| Astronomical Telescope |
I have observed the moon, Jupiter, Saturn and Mars at my leisure with 80 mm refracting and 115 mm Newton reflecting telescopes. Since my desire to make it look more beautiful with my usual bad habits came out, I did some upgrade. Main upgrade contents are to replace eyepieces from 24.5 mm to 31.7 mm, mirrorless single lens reflex camera from NIKON 1 to SONY NEX-5N, and to buy new WEB camera. In addition, I cut the legs of tripod and shortened it to improve the stability and the convenience of traveling by car. Also, I modified the mounting bracket of the equatorial mount so that I can use the reflecting telescope.
1. Change of Eyepiece from 24.5mm to 31.7mm
It is an 80 mm refracting telescope, Halley P-80L made by VIXEN Japan. I bought it for about
10,000 yen at the net auction. I could not realize my dream of seeing stars with a telescope
when I was a child. So I realized this dream at last in the age of 70. The length of this
telescope is 1,200 cm and the maximum magnification is 120. Handling is a little troublesome
because the legs of tripod are long.
If you put the mouse over the image, it will be enlarged. (Same below)
It is a 115mm Newtonian reflecting telescope, DS-115 made by MEADE USA. I bought it for about
6,000 yen at net auction. I observed the moon and other planets with 80 mm refracting telescope,
but eventually I thought that I wanted to see the stars more brightly. So I bought the reflective
telescope this time. Handling is easy because it is as short as 90 cm. The maximum magnification
is 80.
Both 80 mm refracting and 115 mm Newton reflecting telescopes use 24.5 mm (Zeiss size) eyepiece,
so the visual field is narrow and dark. Although there was no complaints when I was a beginner of
astronomical observation, recently I wanted to upgrade eyepieces to 31.7 mm (American size).
Therefore, when examined by the internet, it turned out that it is good if 36.4 mm ¨ 24.5 mm
adapter which is screwed into the draw tube of 80 mm refracting telescope should be replaced
from 36.4 mm to 31.7 mm. Since it was sold at shipping included 2,000 yen or less in the net
auction, I bought it immediately. On the other hand, the 115 mm reflecting telescope has a 54
mm plastic part screwed into the draw tube and 24.5 mm sleeve is integrated, so its remodeling
seems to be considerably difficult.
Next is purchasing 31.7 mm size eyepiece. Compared to the size of 24.5 mm, there are plenty of
kind and price, so I donft know which one to buy. Considering my telescope, equatorial mount,
grade of tripod, I decided to buy cheap eyepiece of less than 5,000 yen. Eventually I bought a
15 mm ultra wide 66 degrees eyepiece of VIXEN. I, poor man, thought that I replace the tube of
existing 24.5 mm eyepiece with 31.7 mm after buying one ready-made eyepiece and referring to it.
The picture is eyepieces of 24.5 mm and 31.7 mm, but the size of the lens, the thickness of the
cylinder, and the weight are greatly different.
I tried to insert and adhere the lens part of existing 24.5 mm eyepiece into 31.7 mm cylinder,
but I can not find the most important 31.7 mm pipe. Iron pipe of 31.8 mm is sold on the net,
but if it is iron it is hard to work so I searched for aluminum pipe. Then I found 32 mm aluminum
pipe in the wreckage of the amateur radio GP antenna. Ii is good to polish this by about 0.3 mm
with some means. As a result, the pipes were fixed to the chuck of the electric drill with gum
tape and polished using water resistant sandpaper while applying water. I polished it by 360th
sand paper for about 10 minutes and finished it with the 1,000th sand paper at the end. The picture
shows just started cutting.
I made four cylinders after cutting four pipes of 31.7 mm with a cutting saw. I paint the interior
of the cylinder with black or brown spray to prevent diffused reflection inside. Although the lens
part and the tube are fixed at four places with glue, there is no problem as it is the place where
no force is applied. I bonded plastic ring so that the eyepiece does not slip into the lens barrel.
This means that five 31.7 mm eyepieces were complete. It is, from the left, Or 6 mm, Or 9 mm, K
20 mm, K 28 mm modified to American size.
The 24.5 mm sleeve which is integrated with the resin part screwed in the draw tube of the
reflection telescope has only a method of removing it, so it is difficult to focus because the
eyepiece part is made of plastic and the backlash is severe. Therefore I decided to exchange
the eyepiece part. I purchased eyepiece part with 5,000 yen including shipping cost from the
SCOPE TOWN, because TAKAHASHI or first-class goods will cost tens of thousands yen. Since the
diameter of the lens barrel was 140 mm, it was perfect, but the position of the screw hole was
about 10 mm aside, so I drilled three holes with electric drill. It is inexpensive but since
the tube and sleeve are made of metal, the movement is very smooth. Although it was understood
from the beginning, this reflection telescope can not only focus on infinite focus but also
collimate photography because it can not focus at infinity either in direct focus photography
or in enlarged photography using a commercially available adapter. Because it is caused by short
outside focal length, I decided to consider separately how to move the primary mirror forward and
how to reduce the distance between the T ring and the mirrorless single lens reflex camera sensor.
The newly purchased draw tube of eyepiece part is quite long and when focused on infinity, it
protrudes about 30 mm into the lens barrel so I am worried about the adverse effect of interference.
There is also a method called cutting the draw tube, but I decided to cut the lens barrel so that
I can do the direct focus and enlarged photography using the commercially available adapter. I made
my own equipment for optical axis adjustment, and since it is cheap telescope, there is no scary
thing. The photograph was cut with the cutting saw by about 25 mm and then it was scratched and
shaped with sandpaper. Three screws fixing the main mirror part were able to fix well by twisting
the screw after inserting the hole as small as 0.5 mm and screwing it. Even if the main mirror
part is slightly misaligned, there is no problem if adjusting the optical axis correctly.
When the lens barrel was cut by 25 mm and the adjustment of the optical axis was completed, the
enlarged photography using the commercially available adapter became focus on. The protrusion of
the draw tube was solved and the cutting was a correct answer, but the direct focus photography
was out of focus yet. This is because the back focal length of T2-NEX ring at the time of direct
focus photography is as long as 55 mm. So I drilled a hole in the body cap of the camera and glued
31.7 mm sleeve to shorten back focal length by 30 mm (left side of the photo). With this
countermeasure, it became possible to take the direct focus photography with the reflective
telescope at last. The direct focus photography with the telescope of focal length of 900 mm is
not suit against planet image because the image is too small. I think it is effective for
photographing the moon.
Next to the eyepiece is purchasing a zenith mirror. The reflecting telescope does not have any
problem because the eyepiece height is the same as the level of eyes, but it is more convenient
for the refracting telescope of long lens barrel to have the zenith mirror for easy observation.
Although the zenith mirror is diverse, I got one cheaply for 3,000 yen. The left side of the
photo is conventional zenith mirror for 24.5 mm eyepiece and the right side is for 31.7 mm.
2. Purchase of Mirror Less Reflex Camera
I bought new mirrorless single lens reflex camera due to change of eyepiece to 31.7 mm. To tell
the truth, NIKON 1 had a major disadvantage that the internal exposure meter did not work when
using an external lens. Therefore, in order to obtain the proper exposure, it is necessary to set
the aperture priority mode once to memorize the optimum shutter speed, then set to the manual
mode and set the shutter speed. The shutter can not be released in aperture priority mode with
external lens. Actually, I could not do such a thing in the dark photography site, so I got SONY
NEX-5N body in Yahoo auction. Price is a little cheaper by 10,000 yen than NIKON 1, the internal
exposure meter always operates, the ISO sensitivity is up to 25,800, and because the imaging sensor
is APS-C it is much larger than NIKON 1 (3.2 times in area), angle adjustment of the LCD monitor
is possible, I can press the shutter with infrared remote control. I think it is the best for
astrophotography.
If I just look at the moon, Jupiter's satellite, Saturn's ring, I can do it with the single
focus camera, but still I need to try the enlarged photography to see the details of the planet.
With the collimating method, three lenses are used, but if it is the enlarged photography, only
two lenses are required, clearer image and larger magnification rate can be expected. For that
reason, an adapter for enlarged photography is indispensable. For high-class adapter, I will
spend 20,000 yen, but the poor man purchased ORION's bulk adapter at under 5,000 yen. The left
side is the T2-NEX ring which connects the camera and the adapter, and the three on the right
side are enlarged photography adapters. I hold inside the 31.7 mm eyepiece and connect the right
pipe to the telescope. The enlargement rate varies depending on the focal length of the eyepiece
and the distance from the eyepiece to the camera sensor. Since this adapter can vary the distance
by 34 mm, I can change the enlargement ratio.
After I finished changing the eyepieces to 31.7 mm, I made my own infrared collimator. It is
easy to buy it, but it is unnecessary to put out 10,000 yen for the telescope I bought cheaply.
The infrared light emitting device is sold at 500 yen in AKIZUKI, and all the other parts are
available at the home center. The main parts are PVC pipes, stainless steel screw and nut, Metal
Rock that can be used for anything adhesive, masking tape used for painting as material to fill
the gap between PVC pipes. In addition, I also made a collimation eyepiece that determines the
position of the slanted mirror before adjusting the optical axis with the infrared collimator.
It is the eyepiece without lens with the crossline and 1 mm hole in the center.
The picture is a jig for aligning the optical axis of the collimator itself, and the six screws
were adjusted so that the irradiation point reflected on the wall does not move as much as
possible even when the collimator is rotated. Actually, I placed a cosmetic mirror at a distance
of 5 m, reflected the beam and fixed the screw so that the red dot irradiated on the hand paper
did not move. Before adjusting the optical axis, the position of the slant mirror was adjusted
so that the center of the slant mirror and the main mirror were aligned using the collimation
eyepiece. Now, at the first stage of optical axis adjustment, look through the lens barrel and
adjust the three screws of the diagonal mirror so that the beam will come to the center of the
main mirror. In the second stage, adjust the three screws of the primary mirror so that the beam
which is reflected by the primary mirror and returned to the collimator comes to the center of
the irradiation sensor. In fact, there was a problem that the beam coming back due to the operation
of the focus knob of the eyepiece and the error of the optical axis of the collimator itself
moved about 1 cm.
Since there is no choice, if the reflected beam is inside the irradiation sensor, it is OK as
"almost" the optical axis adjustment is completed. Since it is a cheap reflecting telescope,
it makes no sense even if it becomes too nervous for optical axis adjustment. I found out that
my self-made infrared collimator was also practical enough. I hope that even with anything the
optical axis adjustment will improve the apparent taste of the reflecting telescope even a little.
The infrared collimator can also be used for optical axis adjustment of a refracting telescope.
It was OK if a collimator was attached to the eyepiece and a red dot reflected on the objective
lens came to the center, but in my 1200 mm telescope I drawn a circle about 1 cm radius around
the center. Adjust the three screws that fix the eyepiece to the lens barrel and guide the red
dot to the center by adjusting the three screws. Since the reflected beam from the objective
lens has returned to the center of the collimator, it is judged that the optical axis is correct
did. However, when rotating the collimator in this state, since it draws a circle on one side of
the objective lens, it finally returned to its original state, so a circle is drew in the
center area.
The shutter of NEX-5N can gladly be made by infrared remote. Besides, I can buy its remote
controller for 1,000 yen including shipping cost. Of course the timer of 2 seconds is also OK.
The shutter can be made anywhere within 1 meter around the camera. It is a big help because it
is indispensable in capturing astronomical photographs.
Although I bought NEX-5N it is OK for shooting only astronomic photographs, so I bought an
adapter (NIKON-NEX) so that I can use old lenses for my NIKON film camera. If I shoot in manual
mode I can use the internal exposure meter even with old lenses so there is no problem at all.
The price is also cheap, around the 2,000 yen level. The photograph is the one fitted with the
Nikkor 50 mm F1.4 lens, the focal length converted to 35 mm film camera size is 75 mm.
3. Introduction of WEB Camera
Previously, I had the experience of remodeling a WEB camera and direct focus photographing
with a 60 mm refracting telescope, but at that time I did not know how to shoot movies and
process images with Registax 6. Since the image was not so good and the camera only works
in Windows XP, it has gone to the trash can. However, as I learned how to use Registax 6
little by little, I wanted to try challenging again. I bought LOGICOOL's Qcam C310 WEB camera
and it is cheap not to cost 2,000 yen with postage included. It works with Windows 7 and I
can shoot movies up to 1,280 x 720 pixels. The infrared filter is attached just before the
sensor for remodeling, so I can easily remove it by turning the lens to the left. As a 31.7
mm sleeve, a TS joint for drainage hose (diameter 31 mm, length 60 mm) was cut to 25 mm length
and bonded. I triple the copper foil tape to fill the gap even a little. I confirmed the
operation with a 115 mm reflecting telescope using a neighborhood electric pole, but the
weather has been bad and the astronomical observation has not been reached yet.
4. Improvement of Tripod
The tripod of the 80 mm refracting telescope is too long and handling is inconvenient, so
it was improved. Three legs were cut by about 45 cm each and pasted with adhesive, but the
force works almost in the vertical direction, so it seems that there is no problem in terms
of strength. With this refinement, I was able to sit on the seat and easily observe the stars.
Moreover, it became shorter, so it is stable in terms of strength, and it can be transported
by car while assembled. The picture shows the state that the elevation is set to 50 degrees
in the southeast direction after aligning the equatorial mount to the north pole of the sky.
For reference, I show legs cut by 45 cm in the picture.
Along with this improvement, I decided to use the mount as the original equatorial mount. It
is necessary to move two handles to track the star. In the equatorial mount, once I introduce
the star I can track with just the red ascension handle, it is very convenient if I get used
to it. In order to master the equatorial mount, it is essential to align the polar axis with
the north pole of the sky. In the observation at home, I can not see the North Star so align
the polar axis with a compass. I move the polar axis to the right by 7 degrees from the magnetic
north and set the latitude to 35 degrees using the graduation ring. In automatic tracking, it is
necessary to align polar axis more accurately, but this is sufficient for manual tracking. After
setting the polar axis, manually move the telescope to the south by loosening the red ascension
and declination clamps. With this, it becomes possible to be tracked with only the declination
handle, the star moves in a straight line around the center of the field of vision.
5. Results of Upgrade
I invested nearly 30,000 yen and upgraded again, but depending on the measurement of results,
the responsibility is asked from my wife so I took Jupiter at once. The picture is not processed
anything other than just trimming the image with Jupiter and its satellites which was photographed
with 80mm reflecting telescope at the direct focus. The NEX-5N shot even the satellites sharply
because it is easy to focus even manual shooting with external lens, but since the objective lens
is achromat, blue bleeding around Jupiter can not be helped. The NEX-5N is very easy to shoot
because the internal exposure meter works and the shutter is released with the infrared remote
control. I'd like to take photos of the moon and Saturn, but unfortunately the time is not good,
so I'd like to do someday.
The picture is Jupiter shot by enlarged photography with 80 mm refracting telescope. It is a
still image shot with NEX-5N by attaching 15 mm eyepiece to the enlarged photography adapter
purchased this time and setting it to the maximum enlargement ratio. I did not do any image
processing except trimming, so it is not clear but two stripes are somehow visible. Although
it can be clearly confirmed by eye view, it is only to blur in the photograph. However,
although the seeing was bad, I think that it is the result of upgrade as it is best image
among the photos of Jupiter ever taken.
The picture is Jupiter magnified with 115 mm reflecting telescope of which eyepiece part
was replaced and optical axis was adjusted. The 15 mm eyepiece was attached to the commercially
available enlargement photography adapter and the movie photographed by NEX-5N was stacked with
free software Registax 6, then subjected to wavelet processing. MP4 movie of 640 x 480 pixels
is cropped and Jupiter is closed up, it is converted to WMV file. After it is converted to AVI
file, I finally processed the image with Registax 6. To be honest, I donft understand the use
of image conversion software and Registax 6. So, it became a suspicious image by excessive
processing. Although somehow it was possible to make better image than the captured image, it
is surprising that such an image can be obtained from low resolution movie file. I will not
return to the still picture anymore. In the future, I will study Registax6 more and challenge
enlargement movie photography using 1,200 mm refracted telescope.
After that, since the moon was seen, I took the direct focus photography with 115 mm reflecting
telescope. I shot a 640 x 480 pixel movie and processed it with Registax 6. Although it seems
slightly excessive treatment, it is pretty beautiful.