Quote:The lighter appearance in the outer edge may be due to vignetting. Look down the tube from the objective end. Move your eye off-axis to the edge of the lens and see if the exit pupil you see stays round, meaning it is fully illuminated. On most binoculars it doesn't.
Quote:I recently picked up the 20x60 PCF WPII's used off AM. When I got them they appeared to be out of alignment or collimation. The field's were not merging evenly without some serious effort from my eyes. They also appeared to lose contrast in the outer 10% of the field. In a dark sky the outer 10% had a noticably lighter - almost cloudy look. My guess was that if the 2 fields were not merging I was losing aperture in the area that was limited to one objective. Well, it turns out that Pentax has a no-fault warrantee on these bino's & they didn't even care that I was not the original owner. I sent them in and got them back yesterday. Pretty good service (other than the binos being shipped back to me in a paper thin box 3x the size of the binos with about 6 packing peanuts total- no joke). The alignment is much better now as the 2 fields appear merged. The ojects are sharp almost to the edge - but I still have that lighter appearance in the outer 10% of the field.Does anyone no what is causing this? Has anyone experiences a similar effect? Any suggestions would be appreciated.
Milton Wilcox R.I.P
Quote:He dismissed the possibility of the prisms being undercut due to the tight tolarances of the automated manufacturing equipment used. Also, the fact that the collimation had just been done and should be spot on should eliminate that as a potential cause.
MarkLeica 8x20; Nikon Action 7x35; Vixen Apex Pro 8x42; Orion 15x63; Docter Nobilem 15x60WO Megrez II 80 FD / APM 107mm f/6.5 / Mewlon 210 on DM-6 + Berlebach Planet
AS of NSW
AS of Hunter Valley
Fact: I like reflectors and big ones. All the refractors I own are either finderscopes, binoculars, or riflescopes.
18"/F4.5 Obsession #1333 fully optioned (OMI Optics)
14"/F4.5 SDM #33 fully optioned (Zambuto Optics)
10"/F5.3 SDM #50 fully optioned (Suchting Optics)
Pentax XW's, T4 & T5 Naglers , UO HD orthos, 6mm Delos, 8mm Radian, 8.5mm Pentax XF, 13mm Ethos. 12mm Celestron Illum Astrometric eyepiece. Rainbow Optics Spectroscopic Eyepiece Set. Orion Optics UK 250 lpi Ronchi grating eyepiece. 2" Astronomiks UHC, OIII & H-Beta filters, 2" DGM Optics NPB filter. 2" Variable Polariser. 2" Hoya colour filters.
Leupold 10x42 & Pentax 16x60 binos.
Pentax PF-80ED,Meade 102ED APO,Orion EON 72,120ST Apex 127,C6 XLT,C6R,C9.25,XT10 ,Celestron Regal 100 F-ED, CT152 Zeiss 7x42 FL,Canon 10x42L IS WP,15x50 IS 12x36 IS II , Pentax 8x32 ED Garrett Optical 28x110 HD-WP Signature Series Oberwerk BT-80 45, Apogee RA-88-SA Denk II Power x Switch binoviewer w/13mm Ethos, 20mm Pentax XW's, 20mm Widescan III's. 21mm Ethos,17mm Ethos, 22mm Nagler, 40mm Pentax XW, 14mm Pentax XL, 5.2mm Pentax XL, 8-24mm Pentax XL Zoom, 31mm Axiom LX
Quote:To minimise errors, I keep the caliper square on and next to the eyepiece lens, took ten measurements at various angles of the exit pupil for each eyepiece, discard the two extreme readings, and average out the result. The 20x80's exit pupil is measured at 4.0mm, while the Pentax 20x60's exit pupil is measured at 3.4mm! Can anyone help to explain that?
Shouldn't the exit pupil be measured at the eye relief distance from the eye lens, not next to it? I believe the cross-section through the light cone will be larger next to the lens.
Binoculars: Miyauchi Saturn III - 33/39/50/71/150x100, WO 22x70ED, Fujinon 16x70 FMT-SX Pentax 10x50 PCF-V, 10x43 DCF-SP, 6.5x21 Papilio
Nikon 10x35 EII, 7x35 E, 8x30 EII, 8x23CF AS Diplomat
B&L 7x26 Custom
Scopes: C9.25, TMB130SS/FT, SV80S-LOMO 80/480
Quote:I've never seen the exit pupil appear larger at the surface of the lens. However, if projecting the exit pupil on to a piece of paper, it can be seen to vary in size.edz
Quote:Jeff,earlier you described a brighter ring around the outer edges of the field of view. Vignetting would result in a darker ring around the outer edges.edz