I have some close-up lenses at hand.
It is quite useful because it will be in focus even closer than the shortest shooting distance you are using.
The shortest shooting distance of recent lenses is quite close, but the frequency of use of close-up lenses is decreasing.
Looking at the filter for the first time in a while,
I had a 58mm diameter AC close-up lens at hand.
When I looked at the filter for the first time in a while, I found a beautiful world of mold on its surface.
"Yes!"
Mold was found only on the surface of the filter, and fortunately it was not inside.
It was so beautiful that the photo I took is above.
This AC means achromat.
A combination of two lenses with different properties that eliminates the chromatic aberration that occurs and improves performance.
No2 means 1,000 ÷ 2 = 500 mm
Focal length, 500mm
By the way, the No. 1 focal length is 1000mm.
N0.3 focal length is 333mm
No./1000mm is the focal length of the close-up lens.
Considering that the filter diameter is 58 mm and the diameter is the same as the filter diameter, the diameter ratio (F value) is
500 ÷ 58 = 8.6
This lens is a 500mm f8.6 lens.
The surface of the lens has a high-quality multi-coating, which, combined with the achromatic achromatic lens, seems to be usable as a telephoto lens.
I was curious about how much image quality would be obtained if I took a picture with this AC close-up lens.
So, I decided to make a telephoto lens that doubles as a telephoto lens.
I wondered if there was an affordable cylinder.
PVC pipes and thicknesses are also available in various sizes such as 5 cm in diameter and 7.5 cm in diameter.
After all, the price is cheap.
By combining these two with different thicknesses, it seems that a simple focus system can be created.
To fill this gap, I expected that a suitable urethane cushion material could be used.
So I prepared these materials.
Material used this time
From the top, 7.5 cm PVC pipe, 5 cm PVC pipe, filling gaps in each part of the car, urethane material purchased for vibration isolation, pieces of yoga mat, Nikon body cap, close-up lens, 58 mm filter frame of broken filter, permacel tape
For the simple camera mount, I decided to make a hole in the body cap.
The PVC pipe was cut to the approximate size at the time of purchase, so I first aligned the ends.
For this purpose, I bought only PVC pipes, and the rest were available, and the material cost was about 300 yen.
PVC pipe with aligned ends
The focal length of the lens of the main cylinder is 500mm, so I first cut it to 480mm.
It turned out that the focus did not come infinitely with this, so I gradually packed it to a reasonable length.
Simplified camera mount
There was one body cap of unknown manufacturer, so I decided to sacrifice it.
I made a hole with a soldering iron.
The eyepiece and mount are fixed with permacel tape.
The yoga mat was a little loose, so it seems that something needs to be pinched and adjusted.。
Lens tip
The black urethane was perfect, and the lens filter frame was fixed quite tightly.
The close-up lens is screwable and can be attached and detached.
Since the lens barrel is thick, it can handle up to 77 mm diameter filters.
Adjust the optical axis by pushing or pulling with your finger.
Temporary assembly completed for the time being 500mm f8.6 telephoto lens
There was a thin cloud, but at the moment when the cloud was slightly interrupted, I tried to release the shutter toward the moon.
First light, a telephoto lens that uses a close-up lens!
Crop to a suitable size
Pixel 1x with D850
There was a thin cloud, but it looked better than I expected.
Although it is a little soft, there is almost no color bleeding due to chromatic aberration.
As expected, it is an AC close-up lens.
With f8.6, you can go quite well with an achromat!
It seems that the combination of achromatic lenses, lens accuracy, etc. are fairly well made.
It has sufficient performance as an achromatic telescope.
The moon was well captured, even though I hadn't processed the internal reflections at all.
but,
This street is taken during the day.
I aimed the lens out of the window in the morning and took a picture
As expected, no reflection processing is performed inside the lens barrel, and there is no hood.
The contrast is very low.
From now on, I'm thinking of processing the internal reflection, attaching the hood, and attaching the tripod mount.
Now, how much better the image quality?
The strongest close-up lens that makes a telescope is
It will be the No. 1 AC close-up lens with a diameter of 82 mm.
If you make a telescope with this, the aperture will be 82 mm, the focal length will be 1000 mm, and f12.2.
Don't get too long.
It may continue next time.
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