TMB Aspheric Ortho 25mm


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Brand and Model:TMB Aspheric Ortho 25mm
Price ($USD):295
Type:Orthoscopic
Focal Length:25 mm
Barrel Size:1.25
Apparent FOV:55.0 degrees
Field Stop Dia.:24.0 mm
Eye Relief:20 mm
Elements:0
Weight (lbs):
Description:

Vote Highlights Vote
TMB Aspheric Ortho 25mm
I purchased this eyepiece to supplement my TMB 175 f/8 APO refractor. Even though the focal length of this e.p. is not too different from my Panoptic 27 , I wished to obtain an eyepiece with fewer optical elements and higher light transmission by virtue of fewer elements and air/glass surfaces. I really did not know what to expect in performance. My favorite items for viewing are globular clusters , bright nearby galaxies , and double stars.

My first trial of this eyepiece (56x in my TMB) was very encouraging ; I was able to clearly resolve M8 , M22 , and M13 into a fine dust of individual pinpoint stars! I was expecting to need a Barlow on M13 , but it really gave me an awesome view of the cluster. Very bright and contrasty against an almost velvet black. As a comparison , I tried my Televue Panoptic 27 on the same objects. I found M8 and M22 resolved , and M13 as a grainy disk verging on resolution. Score one for the TMB aspheric ortho.

I also tested the TMB on Rasalgethi (alpha-Herculis) , an approximately 4" seperation double. To my amazement , I saw a TINY dot of light almost touching the primary. Not touching , not a figure 8 , but clearly split! I ususlly need my Nagler 12 T4 to split this double (117X). Score 2 for the TMB.

I finally tried a look at M33 in Triangulum ; the skies were not really great for galaxy hunting that night , but the view that I was able to obtain in the TMB Aspheric Ortho was the best of the 3 ep's I used that night ( Panoptic 35 , and Panoptic 27). II was able to clearly see NGC 604 , an emmission nebula in the galaxy.This is an outstanding eyepiece.

Technical data: Field stop: 24 mm ; Tube diameter 1.25 " ; Focal length : 25 mm ; FOV : 55 degrees : Eye relief : 20 mm.

Overall Rating: 10
Optics:10 Value:9
Weight: 5 (Veritable Vote)
Date:
By: rodgerraubach
Link to this vote: http://excelsis.com/1.0/displayvote.php?voteid=405595

>I also tested the TMB on Rasalgethi (alpha-Herculis) , an approximately 4" seperation double. To my amazement , I saw a TINY dot of light almost touching the primary. Not touching , not a figure 8 , but clearly split! I ususlly need my Nagler 12 T4 to split this double (117X). Score 2 for the TMB.
>

There must be something wrong with your 7-inch TMB APO if it usually needs a power of 117x to cleanly split a wide double of 4 arcseconds, such as Ras Algethi. Please check again and take high-end orthos, but not Naglers. In my 6-inch f/9 Meade ED APO, Ras algethi is cleanly split at 55x and 76x using Kasai Ortho 25mm and Baader Genuine Ortho 18mm (same as UO HD Ortho), respectively.

Regards, Cord
cord.naujokat@med.uni-heidelberg.de
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