44 cm f3.4
July 2016
The idea started when I thought of a large deepsky telescope that would fit in one piece in my Renault kangoo van. Jilles Eindhoven in Buurse had a 45 cm 34 mm thick pyrex disk that was excavated to around f4 .
So I had to excavate it further.
I use a 15 cm diameter steel ring with a 3 kg weight on it ,C80 powder and a straight stroke over the center. Now and then a W-stroke to prevent too much deviation from the sphere.
Sagitta meter works over 340 mm . Sagitta is now 4.05 mm and has to be around 5 mm
60 min : sag = 4.25 mm
T= 200 min : sag =4.55 mm
Now I am going to use a 9 cm steel weight (and the 15 cm steel ring( with 10 kg of extra weight) to excavate further.The 9 cm weight makes a deeper curve.
August 9, 2016
After 335 min : S= 5.05 mm
Time to make a plaster tool.
The tool is ready in september and I glued ceramic tiles to it with polyurethane glue .
The tiles were 19x19x 2 mm
Sept 19
TOT with large tile tool , C80 and ¼ straight stroke and narrow W-stroke
Not all the tiles were ground after 45 min (easy to find out with the help of waterproof ink on the tiles).
Sag = 4.95 mm over 340 mm
After 75 min all tiles ground.
C180
TOT ¼-1/5 Straight stroke and narrow W-stroke
Total time : 340 min ( all large pits gone; I check that with a loupe and a strong backlight)
Oct 20
C320
60 min
C400
Total time : 180 min
C800
One wet : 4 turns per charge
total time : 120 min
9 micron Microgrit
Method:
1. 1 teaspoon of powder on the mirror .
2. Spray water and smear out
3. 5-6 min of grinding
4. After 10 min I squirt extra new suspension on the mirror and go on grinding
After 30 min this process is repeated with a new charge of dry powder.
Total time : 3 hours
5 micron Microgrit
This is added as a suspension while the tool is still on the mirror at the end of the 9 micron grinding.
Total time : 30 min
POLISHING
I started with an old 35 cm f4.3 pitchalp that I had used to polish a 35 cm mirror.
Th pitchlap was thickened with fresh pitch on top.
Pitch squares 4 cm.
W-stroke TOT 5 cm overhang
It is not going well during the first hour.Polishing goes jerky.
Warm pressing helps
After 15 h 40 min the reflection test with the laser pointer shows a weak reflection in the edge area. I find out that polishing with the more expensive Ceri Hex goes better than with the stuff from MTN
24 hrs: central reflection not visible; edge very weak
30 hrs : edge reflection invisible in the dark
CORRECTION
I made a full size pitchlap on a thick plywood base ( 54 mm) with 2 hardboard disks of 3 mm each on it. In that way the pitchlayer is not too uneven.
To start with,I made a 10-zone Coudermask to keep an eye on the figure.
Also I made a 20 cm correction pitchlap.
Pitch : 26,5 deg from Stathis kafalis in Munchen.I added some linseed oil to soften the pitch.
May 5, 2017
Ronchitest of polished mirror: straight lines that bend sharply inward in the outer zones
( < F)
Foucault: diff ring at the right a bit brighter than left
Step 1
a. 45 cm lap TOT 1/5 straight stroke 2x 15 min
b. 5 min pressing 10 kg
c. TOT 1/5 str stroke 1/5
d 30 min lying with no weight
e. TOT 15 min str stroke
Test : Ronchi : lines more straight; outer zones turned less.
Fouc: zone 10-9-8 : 0.47-0.26-0 There is correction in the outer zones
Step 2
a. Warm pressing and cold pressing
b. TOT 45 cm tool 1/5 str stroke and narrow W-stroke 10 min
c. 3 min cold press 10 kg
d. 45 cm lap TOT 1/5 str stroke and narrow W 10 min
e. Cold press 3 kg 25 min
f. 45 cm TOT 1/5 str stroke and narrow W 10 min
g. Cold press 10 kg 4 min
h. 45 cm TOT 1/5 str stroke and narrow W 10 min.
Ronchi : spherical with turned up edge ??
Fouc: diff ring now lighter on the left( was the other way around after the polishing!)
Step 3 temp 17 deg
Time to start excavating to the parabola. Ceri Hex polishing powder.
I use a 15 cm pitchlap that I work in on a 25 cm f3.3 mirror that has been polished out
( not yet corrected). Pitch squares are 30 mm wide and tapered in the edge area.
15 cm + 3kg weight on top of the lap:
– Straight stroke 1 cm left of center and 2 cm overhang : 4 turns
– Str stroke 3-4 cm left of C 4-5 cm overhang : 4 turns
– During the strokes I walk around the polishing stand; cold press of the lap every 6-7 min
I repeat this session 8 times
Ronchi: regular bending out of the lines
Fouc 11 zone mask made! : 1 – 6 – 11 : 0 – 0.3 – 0.9
I use the tester in the slitless way over a 3 mm hole.
Step 4
15 cm pitchlap + 3 kg weight:
4 turns str stroke 1 cm from C and 2 cm overhang
4 turns 3-4 cm from C and 5 cm overhang
This session 10 times ; frequent cold press
Ronchi: lines expanded more
Fouc 7 zone Couder mask:
Zone readings parabola R= 2967 mm
1 0 0
2 0.26 1.13
3 0.63 2.25
4 0.69 3.37
5 1.13 4.45
6 1.10 5.57
7 1.36 6.69
Step 5
Repeat of step 4
Zone readings parabola
1 0 0
2 0.57 1.13
3 1.07 2.25
4 1.36 3.37
5 1.59 4.45
6 1.84 5.57
7 2.07 6.69
Step 6 temp = 20.5 deg
Same work as in step 4
Ronchi : lines are bending out inside focus. A slight kink is appearing at 50 %
Fouc:
Zone readings parabola
1 0 0
2 0.66 1.13
3 1.58 2.25
4 1.94 3.37
5 2.20 4.45
6 2.56 5.57
7 2.88 6.69
Step 7 temp = 21-22 deg
Correction has to go a bit more to the outer zones:
a. 15 cm tool str stroke 0-1 cm from C; no overhang 3 turns
b. Id 3-4 cm from C ;5 cm overhang 5 turns
This session 10 times
c. Smoothing with W-stroke with 15 cm lap (tapered) 5 cm overhang 4 turns
Ronchi: lines not regularly bending. Looks like a flat part from 40-80%
Fouc:
Zone readings parabola
1 0 0
2 0.85 1.13
3 1.68 2.25
4 2.09 3.37
5 2.42 4.45
6 2.77 5.57
7 3.19 6.69
Figure XP : take figure for 3.19/ 6.69 = 48 % parabola: after offset it is clear I have to work on central area ( 0- 125 mm)
Step 8 T= 20 deg
20 cm tapered tool + 3 kg
a. Straight stroke over r=10 cm with 5 cm overhang 2×5 turns
b. W-stroke with center of lap within r=8 cm : 3×3 turns
c. Large W-stroke 5 cm overhang: 3 x 1 turn
Cold pressing during 3 min finds place regularly
Ronchi: weak kink at 50 % ; lines > F not regular
Zone readings parabola
1 0 0
2 0.63 1.13
3 1.49 2.25
4 1.99 3.37
5 2.35 4.45
6 2.74 5.57
7 3.17 6.69
Step 9
Correction has to be increased, especially in outer zones
20 cm tapered lap + 3 kg weight on top
– str stroke 0-2 cm from C ; 5 cm over : 2 turns
– str stroke 4-5 cm from C 5 cm over : 3 turns
– str stroke 10 cm from C 5 cm over : 3 turns
This session 8 times
Then : large W-stroke 5 cm over : 5 turns
Ronchi : lines more regular ; < F weak kink at 50%
Foucault : 9 zone mask
Zone readings parabola
1 0 0
2 0.38 1.09
3 0.96 2.01
4 1.64 2.92
5 2.04 3.82
6 2.47 4.70
7 2.84 5.63
8 3.17 6.50
9 3.54(48%) 7.42
High zones r= 125 mm and edge
Step 10
a.15 cm tapered lap
– Str stroke through C 4 turns
– Str stroke 4-5 cm from C 4 turns
5 cm overhang
This session 10 times
b.20 cm tapered lap: large W-stroke 5 cm over 5 turns
Ronchi : no obvious kinks, except little TDE. Bit flat at 80-90%
Zone readings parabola
1 0 0
2 0.41 1.09
3 1.0 2.01
4 1.65 2.92
5 2.04 3.82
6 2.51 4.70
7 2.92 5.63
8 3.38 6.50
9 3.77 7.42
Step 11
More correction,that’s the message
15 cm tapered tool + 3kg
– str stroke 0-2 cm from C 5 cm over 4 turns
– str stroke 12 cm from C 5 cm over 3 turns
-large W-stroke 5 cm over 1 turn
This session 10 times
Ronchi: looks like last one
Zone readings Parabola
1 0 0
2 0.58 1.09
3 1.30 2.01
4 1.69 2.92
5 2.13 3.82
6 2.48 4.70
7 2.94 5.63
8 3.45 6.50
9 4.01(54 % ) 7.42
54 % parabola: offset -0.088 mm : zone 1-2-3 too high
Step 12
20 cm tapered tool + 3 kg
– Str stroke 1 cm from C 4 turns
– Large W 5 cm over
– This session 10 times
Zone readings Parabola
1 0 0
2 0.54 1.09
3 1.22 2.01
4 1.75 2.92
5 2.17 3.82
6 2.58 4.70
7 3.03 5.63
8 3.55 6.50
9 4.13 7.42
Ronchi : slightly kinky
Step 13 ( may 16) 20-21 deg
15 cm tapered tool
– Str stroke 0-1 cm from C 4 turns
– Str stroke 4-5 cm from C 3 turns
– Str stroke 8-10 cm from C 3 turns
5 cm over
This session 9 times
– Large W-stroke 5 cm over 5 turns
Zone readings Parabola
1 0 0
2 0.40 1.09
3 1.02 2.01
4 1.57 2.92
5 1.95 3.82
6 2.41 4.70
7 3.04 5.63
8 3.51 6.50
9 4.17 7.42
No improvement; I work too little on the inner zones
Step 14
15 cm tapered tool with 3 kg
– str stroke 0-1 cm from C 5 cm over 4 turns
-str stroke 5 cm from C 5 cm over
This session 10 times
– large W-stroke 5 cm over : 2 turns
Zone readings Parabola
1 0 0
2 0.68 1.09
3 1.42 2.01
4 2.12 2.92
5 2.63 3.82
6 3.12 4.70
7 3.69 5.63
8 4.33 6.50
9 4.97 (67 % ) 7.42
Parabola 67% : best fit 1/3.8 labda. High outerzones and high 90-120 mm
Step 15 May 16 temp = 26.5 deg
Increase correction and excavate center
a. 12 cm tapered tool + 0.5 kg weight
– Str stroke 0-1 cm from C 4 turns
– Str stroke 3-4 cm from C
3-4 cm overhang
This session 6 times
b. 20 cm tapered lap + 3kg: large W 3-4 cm overhang 2 turns
Zone readings Parabola
1 0 0
2 0.66 1.09
3 1.40 2.01
4 2.10 2.92
5 2.63 3.82
6 3.14 4.70
7 3.65 5.63
8 4.26 6.50
9 4.99 7.42
Hardly any change.Didn’t press enough with the lap
Step 16
a. 12 cm tapered lap + 3 kg
Str stroke 0-1 cm from C 4 turns
Str stroke 4-5 cm from C 3 turns
This session 10 times
b. I want to do somthing about zone 5-6-7
20 cm tool + 3 kg: W-stroke inside edge mirror.No overhang : 3 turns
Ronchi: there is a hole in the center! I worked too long with the small lap
Zone readings Parabola
1 0 0
2 1.22! 1.09
3 2.06 2.01
4 2.81 2.92
5 3.42 3.82
6 3.94 4.70
7 4.55 5.63
8 5.16 6.50
9 5.89(79%) 7.42
79 % parabola: 1/1.1 labda Correction of zones 4-8 too low
Step 17 May 19 T=20 deg
I will try to do something about zone 5-6-7
15 cm tool + 3 kg
-str stroke 5 cm from C 3 turns
-Str stroke 10 cm from C
– large W-stroke 1 turn
This session 5 times
Test:
Ronchi: < F : hole in center
Outside F : lines in outer area bit kinky ( not flowing)
Zone readings Parabola
1 0 0
2 0.74 1.09
3 1.45 2.01
4 2.18 2.92
5 2.75 3.82
6 3.32 4.70
7 3.89 5.63
8 4.52 6.50
9 5.35 7.42
– Bit of dog biscuit surface because of new lap
– Outer zone is getting flatter
– Correction less because of work on r=10 cm
Step 18
Work on outer zones to prevent flattening:
10 cm tapered lap (new, worked in on the 25 cm f3.3 mirror)
a. Circular stroke on edge: 5 min ( while walking around the mirror)
b. Elliptical stroke r= – 1 to +21 cm 5 min
Light pressure.The elliptical stroke is necessary to kep the correction
Zone readings Parabola
1 0 0
2 0.87 1.09
3 1.59 2.01
4 2.41 2.92
5 2.89 3.82
6 3.44 4.70
7 4.02 5.63
8 4.72 6.50
9 5.50 7.42
Outer zones less flat
Stap 18a May 21 22 deg
a. Increase correction with 15 cm tapered lap (new) with 3 kg
-Str stroke 1-2 cm from C 4 turns
– str stroke 5-6 cm from C 4 turns
This session 10 times
10 cm starlap
b. elliptical stroke r= 15 to r=20 cm 5 min
c. Elliptical stroke r= -1 to r= 20 cm 5 min
5 cm overhang in all strokes
Ronchi: <F hole in center ; >F kinky in outer zones; kink at 50 %
Zone readings Parabola
1 0 0
2 0.81 1.09
3 1.85 2.01
4 2.60 2.92
5 3.24 3.82
6 3.75 4.70
7 4.33 5.63
8 5.05 6.50
9 5.83 7.42
Fig XP : 2.7 labda P-V S= 0.03
79 % correction: high in 90-125 mm area and edge area. Move ROC with – 0.189 mm: high from r=30 to r=150 mm
Step 19 May 22
1. 10 cm starlap on r= 10-11 cm : straight stroke with a side stroke to the center after every two strokes.This happens while I walk around the mirror.It is a tangential stroke : 5 min
2. 15 cm tapered lap + 1kg
– Str stroke 1 cm from C : 4 turns
– Str stroke 5-6 cm from C : 4 turns
– Large W-stroke : 1 turn
–
This session 7 times ; all the time max overhang: 5 cm
Zone readings Parabola
1 0 0
2 0.83 1.09
3 1.85 2.01
4 2.60 2.92
5 3.15 3.82
6 3.75 4.70
7 4.43 5.63
8 5.29 6.50
9 6.04 7.42
Step 20 23 deg
1. 10 cm starlap same stroke as in step 19 nr 1 : 7 min with light pressure
2. 12 cm tapered lap : elliptical stroke from 2= -1 to 2=20 cm : 10 min
Ronchi: <F : hole in center?
F: lines outside 50% a bit kinky; not smooth
Zone readings Parabola
1 0 0
2 0.93 1.09
3 1.84 2.01
4 2.72 2.92
5 3.39 3.82
6 3.94 4.70
7 4.62 5.63
8 5.29 6.50
9 6.13 7.42
Zones 5-8 not enough corrected
Fig XP: 2.27 labda P-V S=0.036
For 82% parabola: ½ labda ; area from 40 to 130 mm has to be polished
Step 21 May 23 ; temp = 23 deg
15 cm tapered lap: work upto and including zone 7
W-stroke within r=18 cm with 3 kg weight : 10 min
Zone readings Parabola
1 0 0
2 1.05 1.09
3 1.95 2.01
4 2.75 2.92
5 3.41 3.82
6 4.07 4.70
7 4.74 5.63
8 5.54 6.50
9 6.38 7.42
Fig XP : 1.9 labda P-V S=0.027
Zones 5-5-7-8 stay behind ( 150 – 200 mm from center)
Step 22
I have to leave the edge area alone. I use the lap not further than r=18 cm.
Try a 20 cm strongly tapered lap.
W-stroke with 3 kg within r=18 cm: 4x 5 min
Ronchi: kink at 70% ; outer area too flat
Zone readings Parabola
1 0 0
2 0.96 1.09
3 2.01 2.01
4 2.93 2.92
5 3.72 3.82
6 4.41 4.70
7 5.08 5.63
8 5.84 6.50
9 6.71 7.42
Intermezzo:
I asked advice from professional Rik ter Horst.
I should have started with a bigger pitchlap and not have hollowed out the center so soon. Use 15 and 20 cm pitchlaps that don’t have a starform: they excavate the center too much
From now on:
1. Leave outer area zones 7-9 alone for the moment
2. Treat area within zone 7 with 15 or 20 cm pitchlap (no star!) with elliptical stroke or W-stroke. Do this until the curve is OK for conic constant 0.7, 0.8 or 0.99 I can choose) . After that: go for 100 % parabola with large W-stroke
Step 23
May 29 T= 24 deg
I made two new pitchlaps , 15 and 20 cm with pitch 26, 5 deg from Stathis + some linseed oil to soften it. These laps were worked in on the unfinished 25 cm f3.3 mirror
20 cm lap + 3 kg; edge squares a bit tapered. : W-stroke within 18 cm : 5 turns
I discovered that the outer squares of the pitchlap touch the mirror only for a small part!
Press again!
Second try: 5 turns
Zone readings Parabola
1 0 0
2 0.76 1.09
3 1.74 2.01
4 2.88 2.92
5 3.72 3.82
6 4.50 4.70
7 5.17 5.63
8 5.92 6.50
9 6.79 7.42
Center becomes flatter!
Fig XP : 1/1 Labda S=0.083
ROC offset til louter zones become flat: now there is a high that increas from 0 at r=200 mm to 845 nm at center
Step 24 26 deg.
1. 15 cm lap (not tapered or in starform) + 3 kg
Str stroke 1-2 cm from C till r= 18 cm (edge of lap does not extend beyond 18 cm)
10 turns
2. 20 cm lap (not tapered or in starform) W-stroke till r = 18 cm : 10 turns
Ronchi : < F : hole in center. Weak kink at 60-70 %
Zone readings Parabola
1 0 0
2 0.85 1.09
3 1.85 2.01
4 3.04 2.92
5 4.01 3.82
6 4.86 4.70
7 5.63 5.63
8 6.38 6.50
9 7.22 7.42
Fig XP : 1/1.9 labda S=0.315
ROC offset – 0.205 mm: high starts at r=170 mm and rises to 400 nm at center
Step 25
15 cm tool (outer squares a bit tapered)
W-stroke within 170 mm : 3 turns
Zone readings Parabola
1 0 0
2 0.75 1.09
3 1.88 2.01
4 3.10 2.92
5 4.11 3.82
6 4.97 4.70
7 5.73 5.63
8 6.48 6.50
9 7.35 7.42
Fig XP : worse! 1/1.2 labda P-V S= 0,103
ROC – 0.139 mm : high area starts at r=175 mm and reaches maximum at 325 nm and goes to 250 nm at center
Step 26
a. 10 cm lap : circular stroke on r=115 mm : 5 min
b. 45 cm lap (Made to fit again after some weeks!) ½ W-stroke 1 turn MOT
c. 45 cm lap 1/3 W-stroke 1 turn
Ronchi : 70-80 % too flat
Zone readings Parabola
1 0 0
2 0.77 1.09
3 1.72 2.01
4 2.84 2.92
5 3.92 3.82
6 4.76 4.70
7 5.56 5.63
8 6.32 6.50
9 7.18 7.42
Fig XP : ½ Labda S = 0.363
ROC – 0.142 mm: High that starts at ca 200 mm and reaches ca 300 nm at 125 mm and dips only slowly tot he center
Step 27 temp = 25 deg
W-stroke with 15 or 20(??) cm lap within 160 mm radius with tapered lap
a. 2 turns with 1 kg
b. Elliptical stroke from r = -1 to + 18 cm( center of lap) 2 min with light pressure.
Zone readings Parabola
1 0 0
2 0.84 1.09
3 1.79 2.01
4 2.96 2.92
5 4.01 3.82
6 4.87 4.70
7 5.69 5.63
8 6.44 6.50
9 7.26 7.42
Fig XP : worse! 1/1.6 labda
S= 0.253
ROC -0.135 mm : high of 300 nm from 125 mm to center. After 125 mm it descends quickly
Step 28 June 1
a. 10 cm lap circular stroke on r = 125 mm ;light pressure 5 min
b. 15 cm lap + 3 kg W –stroke within 160 mm 3x 1 turn with pressing in between
Zone readings Parabola
1 0 0
2 0.90 1.09
3 1.74 2.01
4 2.95 2.92
5 4.10 3.82
6 4.93 4.70
7 5.75 5.63
8 6.48 6.50
9 7.36 7.42
Worse!
1/1.3 Labda P-V S=0.145
ROC -0.094 mm: big high (260 nm) at r=130 mm. Diminishes a bit tot he center
Step 29
12 cm starlap: tangential stroke on r=130 mm. After every two stroke a stroke veering of to the center. 5 min walking around the mirror
Zone Readings Parabola
1 0 0
2 0.91 1.09
3 1.90 2.01
4 3.01 2.92
5 4.10 3.82
6 4.95 4.70
7 5.77 5.63
8 6.51 6.50
9 7.41 7.42
1/!.5 labda P-V S=0.262
ROC offset: High (240 nm) at r=125 mm
Step 30
10 cm lap : circular stroke on r=125 mm 10 min
Zone Readings Parabola
1 0 0
2 1.01 1.09
3 1.91 2.01
4 2.89 2.92
5 4.04 3.82
6 4.89 4.70
7 5.75 5.63
8 6.57 6.50
9 7.43 7.42
½ Labda S=0.464
ROC -0.051 mm: high (160 nm) at r= 130 mm
Step 31 June 3 New pitchlaps 10 and 7 cm
10 cm lap, weakly tapered : circular stroke on 130 mm. Every 5 sec a stroke veering of tot he center ( to avoid a high center)
Zone readings Parabola
1 0 0
2 1.15 1.09
3 1.91 2.01
4 2.91 2.92
5 3.92 3.82
6 4.93 4.70
7 5.71 5.63
8 6.51 6.50
9 7.41 7.42
Fig XP ¨1/3.7 labda P-V S = 0,742
ROC -0,06 mm: high area(130 nm) starting some what further than 130 mm and going on to the center
Step 32
10 cm lap : elliptical stroke r=90 to r= 130 mm( center of lap) 2×5 min
Zone readings Parabola
1 0 0
2 0.87 1.09
3 1.73 2.01
4 2.72 2.92
5 3.74 3.82
6 4.71 4.70
7 5.52 5.63
8 6.34 6.50
9 7.20 7.42
1/ 3.5 Labda S=0.712
ROC offset – 0.068 mm :high area starts at 175 mm .Max 150 nm
Step 33
a. 12 cm starlap W-stroke within r=160 mm (edge of lap stays within 160 mm!) 2x 1 turn. Reasonable pressure
b. 12 cm starlap circular stroke on r=125 mm with a frequent stroke veering off to the center 5 min
c. 12 cm starlap : elliptical stroke r= -1 to + 20 cm : 2 min
Zone readings Parabola
1 0 0
2 1.04 1.09
3 1.88 2.01
4 2.82 2.92
5 3.94 3.82
6 4.86 4.70
7 5.72 5.63
8 6.54 6.50
9 7.40 7.42
1/ 2.5 Labda S= 0.552
ROC – 0.038 mm
High (130 nm) at r= 140 mm going down to 70 nm at inner zones
Step 34
a. 12 cm tapered lap: tangential stroke on r=140 mm .Every stroke is followed by a side stroke to the center,again to prevent rising the center. 2x 5 min
b. Elliptical stroke from -1 to +20 cm : 3 min
Zone Readings Parabola
1 0 0
2 0.98 1.09
3 1.84 2.01
4 2.77 2.92
5 3.85 3.82
6 4.83 4.70
7 5.67 5.63
8 6.55 6.50
9 7.43 7.42
1/ 2.4 Labda S=0.456
I can’t get the outer zones flat in Fig XP
Without offset there is a high hill( 110 nm) centered on r= 150 mm
Step 35
10 cm lap circular stroke on r=150 mm 2×5 min
Now and then I make a stroke tot he center.
Ronchi looks nice
Zone readings Parabola
1 0 0
2 1.15 1.09
3 2.01 2.01
4 2.94 2.92
5 3.98 3.82
6 4.91 4.70
7 5.78 5.63
8 6.61 6.50
9 7.55 7.42
1/3 labda S=0.724
High ( 90nm) centered on r=150 mm
Step 36 temp = 23 deg
a. 7.5 cm lap : circular stroke on r=150 mm : 2 x 5 min
b. 45 cm lap MOT 1/3 W-stroke 2x 1 turn
Zone Readings parabola
1 0
2 0.73
3 1.39
4 2.12
5 2.77
6 3.59
7 4.24
8 5.01
9 5.61
10 6.31
11 7.02
1/8 labda P-V S= 0.956
Fig XP high (35 nm) at r=150 mm
Startest Polaris 9-10 June 2017 23.45-00.30
10 mm OR + 2xBarlow
Secondary shadow appear about the same distance when going <F and > F
6.3 OR + 2xB
> F :bright outer ring on outside of star image ( defocused) that is not visible <F
Overcorrection?
Sec shadow appears about the same time going <F and >F
Wega through Ronchi screen: straight lines
Image of Epsilon Lyra at 300x good. Sharp stars with black space between the stars
Coating Jilles Eindhoven (Buurse) june 2018 e200
First use of telescope: august 2018
January 31,2022
I did the Bath interferometer test in 1 postion.
I often had misgivings about this mirror because of often lousy images.But it had to do with the lousy seeing and wrong position of the coma corrector/.
3 different interferogrampostions
Average of 10 igrams: Strehl = 0,98 ; correction -1,00