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F15Rules

Help with eyepiece/barlow combinations please?

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Hi all,

I'd like to tap into your  wisdom regarding ep and barlow combinations please..

My scope focal length is 1040mm. Using a 10.5mm eyepiece on it's own gives me 1040/10.5= 99x, right?

So, adding in a Baader 2.25x barlow lens threaded in to the bottom of the 10.5mm gives me 99 x 2.25 = 222x (approx), right?

Finally, (and this is the bit I'm not sure of), if I thread in a x1.6 barlow nosepiece into the bottom of the 2.25x barlow (so there are then two barlows "stacked" in the bottom of the 10.5mm eyepiece, does that then give me 222x1.6 = 355x magnification in total? Or am I missing something that I should take account of in the calculations with two barlows being used stacked one on top of the other?

The images and their scaleI see seem to suggest I am about right, but it would be good to get some independent confirmation or correction from the more mathematically able among you! 😊

Many thanks,

Dave

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Stacking Barlows on top of each other 😵. That's a new one on me ,and I thought I try different things. Your Tak FS128 deserves better.  Stop being so tight and get some proper high power eyepieces😀

 

 

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The Baader 2.25x gives 1.3x amplification when the optical element is threaded directly into an eyepiece barrel.

 

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11 minutes ago, John said:

The Baader 2.25x gives 1.3x amplification when the optical element is threaded directly into an eyepiece barrel.

 

Hi John,

The baader barlow 2.25x I have is made up of 3 parts, the lenses being in the bottom two parts, the top section having a T2 thread I believe. The bottom of the two bottom parts won't unscrew from the "middle" part of the three, (it was like that when I bought it on SGL from another member): the top of the middle part is threaded and is the part that screws into the eyepiece barrel. Hope that makes sense? So, are you saying that without the T2 top component the bottom two sections only deliver 1.3x magnification?

Thanks,

Dave

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24 minutes ago, Timebandit said:

 

 

Stacking Barlows on top of each other 😵. That's a new one on me ,and I thought I try different things. Your Tak FS128 deserves better.  Stop being so tight and get some proper high power eyepieces😀

 

 

Thanks, thats really helpful.

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Stacking barlows is apparently a common and well known practice, and there is a fair amount of discussion on CN for a start. I cannot begin to suggest the mathematics involved, but your suggestion Dave that it is a product of the two barlows, if I understand you correctly, ie 1.6 x 2.25 = 3.6x 99= 356x seems to be in agreement with what I have read.

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39 minutes ago, F15Rules said:

Hi John,

The baader barlow 2.25x I have is made up of 3 parts, the lenses being in the bottom two parts, the top section having a T2 thread I believe. The bottom of the two bottom parts won't unscrew from the "middle" part of the three, (it was like that when I bought it on SGL from another member): the top of the middle part is threaded and is the part that screws into the eyepiece barrel. Hope that makes sense? So, are you saying that without the T2 top component the bottom two sections only deliver 1.3x magnification?

Thanks,

Dave

Hi Dave,

On my Baader 2.25x barlow (the Q-Turret type) the bottom most part unscrews and that contains the lens element. That unit can then be screwed directly into the filter threads on the bottom of a 1.25" eyepiece barrel and in that mode you get 1.3x. This only works with eyepieces that do not have optical elements within their 1.25" barells though so orthos, plossls etc, etc.

 

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15 minutes ago, Saganite said:

Stacking barlows is apparently a common and well known practice, and there is a fair amount of discussion on CN for a start. I cannot begin to suggest the mathematics involved, but your suggestion Dave that it is a product of the two barlows, if I understand you correctly, ie 1.6 x 2.25 = 3.6x 99= 356x seems to be in agreement with what I have read.

Thanks Steve, that was my train of thought. Optically the combination works well, although at c355x I was getting bad floaters and so found the 222x view cleaner. I confess I get frustrated by finding the performance of my previously good right eye deteriorating as I get older.

I'm training my left eye (which is quite a lot better than my right these days) to be my main cyclops viewing eye, and am increasingly finding binoviewers more comfortable on the Moon and, I hope later this year, the planets.

Using barlows, singly or stacked, helps preserve eye relief which again I find more comfortable than using 3.5-5mm eyepieces.

Dave

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Dave when I used binoviewers I sometime used a 2X and 1.6X barlow screwed into bottom to get higher magnification. It seemed to work although I never calculated the exact magnification.

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You could measure the exit pupil to find the magnification, but the measurement needs to be precise.

Exit pupil = D/M therefore M= D×E

I think! 

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Multiplying barlow magnifications together might not work precisely if the barlows won't seat all the way into each other, as would be the case with older, long barlows.  You might not be able to reach focus in that case, either.

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23 hours ago, Timebandit said:

 

 

Stacking Barlows on top of each other 😵. That's a new one on me ,and I thought I try different things. Your Tak FS128 deserves better.  Stop being so tight and get some proper high power eyepieces😀

 

 

 

22 hours ago, F15Rules said:

Thanks, thats really helpful.

 

 Sorry Dave you did not find my banter helpful😉. Obviously a different sense of humour. 

But if I had a top quality frac like the Tak FS 128 , then I would not be stacking Barlows. I personally would have a set of Pentax XW 3.5 to the 10XW , for normal high power viewing, and a set of Vixen HR for the nights of exceptional viewing conditions (when we are lucky enough in the UK) . I think a scope like yours deserves top quality eyepieces to get the best out of it. As a scope is only as good as the weakest link in the optical chain. 

 

 

 

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Probably not very helpful, but a 1.6X extender-Q is an unbelievably pure image amplifier that works great with a barlow to give high or even extreme magnifications. It would turn your FS128 into an F13. Adding a barlow to the mix will give some jaw dropping views of the Moon and double stars. It's one of those things I deeply regret selling. 😢 At 282X with a binoviewer my stomach literally rolled as I drifted over the edge of the Appenine mountains. :icon_puke_r:

Edited by mikeDnight
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5 hours ago, Louis D said:

Multiplying barlow magnifications together might not work precisely if the barlows won't seat all the way into each other, as would be the case with older, long barlows.  You might not be able to reach focus in that case, either.

I had a quick go last night before the clouds rolled in, for around 40 minutes.

The baader 2.25x Barlow bottom two sections (the top two shown in the photo below), which contain the optical elements threaded into my eyepieces fully with no problems.

The 1.6x WO nosepiece Barlow then threaded into the bottom of the baader Barlow, again fully and with no problems, so I am fairly confident that the magnification multipliers referred to above are accurate.

Accurate or not, the views put up in each of the eyepieces I tried them in were truly wonderful. The seeing last night for a short time was the best I have had here for many months.

Although I'm not the biggest Lunar fan, I was just rivetted by the lunar landscape and just how sharp it was, however much magnification I threw at it! Based on the stacked Barlow in my Carton zoom at its highest power 7mm setting I was getting c 355x with no image breakdown: however, at that magnification the floaters in both my eyes were quite distracting, so I dialled the zoom back a bit to an estimated 270x which gave me a cleaner view.

I do believe I spotted 2 or 3 craterlets in Plato last night, visible as lighter "spots" on the crater floor, so I was well chuffed with that😊👍.

In my excitement I forgot to try for the craterlets with my binoviewer, I have read that they can be easier to see with bv vision. If it clears later I might try for that tonight.

Davedownload.jpeg.08b1bbfdb43b655ad7ef707917762f18.jpeg

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16 minutes ago, F15Rules said:

I had a quick go last night before the clouds rolled in, for around 40 minutes.

The baader 2.25x Barlow bottom two sections (the top two shown in the photo below), which contain the optical elements threaded into my eyepieces fully with no problems.

The 1.6x WO nosepiece Barlow then threaded into the bottom of the baader Barlow, again fully and with no problems, so I am fairly confident that the magnification multipliers referred to above are accurate.

Accurate or not, the views put up in each of the eyepieces I tried them in were truly wonderful. The seeing last night for a short time was the best I have had here for many months.

Although I'm not the biggest Lunar fan, I was just rivetted by the lunar landscape and just how sharp it was, however much magnification I threw at it! Based on the stacked Barlow in my Carton zoom at its highest power 7mm setting I was getting c 355x with no image breakdown: however, at that magnification the floaters in both my eyes were quite distracting, so I dialled the zoom back a bit to an estimated 270x which gave me a cleaner view.

I do believe I spotted 2 or 3 craterlets in Plato last night, visible as lighter "spots" on the crater floor, so I was well chuffed with that😊👍.

In my excitement I forgot to try for the craterlets with my binoviewer, I have read that they can be easier to see with bv vision. If it clears later I might try for that tonight.

Davedownload.jpeg.08b1bbfdb43b655ad7ef707917762f18.jpeg

That is brilliant Dave. I bought a William Optics 2X nose-piece and screwed that into the William Optics 1.6x that came with the binoviewers. The mag was incredible and I was viewing the Moon with my 12" Dob. As I said before I was not certain about the mag but it was HIGH.

 

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1 hour ago, Timebandit said:

 

 

 Sorry Dave you did not find my banter helpful😉. Obviously a different sense of humour. 

But if I had a top quality frac like the Tak FS 128 , then I would not be stacking Barlows. I personally would have a set of Pentax XW 3.5 to the 10XW , for normal high power viewing, and a set of Vixen HR for the nights of exceptional viewing conditions (when we are lucky enough in the UK) . I think a scope like yours deserves top quality eyepieces to get the best out of it. As a scope is only as good as the weakest link in the optical chain. 

 

 

 

Hi Timebandit,

Don't worry about it..😊

I like to think I have a good sense of humour, but last night I was looking for actual feedback and advice on the subject in hand as I had just been trying out the various Barlow permutations available to me.

I fully agree that my FS128 "deserves top quality eyepieces". Indeed, before I retired 6 months ago it was fed with a mixed diet of Pentax, Morpheus and Vixen HR eyepieces. But enforced retirement brought about a change in my circumstances and I had to let a lot of nice things go to supplement my income in the (hopefully) short term.

I make no complaints about that as I have been able to keep the Tak (my most prized astro possession), and, in place of the more modern wider angle eyepieces I have built a small collection of extremely good but older Japanese eyepieces. These include a Tak ortho, a Nihon Seiko (NS) volcano top ortho, and three Carton Japan units with fov from 55-65 degrees in 1.25" barrels..believe me, these deliver views on axis every bit as sharp as any XW or Morpheus I have ever used.

My real problem more recently is eye relief..very short eps are quite uncomfortable for me these days and hence my interest in Barlow experimentation as these help give high magnifications but maintain the longer eye relief you get with longer focal length eyepieces. And on all too rare really good night's, the FS128 will take ridiculously high levels of power-indeed, the scope manual encourages owners to go up to or beyond x100 per inch of aperture..that's 500x or more for my scope! sadly, my floaters will kick in long before that level!

The Vixen HR 3.4mm was a notable exception, having good eye relief and was very comfortable, I found. When circumstances allow, that will be one of the first "hi end" eyepieces I aim to re-acquire!👍😊.

Dave

 

Edited by F15Rules
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Hi Dave,

Do you use a binoviewer? Ive found that binoviewing with the moon and planets greatly reduces the irritation of floaters, and for some reason seems to decrease the effects of atmospheric turbulence. I suppose with floaters, one eye cancels the other out, or at least partially, so floaters are not as readily visible. 

I agree totally that good quality simple design eyepieces perform on axis every bit as good as the venerable Pentax XW's, and it was because of that, that i sold off all my expensive wide angle eyepieces. In their place I now use paired pseudo Masuyama's. And the magnifications i use can reach ~ 395X in my binoviewer.  This of course is dependent on seeing conditions and the object I'm looking at.

I think modern barlows are excellent, and even the humble 2X SW Delux that's as cheap as chips if a superb  Barlow. I've even double stacked them and still they give razor sharp views. A few years ago, Roger Vine who writes some great scope reviews, came to my little observatory to check out these new FC100 refractors. With them being shorter than the FS series he was curious about how well they dealt with colour correction. It was a superb night with perfect seeing, and the spring Moon was high in the sky at around 1st quarter. Looking through the BV that was in my FC100DC he instantly exhaled a "Wow!" The eyepieces in the BV were cheap 16.8mm super Abbe Orthoscopics costing around £39 each. Comparing the view with Roger's 6mm Ethos, and 5mm TMB Super Mono, the binoviewer image wasn't only more comfortable, but detail was easily more obvious and every bit as sharp, and at a fraction of the price. The Ethos and a 5mm Nagler were not really on the same playing field if you know what I mean. The super mono was stunning, but the paired cheap ortho's were better. I was using a cheap Revelation binoviewer and a SW 2X Delux Barlow. 

Today my simplified eyepiece collection might be considered somewhat antiquated,  but it will give any high end eyepiece a major run for its money on lunar and planetary and thrash all but the very very best. In the attached pic, all my pseudo Masuyama pairs have been uncapped. There's a Celestron Ultima 2X barlow to the right of centre and a line up of Vixen HR eyepieces along the back right. The only wide field eyepiece I currently have is a 17.5 Baader Morpheus at the front right of centre, and of course my trusty but not rusty Revelation Binoviewer. 

889624860_2020-02-0609_34_46.jpg.2d4ccbaf3eee75ccc96066097344e2f8.jpg

Edited by mikeDnight
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@mikeDnight as always your reports / recollections have me hooked.
I am between yourself. @F15Rules and others moving towards a binoviewer with my very fine ED103s Vixen.

One question on the pseudo Masuyama's, were any made with rubber eye guards at all?
It is something that I 'need' to be present on an eyepiece.

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Hi Alan

The original Celestron Ultima and Parks Gold Ps Masuyamas did come with folded eyecups. I'm not sure about all the other versions, I suspect the Baader Eudiascopics do/did too.

See photo below of what they look like.. (not my set, sadly!😱😁).

They really do work well too, in my experience.

HTH,

Dave

730874-1.jpg

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4 hours ago, mikeDnight said:

Hi Dave,

Do you use a binoviewer? Ive found that binoviewing with the moon and planets greatly reduces the irritation of floaters, and for some reason seems to decrease the effects of atmospheric turbulence. I suppose with floaters, one eye cancels the other out, or at least partially, so floaters are not as readily visible. 

I agree totally that good quality simple design eyepieces perform on axis every bit as good as the venerable Pentax XW's, and it was because of that, that i sold off all my expensive wide angle eyepieces. In their place I now use paired pseudo Masuyama's. And the magnifications i use can reach ~ 395X in my binoviewer.  This of course is dependent on seeing conditions and the object I'm looking at.

I think modern barlows are excellent, and even the humble 2X SW Delux that's as cheap as chips if a superb  Barlow. I've even double stacked them and still they give razor sharp views. A few years ago, Roger Vine who writes some great scope reviews, came to my little observatory to check out these new FC100 refractors. With them being shorter than the FS series he was curious about how well they dealt with colour correction. It was a superb night with perfect seeing, and the spring Moon was high in the sky at around 1st quarter. Looking through the BV that was in my FC100DC he instantly exhaled a "Wow!" The eyepieces in the BV were cheap 16.8mm super Abbe Orthoscopics costing around £39 each. Comparing the view with Roger's 6mm Ethos, and 5mm TMB Super Mono, the binoviewer image wasn't only more comfortable, but detail was easily more obvious and every bit as sharp, and at a fraction of the price. The Ethos and a 5mm Nagler were not really on the same playing field if you know what I mean. The super mono was stunning, but the paired cheap ortho's were better. I was using a cheap Revelation binoviewer and a SW 2X Delux Barlow. 

Today my simplified eyepiece collection might be considered somewhat antiquated,  but it will give any high end eyepiece a major run for its money on lunar and planetary and thrash all but the very very best. In the attached pic, all my pseudo Masuyama pairs have been uncapped. There's a Celestron Ultima 2X barlow to the right of centre and a line up of Vixen HR eyepieces along the back right. The only wide field eyepiece I currently have is a 17.5 Baader Morpheus at the front right of centre, and of course my trusty but not rusty Revelation Binoviewer. 

889624860_2020-02-0609_34_46.jpg.2d4ccbaf3eee75ccc96066097344e2f8.jpg

Simplified is good Mike !

I use two different binoviewers, one with a power switch which means 3 magnifications from one pair, hence the crowding at the longer focal lengths.  I have come close to parting with the 26mm Meade Pseudo Masuyamas a couple of times in the last several years, but fortunately came to my senses; they are superbly sharp with stunning clarity.

I did have a couple of the 18mm Ultimas but let one go as I love my UOVT'S more than anything. I would love to find another 24mm Ultima but that is unlikely to happen I think. I also have a few pairs of wide angle eyepieces, but we won't mention them in this company !

IMG_1533.JPG

Edited by Saganite
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48 minutes ago, F15Rules said:

Hi Alan

The original Celestron Ultima and Parks Gold Ps Masuyamas did come with folded eyecups. I'm not sure about all the other versions, I suspect the Baader Eudiascopics do/did too.

See photo below of what they look like.. (not my set, sadly!😱😁).

They really do work well too, in my experience.

HTH,

Dave

730874-1.jpg

Other brandings of these were the Orion Ultrascopics and Antares Elite Series. Both of those came with fold up eyecups of the same pattern that the Ultimas in Mikes photo are wearing. Not the best design eyecup design IMHO but better than the bare metal. 

I've owned quite a few of these over the years. Interesting that they are still well though of now.

I've always felt that these eyepieces came from the same factory that made the Baader Genuine Orthos, Fujiyama HD orthos etc, etc. There is something about the design and finish that is very, very similar. 

 

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On 06/02/2020 at 12:37, Alan White said:

@mikeDnight as always your reports / recollections have me hooked.
I am between yourself. @F15Rules and others moving towards a binoviewer with my very fine ED103s Vixen.

One question on the pseudo Masuyama's, were any made with rubber eye guards at all?
It is something that I 'need' to be present on an eyepiece.

Hi Alan,

I'm not sure if they all came with winged eye guards initially. I've bought all mine second hand with the exception of the 35mm Eudiascopic, and some had the original eye guard. The Eudiascopic came with a winged eye guard from new. I also bought a 20mm and 5mm Orion Ultima from Keiron at SCS a few years ago and they too had the rubber eye guards.

It wasn't long ago i saw eye guards on sale but can't remember which vendor had them in stock. They are easily attainable if you really need them.

Edited by mikeDnight
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Hi Mike,

Yes, I too have a pair of Revelation binoviewers, the later model with compression ring/helical focusing eyepiece holders (I sold my wonderful Celestron/Baader 45 degree angled bv's last year as part of my slimming down exercise).

I really like the Revelations, although I've had very limited use so far due to the lousy weather. I have cheap pairs of 15mm and 30mm plossls and in daylight the other day I tried using a pair of 1.6x nosepieces (attached to the filter thread of each ep) just to see if the magnification increase works ok when using the pair.

Using our nearby church tower as a target (about 80-100m away), I could get focus ok, with c 4 or 5mm in-focus to spare. Interestingly, the point of sharp focus seemed hardly different whether using the eps natively, or with the 1.6x nosepieces in place..?? 

Whether I can get sharp focus natively at infinity, ie on the night sky, I hope to find out tonight. I will also try the 1.6x nosepiece threaded into the nosepiece of the binoviewer, which I think will give 3 or 4 times native magnification (is that right?)..that would be the equivalent of c 3.75mm eyepieces, or c 277x - that's about my limit when viewing in Cyclops mode, so will be interesting to see if my floaters are less severe in that situation.

Thanks for all the very useful and interesting feedback, I hope to iron this all out before long now!:confused2::confused:😁

Dave

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1 hour ago, F15Rules said:

I will also try the 1.6x nosepiece threaded into the nosepiece of the binoviewer, which I think will give 3 or 4 times native magnification (is that right?)

My Meade 140 2x Barlow nosepiece yields 2.4x natively in the original housing, 1.6x screwed in to an eyepiece, and 3.0x screwed onto the nose of my Arcturus (Revelation) binoviewer.  Your 1.6x nosepiece might be similar.  On the nose of the binoviewer, I have plenty of focus travel left even in my Dob's low profile focuser.  If you use your 30mm eyepieces, you'll get the equivalent of 10mm eyepieces, which is good for planetary and lunar observing in my experience.

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