new iEQ45 or used Vixen SX-D ?

orly_andico · Post by **orly_andico** » Wed Feb 09, 2011 1:52 pm

subject says it all.

price is about the same.

i've been reading elwaine's review on CN of the iEQ45 and in spite of the design flaw (missing upper bearing) it is a competent imaging platform.

andeelym · Post by **andeelym** » Wed Feb 09, 2011 1:59 pm

Personally, i would go for the iEQ45.

orly_andico · Post by **orly_andico** » Wed Feb 09, 2011 2:06 pm

because of...?

andeelym · Post by **andeelym** » Wed Feb 09, 2011 3:19 pm

similar capabilities at USD1000 less with GPS builtin.

cloud_cover · Post by **cloud_cover** » Wed Feb 09, 2011 4:01 pm

Yep, but as Orly said his price is almost the same, the consideration is used vs new.
Similar load capacity although one is a China build, the other is a Japan build.
Not too sure what the uncorrected PE is like for the EQ45; its supposed to be around 10 arcsec for the SXD with jumps to 30-50arcsec in the declination axis, according to a CN review.
GPS is nice but if imaging generally in the same location, may not be so useful - same numbers throughout.
Other consideration is that SXD is well depreciated but future selling of EQ45 may result in significant price hit.

orly_andico · Post by **orly_andico** » Wed Feb 09, 2011 4:18 pm

reports of the iEQ45 is 20 - 30 arc-seconds peak-to-peak. the iEQ45 has a 216-tooth RA gear (vs 180-tooth on the SX-D) but the iEQ45 gear is aluminum while the SX-D is brass. (the SX-W and Great Polaris are aluminum, the GP-DX / GP-D2 are brass)

i'm not too concerned with declination errors because if your polar alignment is good enough, you will not need to guide in DEC, or if you do guide, it should only be in one direction.

the "problem" being talked about on the iEQ45 is binding on the DEC axis when the gear is de-clutched due to a missing upper bearing. apparently iOptron copied the Sphinx internal layout but omitted the upper bearing which is present on the SX-W and SX-D. this is not a problem during imaging because the gear is clutched (and carrying the axis) during imaging, it becomes a problem when balancing only. not a major issue however.

my biggest concern right now is that the iEQ45 only goes to 5 degrees. i'm not a fan of lowering one tripod leg to get to 1.3 degrees. a good latitude adjustment is critical to good AP.

edit: Kevin, any time you buy used, you get a good deal because the first owner already took the hit. :-) too bad there are no used iEQ45's or Orion Atlas floating around! i think it's precisely because the hit would be so large, nobody wants to stomach such a huge loss so they just keep it.

cloud_cover · Post by **cloud_cover** » Wed Feb 09, 2011 5:20 pm

There was an atlas going around recently, I think. Either A-Mart or CN but it got snapped up.
I didn't realise you were in the market for a mount or I would have highlighted the G-11 with Gemeni, tripod, casing and some extras, recent servicing, $2200 (can bargain - no takers then and price further reduced)
What's the difference between brass and Al gears?
Call me ignorant: if DEC adjustments are not required, then why do I see so many people posting issues with DEC axis jerkiness? I'm curious too since a perfect polar alignment then implies that only the RA axis will be working once the mount is slewed to the target.
I'm not a fan of lowering a tripod leg either: this tilts the entire assembly and shifts the CG which must surely place turning moment on parts designed for axial forces?

andeelym · Post by **andeelym** » Wed Feb 09, 2011 5:22 pm

Oops. misread the thread. Sorry. Well, if that's the case, I might want to go for used SXD and then add a GPS.

Umm I tot the iEQ45 can go down further than 5 degrees? Not thru the tripod legs lowering.

orly_andico · Post by **orly_andico** » Wed Feb 09, 2011 5:41 pm

The 5 - 40 arc-second jumps in the DEC axis are a killer for AP. The guy on CN was only using a 500mm FL (Pentax 75 SDUF) and was having to throw away 20% of his shots at 2 minutes. That's terrible, at 500mm!

http://www.cloudynights.com/ubbthreads/ ... in/3498079

Stuart has already had the problem on the DEC axis on his Sphinx

http://www.singastro.org/viewtopic.php?t=7236

and he has some fix (basically adjust the DEC worm) but based on his tweaks, he can't make it guide that smoothly.

Really makes the iEQ45 seem that much nicer.. elwaine on the CN forum has a very nice 5-minute M1 with a C9.25 EDGE HD on the iEQ45. I looked at Alfred's mods, he actually had to drill a new hole in the iEQ45 so it could get to 1 degree.. but even then he had to have a pier fabricated.

Kevin, G11 costs too much for me, the Gemini is antiquated (the new one fixes that, but spendy $$$) and I don't like the wires dangling all over the place.

cloud_cover · Post by **cloud_cover** » Thu Feb 10, 2011 3:58 pm

I still maintain that a GPS is not useful if you're imaging largely in 1 place or if you have GPS enabled phone (who doesn't nowadays?)
The other issue with EQ45 is consistency of quality: I don't know very much about ioptron QC, but it is well known that it is one thing to produce an excellent demo set but quite another to have to QC to mass-produce mostly excellent units (ALL is just too much to ask for, unless you're buying an AP or Paramount, I guess). I guess if most of the user reviews come back positive then we know that the QC for this line at least must certainly be good