Having read through the thread I'd be interested in how you get on Sancho. It would be nice to see what mag the swaro can handle.
-
Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.
Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
High fixed-mag option for Swaro scope - advice needed (3 Viewers)
- Thread starter Sancho
- Start date
Having read through the thread I'd be interested in how you get on Sancho. It would be nice to see what mag the swaro can handle.
DRodrigues
Well-known member
Sancho you can have a look at http://www.pt-ducks.com/cr-telescopes.htm#Test of 5mm eyepieces and at http://www.pt-ducks.com/cr-telescopes.htm#Test_of_2.5x_magnifiers.
I have to include the Nagler 5mm on the test but I much prefer the XW due to the better eye-relief. If money isn't a problem, a Ethos 6mm might interest you - I'm not sure if it would reach focus due to the 1,25" adapter.
I have to include the Nagler 5mm on the test but I much prefer the XW due to the better eye-relief. If money isn't a problem, a Ethos 6mm might interest you - I'm not sure if it would reach focus due to the 1,25" adapter.
If I get round to choosing a solution, I´ll let you know!:t:
Thanks, David, that sure is a lot of Toys you have there! Incredible testing, many thanks.
Roughneck-BF
Member
You might try a TV Radian 7MM, which should give you about 77X magnification with about 20MM of eye relief before you consider the reduction caused by the adapter. It should be as wide and bright as the zoom EP at 60X, or maybe more so. The exit pupil is pretty small at that magnification, so all the problems that come with that will be present.
You need to be careful, because at higher powers you may start to see the edges of your porro prism. That's one of the reasons why they don't sell high power eyepieces for spotters (over about 60X), and also why they don't use porro prisms for telescopes. A porro prism is a relatively low power device.
The astro EPs also work as well or better to give you a wider and brighter field of view at low magnifications. I have a 32MM Televue Plossl that I use on a friend's Swarovski 65 with the astro adapter. It gives a way brighter view than the Swaro zoom lens set at 20X, with about 14.4X magnification. Every bit as good as the Swaro EP, just brighter, wider and about 20% of the cost. You can keep a whole flock of birds in focus, and it makes following their movements very easy.
You won't just change the magnification, you'll also improve the view by going to fixed power. The problem with zoom EPs is that they're a compromised design, and can never be as bright or clear as a good quality fixed power EP of the same magnifcation. Most people have never looked through anything but a zoom lens, so they think that's as good as it gets.
If you really need magnifications over 100X, you should consider a small telescope like the Televue 76. You'll have way more options than a spotter, but some trade-offs too, like size, weight, not waterproof, etc.
You need to be careful, because at higher powers you may start to see the edges of your porro prism. That's one of the reasons why they don't sell high power eyepieces for spotters (over about 60X), and also why they don't use porro prisms for telescopes. A porro prism is a relatively low power device.
The astro EPs also work as well or better to give you a wider and brighter field of view at low magnifications. I have a 32MM Televue Plossl that I use on a friend's Swarovski 65 with the astro adapter. It gives a way brighter view than the Swaro zoom lens set at 20X, with about 14.4X magnification. Every bit as good as the Swaro EP, just brighter, wider and about 20% of the cost. You can keep a whole flock of birds in focus, and it makes following their movements very easy.
You won't just change the magnification, you'll also improve the view by going to fixed power. The problem with zoom EPs is that they're a compromised design, and can never be as bright or clear as a good quality fixed power EP of the same magnifcation. Most people have never looked through anything but a zoom lens, so they think that's as good as it gets.
If you really need magnifications over 100X, you should consider a small telescope like the Televue 76. You'll have way more options than a spotter, but some trade-offs too, like size, weight, not waterproof, etc.
I tried a 10x21 binocular on my 80's eyepiece. This is not a serious thing, but here's a picture of the tip of a fir tree at 250x. Keep in mind I hand held a binocular in one hand and the camera in the other hand. What I see is of course some bad chromatic abberation. The biocular is a cheap $60 Nikon pocket job. This would work a lot better if I could put the scope at 50x and triple or double it. I did try 500x. I could see the image but it was very dark and eye floaters made it totally unuseful.
At 250x, you do see some useful detail, but probably nothing more than what you would see at 100x. The superior brightness and contrast at a lower magnification may actually reveal more. At this magnification, the exit pupil is about 0.3mm which creates serious problems in viewing with an eye. I have very sharp eyes, no trouble reading 20/15 chart at the OD, but I also get lots of floaters inside, and skin cells and other crud on my cornea. When the image circle is 0.3mm, even the tiniest spec of dust or pollen can obscure a significant part of the image. I can try to blink the pupil clear but generally I find anything under about 0.7mm exit pupil, obstructions in the eye become a problem for me. Other people have less of a problem. Tele Vue advises minimum >0.4mm.
My plan is to evaluate some eyepieces and determine whether they will reach focus first, and then determine at what focal length I no longer gain any detail. My opinion for birding with an 80mm scope, the practical limit is 75x. After that the exit pupil becomes problematic with a daylight restricted human pupil and also the field of view becomes challenging. Since my purpose in this is not birding (planetary and binary system astronomy), the failure of the exercise to be practical for birding should be noted but won't matter. I'll be trying some eyepieces of different designs from 66x up to 184x.
At 250x, you do see some useful detail, but probably nothing more than what you would see at 100x. The superior brightness and contrast at a lower magnification may actually reveal more. At this magnification, the exit pupil is about 0.3mm which creates serious problems in viewing with an eye. I have very sharp eyes, no trouble reading 20/15 chart at the OD, but I also get lots of floaters inside, and skin cells and other crud on my cornea. When the image circle is 0.3mm, even the tiniest spec of dust or pollen can obscure a significant part of the image. I can try to blink the pupil clear but generally I find anything under about 0.7mm exit pupil, obstructions in the eye become a problem for me. Other people have less of a problem. Tele Vue advises minimum >0.4mm.
My plan is to evaluate some eyepieces and determine whether they will reach focus first, and then determine at what focal length I no longer gain any detail. My opinion for birding with an 80mm scope, the practical limit is 75x. After that the exit pupil becomes problematic with a daylight restricted human pupil and also the field of view becomes challenging. Since my purpose in this is not birding (planetary and binary system astronomy), the failure of the exercise to be practical for birding should be noted but won't matter. I'll be trying some eyepieces of different designs from 66x up to 184x.
Attachments
Gentleman BF member StuartCSmith gave me a heads-up on a Swarovski astro-adapter available from Kay Optical for 40 sterling. It looks like the one in the photo posted above. I´ve ordered it, and will report back on this thread when it arrives. Sincerest thanks to Stuart!
Just got some eyepieces.... the Nagler Zoom 6-3mm won't reach infinity focus with the 80HD. It focuses about 100ft like the Pentax. The ones that work are:
TV Nagler 5mm
TV Nagler 3.5mm
TV Radian 3mm
TV Ethos 3.7mm
You might find more by looking at column F in the specs: http://www.televue.com/engine/TV3_page.asp?id=28
but the zoom is specified in a way that it should have worked if that's all we look at
So the Radian 3mm shows a lot of junk in my eye in daylight observing (dust, floaters, specks etc) The exit pupil ~0.5mm is too small for my eye when there is a light background. For astronomy it's doable, but I think I like the Nagler 3.5mm better because of the slightly larger exit pupil that makes even daylight observing doable and it gives more generous AFOV and is smaller in size. It lacks the 20mm eye relief of the Radian but I find the 12mm acceptable - glasses wearers would prefer the Radian.
For daylight views, the Nagler 5mm is certainly the best. A Radian of this focal length would be equally good with the tradeoff being physical size for eye relief.
The Ethos 3.7 is unique because it has a screw-on 2" adapter so unlike the other Ethos eyepieces with a 2" over-sleeve, it works quite well on the Swarovski. It is a bit long and heavy. I've had Ethos before so I knew what to expect from the 110 degree AFOV. It would be better if it wasn't also so high magnification for this scope. I really believe in the Ethos design idea but some of the benefits are diminished by the fact that with this focal length, the limits of the scope are really be pushed. This would be a great eyepiece for a 10" scope no doubt. In optical terms, I would love to have an Ethos 21 for this 80mm scope but in mechanical terms, it's too big and clunky.
I'll be doing some more observing (I have wind and cumulus clouds playing tricks on me). I did get to see Orion and a crescent moon. I'm hoping for Saturn later tonight.
On star testing, I've not been able to do a good job handholding the eyepiece so far but it appears like I have more contrast of the diffraction rings outside focus than I do inside focus. I don't see any change in the brightness from center out though. I don't see astigmatism or coma either.
TV Nagler 5mm
TV Nagler 3.5mm
TV Radian 3mm
TV Ethos 3.7mm
You might find more by looking at column F in the specs: http://www.televue.com/engine/TV3_page.asp?id=28
but the zoom is specified in a way that it should have worked if that's all we look at
So the Radian 3mm shows a lot of junk in my eye in daylight observing (dust, floaters, specks etc) The exit pupil ~0.5mm is too small for my eye when there is a light background. For astronomy it's doable, but I think I like the Nagler 3.5mm better because of the slightly larger exit pupil that makes even daylight observing doable and it gives more generous AFOV and is smaller in size. It lacks the 20mm eye relief of the Radian but I find the 12mm acceptable - glasses wearers would prefer the Radian.
For daylight views, the Nagler 5mm is certainly the best. A Radian of this focal length would be equally good with the tradeoff being physical size for eye relief.
The Ethos 3.7 is unique because it has a screw-on 2" adapter so unlike the other Ethos eyepieces with a 2" over-sleeve, it works quite well on the Swarovski. It is a bit long and heavy. I've had Ethos before so I knew what to expect from the 110 degree AFOV. It would be better if it wasn't also so high magnification for this scope. I really believe in the Ethos design idea but some of the benefits are diminished by the fact that with this focal length, the limits of the scope are really be pushed. This would be a great eyepiece for a 10" scope no doubt. In optical terms, I would love to have an Ethos 21 for this 80mm scope but in mechanical terms, it's too big and clunky.
I'll be doing some more observing (I have wind and cumulus clouds playing tricks on me). I did get to see Orion and a crescent moon. I'm hoping for Saturn later tonight.
On star testing, I've not been able to do a good job handholding the eyepiece so far but it appears like I have more contrast of the diffraction rings outside focus than I do inside focus. I don't see any change in the brightness from center out though. I don't see astigmatism or coma either.
John Russell
Well-known member
Interesting observations, Ben. Thanks for posting.
John
John
Kevin Purcell
Well-known member
Given the issues on other scopes (Pentax) there might not be enough back focus with the M57 to 1.25" plus Swaro astro adaptor to reach infinity focus.
But it would be worth a try.
But it would be worth a try.
DRodrigues
Well-known member
Sancho,
If you use this barlow http://www.pt-ducks.com/cr-telescopes.htm#Test_of_a_1.6x_magnifier on the Baader zoom you will get a high power zoom of good image quality that should reach focus on your telescope
If you use this barlow http://www.pt-ducks.com/cr-telescopes.htm#Test_of_a_1.6x_magnifier on the Baader zoom you will get a high power zoom of good image quality that should reach focus on your telescope
Thanks David! Just tried the Brightstar website, it´s currently unavailable. But at least now I know what to look for! :t:
stuart C smith
swansong
sancho, is that the same thing as the magni-max 1.6x sold by scopes n skies for £22.49. ? regards stuart.
Thank you once again, Stuart, that looks just the job! So now I think I´ll try the Swaro Astro-adapter, plus this Magni-Max doohickey, and an astro eyepiece, possibly the Baader Hyperion, and see what comes out of the mix. Although maybe I should try a lesser fixed-mag astro ep, because multiplied by 1.6, most of the B-H zoom range would be pretty unusable. I´ll report when all the bits come together.
Crake Dude
Well-known member
Does anyone own the old Emoskop, and would it work on eyepieces in the same way as the
Opticron booster and Zeiss 3x12 monocular? Here it is:
http://www.monocular.info/emoskope.htm
....and, you lucky folks in the USA may be still able to get the multicoated 3x version:
http://www.emoscop.com/11.htm
I think the Haverhill Episcope is similar:
http://www.submin.com/binocular/collection/seibert/episcope_haverhills.htm
What about using one side of opera glasses? I know there's no prism, but they are usually 2x or 3x mag only. Also, one quite often sees them for sale at a reasonable price. Just a thought.
Steve
Opticron booster and Zeiss 3x12 monocular? Here it is:
http://www.monocular.info/emoskope.htm
....and, you lucky folks in the USA may be still able to get the multicoated 3x version:
http://www.emoscop.com/11.htm
I think the Haverhill Episcope is similar:
http://www.submin.com/binocular/collection/seibert/episcope_haverhills.htm
What about using one side of opera glasses? I know there's no prism, but they are usually 2x or 3x mag only. Also, one quite often sees them for sale at a reasonable price. Just a thought.
Steve
Last edited:
henry link
Well-known member
Steve,
It will work in the sense that the magnification will be increased, but the AFOV will be very very tiny, probably no more than 10-15 degrees. That's because the Emoskop is a Galilean telescope (essentially one barrel of an opera glass). In a scope like that the AFOV is determined by the diameter of the objective lens which acts as the fieldstop. When placed behind the eyepiece of another scope the effective size of the objective is reduced to the exit pupil of the scope in front, so the FOV literally shrinks to the size of a soda straw.
Henry
It will work in the sense that the magnification will be increased, but the AFOV will be very very tiny, probably no more than 10-15 degrees. That's because the Emoskop is a Galilean telescope (essentially one barrel of an opera glass). In a scope like that the AFOV is determined by the diameter of the objective lens which acts as the fieldstop. When placed behind the eyepiece of another scope the effective size of the objective is reduced to the exit pupil of the scope in front, so the FOV literally shrinks to the size of a soda straw.
Henry
Crake Dude
Well-known member
Many thanks for that, Henry.
Does this mean that one should only consider a low-power, prismatic monocular for use as an eyepiece booster? Seems really strange how a 3x Galilean-type should differ in effect from a 3x prismatic-type, really weird is that.....but I do believe you!
Steve
Does this mean that one should only consider a low-power, prismatic monocular for use as an eyepiece booster? Seems really strange how a 3x Galilean-type should differ in effect from a 3x prismatic-type, really weird is that.....but I do believe you!
Steve
henry link
Well-known member
Steve,
Galilean telescopes use a negative lens placed in front of the objective's focal plane as an "eyepiece". When you look through the eye lens you see a blurry image of the objective lens with the magnified focused image of the object space beyond confined within the fuzzy circle formed by the edge of the objective. In that case the bigger the objective lens the larger the AFOV. In Keplerian scopes like prismatic monoculars the eyepiece is placed behind the objective lens focal plane where it magnifies the aerial image that forms at the focal plane. In that case the AFOV is limited by the eyepiece fieldstop and is completely independent of the objective lens size.
Henry
Galilean telescopes use a negative lens placed in front of the objective's focal plane as an "eyepiece". When you look through the eye lens you see a blurry image of the objective lens with the magnified focused image of the object space beyond confined within the fuzzy circle formed by the edge of the objective. In that case the bigger the objective lens the larger the AFOV. In Keplerian scopes like prismatic monoculars the eyepiece is placed behind the objective lens focal plane where it magnifies the aerial image that forms at the focal plane. In that case the AFOV is limited by the eyepiece fieldstop and is completely independent of the objective lens size.
Henry
DRodrigues
Well-known member
Benm, did you did further tests with the TV eyepieces?
Did you tried a Ethos 6mm?
Did you tried a Ethos 6mm?
