Takahashi or Televue 4" Refractors

heyjojos · Post by **heyjojos** » Wed Jun 08, 2011 11:29 pm

Hi
Thanks to all of you for your valuable advise. Looks like they are a comparable scope. What orly_andico said is true... I'm also considering a mount and of course $$$ is a constraint for me. I'm trying to look for a resale Vixen Sphinx Delux mount and see if I can get it at a cheaper price.

I have a question on Televue. There is this model of NP101 with a 2" Everbrite dielectric star diagonal with 1.25" eyepiece adapter. It looks like a good thing to have since I won;t have to bend my back to look into the eyepiece. I'm not sure if that will affect the quality? I'm also surprise its cheaper???? Did I miss something?
Does anyone know what's the back focus avail for a Televue?

Really looking forward to my scope !!!

cloud_cover · Post by **cloud_cover** » Thu Jun 09, 2011 12:04 am

I use a TV 2" Everbrite and I have absolutely no complaints about its quality.
The 1.25" adapter is useful for using 1.25" eyepieces, which given the relatively short focal length of the NP101, most of your EPs will probably be of the 1.25" variety.
I suggest looking for used equipment; most owners of premium equipment usually take very good care of their equipment. The cheapest deal on an NP101 plus diagonal plus starbeam with hardcase is USD1700 for an 7-8 year old item with dusty but no scratched lens, lives in a desert so no issue of fungus. I'm not sure if this one is sold yet.
I spoke to David on the phone (heir apparent of televue) and he told me that the NP101 was designed in the days when sensors were smaller so an APS-C sized chip is generally the upper advised limit due to vignetting.
Also do take note the Petzval design is more susceptible to miscollimation and there have been owner complaints on focuser slop in the NP-101. A dual speed focuser upgrade is available (Focusmate).
But if you're after imaging, I think its an outstanding scope and if you don't run into these issues, it'll be a fantastic imaging lens since you don't have to worry about field curvature, false color etc.
Oh - servicing for an NP-101 (lens cleaning, recollimation, focuser servicing) will be in the order of USD200 if sent back to TV in Chester, NY. Domestic shipping to your forwarder will probably be more than USD50. Consider this as an option if purchasing a well used scope

wucheeyiun · Post by **wucheeyiun** » Thu Jun 09, 2011 9:41 am

I used the 1.25" WO dielectric diagonal for $65 for binoviewing ( to come to focus ) ... and 2" Premium Baader maxbright - special coating quartz based ( bought for $350 ) for any other uses and also with DSLR ( due to longer back focus issues ). Frankly i cannot tell the difference or just a tad little brighter - or just plain psychological .

Just get any decent dielectric type will do.

orly_andico · Post by **orly_andico** » Thu Jun 09, 2011 9:48 am

Stuart

I read a message from someone using the NexSXD. Apparently the PCB doesn't have an insulating coating, and the design of the Sphinx enclosure allows moisture to drip into the PCB housing (ack!) this is the (sole) design flaw of the NexSXD. The guy who posted it said he'd suggest to Maite that she coat future NexSXD boards.

In your case.. well maybe the board just needs to be dried out. That, or fix the USB hub issues.

With regards to GoTo accuracy, the Celestrons don't get really accurate until you add at least 2 calibration stars (across the meridian from the 2 alignment stars).

heyjojos · Post by **heyjojos** » Thu Jun 09, 2011 8:53 pm

cloud_cover wrote:I use a TV 2" Everbrite and I have absolutely no complaints about its quality.
The 1.25" adapter is useful for using 1.25" eyepieces, which given the relatively short focal length of the NP101, most of your EPs will probably be of the 1.25" variety.
I suggest looking for used equipment; most owners of premium equipment usually take very good care of their equipment. The cheapest deal on an NP101 plus diagonal plus starbeam with hardcase is USD1700 for an 7-8 year old item with dusty but no scratched lens, lives in a desert so no issue of fungus. I'm not sure if this one is sold yet.
I spoke to David on the phone (heir apparent of televue) and he told me that the NP101 was designed in the days when sensors were smaller so an APS-C sized chip is generally the upper advised limit due to vignetting.
Also do take note the Petzval design is more susceptible to miscollimation and there have been owner complaints on focuser slop in the NP-101. A dual speed focuser upgrade is available (Focusmate).
But if you're after imaging, I think its an outstanding scope and if you don't run into these issues, it'll be a fantastic imaging lens since you don't have to worry about field curvature, false color etc.
Oh - servicing for an NP-101 (lens cleaning, recollimation, focuser servicing) will be in the order of USD200 if sent back to TV in Chester, NY. Domestic shipping to your forwarder will probably be more than USD50. Consider this as an option if purchasing a well used scope

I dont mind a resale scope at all. Any idea what the website is for this USD1700 scope that you mentioned. I have been checking our Astromart and SingAstro but have not come across a NP101 yet

Certainly dont mind paying a little extra to get the scope cleaned!!

Cheers
HJ

cataclysm · Post by **cataclysm** » Thu Jun 09, 2011 10:59 pm

These are topnotch refractors, can't go wrong with either one.

heyjojos · Post by **heyjojos** » Fri Jun 10, 2011 9:08 pm

croys wrote:@

One last thing: recently I've been using a long focus refractor. There are benefits to a longer focal ratio that make them sharper and more pleasant for visual use. Of course the ergonomics get tricky. I think the TSA-102 is at a sweet spot here.

I

croys.. pardon me for asking, why would a longer focal ratio make an image sharper and more pleasant for viewing? I intend to use NP101 for viewing as well.
Will that hinder my viewing pleasure?

Cheers
HJ