Denkmeier Binoviewer Special Offer (closed)
Not that one should avoid that forum. When I read that forum, I can see the obvious bias, but one should also read objectively with that info, and sometimes read between the lines.If one wants to read objective reviews on binoviewers, don't go to the CN binoviewer forum. A lot of "D" cheerleaders there...
This is a 2" binoviewer that cost USD $2300+shipping after you add in the necessary "options", but you must wait at least one year upon ordering. This is excellent if you want to use an expensive pair of 2" 70 deg AFOV 40mm premium eyepieces to get a low-power wide-field view. But for many experienced observers, the best detailed views of deepsky objects are at medium power using 18-25mm eyepieces and this is already well served by 1.25" binoviewers. When I use a binoviewer, the object apparently appeared bigger than seen through one eyepiece of the binoviewer, and the AFOV also increases, ie, a 60 deg EP appears like a 70 deg EP. Hence I don't need the low wide field view through a 2" binoviewer, though the view would be really nice. I think the dielectric mirror system should be fine, though secondary to other considerations.Wow, this is tempting...
what is holding me back is the Siebert Black Knight Elite 40 2" Binoviewer. ( This is my impossible dream Binoviewer - dielectric mirror base)
Last edited by rlow on Thu Aug 24, 2006 9:28 pm, edited 2 times in total.
Also, 2" binoviewer is not for everyone, as you must have enough Inter-Pupillary Distance (IPD) to be able to merge one image through two nos. of 2" fat eyepieces. For example, my IPD is 63mm and I am able to merge one image using a pair of Pentax 20XW. This is a fat eyepiece similar in diameter to 2" eyepieces. Some poeple are not able to use a pair of Pentax 20XW, if their IPD is 60mm and below.
i do feel that 2" binoviewers are not realistic. interpupilary distance is definately gonan be a problem. no fun spending so much on a binoviewer, matching scope and a pair of nagler 31, only to find out that u cannot merge the image.
also, even if u can merge the images, u either have a secondary of 40% or larger, or u enjoy using ur scope at reduced aperture, or u enjoy sticking in that 2" barlow that works at maybe 8x or 10x.
i personally feel that a pair of denk with 19mm panos on a matching scope would serve the purpose better. say maybe a custom made 10" f/5 premium dob, with shorten tubes and maybe slightly oversize diagonal, outfitted with argo navis dsc and maybe a bluetooth pda. or maybe one of those sexy 15" zambutos outfitted with a paracorr.
the debate between denk and those burgess/wo/sv binoviewers, i can't comment too much abt quality. the burgess ones i tried out some time back seem to be very well built, optically i dun see any flaws, but that is at pretty low power, which i feel would be the way most would be using it.
however, one should note the clear aperture between the denks and the burgess version is different. there would be some slight vignetting on the burgess with eyepieces over 23mm, 50 degrees fov. or say maybe 16-17mm 65 degrees fov. whereas the denk would take a pair of 19mm pano happily, which i feel many would love to.
whichever one u buy, most importantly would be matching ur scope and eyepieces. just be happy at the end of the day. i have a feeling rlow would be very happy with this purchase, esp with blueprints for the ultimate visual scope in his safe.
~MooEy~
also, even if u can merge the images, u either have a secondary of 40% or larger, or u enjoy using ur scope at reduced aperture, or u enjoy sticking in that 2" barlow that works at maybe 8x or 10x.
i personally feel that a pair of denk with 19mm panos on a matching scope would serve the purpose better. say maybe a custom made 10" f/5 premium dob, with shorten tubes and maybe slightly oversize diagonal, outfitted with argo navis dsc and maybe a bluetooth pda. or maybe one of those sexy 15" zambutos outfitted with a paracorr.
the debate between denk and those burgess/wo/sv binoviewers, i can't comment too much abt quality. the burgess ones i tried out some time back seem to be very well built, optically i dun see any flaws, but that is at pretty low power, which i feel would be the way most would be using it.
however, one should note the clear aperture between the denks and the burgess version is different. there would be some slight vignetting on the burgess with eyepieces over 23mm, 50 degrees fov. or say maybe 16-17mm 65 degrees fov. whereas the denk would take a pair of 19mm pano happily, which i feel many would love to.
whichever one u buy, most importantly would be matching ur scope and eyepieces. just be happy at the end of the day. i have a feeling rlow would be very happy with this purchase, esp with blueprints for the ultimate visual scope in his safe.
~MooEy~
some additional notes
it's true that surface accuracy of a diagonal is not that much of a concern, since it's flat and also due to the fact that it's very near to the focal point. even with a large error, the most it would only cause astigmatism at the eyepiece.
howver, the acurracy of the surface is much more impt in a binoviewer than in a normal diagonal, since in this case, ur binoviewer is much more "inside" the light path than a normal diagonal whereby it's located nearer to focus. how much of a difference it would make, i can't really tell.
scd is another point. i noticed that the burgess version comes with 3 nylon screws for u to center the eyepiece. at one point i wonder, which is more impt, the accurate collimation of the prism inside the diagonal? or the centering of the eyepiece? would not centering the eyepiece actually make a problem. have not seen anyone complaining abt it, i would like to hear some opinions.
~MooEy~
it's true that surface accuracy of a diagonal is not that much of a concern, since it's flat and also due to the fact that it's very near to the focal point. even with a large error, the most it would only cause astigmatism at the eyepiece.
howver, the acurracy of the surface is much more impt in a binoviewer than in a normal diagonal, since in this case, ur binoviewer is much more "inside" the light path than a normal diagonal whereby it's located nearer to focus. how much of a difference it would make, i can't really tell.
scd is another point. i noticed that the burgess version comes with 3 nylon screws for u to center the eyepiece. at one point i wonder, which is more impt, the accurate collimation of the prism inside the diagonal? or the centering of the eyepiece? would not centering the eyepiece actually make a problem. have not seen anyone complaining abt it, i would like to hear some opinions.
~MooEy~
I see 2" binoviewer as more of a luxury, not a necessity, as I have explained earlier. Nagler 31T4 is out, unless your mount & focuser can take 2kg worth of eyepieces! You probably can't accomodate your IPD on a pair of N31T4 anyway! Don't even mention the Meade UWA 30mm 5000 series!i do feel that 2" binoviewers are not realistic. interpupilary distance is definately gonan be a problem. no fun spending so much on a binoviewer, matching scope and a pair of nagler 31, only to find out that u cannot merge the image.
I see the following distinctive advantages for any of the Denkmeier Package:the debate between denk and those burgess/wo/sv binoviewers
1. Self-Centering Dioptre for sharper image,
2. 26mm clear aperture for widest-fieldstop EPs and better light throughput,
3. 1.2x OCS in 2" format for lowest power on any fast scope,
4. 2-arm PowerSwitch (PxS) for convenient switching of magnification,
5. PxS gives focal reducer mode for SCTs
6. PxS plus OCS gives coma correction on Newtonians,
7. 'universal package' for the flexibility to use on any scope (refractor, newtonian, SCT),
8. in-house USA manufacturing/quality control (not China OEM),
9. excellent customer service from Russ.
10. Denk also has a Warranty, Return Policy and Repair/Maintenance/Re-collimation Service.
I believe the surface accuracy for diagonal is important, as there is no point having dielectric coatings with 99% reflectivity if the mirror surface does not have a good polished finish that causes light scattering. Otherwise why would TV, AP, WO etc needlessly make 1/10th wave diagonals? Why would some premium dobs matched a CZ mirror with a premium quartz diagonal?it's true that surface accuracy of a diagonal is not that much of a concern, since it's flat and also due to the fact that it's very near to the focal point.
Last edited by rlow on Thu Aug 31, 2006 9:58 pm, edited 4 times in total.
To get the best sharp abberration-free image, you don't want to compromise the optical train, by optically aligning everything properly. The best way is to collimate your scope with the binoviewer in place. This is especially important for high-powered planetary binoviewing.scd is another point. i noticed that the burgess version comes with 3 nylon screws for u to center the eyepiece. at one point i wonder, which is more impt, the accurate collimation of the prism inside the diagonal? or the centering of the eyepiece? would not centering the eyepiece actually make a problem. have not seen anyone complaining abt it, i would like to hear some opinions.
Self-centering holders are easier to maintain collimation when you switch eyepieces. They also ensure both eyepieces are optically centred at the same time, as opposed to 3-screws holders which have a possibility for off-centering one eyepiece against the other.