Would it be possible to use two doublers to make a kind of bino-scope!?
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Biggest eyepiece ocular lens - is there bigger than swarovski SLC 8x56 ? (1 Viewer)
- Thread starter kimmik
- Start date
Thotmosis
Well-known member
Besides the alignment issue it's also quite expensive to have two doublers i guess, so better to buy a dedicated high magnification bino.
Everybody should have at least one 15x binocular
kimmik
Well-known member
So I tried piggy backing the 7x21 onto the swarosaur 8x56.
It works as far as getting an image and seeing more resolution, but it is awkward and unrewarding lol. The contrast dropped significantly though I couldn’t figure out why, and the exit pupil is too small to be practical.
Can say though - central resolution on slc is excellent!
It works as far as getting an image and seeing more resolution, but it is awkward and unrewarding lol. The contrast dropped significantly though I couldn’t figure out why, and the exit pupil is too small to be practical.
Can say though - central resolution on slc is excellent!
Tried it on the SLC 7x50s and whilst it worked, it was awkward to use with a very narrow FoV and degraded the image too much for me to enjoy. One is fine as an emergency short scope, but I'd much rather use my SLC 15x56's.
PeterPS
Well-Known Member
Here is a pic of the older SLC 8x56 with 2 doublers, a bit too long for my taste but it might work on a tripod as a 16x56.
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John A Roberts
Well-known member
Doublers?
While the convenience of a doubler appears to be attractive for JIC (just in case) use,
it’s long seemed to me that it's 'too much of a good thing' even for that.
With a doubler, a 6x binocular (and how common is that?) becomes a 12x monocular. So at the least it requires a very steady hold
- or preferably resting it on some sort of support - for anything other than the quickest of looks at something.
At least as significant for improvised use (verses from a tripod), is the reduction of the size of the exit pupil.
The diameter of the EP is reduced to half - so the area of the EP is reduced to one quarter!
Even if we start with a binocular with a larger than usual EP:
• an 8x56 becomes a 16x56, with the EP diameter reducing from 7 to 3.5 mm, and;
• a 7x42 becomes a 14x42, reducing from 6 to 3 mm.
So with the later, likely OK for improvised use.
However, with something far more common like an 8x42, the EP diameter reduces from a generous 5.25, to a likely marginal 2.6 mm
- with only 3/4 the area of a 3 mm EP.
And an 8x32 reduces to 2 mm - with less than half the area of a 3 mm EP.
Also significantly:
So usually a loose, loose, loose situation.
- - - -
Swarovski once offered a 2x booster for both the original SLC series (except the x30’s) and the original EL series,
see: How to make 2x Booster compatible with current SLC 15x56
Jan also describes an easy way to adapt the booster to other binoculars. And as I indicated, they’re reasonably common on second hand sales sites,
and are usually in very good condition consistent with little use.
And for a report on one in use, on an original SLC 15x56, see Roger at: Swaro Booster Review
- - - -
A lower power 1.5x magnifier would seem to actually offer more for occasional use.
For example:
• the commonly used 8x42 becomes a 12x42, and;
• the less common 10x50 becomes a 15x50 (and kimmik’s 8x56 becomes a 12x56).
So resulting in both a more useable exit pupil, and less magnification of various optical limitations.
Which is in effect what Leica does with their Duovid 8+12x42 and 10+15x50 models.
See at: Duovid Optical Construction
(And what Leupold did less well with their 1.7x Gold Ring 7/12x32 and 10/17x42 models.
See: Leupold Golden Ring Switch Power 7/12x32 vs. Golden Ring HD 8x32
and: Leupold Switch Power review (10/17x42) )
. . . So although necessarily a niche product, would a less ambitious 1.5x booster be of more use?
John
Some eye candy. The Leica dual power models, and the Leupold x32 model:
While the convenience of a doubler appears to be attractive for JIC (just in case) use,
it’s long seemed to me that it's 'too much of a good thing' even for that.
With a doubler, a 6x binocular (and how common is that?) becomes a 12x monocular. So at the least it requires a very steady hold
- or preferably resting it on some sort of support - for anything other than the quickest of looks at something.
At least as significant for improvised use (verses from a tripod), is the reduction of the size of the exit pupil.
The diameter of the EP is reduced to half - so the area of the EP is reduced to one quarter!
Even if we start with a binocular with a larger than usual EP:
• an 8x56 becomes a 16x56, with the EP diameter reducing from 7 to 3.5 mm, and;
• a 7x42 becomes a 14x42, reducing from 6 to 3 mm.
So with the later, likely OK for improvised use.
However, with something far more common like an 8x42, the EP diameter reduces from a generous 5.25, to a likely marginal 2.6 mm
- with only 3/4 the area of a 3 mm EP.
And an 8x32 reduces to 2 mm - with less than half the area of a 3 mm EP.
Also significantly:
So usually a loose, loose, loose situation.
- - - -
Swarovski once offered a 2x booster for both the original SLC series (except the x30’s) and the original EL series,
see: How to make 2x Booster compatible with current SLC 15x56
Jan also describes an easy way to adapt the booster to other binoculars. And as I indicated, they’re reasonably common on second hand sales sites,
and are usually in very good condition consistent with little use.
And for a report on one in use, on an original SLC 15x56, see Roger at: Swaro Booster Review
- - - -
A lower power 1.5x magnifier would seem to actually offer more for occasional use.
For example:
• the commonly used 8x42 becomes a 12x42, and;
• the less common 10x50 becomes a 15x50 (and kimmik’s 8x56 becomes a 12x56).
So resulting in both a more useable exit pupil, and less magnification of various optical limitations.
Which is in effect what Leica does with their Duovid 8+12x42 and 10+15x50 models.
See at: Duovid Optical Construction
(And what Leupold did less well with their 1.7x Gold Ring 7/12x32 and 10/17x42 models.
See: Leupold Golden Ring Switch Power 7/12x32 vs. Golden Ring HD 8x32
and: Leupold Switch Power review (10/17x42) )
. . . So although necessarily a niche product, would a less ambitious 1.5x booster be of more use?
John
Some eye candy. The Leica dual power models, and the Leupold x32 model:
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kimmik
Well-known member
A few thoughts after a week of 8x56:
1. I’m use to hearing “wasted exit pupil” as a reason for buying small size - this is a myth. Big EP has far more benefit than just low light observing. In fact the reverse is true if you want daytime viewing comfort with no blackouts. Portability is the only negative.
2. As Henry Link has previously analysed for the Zeiss 8x56, big EP lets your anatomical pupil to “stop down” the binocular, sharpening up the view considerably.
3. The longer length of 56mm vs 42mm bino adds stability, and this is clear when going from my 28mm and progressively to 56mm, even though all are 8x.
4. I like the record level eye-relief. Longer ER reduces fogging and keeps the ocular lens cleaner for me.
1. I’m use to hearing “wasted exit pupil” as a reason for buying small size - this is a myth. Big EP has far more benefit than just low light observing. In fact the reverse is true if you want daytime viewing comfort with no blackouts. Portability is the only negative.
2. As Henry Link has previously analysed for the Zeiss 8x56, big EP lets your anatomical pupil to “stop down” the binocular, sharpening up the view considerably.
3. The longer length of 56mm vs 42mm bino adds stability, and this is clear when going from my 28mm and progressively to 56mm, even though all are 8x.
4. I like the record level eye-relief. Longer ER reduces fogging and keeps the ocular lens cleaner for me.
Hmm. Interesting.
My 20x80 Celestron Japanese binocular was hand selected and is good optically.
There was a hotel 11 miles away and I tried to read the name, but not a hope with my eyesight.
So I put the binocular on top of a thick telephone catalogue, and put half of a good 7x binocular behind one side of the 20x80.
I could easily read the hotel name.
All this talk of 2mm exit pupils being too small.
I had no trouble at all with a 0.6mm exit pupil, nor did I with 0.3mm exit pupils using one eye using telescopes.
Using two eyes with a binocular, I have no trouble using 1.5mm exit pupils.
Regards,
B.
My 20x80 Celestron Japanese binocular was hand selected and is good optically.
There was a hotel 11 miles away and I tried to read the name, but not a hope with my eyesight.
So I put the binocular on top of a thick telephone catalogue, and put half of a good 7x binocular behind one side of the 20x80.
I could easily read the hotel name.
All this talk of 2mm exit pupils being too small.
I had no trouble at all with a 0.6mm exit pupil, nor did I with 0.3mm exit pupils using one eye using telescopes.
Using two eyes with a binocular, I have no trouble using 1.5mm exit pupils.
Regards,
B.
kimmik
Well-known member
Probably comes down to purpose.
Maximising detail in a static object, eg observing a planet, distant signage, can be best achieved with small EP high magnification. Best done on a physical support.
Handheld walkabout looking around and chasing wildlife - hmm.
I also enjoy my ED refractor telescope with its variety of exit pupils.
John A Roberts
Well-known member
Hi B (post #30),
I don’t think that we’re really disagreeing. As kimmik indicates, circumstances may vary . . .
Telescope are used with small exit pupils and high magnification all the time, off suitably solid tripod/ head combinations.
And likewise at home indoors one can improvise a similarly solid rest e.g. what was the phone book resting on?
But the amount of stability that someone can quickly arrange outdoors, is not necessarily going to be anywhere near the same.
It’s likely to vary with things such as:
• is there something available to improvise as a rest?;
• if so, is it vertical or horizontal?;
• if horizontal is at a comfortable height?;
• is it completely motionless?;
• does it allow a perfectly solid connection without the bino/ booster combination being held?;
• if the combo does needs to be held, does it teeter?; and if so how much?;
• even if it doesn’t teeter, are vibrations from holding it disturbing the image? and if so how much?;
• so how comfortable can the user get behind the combo?
In such circumstances a significantly larger EP might be a practical necessity?
John
I don’t think that we’re really disagreeing. As kimmik indicates, circumstances may vary . . .
Telescope are used with small exit pupils and high magnification all the time, off suitably solid tripod/ head combinations.
And likewise at home indoors one can improvise a similarly solid rest e.g. what was the phone book resting on?
But the amount of stability that someone can quickly arrange outdoors, is not necessarily going to be anywhere near the same.
It’s likely to vary with things such as:
• is there something available to improvise as a rest?;
• if so, is it vertical or horizontal?;
• if horizontal is at a comfortable height?;
• is it completely motionless?;
• does it allow a perfectly solid connection without the bino/ booster combination being held?;
• if the combo does needs to be held, does it teeter?; and if so how much?;
• even if it doesn’t teeter, are vibrations from holding it disturbing the image? and if so how much?;
• so how comfortable can the user get behind the combo?
In such circumstances a significantly larger EP might be a practical necessity?
John
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The phone book was on the window ledge.
I have often used my car roof as a stable platform.
Also fences, but these are not very stable.
And trees. Again not very stable.
A friend's shoulder. Not very stable.
On my back in a field for star observations.
What is surprising is the very wide variability of large binocular optics.
I have two Pentax 20x60 binoculars, maybe Chinese, both rubbish. One new, one secondhand messed with by the previous owner.
The Pentax 16x60 is better, but not great.
Celestron Japanese 20x80 best of three. Very good.
I drove to Park cameras, Burgess Hill who had 3 Japanese 30x80s for sale at £50 each.
They let me take them out to the park in front of their premises.
I used a tree and bought the best.
In fact I don't use it as the eye relief is too small even for me.
The 25-135x80 Japanese binocular is aligned at all magnifications. Runs out of steam at 80x.
Has to be on a tripod.
30x50 Yukon. Very good. 6.5 arcsecond double stars split.
Steiner 15x77 Good.
Soviet 20x60 specially made for Jim Hysom. Excellent. Used daily for 15 years.
I have had about 8 standard 20x60s. Some are O.K. some poor.
Hensoldt 16x56 superb quality.
I value 1.5x teleconverters for several camera mounts.
I use these with eyepieces to evaluate optics.
I also have various 2x teleconverters and a few 2x to 3x teleconverters, as well as dedicated 2x specially matched to lenses.
What surprises me is that sometimes cherry optics binoculars are found, yet the testers let them go.
They should try their best to buy and keep them, as cherries don't grow on trees.
Regards,
B.
I have often used my car roof as a stable platform.
Also fences, but these are not very stable.
And trees. Again not very stable.
A friend's shoulder. Not very stable.
On my back in a field for star observations.
What is surprising is the very wide variability of large binocular optics.
I have two Pentax 20x60 binoculars, maybe Chinese, both rubbish. One new, one secondhand messed with by the previous owner.
The Pentax 16x60 is better, but not great.
Celestron Japanese 20x80 best of three. Very good.
I drove to Park cameras, Burgess Hill who had 3 Japanese 30x80s for sale at £50 each.
They let me take them out to the park in front of their premises.
I used a tree and bought the best.
In fact I don't use it as the eye relief is too small even for me.
The 25-135x80 Japanese binocular is aligned at all magnifications. Runs out of steam at 80x.
Has to be on a tripod.
30x50 Yukon. Very good. 6.5 arcsecond double stars split.
Steiner 15x77 Good.
Soviet 20x60 specially made for Jim Hysom. Excellent. Used daily for 15 years.
I have had about 8 standard 20x60s. Some are O.K. some poor.
Hensoldt 16x56 superb quality.
I value 1.5x teleconverters for several camera mounts.
I use these with eyepieces to evaluate optics.
I also have various 2x teleconverters and a few 2x to 3x teleconverters, as well as dedicated 2x specially matched to lenses.
What surprises me is that sometimes cherry optics binoculars are found, yet the testers let them go.
They should try their best to buy and keep them, as cherries don't grow on trees.
Regards,
B.
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Yes, Made in Japan.
It is possible these 1970s and 1980s Japanese 80mm binoculars used high quality objectives from one or two makers.
Then used by a few makers to build the binoculars.
There were cottage industries in Japan making telescope eyepieces.
The circle T mark were highly regarded and apparently made by one optician for about 50 years or so.
However, I suspect some of the best of these orthos contain thorium glass.
B.
It is possible these 1970s and 1980s Japanese 80mm binoculars used high quality objectives from one or two makers.
Then used by a few makers to build the binoculars.
There were cottage industries in Japan making telescope eyepieces.
The circle T mark were highly regarded and apparently made by one optician for about 50 years or so.
However, I suspect some of the best of these orthos contain thorium glass.
B.
William Lewis
Wishing birdwatching paid the bills.
Sorry to put a slight tangent in this thread but as a few had commented on the use of doublers here I though it may have well versed participants already watching it.
I'd like to test the resolution of some of the binoculars I have, I know the usaf chart is mostly used as a target so that's ok.
My question is one of economy, I already have a camera with a 600mm optical Leica (zooom) lens, if I test this independently to see what aberrations it throws up and take them into account if there are any significant ones could I use this as a replacement for a doubler - I don't really want to have to spend out on one.
Also as I suppose the camera will be used at some point maybe not using a doubler as well wouldn't present too many additional problems.
I know 600mm is effectively 12x magnification, 400mm is 8x so 200mm should be 4x and 100mm 2x. I believe the correct sum for getting the magnification of a 35mm camera lens is focal length divided by 50.
Any thought greatly appreciated.
Will
I'd like to test the resolution of some of the binoculars I have, I know the usaf chart is mostly used as a target so that's ok.
My question is one of economy, I already have a camera with a 600mm optical Leica (zooom) lens, if I test this independently to see what aberrations it throws up and take them into account if there are any significant ones could I use this as a replacement for a doubler - I don't really want to have to spend out on one.
Also as I suppose the camera will be used at some point maybe not using a doubler as well wouldn't present too many additional problems.
I know 600mm is effectively 12x magnification, 400mm is 8x so 200mm should be 4x and 100mm 2x. I believe the correct sum for getting the magnification of a 35mm camera lens is focal length divided by 50.
Any thought greatly appreciated.
Will
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henry link
Well-known member
Hi Will,
You already have something better to use for this purpose than a doubler. Any of your other binoculars can be used to boost the magnification of the binocular you want to test. For instance, I often use an 8x binocular behind the eyepiece of another 8x binocular to boost the magnification to 64x for resolution measurements. Of course you'll need a second tripod and some patience to get the binoculars properly aligned. Doubling or even tripling the magnification of a good 8x42 is not sufficient for a person with 20/20 vision to see the smallest line pairs on the USAF chart that the binocular is capable of resolving.
Henry
You already have something better to use for this purpose than a doubler. Any of your other binoculars can be used to boost the magnification of the binocular you want to test. For instance, I often use an 8x binocular behind the eyepiece of another 8x binocular to boost the magnification to 64x for resolution measurements. Of course you'll need a second tripod and some patience to get the binoculars properly aligned. Doubling or even tripling the magnification of a good 8x42 is not sufficient for a person with 20/20 vision to see the smallest line pairs on the USAF chart that the binocular is capable of resolving.
Henry
William Lewis
Wishing birdwatching paid the bills.
Thanks Henry. Greatly appreciated, i have access to a couple of tripods so I'll give that a go and let you know how I get on. 👌
ragin-cajun
Well-known member
56s are heavy but what a view... I call 'em the light monsters.
