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What was going on with my eyes? |
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slowr1der
Optics Apprentice Joined: March/25/2010 Status: Offline Points: 247 |
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Posted: February/05/2011 at 12:56 |
I went to do some shooting yesterday with a friend. I took my rifle that wears a Nikon Prostaff 3-9x40. When I got there, the first thing I noticed was snow on the ground. No big deal, so I set the targets and everything up and got ready to shoot. When I looked through the Nikon Prostaff, I immediately noticed that it was like I was getting blue flare off of the white snow. I'm not sure if that's the best way to describe it or not. It just looked like the lines of where the snow was were very blurry and blue around the edges of the snow. I also noticed, it looked like after looking through the scope at the target for a couple of seconds it looked like the bullseye was getting really blurry. I'm not sure if it was because I was being distracted by the blue flare all over the scope or not. It made it very difficult to shoot. I've not done much using this scope in the snow before so this was new to me. I used it hunting in the snow one day, and shot a deer with it, but the deer was running at full speed so I threw the gun up and shot the deer and it was a very quick shot so I didn't have time to pay attention to if what the snow had looked like.
I then looked through a cheap Bushnell scope, and it didn't do it at all. The glass of the Bushnell isn't normally as clear as the Nikon, but it didn't have any of this flare. Any idea what's causing this? I'm not sure if it's my eyes, or the scope, or that my eyes just don't work well with the scope. This was the first time I've ever seen anything like this, so I wasn't sure what it could be. |
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Klamath
Optics Master Joined: May/20/2007 Location: United States Status: Offline Points: 1308 |
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Nothing is wrong with your eyes. What you are seeing is a phenomena known as Chromatic Aberration (or just CA). You describe a textbook example of what it looks like, and bright snowy conditions like you describe are perfect for it to show up. Some people are pretty sensitive to it and it can be an expensive distraction because it can take several good optics to find one you can live with. It does not show up for others, and some can ignore it. It sounds like there may be some focus problems with the scope too. But you may have been squinting enough at the target that you were getting some eye fatigue or parallax was starting to give you a problem. I think I'd see if I could ignore it unless you are going to use it a lot in the bright snow.
Edited by Klamath - February/05/2011 at 22:55 |
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Steve
"Everything that can be counted does not necessarily count; everything that counts cannot necessarily be counted". William Bruce Cameron |
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slowr1der
Optics Apprentice Joined: March/25/2010 Status: Offline Points: 247 |
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dsr
Optics Apprentice Joined: May/31/2007 Location: United States Status: Offline Points: 244 |
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Would a colored camera filter help eliminate some of the effect he is describing – if so what filter/filters should he try? dsr |
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cruft
Optics Apprentice Joined: November/20/2005 Status: Offline Points: 88 |
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Chromatic aberration is the major reason why an uberscope costs three or more times what an adequate scope will. A lens is made up of two prisms either apex to apex in a minus lens or base to base in a plus. In a prism, think the pyramids, white light is bent toward the base and separated into the color spectrum. This is what you're seeing. Google 'chromatic aberration'. There are two ways to compensate by using an APO (google it) and/or HD or ED glass; that is fluorite/high density/extreme dispersion. Perhaps one of the sales reps will kick in with a follow up comment. Japanese glass is generations improved but probably viewed as a trade secret as what is used in scopes. Coatings vary tremendously as to effectiveness and cost while producing seemly minute percentage gains. While on paper these gains appear small, say going from 95% to 98%, the increase in visual comfort and clarity is not found in just the numbers. It is stated that there is no reason to be concerned with the origin of glass but the country of manufacture does not describe the level of quality. Very high end glass; nikon, pentax, sieko (not limited to) is probably equal to German glass ie; Ziess & Schott but you can be sure when you get a scope such as IOR you get Schott not some lesser lens as MAY be the case with Vortex. My comments may not be absolutely accurate so where incorrect please point out specifics so we all can appreciate what goes into the design & manufacture of these magnificent instruments. |
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koshkin
MODERATOR Dark Lord of Optics Joined: June/15/2004 Location: United States Status: Offline Points: 13182 |
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Since we are on the whole glass thing again... Schott makes all sorts of glass, some very consistent and some not so consistent. When a scope maker simply says that the use Schott glass it means absolutely nothing. Glass is made to a particular price point. Besides, when you say "Schott glass" which Schott factory are you talking about? They have factories in Europe, US, China, Korea, etc. Since you think that "a country of manufacture does not describe the level of quality", is Chot glass from Korea superior to that from China? What do you think? Back when I was in the microoptics business, we were using some rather specific glass types for athermal interferometers we were trying to make. I had to dig through huge databases of different glass types made by different companies. I ended up zeroing in on Schott and Ohara. In the end we went with Ohara because they has some specific glass-types we needed, but as far as quality goes, for the same money, there was no difference between the two. Moreover, I suspect that for the same money other glass makers (Kyocera and Hoya, for example) can also make excellent stuff. It really comes down to ordering the right type of glass shaping it properly and making good quality design. Specific glass types used in a particular optical system are indeed, a trade secret more often than not. ILya
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cruft
Optics Apprentice Joined: November/20/2005 Status: Offline Points: 88 |
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Ilya, This is the point. You are the man. Actually our man. The way costs can easily be constrained by adjusting materials we, ok me, want Snow White to test & review what's out there. So Zeiss may substitute a slightly lesser lens or one whose coatings are not as good but may keep the same designation. As you must work and time is money so therefore the ONLY way for you to function is by the loan of scopes from forum members and certainly not the provision of them by the manufacturers. It is so easy for a company to downgrade materials and keep this from the consumer under the rubric of 'trade secret'. Hope you can keep yourself untainted from the corporate types who thru personal relations, and they are trained in this, expect value for service. This is never openly stated just understood. No sense in railing against this, it's the way of the world.
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demo_slug
Optics GrassHopper Joined: November/11/2010 Status: Offline Points: 26 |
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I get CA on my Vector viper, and on my Nikon monarch. and that is pretty much the top of my budget. I just decided that I'm sensitive to it. and once I got past worrying if something was wrong with my scopes, it has stopped bothering me. and it doesn't effect getting bullets on target. which my scopes do very well
To some level, I get the same effect with binos and spotting scopes, but If I get the focus "perfect" it goes away.
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koshkin
MODERATOR Dark Lord of Optics Joined: June/15/2004 Location: United States Status: Offline Points: 13182 |
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If a company changes something about a scope half way through its lifecycle, I will not catch it. I look at one or two samples. I do not have the bandwidth to look at a statistically significant number of samples. As far as borrowing scopes from forum members goes, while I do that a fair bit, that does not always work well, since I need to get my hands on product that is in "new", or as close to it as possible, condition. Considering an occasional screwed up scope I get directly from manufacturers, I doubt they cherry pick them. Also, a number of scopes I test comes from retailers who are rather agnostic of which one I like more. For example, if SWFA sends me a Minox and a Meopta to look at, they could not care less which one I recommend. They will gladly sell you either one. ILya
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PopCulture
Optics GrassHopper Joined: January/11/2011 Status: Offline Points: 15 |
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This may sound crazy. But did it help with sunglasses? Do you use sunglasses when using a scope. Here's a link to a giant compare to find the best deal website. They have sunglasses. <looked like spam to me> if you need them. This is a first and last warning. No spam. Edited by koshkin - February/23/2011 at 13:59 |
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dsr
Optics Apprentice Joined: May/31/2007 Location: United States Status: Offline Points: 244 |
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Anyone, Would something like Alumina Intensifier Kit from Leupold (maybe different filters) help mask some of the effects of chromatic aberration? Thanks, dsr |
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Bitterroot Bulls
Optics Master Extraordinaire Joined: May/07/2009 Location: Montana Status: Offline Points: 3416 |
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Nope, won't help. What will help is a really nice riflescope with extra-low dispersion (ED, XD, HD) glass in the objective. Riflescopes seem to be pretty prone to show CA. For the record, my Vortex Viper shows CA, but much less than other similarly priced scopes. My Swarovski Z3 shows even less, and Swarovski does not advertise ED glass in its construction. |
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-Matt
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Smokey53119
Optics Apprentice Joined: November/02/2005 Status: Offline Points: 165 |
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What was going on with my eyes?I have a hunch you may be going blind, as in "stop that or you will go blind" :) |
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dsr
Optics Apprentice Joined: May/31/2007 Location: United States Status: Offline Points: 244 |
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Bitterroot Bulls, Thanks, nice to know that some of the effects could not be “cleaned up” by using filters. My first spotter was a very cheap Tasco 20-60X60 (60mm-I think) that I purchased because it had a desktop tripod that has screw adjustments for traverse and elevation. The tripod was worth more than the scope. I think that spotter has every optical fault that can be named. I will have to get that spotter out again just to see how many faults I can find in it. Thanks, dsr |
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