Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Barlows

  • Please log in to reply
5 replies to this topic

#1 dhmiller

dhmiller

    Vostok 1

  • *****
  • topic starter
  • Posts: 108
  • Joined: 30 Jul 2020

Posted 14 August 2020 - 08:16 PM

Just purchased an Esprit 100 with AZ-EQ mount. I am in need of both 2x and (I think) 3x Barlows (or focal extenders). The OTA has a 2" eyepiece and comes with a 1.25" adapter. I have found available Explore Scientific 2" 2x Focal Extenders in both 2" and 1.25" sizes (2" is double the price.) At some point before long, I will be using the setup with my Nikon DSLR and/or a CCD camera, but I also hope to do observing with the rig. Can anyone tell me if the 2" is a far better purchase and if so, for what reason, given the described usage? Also, an ES  3x is available in both sizes and I would like the capability it provides, but I am worried the 3x might be beyond the abilities of my OTA (or so I've heard). Also, all TV Powermates are out of stock (and I believe they don't make a 3x), so I'm hoping the Explore Scientific will be of very high quality (I just bought several of their eyepieces). And is there any disadvantage of a focal extender v an actual Barlow? Thanks for any feedback.  


Edited by dhmiller, 14 August 2020 - 08:25 PM.


#2 TOMDEY

TOMDEY

    Fly Me to the Moon

  • *****
  • Posts: 7,497
  • Joined: 10 Feb 2014
  • Loc: Springwater, NY

Posted 14 August 2020 - 09:07 PM

Nice Telescope! Have you just started this hobby, or just new to Cloudy Nights? A 3x Barlow is pushing the F# way up, which is why most of us rarely go there. Your experience level should enter into what makes the most sense regarding observing for now and what/when more purchases, and diving into imaging. It might be prudent to exercise the telescope and your eye with the several eyepieces you just bought. Give it a few months. By then, you will know what should come next!    Tom


  • jim kuhns likes this

#3 dhmiller

dhmiller

    Vostok 1

  • *****
  • topic starter
  • Posts: 108
  • Joined: 30 Jul 2020

Posted 14 August 2020 - 09:19 PM

Thanks much - very good advice. Brand new, absolute beginner to all things astro (lots of terra photo), and I prefer to buy where I want to be ultimately, rather than buy low, then upgrade, and upgrade and upgrade. So I found the combo I wanted and went for it ;-) But clearly a massive amount to learn, and then there's the software... Just read (here) that focal extenders are not quite the quality of good Barlows, though I guess they also have an advantage or two. It's a challenge making purchasing decisions now when so many things are unavailable (there are fare worse problems..). Btw, what did you mean by "F#" - "A 3x Barlow is pushing the F# way up,..."  As a musician, that caught my eye. ;-)

Nice Telescope! Have you just started this hobby, or just new to Cloudy Nights? A 3x Barlow is pushing the F# way up, which is why most of us rarely go there. Your experience level should enter into what makes the most sense regarding observing for now and what/when more purchases, and diving into imaging. It might be prudent to exercise the telescope and your eye with the several eyepieces you just bought. Give it a few months. By then, you will know what should come next!    Tom



#4 TOMDEY

TOMDEY

    Fly Me to the Moon

  • *****
  • Posts: 7,497
  • Joined: 10 Feb 2014
  • Loc: Springwater, NY

Posted 14 August 2020 - 09:31 PM

Thanks much - very good advice. Brand new, absolute beginner to all things astro (lots of terra photo), and I prefer to buy where I want to be ultimately, rather than buy low, then upgrade, and upgrade and upgrade. So I found the combo I wanted and went for it ;-) But clearly a massive amount to learn, and then there's the software... Just read (here) that focal extenders are not quite the quality of good Barlows, though I guess they also have an advantage or two. It's a challenge making purchasing decisions now when so many things are unavailable (there are fare worse problems..). Btw, what did you mean by "F#" - "A 3x Barlow is pushing the F# way up,..."  As a musician, that caught my eye. ;-)

Yeah, that is indeed not to be interpreted as F Sharp, but rather F-Number.

 

A 3x Barlow will increase the Focal Ratio F# of your telescope from F/5.5 to F/16.5. So it goes from a reasonably fast telescopic lens to a very slow one.    Tom



#5 KTAZ

KTAZ

    Viking 1

  • *****
  • Posts: 972
  • Joined: 09 Apr 2020
  • Loc: Scottsdale, AZ

Posted 14 August 2020 - 09:47 PM

Since we seem to be talking purely visual, it would help to understand what your eyepiece collection consists of.

 

Barlows will double your power, your F#, and the eye relief of your eyepieces. That can make some eyepieces work better (those with short eye relief) and some worse (those with long eye relief). So it is a mixed bag. Extenders only differ in their ability to double power and F#, but not effect eye relief. At least that is my understanding (if I’m wrong, someone will be along shortly to say so wink.gif ).

 

So why do you think you need them? Are you looking to push your power for planetary observing? Be careful that you do not overpower your scope, because you will see only mush in the end. Your 4” aperture should do 200x, but not much more.


Edited by KTAZ, 14 August 2020 - 09:48 PM.


#6 dhmiller

dhmiller

    Vostok 1

  • *****
  • topic starter
  • Posts: 108
  • Joined: 30 Jul 2020

Posted 14 August 2020 - 10:58 PM

Yeah, that is indeed not to be interpreted as F Sharp, but rather F-Number.

 

A 3x Barlow will increase the Focal Ratio F# of your telescope from F/5.5 to F/16.5. So it goes from a reasonably fast telescopic lens to a very slow one.    Tom

Well the goal is for my daughter to see the rings of Saturn - big ;-)  Really, though, I am trying to set up up a system that would provide viable/satisfactory viewing experiences for family members, while my own priorities are entirely AP. So the 3x, if it is even feasible on my OTA, is mostly for visual, while I would expect to use the 2x for both imaging and viewing. So far, I have a 4.7 and 14mm on order, and I THINK I just scored a 6.7 and 8.8 today... So that's the range of eye pieces I expect to have in the collection as things begin to arrive at my door. Thanks foryour feedback..

Since we seem to be talking purely visual, it would help to understand what your eyepiece collection consists of.

 

Barlows will double your power, your F#, and the eye relief of your eyepieces. That can make some eyepieces work better (those with short eye relief) and some worse (those with long eye relief). So it is a mixed bag. Extenders only differ in their ability to double power and F#, but not effect eye relief. At least that is my understanding (if I’m wrong, someone will be along shortly to say so wink.gif ).

 

So why do you think you need them? Are you looking to push your power for planetary observing? Be careful that you do not overpower your scope, because you will see only mush in the end. Your 4” aperture should do 200x, but not much more.




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics