August 7th 2023Coalinga Range in California. We were able to test a 63X high-magnification spotting telescope in near-ideal circumstances at the CA Long Range Championship. On the last day of the event, we arrived at 545 am as the sun was cresting over the horizon. I quickly deployed my Pentax PF 100ED spottingscope, equipped with a Pentax SMC XW 10mm fixed power eyepiece. This 10mm eyepiece can magnify 63X when used with the Pentax 100mm scope. This eyepiece is a great value for $299.00. It is very sharp and clear. At the crack of dawn viewing conditions were perfect. No mist, no mirage, no wind. First thing I noticed as a Editor was that there were metal nail heads on target boards. This was amazing. To my surprise, as soon as the first practice target was up, I could see bullet holes of 6.5mm, 7mm and 30 caliber in the white at 1,000 yards. It’s true…I could see bullet holes from 1000 yards. I know that many of you may not believe it, but I was able to see a 7mm round cut through the white line that separated the Nine Ring from the Eight Ring on the target. I was watching the target as it was shot and saw the hole form. When I looked at the targets for 30-cal, the bullet-holes in the white were very visible. In these perfect conditions, I could also make out 3/8″? The human factor — good vision required
I used my left eye to view the bullet holes (no magnifying glasses or safety glasses). I also had a lens in my left eye (needed for distant vision). To my surprise, I was able to see the bullets with ease with my left eye. However, the right eye was fuzzier, and the image was slightly blurrier, even after I refocused the scope. The contact lens was reducing the fine resolution. I then invited 3 or 4 other shooters to take a look through the scope. One young man with good eyesight said: “Yeah. I can see the hole — right there at four o’clock, and seven o’clock.” Wow.” Wow.” The image can be affected by anything between the scope eyepiece, and your eyeball. You may be better off taking your glasses off if you still achieve good focus sharpness with the diopter adjustment. I tested my left and right eyes a dozen times. I could see fine details at 1000 yards without glasses, but I couldn’t see them with my right contact lens. I had to refocus the scopes for each eye because one was fitted with a corrective glass and the other didn’t. Mirage reduces image sharpness and resolution
After a few hours, the “magic light”, which was a kind of light show, began to fade. As soon as mirage appeared, I could no longer see bullet holes. However, I could still see black pasteers on the black bulls. The sharpness of the image was greatly reduced when the mirage began. By mid-morning, I could barely see the numbers on the scoring ring. At dawn I could see bullets. You need perfect conditions to test your optics’ ultimate resolution.
As the light and mirage intensified, I began to see blue and crimson fringing around the edges of the spotting disc and the large numbers. This was very noticeable. The photo below was taken with a point-and-shoot camera and the Pentax lens. The sharpness was much better than the photo shows. However, the image taken through the lens clearly shows the red and the blue fringing. This fringing occurs because of chromatic Aberration, which is the failure of the lens to focus on the same point for all colors. Chromatic Aberration is most noticeable at high magnification. It causes different wavelengths to have different focal lengths. Chromatic Aberration is manifested as “fringes” along the boundaries that separate the dark and bright portions of an image. This is because each color of the optical spectrum can’t be focused at one common point on the optical plane. Remember that the Pentax has “ED” low-dispersion glasses, so the effect will be even more dramatic if you use a cheaper spottingscope.
Click HERE to see a LARGE PHOTO which shows aberration clearly. If you’re wondering why expensive spotting telescopes like the $2980 Swarovski ATS80 cost so much, it’s because they deliver even LESS chromatic distortion at long distances and high magnification. Using apochromatic glass (APO), some ultra-high-end spotting telescopes can deliver images without the color edging that you see in the above photo. The Pentax PF100ED is a great spottingscope. Any scope that can resolve a bullet hole at 1000 yards is impressive. If you want the best optical performance with minimal chromatic distortion, you’ll need to upgrade to the 88mm Kowa Prominar with Flourite Crystal Lenses ($2325.50 for the body only) or the 82mm Leica with 25-50X Eyepiece ($3598.00). We can resolve 6mm bullets at 600 yards with this Pentax 100mm and a Swarovski80mm. This performance is only possible under very good viewing conditions. Even with the Pentax 100mm at 75 power at 10:00 am, it is “iffy” to see 6mm bullets at my range by 10:00 am. Don’t mortgage your house to buy an expensive $4000 optical in the hope of being able to see your shots at 1,000 yards. If the conditions are not perfect, you will be lucky to see bullets at 500 yards. Set up a remote camera that can broadcast a video image to a screen in your shooting station. We recommend the LongShot LR-3 2 mile UHD among the target cams available on the market. This modern target cam boasts an excellent resolution and an incredible range. The LongShot LR-3 is used in major ELR events. The LR-3 is listed at $899.00, but it is currently on Amazon for $800.99.
Tags: Distance vision, Kowa Longshot Targe Spotting Scope, Kowa Chromatic Aberration
