1390 replies to this topic

[Ihtegla Sar]

Once you add Barlow, the finest Barlow available, to a minimum glass eyepiece you have increased the number of elements, the resulting setup is no longer a minimum glass eyepiece, pure and simple.

It's still a minimum glass eyepiece. It's a minimum glass eyepiece with a Barlow.

If one really wants to be "pure" about minimum glass, then they should be observing straight through with an oiled lens. No air spaced triplets, no diagonals.

[SandyHouTex]

Once you add Barlow, the finest Barlow available, to a minimum glass eyepiece you have increased the number of elements, the resulting setup is no longer a minimum glass eyepiece, pure and simple.

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But there is one important issue to consider, if you view the object with a minimum glass eyepiece and a Super Barlow, if in your opinion, nothing is compromised then the answer to this question for you is that the resulting setup is just as good as the minimum glass eyepiece without a Barlow.

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This is all a judgment call on your part, someone else's opinion on the subject is just an opinion, my opinion is once you add a Barlow you no longer have a minimum glass setup.

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Vahe

My opinion is anything with less than 6 elements is a minimal glass eyepiece.  The vaunted Pentax XO 2.5mm has 6, the XO5 has 5, so if you use an achromatic barlow with 2 elements and an Abbe Ortho, you're at 6.

[Scott99]

There's no rules or standards for minimum glass.   Just get out there with your scope and start scrutinizing DSO's.  I see details with 4-element eyepieces that disappear when I put the Pentax XW in.  IMO, smaller objective, high-end optical trains benefit the most - i.e. apo refractors.  Effect becomes stronger with larger refractors. 

 

Never saw much need for minimum glass in my friends' big dobs and SCTs.  If you're observing under washed-out suburban skies, not much need for it there either.  Obviously for those that get thrills from a wide-field view, not good for them.  What kind of observer are you?  Everyone's different. 

Edited by Scott99, 04 August 2023 - 11:01 AM.

[leonard]

Once you add Barlow, the finest Barlow available, to a minimum glass eyepiece you have increased the number of elements, the resulting setup is no longer a minimum glass eyepiece, pure and simple.

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Vahe

     Amen , here we have an example of common sense . More glass is more glass , there is no way around that . Even if the Barlow had a super polish, say scratch/dig 10-5(good luck) it’s still more glass .

I have read many times here at CN about barrows that take away nothing from the view , they do the same thing all glass does . True they can do things for the view that’s positive and that’s what there for , but

not adding any glass problems to the stack is not one of them .

Edited by leonard, 04 August 2023 - 11:42 AM.

[TG]

An oft overlooked Barlow is the Tele Vue 1.25in one. I've looked very closely with it with several high quality objectives, and I see no wavefront degradation with it. It's as if it's not there at all.

[WE349A]

Sometimes you just have to look rather than think.

[Thomas_M44]

Sometimes you just have to look rather than think.

Lol!
 

+1 

[norvegicus]

Mine arrived yesterday and look great.  I might get a chance to try them this weekend...

[Sarkikos]

There's no rules or standards for minimum glass.   Just get out there with your scope and start scrutinizing DSO's.  I see details with 4-element eyepieces that disappear when I put the Pentax XW in.  IMO, smaller objective, high-end optical trains benefit the most - i.e. apo refractors.  Effect becomes stronger with larger refractors. 

 

Never saw much need for minimum glass in my friends' big dobs and SCTs.  If you're observing under washed-out suburban skies, not much need for it there either.  Obviously for those that get thrills from a wide-field view, not good for them.  What kind of observer are you?  Everyone's different. 

I think the use of minimum glass eyepieces purposefully for deep sky - and not just because they were the only eyepieces available - is a relatively new thing.  Some observers with big Dobs have reported that they can see deeper and see more structure in deep sky objects when using specific simple-glass eyepieces, when compared to more complex modern designs.  

 

But for the most part, the main reason for choosing simple-glass over complex eyepieces, is that the images of bright planets - and to a lesser extent, the Moon and double stars - are said to appear sharper with less scatter, more contrast, and improved color saturation.

 

Some simple glass eyepieces, otherwise praised as planetary eyepieces, are inferior for deep sky compared to complex, modern eyepieces.  This is often because of the simple coatings on the simple glass.  FMC will provide higher light transmission than FC.  I would give as examples Brandons, RKE's, Edmund Plossls, Edmund Orthos, as well as many other older styles of Plossls and Abbe Orthos.  Simple single coatings are not best for deep sky.  FMC will allow greater light throughput.  

 

Mike

Edited by Sarkikos, 04 August 2023 - 02:21 PM.

[25585]

Should these new Tak EPs come with a health warning?

Just the usual addiction warning that Takahashi addiction can damage your wealth. 

[Thomas_M44]

I think the use of minimum glass eyepieces purposefully for deep sky - and not just because they were the only eyepieces available - is a relatively new thing.  Some observers with big Dobs have reported that they can see deeper and see more structure in deep sky objects when using specific simple-glass eyepieces, when compared to more complex modern designs.  

 

But for the most part, the main reason for choosing simple-glass over complex eyepieces, is that the images of bright planets - and to a lesser extent, the Moon and double stars - are said to appear sharper with less scatter, more contrast, and improved color saturation.

 

Some simple glass eyepieces, otherwise praised as planetary eyepieces, are inferior for deep sky compared to complex, modern eyepieces.  This is often because of the simple coatings on the simple glass.  FMC will provide higher light transmission than FC.  I would give as examples Brandons, RKE's, Edmund Plossls, Edmund Orthos, as well as many other older styles of Plossls and Abbe Orthos.  Simple single coatings are not best for deep sky.  FMC will allow greater light throughput.  

 

Mike

I substantially agree, with some modest reservations.

 

BTW:

 

I think the humble TeleVue Plossls are an under-appreciated faint DSO eyepiece. They have excellent FMC coatings, good core optical quality and design, and only four air-to-glass surfaces. Also, I find the subjective color rendition and saturation superior to the KK Abbe orthos or RKEs.  Because they are also compatible with fast scopes of down to at least f/4 or so, they are exceptionally versatile for a low-element-count eyepiece. IMO, there are only three substantial caveats with them:

 

 

(1) 32mm through 15mm will vignette with essentially all conventional Barlows. Telecentric amplifiers are requisite. 

 

(2) Modest (by contemporary standards) 50-degree AFOV.

 

(3) Rather tight ER below the 20mm FL —which is unfortunately normal for Plossl-type eyepieces.

 

 

Otherwise, I find the TV Plossls to be incredibly versatile and possessing excellent all-around performance. Good for bright objects, good for faint DSOs.

 

IMO, they are an enduring bargain.

Edited by Thomas_M44, 04 August 2023 - 03:44 PM.

[davidgmd]

Sometimes you just have to look rather than think.

  
I need to increase my look/think ratio.

  
[EDIT]

Hopefully more looking, not less thinking…

Edited by davidgmd, 04 August 2023 - 04:04 PM.

[PatientObserver]

I need to increase my look/think ratio.

[EDIT]
Hopefully more looking, not less thinking…

I need the sky to clear so I can look. So many clouds since I bought my scopes ...

[Ihtegla Sar]

Three blue boxes arrived today, and they weren't from Tiffany's. As expected, clouds arrived with the boxes.

[norvegicus]

Canadian smoke came with my boxes.

[Kevin Barker]

An oft overlooked Barlow is the Tele Vue 1.25in one. I've looked very closely with it with several high quality objectives, and I see no wavefront degradation with it. It's as if it's not there at all.

My brother just this week reported excellent results with an old 1.8X Televue barlow whilst using Takahashi 0.965" orthoscopics. Scope was a very nice fc-100 from around 1990. He also has an old Intes 2.4?X barlow and he saw a little CA creep in using the Intes. He was probably using 7 and 9 mm Orthos.

 

He had near perfect seeing one night and split Antares easily.

[Sarkikos]

Canadian smoke came with my boxes.

I like their bacon.  They can keep the smoke.

 

Mike

[Thomas_M44]

My brother just this week reported excellent results with an old 1.8X Televue barlow whilst using Takahashi 0.965" orthoscopics. Scope was a very nice fc-100 from around 1990. He also has an old Intes 2.4?X barlow and he saw a little CA creep in using the Intes. He was probably using 7 and 9 mm Orthos.

 

He had near perfect seeing one night and split Antares easily.

Excellent!
 

Your brother has just enough choice relics assembled there to start a small astro gear museum —Lol!

 

But seriously, I have heard very good things about the Takahashi 0.965” orthos. 
 

Neat stuff 

Edited by Thomas_M44, 04 August 2023 - 07:50 PM.

[Kevin Barker]

Excellent!
 

Your brother has just enough choice relics assembled there to start a small astro gear museum —Lol!

 

But seriously, I have heard very good things about the Takahashi 0.965” orthos. 
 

Neat stuff 

Phil and I are both afflicted with the bug...... The Tak orthos are very sharp little eyepieces. Phil who is my twin lives 1000 km away and recent weather has favoured his location.

 

I have the 4.0 mm Tak Hi-Or which I intend to compare to the TOE one day. Just need a well placed planet and some decent air. I once viewed through a friend's 2.8 mm Hi-Or at a double star. If you ever see one of those snap it up.

 

I confess I have a pair of 12.5 mm TPL's arriving soon...for binoviewing.

[norvegicus]

I did a solar shootout just now.

 

Conditions:  46°N, 1:30pm, Astrospheric reports 10% clouds, poor transparency,  average seeing, yellow/orange zone of smoke, which I agree with.  Not ideal and probably limited my view enough to muddy this comparison.

 

Rig:  FS-60Q with Lunt LS60THa front etalon, B1200 blocking filter.  On a Vixen Porta II on a home made portable pier that lives in my backyard year round.

 

Me:  not an expert observer nor eyepiece tester, as I've only been doing this for a few years.  Rank beginner solar observer.  

 

Target:  Sol, taking up about 75% of the view at 12.5mm

 

Tested:  

 

Tak TPL 12.5mm best contrast and details, almost uncomfortable eye relief

 

Tak LE 12.5mm same view, slightly but noticeably better eye relief

 

AT Paradigm Dual ED 12mm 95% as nice view, larger apparent disc size, wider AFOV in a very good way that allowed me more viewing time before adjusting the mount, much better eye relief.  Instantly comfortable, which is still why I own two of these $60 gems.  I had to compare VERY carefully several times to prove to myself that the Taks showed slightly more and sharper details.

 

Parks K12mm slightly less details than above, comfort equivalent to the TPL, I'll be selling my pair of these

 

Celestron Ultima 12.5mm same as the LE in every way

 

Vixen LV 12mm noticeably less detail and soft view.  I'll be selling this one.

 

 

2nd comparison:

 

Tak TPL 18mm vs. Tak LE 18mm - exactly the same in every way.  I feel like I could use these two as a bino pair.  Comfortable, no down sides.

 

 

Comments:

 

Interestingly the TPL, LE, Ultima, and Paradigm were parfocal.

 

I tested the TPL first and didn't think about the eye relief until I dropped the Paradigm in and said wow! out loud because it was so much nicer.  When I went back to the TPL it became annoying.

 

I'm not ready to trash the TPL but it won't be a bino pair choice, as comfort is a huge factor, for me.  I need to evaluate it on planets and stars in a month or two when I don't have to stay up so late to see them. 

 

 

There is a LOT going on with the sun right now.  I recommend a look if you have the equipment.  So many filaments and prominences.

 

 

Edited by norvegicus, 05 August 2023 - 01:40 PM.

[jrazz]

That rig looks amazing. Super neat!

 

I agree the TPL is very tight for eye relief. I think the reason it didn’t bother me is because I’m used to much chonkier eyepieces that make smaller IPDs more challenging.

 

 I feel lucky the eye relief doesn’t bother me.

[StarDust1]

Sean, Thanks for the review! Looking forward to your review on the planets.

 

I'm not sure if you have access to the Delites, would love to hear how the TPL compares to the Delites...

Edited by StarDust1, 05 August 2023 - 03:12 PM.

[norvegicus]

Sean, Thanks for the review! Looking forward to your review on the planets.

 

I'm not sure if you have access to the Delites, would love to hear how the TPL compares to the Delites...

No I don't.  I had a Delite 11 once and disliked it and sold it.  I think I read somewhere since then that the 11 is the worst one.

[Kevin Barker]

No I don't.  I had a Delite 11 once and disliked it and sold it.  I think I read somewhere since then that the 11 is the worst one.

I like my 11 mm Delite.

I did a comparison of the 11 mm TV Delite and a 11 mm TV Plossl last year. Scope was an IM603 f-10 6 inch Mak on a driven mount. Scope well cooled and insulated the comparison was over a decent period of time.

 

Viewing Jupiter at around 140 X in good seeing I thought they were neck and neck in terms of fine detail seen etc. The Delite had an easier view due to the 20 mm eye relief and 62 degree AFOV. But detail was identical. 

 

Going into this comparison I expected the TV Plossl to have an edge over the Delite. 

[iseegeorgesstar]

I did a solar shootout just now.

 

Conditions:  46°N, 1:30pm, Astrospheric reports 10% clouds, poor transparency,  average seeing, yellow/orange zone of smoke, which I agree with.  Not ideal and probably limited my view enough to muddy this comparison.

 

Rig:  FS-60Q with Lunt LS60THa front etalon, B1200 blocking filter.  On a Vixen Porta II on a home made portable pier that lives in my backyard year round.

 

Me:  not an expert observer nor eyepiece tester, as I've only been doing this for a few years.  Rank beginner solar observer.  

 

Target:  Sol, taking up about 75% of the view at 12.5mm

 

Tested:  

 

Tak TPL 12.5mm best contrast and details, almost uncomfortable eye relief

 

Tak LE 12.5mm same view, slightly but noticeably better eye relief

 

AT Paradigm Dual ED 12mm 95% as nice view, larger apparent disc size, wider AFOV in a very good way that allowed me more viewing time before adjusting the mount, much better eye relief.  Instantly comfortable, which is still why I own two of these $60 gems.  I had to compare VERY carefully several times to prove to myself that the Taks showed slightly more and sharper details.

 

Parks K12mm slightly less details than above, comfort equivalent to the TPL, I'll be selling my pair of these

 

Celestron Ultima 12.5mm same as the LE in every way

 

Vixen LV 12mm noticeably less detail and soft view.  I'll be selling this one.

 

 

2nd comparison:

 

Tak TPL 18mm vs. Tak LE 18mm - exactly the same in every way.  I feel like I could use these two as a bino pair.  Comfortable, no down sides.

 

 

Comments:

 

Interestingly the TPL, LE, Ultima, and Paradigm were parfocal.

 

I tested the TPL first and didn't think about the eye relief until I dropped the Paradigm in and said wow! out loud because it was so much nicer.  When I went back to the TPL it became annoying.

 

I'm not ready to trash the TPL but it won't be a bino pair choice, as comfort is a huge factor, for me.  I need to evaluate it on planets and stars in a month or two when I don't have to stay up so late to see them. 

 

 

There is a LOT going on with the sun right now.  I recommend a look if you have the equipment.  So many filaments and prominences.

 

 

solarig.jpg

IMG_3695.jpg

The constricted day light exit pupil might be a factor too. I remember when I had a lunt 50 pst for a short time. I had to be hooded for a few minutes before my eyes really adjusted to the detail that was there/visible. 

 

How was the straylight performance across the different EPs?