Bernard Kaye
15-Dec-2007, 22:37
Ground Glass focusing being difficult for a senior who needs a long loup to extend from the GG (through the opened hood) more than 4" for 9 x 12cm. camera and more than 6" for 13 x 18cm. (5 x 7") camera, I have may have found a solution:
it is a Pentax 7 x 20 Monocular that comes with a 22x close-up lens that attaches to the monocular tube body and clear plastic "stand" that attaches to the close-up lens to make a low power microscope that stands 7" tall. Ambient or directed light passes through the clear plastic stand to light the subject, such as cloth, an insect, etc.
I covered the clear plastic with black cloth gaffer tape to eliminate all light but that coming through the GG, making sure not to overlap the end of the stand which will change focusing distance from lens to GG though others might want to extend it.
I focused it on the GG with light from a window; the focusing ring goes to one end of its travel for my eyes; I fixed it there with tape. No need to adjust the monocular focus when focusing the camera. I focus the camera image on the GG, first with eyes and eyeglasses, then on a spot or place through the monocular, again only with camera movement.
It seems to be working though the field is a only 7.5 degrees. It is, or was, since this is in an old, beat-up cardboard box on a buy this please counter, Pentax Nr. 61305. There is, or was, an 8 x 30 that was larger and had a close-up focusing ring for its 25x close-up lens, (the 7 x 20 close-up lens does not have its own focusing ring) a 6.2 degree field and relative brightness of 14.4, the 7 x 20 has a relative brightness of 8.4.
The view of the 8 x 30 at 1,000 meters is 108m. and 131m. for the 7 x 20 though the 8 x 30 for which I do not have a Pentax number is larger, longer and heavier.
Perhaps this will help some one, many of you have helped me. If we find other NOS loups like this???
Bernie
it is a Pentax 7 x 20 Monocular that comes with a 22x close-up lens that attaches to the monocular tube body and clear plastic "stand" that attaches to the close-up lens to make a low power microscope that stands 7" tall. Ambient or directed light passes through the clear plastic stand to light the subject, such as cloth, an insect, etc.
I covered the clear plastic with black cloth gaffer tape to eliminate all light but that coming through the GG, making sure not to overlap the end of the stand which will change focusing distance from lens to GG though others might want to extend it.
I focused it on the GG with light from a window; the focusing ring goes to one end of its travel for my eyes; I fixed it there with tape. No need to adjust the monocular focus when focusing the camera. I focus the camera image on the GG, first with eyes and eyeglasses, then on a spot or place through the monocular, again only with camera movement.
It seems to be working though the field is a only 7.5 degrees. It is, or was, since this is in an old, beat-up cardboard box on a buy this please counter, Pentax Nr. 61305. There is, or was, an 8 x 30 that was larger and had a close-up focusing ring for its 25x close-up lens, (the 7 x 20 close-up lens does not have its own focusing ring) a 6.2 degree field and relative brightness of 14.4, the 7 x 20 has a relative brightness of 8.4.
The view of the 8 x 30 at 1,000 meters is 108m. and 131m. for the 7 x 20 though the 8 x 30 for which I do not have a Pentax number is larger, longer and heavier.
Perhaps this will help some one, many of you have helped me. If we find other NOS loups like this???
Bernie