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

An 11mm worth it in my 6” mak

  • Please log in to reply
17 replies to this topic

#1 Jond105

Jond105

    Fly Me to the Moon

  • *****
  • topic starter
  • Posts: 5,344
  • Joined: 19 Feb 2018
  • Loc: Detroit

Posted 07 April 2020 - 05:31 PM

I’m sitting here with an ES82 11mm in my cart from astronomics right now. It will be my last of astronomy funds for a while. With my eyepieces right now it goes as follows(just the in between)

 

APM HDC 13mm at 138x

ApM HDC 9mm at 200x

 

Would the 11mm at 163x be worth it you think. It’s really tough for myself to figure out on my own, so wondering what some of you other 6” mak users think. 



#2 SeattleScott

SeattleScott

    Cosmos

  • *****
  • Posts: 7,857
  • Joined: 14 Oct 2011

Posted 07 April 2020 - 05:34 PM

There isn’t much of a gap between 9 and 13. Plus it would have about the same FOV as the 9/100. So I would pass and look more at a longer FL, which you might already have covered. Or maybe a zoom?

Assuming you have a 2” diagonal, you are probably getting 160x with the 13 and 230x with the 9. So 44% change. Most people feel like 30-40% is optimal. So 44% isn’t quite ideal, but is it a big enough gap to split? Then you basically get two 20% increments. I suppose if you are a hardcore planetary observer and really want to tweak the view for the maximum useful magnification on a given night, sure. But again, if you are that obsessive about perfect magnification, maybe a zoom is in order. At these powers you generally aren’t looking at big stuff, and when you are, you have the XWAs.

FWIW my spacing is 13, 10, 8.

Scott

Edited by SeattleScott, 07 April 2020 - 05:43 PM.

  • Gary Z, ShaulaB and Jond105 like this

#3 junomike

junomike

    Hubble

  • *****
  • Moderators
  • Posts: 18,644
  • Joined: 07 Sep 2009
  • Loc: Ontario

Posted 07 April 2020 - 05:42 PM

Also, being 100°, your HDC 9mm should offer the same FOV with more magnification


  • ShaulaB and Jond105 like this

#4 Jond105

Jond105

    Fly Me to the Moon

  • *****
  • topic starter
  • Posts: 5,344
  • Joined: 19 Feb 2018
  • Loc: Detroit

Posted 07 April 2020 - 05:52 PM

This is what I started thinking myself as I was about to hit purchase. I’m not much of a tweaker in magnifications would it’s not too concerning with me. I’m glad I got some more input. I wish I could come to grips and try a zoom, but I like my wide fields I don’t know if I’d use it. My other option is an SCT external focuser from Agena or save longer for the Feather Touch focuser. That has the issue with clearance for a 2” diagonal though and I can’t seem to find an L Bracket I could use on my Alt AZ mount for this scope. 



#5 eyeoftexas

eyeoftexas

    Messenger

  • *****
  • Posts: 453
  • Joined: 01 Mar 2019

Posted 07 April 2020 - 05:56 PM

I have to agree with what the others suggested.  It just doesn't seem like a major gap.  Also, you get a Barlow and the APM 20mm would basically play the same role as the 11mm, but with wider FOV.


  • Jond105 likes this

#6 Garyth64

Garyth64

    Aurora

  • *****
  • Posts: 4,795
  • Joined: 07 May 2015
  • Loc: SE Michigan

Posted 07 April 2020 - 06:39 PM

I'd say get the 11mm. 163x fits in nicely between 200x and 134x. 

Maybe get an 18mm next, and then about a 24mm, even a 6.5mm if the Mak will take it.

I like to have eyepieces available to what the conditions are.

 

With my 130, I have 4.5, 5.5, and 6.5mm eyepieces giving 202x, 165x, and 140x.  That sorta matches your spread too.

 

With my 6" f/10 newt, I get 325x, 265x, and 225x, a good spread with those same eyepieces.

 

I also have 8.8, 14, and a 24mm for lower powers.  (and I have a 3mm for those rare excellent nights.)

 

When conditions are good, I want everything at hand to be able to use.

 

But that's me.


Edited by Garyth64, 07 April 2020 - 06:44 PM.

  • catboat and Jond105 like this

#7 Jond105

Jond105

    Fly Me to the Moon

  • *****
  • topic starter
  • Posts: 5,344
  • Joined: 19 Feb 2018
  • Loc: Detroit

Posted 07 April 2020 - 06:55 PM

I'd say get the 11mm. 163x fits in nicely between 200x and 134x. 

Maybe get an 18mm next, and then about a 24mm, even a 6.5mm if the Mak will take it.

I like to have eyepieces available to what the conditions are.

 

 

The 11mm in the mak was really the only gap I felt I have. My other eyepieces are the ES82 30mm and 6.7mm, as well as the APM HDC 20mm and 4.7mm


  • Garyth64 likes this

#8 luxo II

luxo II

    Surveyor 1

  • -----
  • Posts: 1,844
  • Joined: 13 Jan 2017
  • Loc: Sydney, Australia

Posted 07 April 2020 - 07:06 PM

Jon I appreciate the feeling.

 

There are times when you find 13mm isn't enough power but 9 is way too much and yes 11 will be useful. I've ended up with 1mm increments spanning 6...15mm.


  • eros312 and Jond105 like this

#9 SeattleScott

SeattleScott

    Cosmos

  • *****
  • Posts: 7,857
  • Joined: 14 Oct 2011

Posted 07 April 2020 - 08:59 PM

It just depends. Some people keep swapping out eyepieces to try and find the perfect magnification or exit pupil. Others, like me, tend to like bigger gaps where I know which eyepiece will do a good job on the target. It might not be perfect, but good enough. Sounds like Jon is more like me.

Scott
  • Jond105 likes this

#10 Jond105

Jond105

    Fly Me to the Moon

  • *****
  • topic starter
  • Posts: 5,344
  • Joined: 19 Feb 2018
  • Loc: Detroit

Posted 07 April 2020 - 09:06 PM

It just depends. Some people keep swapping out eyepieces to try and find the perfect magnification or exit pupil. Others, like me, tend to like bigger gaps where I know which eyepiece will do a good job on the target. It might not be perfect, but good enough. Sounds like Jon is more like me.

Scott

Id say I’m exactly like that as well. It’s why I cut so many eyepieces out a while back. I felt I was doing too much swapping feeling just maybe, and not enough observing. 


  • SeattleScott likes this

#11 whizbang

whizbang

    Viking 1

  • *****
  • Posts: 651
  • Joined: 18 Mar 2018
  • Loc: NE of Seattle, WA

Posted 08 April 2020 - 01:51 PM

No.  Don't bother.

 

I have a 1500 FL MAK and a 2000 FL SCT and I use both for Double Star observing.  Right now, I have good 1.25 inch 9, 16, 20, and 24mm eyepieces.  There is a big gap between the 9 and 16 that I wanted to fill.

 

I noticed in my last several Double Star sessions I had no problem swapping between the 9 and 16 on tight splits.  An eyepiece in between really doesn't help.

 

Forget about it.


  • Jond105 likes this

#12 Garyth64

Garyth64

    Aurora

  • *****
  • Posts: 4,795
  • Joined: 07 May 2015
  • Loc: SE Michigan

Posted 08 April 2020 - 03:03 PM

Jond105, I like the range of eyepieces that you have.  The 11mm fills in a gap.

I also like having a similar range of eyepieces.

For higher magnifications, flexibility is needed depending on sky conditions.  Even though some eyepiece f.l. may look too close together, they actually are not.

Your 4.7mm gives 382x and your 6.7mm gives 268x.  You have a gap there too.

Maybe get a 5.5mm for that gap.  At 327x it is almost an exact split between the other two.

 

I, myself, don't care for, and don't use barlows.

Let's say an older 5mm eyepiece doesn't have a lot of eye relief.  Using a 2x barlow with a 10mm will give you the same magnification with a better eye relief.

But todays eyepieces, even at 5mm have very good eye relief.

 

These are the ES eyepieces that I have:  3mm, 4.5mm, 5.5mm, 6.5mm 8.8mm 14mm and a 24mm.  They cover the range in magnification that I want.  With my 130 with a 910 f.l., I actually want to get a 3.6mm eyepiece.  It will fill in the gap between 300x and 200x.  Having a eyepiece with 250x would be great.


  • Jond105 likes this

#13 Jond105

Jond105

    Fly Me to the Moon

  • *****
  • topic starter
  • Posts: 5,344
  • Joined: 19 Feb 2018
  • Loc: Detroit

Posted 25 April 2020 - 05:42 PM

Jond105, I like the range of eyepieces that you have.  The 11mm fills in a gap.

I also like having a similar range of eyepieces.

For higher magnifications, flexibility is needed depending on sky conditions.  Even though some eyepiece f.l. may look too close together, they actually are not.

Your 4.7mm gives 382x and your 6.7mm gives 268x.  You have a gap there too.

Maybe get a 5.5mm for that gap.  At 327x it is almost an exact split between the other two.

 

I, myself, don't care for, and don't use barlows.

Let's say an older 5mm eyepiece doesn't have a lot of eye relief.  Using a 2x barlow with a 10mm will give you the same magnification with a better eye relief.

But todays eyepieces, even at 5mm have very good eye relief.

 

These are the ES eyepieces that I have:  3mm, 4.5mm, 5.5mm, 6.5mm 8.8mm 14mm and a 24mm.  They cover the range in magnification that I want.  With my 130 with a 910 f.l., I actually want to get a 3.6mm eyepiece.  It will fill in the gap between 300x and 200x.  Having a eyepiece with 250x would be great.

I ended up going this route and grabbing the 5.5 UWA


  • Garyth64 likes this

#14 asterope62

asterope62

    Vostok 1

  • *****
  • Posts: 115
  • Joined: 09 May 2015
  • Loc: Brigham City, Utah

Posted 25 April 2020 - 11:32 PM

I, myself, own a wide range of eyepieces and they get used according to what type of object I'm observing and what the sky conditions are. 



#15 SeattleScott

SeattleScott

    Cosmos

  • *****
  • Posts: 7,857
  • Joined: 14 Oct 2011

Posted 26 April 2020 - 09:01 AM

I ended up going this route and grabbing the 5.5 UWA

Just remember if you use a 2” diagonal, your Mak is probably operating around F14. I find a 5mm too much power for mine (420x or so).

Scott

#16 luxo II

luxo II

    Surveyor 1

  • -----
  • Posts: 1,844
  • Joined: 13 Jan 2017
  • Loc: Sydney, Australia

Posted 27 April 2020 - 02:18 AM

Just remember if you use a 2” diagonal, your Mak is probably operating around F14.

Not likely - do the maths - from f/12 to f/14 involves extending the backfocus 2 x Aperture, or 300mm. They're designed to be used with a star diagonal anyway, so adding a crayford focuser and a 2" diagonal might at most add 50-100mm - on my MK66 it added 50mm. 


Edited by luxo II, 27 April 2020 - 02:20 AM.


#17 SeattleScott

SeattleScott

    Cosmos

  • *****
  • Posts: 7,857
  • Joined: 14 Oct 2011

Posted 27 April 2020 - 04:42 PM

Well it makes my iOptron 6” F12 operate at F14. So it might be model specific. Keep in mind that back focus changes do not equate to FL changes with Mak/SCT the way they do with refractors and newts.

Scott

#18 Eric63

Eric63

    Surveyor 1

  • -----
  • Posts: 1,599
  • Joined: 16 Jun 2012
  • Loc: Ottawa, Ontario

Posted 27 April 2020 - 06:34 PM

The 2" diagonal on my 127 Mak increased the focal length from 1540mm to 1750mm (F15). I also checked it for my C90 with a 1.25" diagonal and it turned out to be 1450mm (F16). Here is a thread on how I computed it.

https://www.cloudyni...k-focal-length/

Eric

Edited by Eric63, 27 April 2020 - 06:48 PM.



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