A Brief Review of the Zeiss Harpia 95 (1 Viewer)

[Torview]

I forgot to add, I found eye placement a bit finicky in order to avoid blackouts, and a need to refocus every time after changing zoom power.

 

[Troubador]

I got to try a Harpia 95 today out in the field in bright conditions, the owner kindly let me look through it.

The biggest wow is clearly the fov, which is impressive, excellent contrast and colour neutrality, the resolution I felt should have been better given the price.

I don`t quite know how I feel about it, the exit pupil was very small at all powers, noticeably so at low power and to me the brightness suffers as a result here, so I`m not sure it will be the best choice on a dull, dark Winter day scanning at its lowest power.

I`d need to spend a lot of time behind one in Winter before I`d take the plunge given the price.

John

The EP gets gradually restricted below 40x mag. Above this mag it uses the full 95mm objective and has a normal EP.

Lee

 

[Torview]

Hi Lee,

Trouble for me is this seems like it's the world's most expensive 50mm scope at 23x !

John.

 

[Vespobuteo]

Hi Lee,

Trouble for me is this seems like it's the world's most expensive 50mm scope at 23x !

John.

I think it's more like 57mm, also your eye pupil will stop down any scope to about that size in daylight.


But, expensive yes, even at 70x mag...

A reasonable edge sharpness and CA control at 23x with that large FOV would probably not be possible without stopping down the scope a bit.

Personally I don't see much visible difference in brightness in most "normal" light conditions between a good 65mm and 80mm+ scope at 25x-30x.

But as you say, in dim late autumn/early winter light the Harpia might not be the optimal scope.

 

[Hauksen]

Hi John,

Trouble for me is this seems like it's the world's most expensive 50mm scope at 23x

Interesting perspective. However, isn't the field of view of the Harpia still larger than that of typical 50 mm scopes at the Harpia's smallest magnification?

I tried to put this into perspective in another thread:

As a Kowa 883 owner, my reference of course is the 25x magnification of the TSN-11WZ, and not the 30x quoted by Dobler. Still, my scope is listed with a 42 m/1000 m field of view at 25x, which is very markedly narrower than the 58.8 m/1000 m listed for the Harpia at 23x. The Harpia also beats the 52 m/1000 m of my Nikon ED50 at 13x, which I always considered a really nice wide field of view.

Regards,

Henning

 

[Troubador]

Hi Lee,

Trouble for me is this seems like it's the world's most expensive 50mm scope at 23x !

John.

LOL! I think Vespobuteo explains this well.

Lee

 

[Torview]

I`m not really looking for a new scope purchase right now, but I`m trying to square £3.5k for a 95mm objective that shrinks to below 60mm at low power.

 

[Troubador]

your eye pupil will stop down any scope to about that size in daylight.

Its a balance of capabilities John and which may not meet your personal needs.

At 2.5mm the EP is similar in size to your pupil in normal daylight and its no coincidence that at this size the human eye is at its most effective with regard to detail. And as Vespo pointed out in normal daylight your pupils will be this size no matter what scope you are using. If you need a scope for late evening this may not be the scope for you.

Lee

 

[Torview]

Its a balance of capabilities John and which may not meet your personal needs.

At 2.5mm the EP is similar in size to your pupil in normal daylight and its no coincidence that at this size the human eye is at its most effective with regard to detail. And as Vespo pointed out in normal daylight your pupils will be this size no matter what scope you are using. If you need a scope for late evening this may not be the scope for you.

Lee

That`s very true but how many of us use this proposal to choose a binocular with a 2.5mm exit pupil for our Birding needs ?, 8x20 sf anyone ?

 

[Troubador]

That`s very true but how many of us use this proposal to choose a binocular with a 2.5mm exit pupil for our Birding needs ?, 8x20 sf anyone ?

Also true but binos don't offer the zoom of a scope and the full 95mm is available from 40x mag upwards. Meanwhile at lower magnifications there is a super-wide field of view.

And scope users are used to small exit pupils of 1.5mm or less at high magnifications. Its a balance of capabilities and clearly this balance doesn't appeal to you. I hope to borrow a test unit from Zeiss soon so I will be able to find out if it appeals to me or not.

Lee

 

[Torview]

Lee,

I would`nt say the balance of capabilities doesn`t appeal to me, its clearly an interesting design, and I only have a first impression to go on, Ohweh has just posted a comparative review and clearly enjoyed the Zeiss more with greater familiarity.

I myself am used to a very small ep on my ats65 at 60x, but I use my scope far more at 20-30x and however good the Zeiss is at high power, not getting the full benefit of that huge objective at 23x would definitely annoy me.

John.

 

[Troubador]

Lee,

I would`nt say the balance of capabilities doesn`t appeal to me, its clearly an interesting design, and I only have a first impression to go on, Ohweh has just posted a comparative review and clearly enjoyed the Zeiss more with greater familiarity.

I myself am used to a very small ep on my ats65 at 60x, but I use my scope far more at 20-30x and however good the Zeiss is at high power, not getting the full benefit of that huge objective at 23x would definitely annoy me.

John.

I can certainly understand that especially if you bird a lot in the evenings.

Lee

 

[range]

I’ve drawn a line chart depicting the relation of mag. and aperture.

http://bbs.imufu.cn/data/attachment/forum/201811/08/001713w1uxneheuvwvw9ut.png

 

[OhWeh]

From where did you get the points?

 

[henry link]

Hopefully "range" will come along to answer, but I notice that his chart appears to track the points from this post by Kimmo Absetz.

https://www.birdforum.net/showpost.php?p=3607800&postcount=112

 

[OhWeh]

Thanks Henry!

One remark: full 95mm are not really possible. The screw-in size for lens hood/filter is 95mm, so the effective diameter of the front lens must be minimal smaller.

For me, this is an advantage, see my review.

 

[barry lowe]

Last week I had an opportunity to briefly examine a just purchased 95mm Zeiss Harpia. The last time I reviewed a scope (the Zeiss Gavia) I found two days was insufficient for a complete review. This time I had about one hour. The design of the Harpia is so unusual that testing it really demands even more time and energy than a conventional scope. For instance, usually a single star test and a single resolution measurement at high magnification are all that’s needed. That’s not true for the Harpia because the objective’s configuration, focal ratio and aperture change with magnification, so it can be reasonably assumed that aberrations and resolution will not remain constant over its entire magnification range. Unfortunately, I didn’t have enough time or enough control over the test conditions to make the multiple tests at different magnifications needed for this scope, so the results here are barely more than suggestive of areas that need closer examination.

I used the flashlight method to measure clear aperture. That confirmed that the aperture remains constant from 70x down to about 40x (my measurement for the largest clear aperture was about 93mm rather than 95mm). At magnifications below 40x the aperture appears to shrink in a linear fashion until it reaches something between 55 and 60mm at 23x. I can’t be more specific because my test method resulted in the internal obstruction that causes the loss of aperture below 40x to cast a fuzzy shadow rather than a sharp one on my ruler.

Very bad (Hurricane Florence) weather made outdoor testing impossible, so I was only able to star test the scope indoors at about 10m and rather than measuring its resolving power I could only roughly compare its resolution and sharpness at 70x and 40x to a 92mm Astro-physics Stowaway APO (with Baader Hyperion Zoom) using a USAF 1951 glass slide at about 7m. At those distances I expect any scope properly corrected for infinity focus to be somewhat under-corrected, so my experience can only really be applied with much confidence to the Harpia’s close focus performance.

In a 70x star test at 10m I found the Harpia’s spherical and chromatic aberrations to be clearly worse than the reference scope. The Stowaway shows an essentially textbook perfect star test at infinity and is slightly under-corrected at the 10m distance of this test. The Harpia did much better at 10m than the Gavia I tried last year, but it still showed considerable asymmetry between the intra-focal and extra-focal diffraction patterns, with hard rings and an overly bright outer ring outside focus and soft rings with an overly bright central spot inside focus. There was a narrow red fringe of longitudinal chromatic aberration around the focused test star that was pretty minor by spotting scope standards, but still indicated less than true APO performance. There was also some mysterious spiking around the entire periphery of the intra-focal diffraction disk, which resembled the appearance of surface roughness in a star test of a mirror. Other potential defects like coma, pinching, astigmatism and roof edge anomalies were very low or absent. However, unlike “normal” scopes the Harpia’s star test appears to deteriorate as magnification is reduced. Evaluating star tests accurately becomes more difficult at lower magnifications, so I didn’t even attempt it at magnifications below about 40x. The one change I was sure I could see was the gradual development of some astigmatism in this particular Harpia unit as magnification was reduced from 70x to 40x. I’m sure this wasn’t related to my eyesight because astigmatism was completely absent at all magnifications in the Stowaway set up next to the Harpia. This suggests to me that the aberrations and optical defects of the Harpia are indeed not constant with magnification and could grow worse as the optical configuration changes from about f/5.6 at 70x to f/3.2 at 40x.

Using a USAF 1951 glass slide I found the image quality of the Harpia to be a bit soft and gauzy at 70x compared to the Stowaway, with a loss of at least one Element of resolution on the chart. Unfortunately I couldn’t quantify the resolution because I didn’t have a way to measure the exact distance to the chart and besides 70x is a little low for my eyesight acuity to reliably detect the Stowaway’s true resolution. But, since I know the Stowaway’s resolution as about 1.25” using the USAF 1951 I can say that this particular Harpia was no better than 1.40”, probably not quite that good. That was no big surprise given the higher star test aberrations, but unlike every other telescope I’ve seen the Harpia didn’t appear to sharpen up as the magnification was reduced. The image appeared to be no sharper, perhaps even slightly less sharp at 40x, than at 70x. Since the Stowaway follows the usual pattern of appearing sharper as magnification is decreased that made the difference in image quality between the two scopes starker at 40x than at 70x.

Visual comparison to a reference scope of known quality is better than no reference, at all but it still mostly falls into the realm of subjective impressions. I couldn’t do any better than that at 40x because in the time available I couldn’t find a way to firmly attach my 3x Zeiss Tripler to the Harpia eyepiece. The booster would have allowed testing the Harpia’s 40x magnification at 120x, plenty high enough to measure the true resolution and properly evaluate the star test. In the end I suspected from the subjective appearance of the 40x image that higher aberrations at 40x probably degrade the actual instrument resolution at 40x compared to 70x even though the aperture is unchanged. That wouldn’t be a surprise given the f/3.2 effective focal ratio at 40x, but without real measurements I couldn’t confirm it.

One last thing I noticed was that the Harpia’s image was dimmer than the Stowaway’s at all magnifications but particularly, as you might expect, at the lowest power. The Harpia’s actual light transmission was almost certainly lower than the Stowaway’s since, as configured for this test, the Stowaway had only 10 glass to air surfaces and one dielectric mirror reflection vs. the Harpia’s 32 glass to air surfaces and 4 internal prism reflections. But, the increasing difference in image brightness between the two as magnification fell below 40x clearly resulted from the Harpia’s shrinking aperture. The window light I was using was approximately equal to what would frequently be experienced outside on a dark overcast day. Under those lighting conditions the reduced exit pupil of the Harpia at lower magnifications is a definite disadvantage compared to conventional scopes.

That’s pretty much all I could gather from my hour with the Harpia. If I ever get another crack at one on my own turf I would certainly want to star test and measure the clear aperture and resolution over the entire magnification range by placing my 3x booster behind the eyepiece. That’s unlikely to happen with this unit since the owner is not local, so for now I’ll be happy to turn things over to my few colleagues here who are inclined to do the same kind of testing.

Henry Link

 

[barry lowe]

hi
\i need to contact zeiss regarding attaching my camera to the scope
please advise

 

[barry lowe]

Hopefully "range" will come along to answer, but I notice that his chart appears to track the points from this post by Kimmo Absetz.

New scope from Zeiss...

thanks henry. My question really relates to the base of the scope. I can't attach my camera to the base