Newbie question: 65mm Diascope vs cheaper 80mm... (1 Viewer)

another quick question- can anyone tell me if 65-straight version is built around a porro- or roof- prism erecting system?

i am finding conflicting info; some sites indicate porro, but adorama describes "P coating on the roof reversal prism" or some such wording.

i was unable to find out anything specific on the ziess site, but will look again,

regards,
utc

Answers are here.

cheers,
Rick

Rick:

wow, that was fast!

thanks so much for the information! i have only porro scopes at the moment, but if this one is in any way kin performance wise to the 7XFL's, i should be in optic nirvana.

it will be interesting to compare the scope to the celestron 65 FED, and esp the little nikon 50.

regards and thanks again,
utc

Schmidt-Pechan roof prism is an odd choice for a straight scope. It's more expensive than Porro, offers no significant advantage in size or weight and is slightly optically inferior from more reflections and mirror coating (especially silver which Zeiss initially used and may still use in the Diascope). Unfortunately Zeiss has now been followed by Leica and Nikon. Swarovski and Kowa still use Porros.

My usual advice about checking for optical defects certainly applies to the Diascope. I've star tested about eight of them. As I recall three were outright lemons and only one was a scope I would have been happy to buy.

Henry, thanks so much, once again, for sharing your experience and expertise in these matters! Optical knockabouts like me are certainly fortunate we have "content experts", like they say in my field, that monitor the threads and are willing to take the time to pull no punches- it is, as they say, what it is. BF is such an invaluable resource... i have not read such frankness, based on actual testing, anywhere else.

i should have guessed this scope is a roofer, from the inline config i suppose. i couldn't resist a zeiss for the price, and it still may be worth what astronomics is blowing them out for. if anyone can do roof gear right it should be ziess, but i must admit after reading your comments i am tempted to just call the deal off. additionally, perusing most of the zeiss threads on BF, along with whatever else i could google up in the way of reviews and comments, it seems there is a wide divergence of opinion on the diascopes, perhaps driven, at least in part, by what you are describing as the luck of the draw. i am all for the end consumer being the final arbitrer of what is and isnt good enough, and have a fair amount of astro experience, and decent enough eyes, so a star test is not beyond my capability. after all, no one/company is perfect... but cripes, 1 out of 8 (!) you would be willing to own? shouldn't their hit rate be higher than that? i am kind of like that vaccuum cleaner chap, dyson i think, who "just think things out to work right". i certainly don't have the time or inclination to go thru that many scopes (besides the dude told me they only had 3) to find one that "works right". if the first one doesn't at least ace the celestron FED 65, back it goes and that's the end of it. astronomics has a 30 day return policy, sans a restocking fee.

the allure of owning a spotter by one of the holy trinity of sport optics is part of it. the 65 diascope is about half the weight of the CFED, with most likely a smoother focus mechanism. i am looking to fill the gap between the Nikon 82 and 50.

fortunately, i will be able to use the hyperion zoom on both the CFED and diascope, albeit not at infinity focus- i think their FL's might be nearly identical. i am going to set them up side by side, try and find a glitter point or maybe even a real star if the clouds ever part, and do an A/B comparo- i believe i will be able to return the CFED by paying a heftier restock fee. may the best scope win.

thanks again, Henry, for sharing your perspective,

regards,
UTC

UTC,

I'd offer the very same advice about any brand, no matter what the price. There's more than a slight chance of a lemon with any of them. A good Diascope will be a very fine telescope, not to mention you already own an excellent zoom eyepiece that fits it.

Henry

maybe i got a good one...

recieved the diascope 65 yesterday, and got a chance to do a bit of informal viewing- so far i am impressed with what i have seen.

the following side-by-side may not be entirely a fair test, considering the difference in price. let me say at the outset that the celestron is the best of the circa-$400 scopes i have looked at. but for me it was meaningful, because if i couldn't see enough difference to make a difference, as they say, the zeiss was going back. i did not pull out the pentax 65 ed since i have all ready determined that (my copy) is inferior to the celestron.

initial impressions out of the box were favorable, quite a bit lighter and more compact than the celestron 65, the best i have on hand as a comparison in the way of a dedicated nature scope.

coatings i would hazard to guess are state-of-the-art, with that neat magenta/maroon overall tone, just like the FL bins. even in bright ambient shade, it was all but impossible to make out the presence of a reflected face, whereas in the CFED i could almost, but probably not quite, count my eyelashes. the interior of the diascope was like a cave, w/ virtually no detail visible at all, and nary a glint surface to be found. indoors, while viewing a globe lamp out the ep end produced the same results. deep coal blackness, with but one very minor brightening at one small spot inside, nothing that comes up to the magnitude of a glint. i did note a few very small specks of dust microscoped on the the roof prism, and very fine joint lines, at the limit of visibility that i assume are part of that erecting assembly. the cfed showed fair amounts of interior detail, including threaded, sliding mechanisms and some evidence of internal reflection, but the latter does not appear widespread.

the baader hyperion, after removing the nosepiece and one retaining ring, easily screws on the exposed collar of the diascope, even allowing adjustment of the ocular so that the power indicator dot, and f/l lettering, is toward the top. neat! the hype wont reach infinity focus on the cfed, but will allow sharp views out to at least 30 feet or so. it was at once apparent that the diascope was a fair amount brighter, with better contrast and color saturation- the distinction wasnt terribly great, but noticable at first glance. it took some searching to find something in the way of a resolution test. i finally decided on some azelea blooms. the base color of the exposed flower petals were pink, but beginning about halfway from the top showed darker pink to mahogony, intricately branched spider veins running down into the center. here the zeiss definitely displayed clear, finely etched lines, and the branching was significantly easier to follow into the interior of the bloom. the cfed displayed the veins, only not as narrow or distinct, wider like, and the branching was much more difficult to follow or even discern. what i noticed with the zeiss that i do not see w/ the cfed, is that the focus "snaps" into relief, with little to no back and forthing required. i have always felt the celestron a bit lacking in this quality. speaking of focus, the dual, slightly separated knobs are quite to my liking. i thought of this as what i could cobble up as a "low contrast" test.

later i was able to take the scope out to a nearby wetland. i think the lenght and diameter of the spotter is just about ideal for a window pod! it takes up much less of the opening than my Nikon 82, so it's easier to look around and over to spot birds. the baader/zeiss combo is a very potent optical rig. starting at 24mm and going all the way to 8, i noticed very little in the way of image degradation. some darkening, but not major, and just a tad increase in lateral CA, i think as you guys refer to it. black vultures perched at an insance distance on some high line towers, at 48X (that's the hightest setting on the hyperion) showed no softening to speak of, and no glare or contast reducing stray light. head wrinkles were very distinct and separate, on from the other, and indivdual feather detail could be seen on the bird's bodies, despite being strongly backlit.

i have not had, however, a chance to do any really critical star testing yet.

i could not produce any glare, veiling or otherwise, depiste pointing the spotter a various angles as close as i dared to the setting sun, over a small pond.

there are a few of these scopes left out there, perhaps one or two at astronomics, and i note amazon has a couple, albeit at slightly higher prices. the close-outs are all straight thru, non-lotutec models. coupled w/ a hyperion for about half, or less, of what zeiss is asking for the zoom, and provided a decent copy of the scope is obtained (as mentioned above) one could wind up w/ a very serviceble rig.

i have ordered the 1 /14 ocular adaptor, and cant wait to tote the scope to our local 'scope outfit and try a Nagler 16mm T4 out w/ the Zeiss!

regards,
UTC

UTC,

Thank you for taking the time to share your comparisons between the two scopes in question. I find I share many of your feelings on the comparisons. I did a similar comparison recently between the Celestron 80 F-ED, a Zeiss Diascope 65 A and my Pentax 65 ED A. The problem I run into is that the Celestron unit that I have in my possession is not the same one that I did all of the extensive testing on in the other thread. This specimen is noticeably poorer optically. Apparent sharpness across the center of the field and especially across the entire field of view seems to be noticeably less than the previous unit. Because of this it does not perform anywhere near the level of the Zeiss Diascope. It does not even perform at the level of my Pentax 65. The difference is noticeable at the lower magnifications but it becomes more pronounced as one moves up the magnification range.

As has been noted previously the strongpoint of the Diascope appears to be its apparent sharpness and contrast. Edge performance and color representations being its two notable weaknesses. The Pentax excels at edge performance and flatness of field with the XW eyepieces. The contrast is a shade less than the Zeiss and the color representation is more neutral. I find it equally apparently sharp though. That says quite a bit in my opinion as you can still find the 65 ED body for around $400-$450 or the 65 ED 2 scope body for between $550-$600. The XW eyepiece can be found for right at $300. That would anywhere from $700-$900 for a scope that comes very close to comparing with one that retails for close to twice the cost depending on which version you choose.

On another, but related note, I did try the Pentax XW20 on the Zeiss 65 via the adapter. Centerfield performance is excellent. Low levels of CA, excellent apparent sharpness and contrast. The bad news is that the field flatness is compromised around the edges and thus greater CA is also present. The performance of the XW 20 is notably more even across the entire field with the Pentax 65 as it should be considering the Pentax spotting scope series was designed with their eyepieces in mind.

Lastly, if anyone is interested, I know of a superb specimen of the Zeiss Diascope 65 angled can be had with the Zeiss zoom (lotutec zoom, non-lotutec body) for $1100.

frank, you are quite welcome and likewise i much appreciate your observations in regards to these spotters as well. never tried the pentax with anything but hyperions, so am most likely missing the boat there.

i have always felt i managed to wind up with a subpar copy of the pentax, based on the many favorable comments here and elsewhere. in fact it was the bvd writeup that originally got me interested in the small pentax ed's. at first i was quite taken w/ the image, but eventually found a softness to the view, some ca, and that bothersome fiddly focus that really cripes me.

with other scopes, mostly astro gear, the baaders stand up very well, so unless there is something a-synergistic with the combo i can only sumise it is somthing intrinisic with the pentax. pity, because i still feel the pent is at the top of the heap though, ergonomics wise, with the best i have owned or used in the 65mm size.

i am very interested in seeing the diascope's performance with the 17 and 13mm hyperions, as they always seemed to outperform the zoom on the celestron 65.

being a sucker for wide field fixed power oculars, i am going to have to try out the pent 14XW on the front end of the diascope! heard and read a great deal of universally complimentary comments on these ep's over the years.

as posted above, it really does pay to closely test a scope, i guess ideally with chart or star as the target.

regards,
UTC

I did try one of the Hyperions on my Pentax 65 and thought it provided a very high quality image in my Pentax 65. It had slightly worse edge performance, in comparison to the XW, and slightly more CA in that outer edge of the image but the contrast, brightness and field of view seemed very comparable. Definitely worth the $115 or so that they are selling for.

I think you may have had a slightly poorer than average Pentax based on your comments as well. My unit does seem to offer very good performance at any price especially with the XWs.

Please do post your experiences with the Hyperions and the Zeiss.

The chart below used to be available at the Japanese Pentax website. It shows the field curvature and astigmatism characteristics of the XW eyepieces. The amount of astigmatism is indicated by the separation of the two lines (DS and DM) that curve away from the vertical line which represents the plane of central focus (the field center is at the bottom and the field edge at the top). The wider the separation between the DS and DM lines the greater the astigmatism. Field curvature is inferred by imagining a curved line exactly midway between the DS and DM curves. The further that imaginary line curves away from the vertical line the greater the field curvature.

The curious thing (since these were designed for general use in astronomical scopes) is that each focal length is different. Some have negative field curvature, some positive, and the amount of astigmatism varies considerably. So, nothing can really be said about the off-axis performance of the XW eyepieces as a group. Each has its own particular set of characteristics and will work better or worse depending on the telescope with which it's mated. It follows that only some of these (I don't know which) could match Pentax spotting scopes especially well.

Henry,

Thank you for the information. Definitely some good reading. I take it that your comments were in reference to what I said about the spotting scopes being designed around the eyepieces.

From my limited experience trying the XW 20 in other spotting scopes that accept 1.25 inch astro eyepieces (Promaster, Diascope and F-ED) it does seem that at least that one particular focal length is more ideally suited for the Pentax 65 specifically. I cannot say anything for the others as I only owned the 10mm and even then only briefly.

Zeiss Diascope 65 and Nikon Fieldscope 82 ED

i had a chance to have both scopes out for some additional field time saturday. targets included shorebirds, terns, scissor-taileds, belted k/fisher, cooper's hawk, loggerhead shrike, among others, and the highlight of the day's outing, a discovery channel moment watching an osprey take a catfish down to the gills, perched quite cooperatively on a telephone pole! i was able to switch out (fairly) quickly between both spotters using a windowpod. incidently, the old nikon tele-pod has finally crapped out with the clamp down mechanisms loose and wobbly, but i found what i hope to be a more robust replacement from bogen. i'm trying to switch out to a complete manfrotto system so as to have the same type quick-release plates on all my equipment.

first thing i must get out of the way is a comment, only from my perspective of course, on what has been mentioned in reference to the warm, or yellowish color cast on the zeiss. well i can say for my part, under the lighting conditions this day, it was obviously apparent, and really not all that subtle. this was surprising, as i had failed to notice the tint earlier in the week. saturday the first decent cold front of the year swung thru, and skies were evenly illuminated horizon to horizon thru a uniform layer of featureless low stratus. this had the effect of erasing all shadows. perhaps the yellowish tone is more readily seen in the absence of bright light and saturated colors, and the "neutral gray" of the landscape brought out the shift.

i scope with both eyes open, and for birds in profile against the clouds, like with the osprey, it was at once clear the scene took on more of a monochrome, yellowish/green look thru the eye that was peering into the ocular, as opposed to the one looking out at the sky. the nikon, OTOH, at the eyepiece produced a view that seemed to be closer to what the unaided eye was seeing. under such circumstances, the nikon threw up an image with more contrast, especially in a bird essentially clad in greys, whites and blacks anyway. this was also the case with the shrike. however, birds like the scissor-taileds, that often show minor variations of tone along the sides, ranging from salmon to almost yellow, displayed the shading clines nicely. it seemed to me that when the eyepiece contained fair amounts of color information the tone wash became less prominent. i can see, though, where the prospect of living long term with such a tint bias might be a deal breaker for some. .

as respects detail retrieval, i remain of the opinion that the zeiss is quite a performer though; crisp and etched. naturally, the big ol Nikon, with a 30X EP at the front end, seemed to tease out slightly more, but it was close. there IS something special about the nikon view that i cant quite quantify, though, call it "easy", "relaxing" or whatever, that i dont find in (my copy) of the zeiss. one is a roof and one is a porro, but i just wont go there.... nor will i start down the path of "digital" vs "analog looking", because that probably has no real meaning at all. but the comparison did cross my mind.

i was able to assess the hyperion fixed EP 13mm and the zoom at approximately the same image scale, and while the fixed EP had just a tad more snap, it was very close. what was apparent, however, is that the fixed was brighter, with a wider field and better uniformity of whole-field focus. like as has been mentioned in connection with the zeiss variable power, i noticed at the lowest, 24mm setting, a large ring of defocused imagery, perhaps 1/2 the AFOV or thereabouts. not seriously blurry, but there. the effect mitigated some at higher settings. another curious effect, is that at stops like 16mm, for example, objects placed on one side of the fov were less defocused (clearer) than when moved to the opposing side! i neglected to check the fixed 13mm baader for the same symmetry of abberation, so cant say if this is intrinsic to the EP, scope or both.

perhaps the diascope deserves better than the baaders, but that is going to dilute the strenght of the deal, though, esp if i have to spring for zeiss' fixed power oculars.

i also havent changed my mind as repects the focus mechanism- it is one of, if not the best, i have used. ergonomics and portability is first class. lack of stray glare, donuts and crescents, and light fog are completely absent. the same can be said of the big Nikon, but i wouldn't want to tote it for any real distance.

all in all, i am going to keep the zeiss, at least for awhile. for those interested in a spotter with european pedigree, it remains, at the closeout prices offered thru some online retailers, a very good investment, if one can cop a decent copy. for those willing or having to spring for the full (albeit discounted, of course...) retail cost, i would say to try, and then look for the color bias, firsthand, and think about the kind of birding you do, and what may be the long term satisfaction quotient here.



regards,
utc

Thanks for posting your impressions, utc. Just a few comments that occurred to me while I was reading, in no particular order.

This particular Zeiss specimen sounds like it has some problems. Even pretty mild to moderate defects and aberrations can have the effect of robbing the image of a really well focused, easy, relaxed view. The eye will tend to accept a mildly aberrated image as OK when seen in isolation, but the problem becomes obvious when you compare a scope like that to a well corrected one. A good Nikon 82ED can have very low aberrations compared to most other expensive birding scopes. What you see in the Nikon is probably just well corrected spherical aberration and the absence of defects like astigmatism and coma.

Your observation of assymetrical off-axis sharpness suggests the possibility of coma from misaligned optics in the Diascope, a common defect which can be identified with a star test. If the problem is in the eyepiece it will rotate when the eyepiece is rotated.

Believe it or not, the Baader Zoom is optically better than the Diascope allows you to see. Place the Baader on a premium astronomical APO and it's capable of showing an image superior to any birding scope.

Henry

UTC,

I would also thank you for sharing your experiences.

Something you mentioned that Henry briefly referenced was the specific performance of the Baader on the Diascope. From my own limited experiences with the Diascope I was under the impression that a good deal of the yellow "tinge" was the result of the eyepiece. I have noted the color bias with the Zeiss zoom but not at all with a fixed Celextron X-cel eyepiece I have been using with the diascope (a superb combination at the 15-16x power the scope produces.) There isn't any color bias at all with that eyepiece.

So, I am then curious why you see it with the Baader zoom. Do you have any other 1.25 inch astro eyepieces handy (assuming you picked up that astro eyepiece adapter).

thanks henry and frank for your comments.

i am going to try a star test sometime this w/end, after the skies clear, or a glimmer spot if i can find one before then. i have a 7mm burgess optical planetary ep, and a 5mm stratus, so i think i should be able to effect a high enough power for this test. i will likely have to post my findings here for others to interrupt the intra and extra focal images, but i might be able to spot something like miscollimation. i will eat the 15% restock fee and return the scope if this eval doesnt come off well. henry, is it necessary to utilize a light source w/ essentially no diameter? or can i employ something like an l.e.d., or power on indicator light from electronic equipment? that would simply matters some.

frank, yes i did get the astro adaptor, and that's what i used to affix the hyperion 13mm to the diascope; i did notice the yellow cast w/ both, but it would be interesting to try a greater variety of oculars to see if there is some cancellection of the tone depending on ocular.

regards,
utc

The color bias and the edge performance at lower powers (Zeiss zoom) are really the only two "complaints" I have seen, and would concur with, about the Diascope. I was hoping the Baader would be better in both respects.

I have a WO clone due in any day now. I will post my comments here.

looking forward to your findings on the wo clone! i dont know why it didnt occur to me beforehand to try out the baader zoom on something other than the diascope, to see if i could reproduce any of the problems i am seeing in the zeiss, as henry suggested.

well, this whole optics comparison thing really is getting kind of interesting- might be more so if it didnt run up the ol credit card bill.

anyway, despite the fact i really did have something else planned tomorrow p.m., i am going to haul out either the wo zenithstar 80mm "flourite" doublet, or the megrez 90, both of which i think are fpl 53, down to the wetland area near the house. i am seriously curious what i am going to see with the baader at the front end.

regards,
utc

FrankD said:

The color bias and the edge performance at lower powers (Zeiss zoom) are really the only two "complaints" I have seen, and would concur with, about the Diascope. I was hoping the Baader would be better in both respects.

I have a WO clone due in any day now. I will post my comments here.

Click to expand...

Frank,

The Baader is a bit better in both respects, but with a narrower apparent field at the lowest magnification so perhaps not a fair comparison.

The photo below shows the color bias of a Zeiss Diascope zoom (top) and a Baader Hyperion zoom (bottom). The background is a piece of white paper and the smaller squares are crops of the same paper phtographed through the eyepieces held up backwards in front of it. This Zeiss zoom is about five years old. Newer production could be more neutral, but even this one is actually OK to my eyes when it's placed on a scope with a neutral color bias. The most recent Diascope body I tested was about three years ago. It had the same color bias, so the eyepiece and body together had a stronger bias than either separately. On that body substituting the Baader zoom reduced the bias, but didn't eliminate it.

Henry

Very interesting Henry. Thank you for taking the time to compare the two and post the results. The difference is obvious but subtle.

The WO clone should be in on any day. I will post more on my impressions of it with the Zeiss shortly afterwards. I have run into a "problem" though. I have just been given an opportunity at a superb deal on a older style 20-60x80 Swaro HD. I need to go see it in person before I decide. I just can't justify the Zeiss and the Swaro without selling something I don't want to.