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Old Monday 21st August 2017, 21:57   #101
kabsetz
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David,

I don't know what to make of it, but the Juelich astro shop in Germany is listing a small selection of astro eyepieces from Baader etc. on their Harpia accessories list, alongside the Harpia eyepiece. This could be a mistake, of course, but would be a rather odd one for a well-established specialist store to make. I'm more inclined to take it as meaning that such eyepieces can be attached to the scope, especially as they list the magnifications that the ep. would give on the Harpia.

However, what I heard from a friend who attended Birdfair and saw the Harpia, though perhaps inconclusive, seemed to offer more weight to the idea that the Harpia zoom vignettes the exit pupil. This would compromise resolution at all magnifications except for the maximum of the zoom range, and relatively speaking more so if one were to use shorter focal length eyepieces with a higher starting magnification. 40x57.5 mm does not sound all that impressive and will not look impressive either, and if the vignetting is linear, then all the middle magnifications would be affected as well.

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Old Monday 21st August 2017, 22:28   #102
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Troub, nice cliff-hanger...

I did some calculus and found that the Harpia will have a 42m FOV/1000m at 43.5x magnification. Most scopes with good zoom EP:s have around 40-42m FOV at 25x mag.. I suspect the Harpia will be a very nice scope for sea watching, if the max aperture is not affected too much by the construction...1 stop is not visible in good light I guess, but in dusk and dim light it might affect things.

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Old Monday 21st August 2017, 22:41   #103
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David,

I don't know what to make of it, but the Juelich astro shop in Germany is listing a small selection of astro eyepieces from Baader etc. on their Harpia accessories list, alongside the Harpia eyepiece. This could be a mistake, of course, but would be a rather odd one for a well-established specialist store to make. I'm more inclined to take it as meaning that such eyepieces can be attached to the scope, especially as they list the magnifications that the ep. would give on the Harpia.

...
Kimmo
Hi Kimmo,

Should be an error since they list also the Diascope eps for the Harpia (Zooms included). Even on the Gavia they list the zooms of the Diascope...
If the astro eps will reach focus, the Baader Morpheus are good options for eye-glass users since have good quality image and are 76. However vignetting probably will be visible for eps higher than 7.5mm, even if there will be no aperture issue.
I don't see any commercial reason for Zeiss not produce an astro-adapter or don't make possible for astro eps to reach focus on the Harpia since this is an selling argument and they can sell only Harpia scopes with their ep included...
They can also produce astro-adapters for astro use of their Harpia ep - they have astro-fans. However, these should be better than those produced for the Diascope eps - Baader produce better ones and less expensive...
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Old Monday 21st August 2017, 23:05   #104
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Or 120 degrees. (Post 100).

I don't like more than 92 degrees.
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Old Tuesday 22nd August 2017, 08:43   #105
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Question

When I first tried the Gavia last year I was rather disappointed with the very shallow depth of field. Just by a touch of movement of the focusing wheel I lost sharpness and the subject. Has it changed with the Harpia?
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Old Tuesday 22nd August 2017, 09:32   #106
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When I first tried the Gavia last year I was rather disappointed with the very shallow depth of field. Just by a touch of movement of the focusing wheel I lost sharpness and the subject. Has it changed with the Harpia?
The focus wheel of the Harpia is according to specs and videos of dual-speed type, so at small movements you get fine focus, and with more turning it's faster geared. (there's a video with Jerry Dobbler from Zeiss explaining it in the thread)

But would be nice to hear about how it works in practice from those who actually tried the scope.
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Old Tuesday 22nd August 2017, 11:08   #107
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Hi,

Quote:
Originally Posted by Vespobuteo View Post
But would be nice to hear about how it works in practice from those who actually tried the scope.
I didn't try the Harpia, but the Diascopes use a two-speed single-knob focuser as well.

It just will switch from slow to fast after having been turned for a while, regardless of you're already close to focus or not. There's no way to engage fast focusing in the moment when you really need it, and no way to keep the scope from engaging fast focusing when you only need a quarter turn more to be in focus, if you've twirled the knob the hardware-determined number of turns before that.

It doesn't provide the immediate response you get from using the fast focusing knob on a dual-knob system, and it will often interfere with focusing if you'd need x+1/4 turns at slow speed to get into focus, but the fast speed kicks in after x turns.

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Old Tuesday 22nd August 2017, 14:20   #108
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Thanks Lee.

I'm not also a fanatic of edge sharpness - I prefer an AFOV of 72, with the out 12 not perfectly sharp, to an AFOV of 60 with the edge totally sharp, but it seems shouldn't be bad. However edge sharpness is very important for digiscopy as well as the aperture issue - the Swaro X are very good for digiscopy. By the way what scope do you use?
I am a general nature observer not a dedicated birder so I have an old Diascope 65 with two focusing knobs which I use mainly for observing Otters in the Western Isles of Scotland.

If the edges of your digi pics are not sharp enough, crop them off. You will probably do this anyway to make the centre image larger.

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Old Tuesday 22nd August 2017, 14:27   #109
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Originally Posted by Vespobuteo View Post
The focus wheel of the Harpia is according to specs and videos of dual-speed type, so at small movements you get fine focus, and with more turning it's faster geared. (there's a video with Jerry Dobbler from Zeiss explaining it in the thread)

But would be nice to hear about how it works in practice from those who actually tried the scope.
See Henning's description which is correct. But I just didn't find this a problem although I can understand why it can sound like one. The zoom ring and the focus ring are next to each other but of different sizes and have very different resistances to overcome so you always know which you are turning. I just didn't have a problem in arriving quickly at a perfect focus and I have always been in love with my old Diascope because of its two separate knobs for fast and slow focusing. This system on Harpia worked fine for me and I was rather skeptical at first.

Lee
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Old Tuesday 22nd August 2017, 14:33   #110
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See Henning's description which is correct. But I just didn't find this a problem although I can understand why it can sound like one. The zoom ring and the focus ring are next to each other but of different sizes and have very different resistances to overcome so you always know which you are turning. I just didn't have a problem in arriving quickly at a perfect focus and I have always been in love with my old Diascope because of its two separate knobs for fast and slow focusing. This system on Harpia worked fine for me and I was rather skeptical at first.

Lee
I've birded with the scope during a test week and didn't find it a problem either. I found it quick and easy to find the right focus and finetuning it. Didn't have the opportunity to compare alongside any of the competitors, but sharpness, clarity and the impression field of view through the entire zoom range gave a very good impression.
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Old Tuesday 22nd August 2017, 23:16   #111
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It would be interesting to know what standard Zeiss used for the stated 72...
Looks to me like the AFOV spec is actually measured. If you convert the FOV specs to degrees and multiply by the magnification the result for the AFOV is about 78. If the ISO method is used the result is about 68. A measured 72 would indicate either a moderate amount of pincushion distortion or some kind of compound mustache distortion.

The question of the Harpia's clear aperture at low magnifications has pointed up the differences between the way camera lenses and telescopes are specified. Just for fun I calculated what the specifications of the kit zoom lens on my Nikon DSLR would be if it were converted to a telescope by adding a 5.5mm eyepiece to the back. As a camera lens it's a 18mm-55mm (f/3.5-f/5.6) lens. Specified as a telescope in the same way Zeiss has done the Harpia it would be a 3.3-10x9.8mm telescope. But, the exit pupil at 3.3x would be only 1.57mm instead of the expected 2.97mm, giving it a clear aperture of only about 5.1mm at that magnification.

Henry

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Old Saturday 26th August 2017, 07:50   #112
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I had a first look at the Harpia 95 and did some experiments with exit pupil sizes at different zoom settings. The method I used was to center a spot of light in the field of view, and then use a variable width rectangular obstruction centrally in front of the objective, looking for the widest obstruction that would still let me see the full field of view, i.e. the central spot. If the obstruction was any wider, a vertical shadow would appear in the center of the image, widening as the obstruction would be widened. If the obstruction is narrowed from this limit width, the image becomes progressively brighter.

Results were rather interesting. Firstly, they support the notion that the zoom vignettes at low magnification zoom settings. Secondly, the vignetting is not linear by any means, but much more pronounced at low magnifications.

Here's the list:

Zoom setting 1x, magnification 23x: clear aperture > 55 mm.

Zoom setting 1.25x, mag. 29x: clear aperture ca. 70 mm.

Zoom setting 1.5x, mag. 35x: clear aperture ca. 80 mm.

Zoom setting 1.75x, mag. 40x: clear aperture ca. 90 mm.

Zoom setting 3.0x, mag. 70x: clear aperture ca. 93 mm.

Zeiss exit pupil specifications are given only for the end magnifications, and assuming correct and exact figures for both exit pupil and magnification, yield 57.5 mm clear aperture at 23x (1x zoom) and 93.8 mm clear aperture at 70x (3.0x zoom).

These clear apertures mean that if fitted with an eyepiece that would give, say, a range from 30-90x, the scope would be a 30x57, but at 37.5x it would already be 70 mm scope and at 45 x an 80 mm scope, which does not sound too bad at all. At any magnification above about 1.75x base magnification, it is near enough to its nominal 95 mm aperture that the difference hardly matters much.

I'll write more later.

Kimmo
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Old Saturday 26th August 2017, 10:49   #113
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Thanks Kimmo.

Are you saying that with a 40x to 120x zoom the aperture would be 57mm at 40x?
Would a Barlow work?

Are you also confirming that the clear maximum aperture is 93.8mm as I thought a 95mm filter thread would indicate?
Is this further slightly reduced with off axis rays, which would only be perhaps 0.5 degrees off axis near maximum magnification.

With my 123mm f/5 telescope 16x using a 3 inch fitting Kodak large eyepiece the exit pupil is larger than my eye now has, so the aperture is reduced but the 4.7 degree field is very useful. At medium and high powers up to 145x normally, the full aperture is used. Although 210x is possible I don't use it.

There are many cases with larger astro telescopes that very low powers reduce aperture but give usefully wide fields for finding things. I point out the reduced aperture to users so they can use magnifications giving full aperture when needed.

I have been using Japanese monocular converter 10mm eyepieces on large lenses including zooms for about 40 years. But the field is about 55 degrees.
I have used other eyepieces as well, but the image is inverted, which is O.K. for testing.

P.S.
I remember that the 600mm f/5 Tewe and some large Astro Berlin photographic lenses were particularly good visually as scopes. Almost of astro quality.
I have used a Sigma 300 f/2.8 lens visually, but I can't recall the quality.
I have also used large T.V. zooms but again cannot remember the quality. One was an Angenieux.

The Den Oude Delft military mirror lens about 140mm aperture was fully up to astro quality. The view of Saturn was magnificent.
The Sigma 500mm f/4 mirror lens is poor visually.
Nikon 500mm f/5 mirror lens was good visually.

Last edited by Binastro : Saturday 26th August 2017 at 21:31. Reason: Removed sentence re zoom eyepiece.
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Old Saturday 26th August 2017, 19:43   #114
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Good work, Kimmo.

I think that settles the question of whether the aperture is variable, no thanks to Zeiss.

Are you able to star-test at different magnifications? I'm curious about the aberrations through the zoom range. Normally a telescope with a focal ratio close to f/3 would be terrible, but who knows in this case as it appears to be done by using some kind of variable focal reducer on an f/5.5 telescope. My guess is that the scope will be subject to the usual aberrations of any 95mm f/5.5 scope at 70x, but I have no idea what the lower magnifications, with both reduced apertures and very low effective focal ratios, will look like.

Using your aperture measurements (and the known 7.48mm focal length of the eyepiece) we can now plot the effective focal lengths and focal ratios at different magnifications.

93mm@70x - FL=523mm, f/5.6
90mm@40x - FL=299mm, f/3.32
80mm@35x - FL=262mm, f/3.27
70mm@29x - FL=217mm, f/3.09
57.5mm@23x - FL=174mm, f/3.02

Looking at it this way there is a rapid drop to alarmingly low effective focal ratios over the higher magnifications exactly because the aperture is dropping so slowly.

Henry

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Old Tuesday 29th August 2017, 21:34   #115
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Quote:
Originally Posted by kabsetz View Post
...
These clear apertures mean that if fitted with an eyepiece that would give, say, a range from 30-90x, the scope would be a 30x57, but at 37.5x it would already be 70 mm scope and at 45 x an 80 mm scope, which does not sound too bad at all. At any magnification above about 1.75x base magnification, it is near enough to its nominal 95 mm aperture that the difference hardly matters much.

I'll write more later.

Kimmo
As you are continuing to torture us with your lack of additional writing... , I remembered to verify what ep would result on the magnifications you want. For high eye-relief with >70 AFOV there is the TV Delos 6 (29-87x, 72) and the Baader Morpheus 6.5 (27-80x, 76). That assuming that astro eps can be used - hope you can verify that also...
In my case I would prefer one of my 5 mm (35-105x) or 4.5mm (39-116x)...
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Old Tuesday 29th August 2017, 21:42   #116
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Zeiss Harpia 95 - Making of

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Old Wednesday 30th August 2017, 08:23   #117
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David,

I have heard from a source I trust that astro eyepieces would work on the Harpia and that an adapter for them will be available. I have no idea how many or which astro ep's would reach infinity focus.

Visual image quality on the pre-production samples I saw was fine. At 70x, I could resolve the same pattern as with a good to excellent sample of the ATX 95 set at 70x. Eye relief seemed shorter, and with the field of view so wide, seeing all of it at once was a bit challenging. These are first impressions, though, without me having had much time to adapt and get used to the scope.

Focus action was very light and the two-speed focus worked fine. It would take a little bit of getting used to before it became second nature to overshoot the right amount for getting the fine focus quickly, but I'm sure that in a few days I'd have it down and like it quite a lot. Zoom ring was quite stiff, rather similar to that of the ATX. The zoom is not marked by magnification but by zoom ratio: 1, 1.5, 2, 2.5 and 3, with lines marking quarters between the halves and full integers.

Lense hood moves rather loosely on the ones I tried, and armoring feels much thinner than on the Swaros. With this scope, I'd probably want to use the neoprene S.O.C. which I'm fine without on the ATX.

Kimmo
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Old Tuesday 5th September 2017, 15:31   #118
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Looking at the specs of the new Harpia, the field of view at 22x on the 85mm is 63m (unless I'm reading it wrong). This is wider by 3m than the fixed 20x eyepiece of the Swaro STS 80. How is this possible with a zoom? Fascinated to know how Zeiss have achieved this.
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Old Tuesday 5th September 2017, 16:49   #119
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Looking at the specs of the new Harpia, the field of view at 22x on the 85mm is 63m (unless I'm reading it wrong). This is wider by 3m than the fixed 20x eyepiece of the Swaro STS 80. How is this possible with a zoom? Fascinated to know how Zeiss have achieved this.
Hi,

further up in this thread there is some info on the design.
Basically we don't have the usual configuration of a fixed focal length objective and a zoom EP (which has a limited true field of view at the low mag end due to a fixed field stop diameter) but what is basically a zoom objective and a fixed and fairy wide angle EP.

This has the implication that the exit pupil at the low mag end of the zoom range is smaller than expected (<2.5mm) - basically the objective is stopped down there.

For astro use this would be a non-optimal solution, for daylight use this seems to be a sensible tradeoff to me since the pupil of the eye will also be around 2mm in bright daylight. At dusk, the usual procedure to lower magnification in order to get a bigger exit pupil and thus a brighter image is limited a bit.

I can't wait to get to see the scope myself!

Joachim
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Old Wednesday 6th September 2017, 15:13   #120
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Thanks Joachim.

I'd like to check out the new scope too!
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Old Wednesday 6th September 2017, 17:21   #121
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Hello to all,
the longer version of this video clip was already available for a short period of time only. Here is a shorter video version in which Gerald Dobler explains the new HARPIA design philosophy very briefly:

https://www.facebook.com/ZEISSBirdin...8035033659917/

Thanks
Michael
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Old Friday 8th September 2017, 09:51   #122
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Tried the new Harpia shortly at Falsterbo Bird Show and I wasn't impressed. I was not able to get a sharp or nearly sharp focus at highest magnificaton, no matter how hard I tried. Hope it was a faulty unit.
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Old Friday 8th September 2017, 10:16   #123
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Tried the new Harpia shortly at Falsterbo Bird Show and I wasn't impressed. I was not able to get a sharp or nearly sharp focus at highest magnificaton, no matter how hard I tried. Hope it was a faulty unit.
Hi,

thanks for the info - to put this in perspective, what were the conditions?

Inside or outside? Through a window? Distance? Weather conditions?

At 75x seeing could spoil the view.

TIA,

Joachim
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Old Friday 8th September 2017, 13:48   #124
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The units I tried at Bird Fair were all pin-sharp at max magnification. Since Zeiss is talking about availability next January we can take it that all the units floating around are pre-production prototypes.

Lee
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Old Friday 8th September 2017, 13:51   #125
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As always, we won't know how good these scopes are until they are carefully tested under controlled conditions. Certainly the reduced effective apertures and crazy low focal ratios make them, even more than usual, guilty until proven innocent.

I tried a little experiment to simulate how the 2.5mm exit pupil at 23x might affect image brightness by placing a removable 50mm mask over the my 90mm Takahashi Sky 90 at 20x. Flipping the mask into the light path resulted in an obviously dimmed image in all but the brightest daylight. Anyone would notice it on a cloudy day, provided a 4mm exit pupil image is available for instantaneous comparison; but without a brighter reference image, maybe not. I hope that this design doesn't take its inspiration from binoculars, where "just good enough" is the acceptable standard.

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