma scales linearly with magnification.
Quote:Why all this talk about the drawtube intruding into the light path at low power but not at high power?
Quote:Mike, when using the binotron's in a newtonian there is a minimum of 4" between the shoulder of the focuser and the OCS. This consists of the regular 2" shaft + a 2" Newtonian spacer which can itself be unscrewed a further 1/2" to help reaching focus in low power if necessary. The newtonian spacer is removed for use in a refractor or SCT thus making the whole system compatible with any type of scope. In my scope (10" f/5) I rack out more than 1.25" for mid power and about 2" for high power.
Quote:I should have picked up on this when you talked about using the binoviewer with a filter wheel. Since you already are able to use the filter wheel in mono, when using the binotron you would have to modify the length of your focuser tube or use an extension tube or pull the whole thing out quite a bit when binoviewing with mid or high power. But using the binotron with the filter wheel is of course not possible.
Quote:BTW I still don't know how you are able to reach focus with the filter wheel's extra inch of height + the extra 3/8" in height for the 3 thumbscrew compression ring holder. The math just doesn't seem to compute for my eyepieces.
Quote:I could see switching to Denk 14s but I have not bothered yet.