Sorry, I'm a bit puzzled. What's the difference between -4.0 and -4? I'm from China and 400 degrees of myopia. Should I choose -4.0 or -4 or 4?
82129
I think -4.0 and -4 are the same. If you are near-sighted, you should choose negative.
1770041
I am not sure if you are asking how low can you go as in is there lower then 1.8, BUT aperture can go as low as 1.2 which is EXPENSIVE. 1.8 is just fine if you are thinking cost effectiveness.
557872
If you wear reading glasses...the kind you purchase at the drug store, get the same magnification. If you don't need reading glasses get the 0.0.
1984672
both .12 and .2 ! if u want farther reach use the .12 but if u want accuracy then u use .2.,, i prefer using .2's
1645861
Paul, thank you. From the specs alone, I agree, but I think there must be some significant difference between the two sets. The only thing I can see from the specs is something about the eyepiece adjustment.
678606
Well, the f/2.8 is a much newer lens and is superior to the f/4 in many performance aspects (AF speed, accuracy, etc). Don't get me wrong, though. The f/4 is still a solid performer. Sometimes, the f/4 captures better photos in the f/4-f/5.6 range than the f/2.8 does in that range.Now, since you stated that weight is a concern for you, I'd point out that the f/2.8 is a whole two times heavier than the f/4. The f/4 is also half the price of the f/2.8.If you shoot in low-light or indoor, then the f/2.8 is for you. If you shoot outdoor and have plenty of light, then the f/4 is just as good. Well, the f/2.8 is a much newer lens and is superior to the f/4 in many performance aspects (AF speed, accuracy, etc). Don't get me wrong, though. The f/4 is still a solid performer. Sometimes, the f/4 captures better photos in the f/4-f/5.6 range than the f/2.8 does in that range.Now, since you stated that weight is a concern for you, I'd point out that the f/2.8 is a whole two times heavier than the f/4. The f/4 is also half the price of the f/2.8.If you shoot in low-light or indoor, then the f/2.8 is for you. If you shoot outdoor and have plenty of light, then the f/4 is just... » Read More Well, the f/2.8 is a much newer lens and is superior to the f/4 in many performance aspects (AF speed, accuracy, etc). Don't get me wrong, though. The f/4 is still a solid performer. Sometimes, the f/4 captures better photos in the f/4-f/5.6 range than the f/2.8 does in that range.Now, since you stated that weight is a concern for you, I'd point out that the f/2.8 is a whole two times heavier than the f/4. The f/4 is also half the price of the f/2.8.If you shoot in low-light or indoor, then the f/2.8 is for you. If you shoot outdoor and have plenty of light, then the f/4 is just as good. « Show Less
187072
I was not sure when I first looked, then I realized the different models had different temperature capabilities, and if I recall some of them had different focus ratio as well.Keeping this in mind, Read descriptions carefully, the differences will be more apparent!
766794
Blue lenses are excellent for all types of light. We currently have the +2.5 in stock but not the +3. Hope that helps.
107802
That equation is correct... it is called spherical equivalent. With a -3.00 sphere and -3.25 cylinder, your spherical equivalent is -4.50. Keep in mind this will give you pretty decent vision - good enough to see at a reasonable distance, but this will not be equal to a full spectacle prescription. I am an optometrist.
15899
The lenses in these are not as sophisticated as the ones you would get from an optometrist. Consider the price! As a rule, I normally go down rather than up, so in your case I would get -3 (rather than -3.5)
478612
Noob question, but does anyone know what glasses will be compatible? I don't want to wait til July, but I also don't want to buy an adapter on the 18th wih no glasses. Thanks!
187070
I was not sure when I first looked, then I realized the different models had different temperature capabilities, and if I recall some of them had different focus ratio as well. Keeping this in mind, Read descriptions carefully, the differences will be more apparent!
2121873
I did mine at least 4 months ago. I noticed the lenses started to have a haze/showing sign of yellow already. Understand, I live in Houston, Texas, where we got sunshine most of the time, including winter.
47633
So you have the option to have a different strength for each eye? I did not when getting swim goggles and went with something in the middle, so in your case, either 2 or 2.5. I have one eye too strong, one not enough, but that does not seem to be a problem.
1372697
Dennis, It depends on what you deem effective. � I've shot mine wide open at f/4 but it may be a little soft in the corners for your liking, doesn't bug me. As long as you have plenty of light f/5.6 is pretty amazing with your subject at about 40-60 feet. f/8 is great as long as you have either the sun or if you don't mind pushing the ISO to keep you shutter speed above at least 1.5x the focal length. I find 1/500th-1/800th ish is plenty, and I don't have the hands of a surgeon by any means. Some of my sharpest images have come from this lens.On Full Frame I use it with the Tamron 1.4x TC to achieve the length you have already with the D7100 beinng DX. Dennis, It depends on what you deem effective. � I've shot mine wide open at f/4 but it may be a little soft in the corners for your liking, doesn't bug me. As long as you have plenty of light f/5.6 is pretty amazing with your subject at about 40-60 feet. f/8 is great as long as you have either the sun or if you don't mind pushing the ISO to keep you shutter speed above at least 1.5x the focal length. I find 1/500th-1/800th ish is plenty, and I don't have the hands of a surgeon by any means. Some of my sharpest images have come from this lens.On Full Frame I... » Read More Dennis, It depends on what you deem effective. � I've shot mine wide open at f/4 but it may be a little soft in the corners for your liking, doesn't bug me. As long as you have plenty of light f/5.6 is pretty amazing with your subject at about 40-60 feet. f/8 is great as long as you have either the sun or if you don't mind pushing the ISO to keep you shutter speed above at least 1.5x the focal length. I find 1/500th-1/800th ish is plenty, and I don't have the hands of a surgeon by any means. Some of my sharpest images have come from this lens.On Full Frame I use it with the Tamron 1.4x TC to achieve the length you have already with the D7100 beinng DX. « Show Less
123475
Good question. The difference is better optics at 1.4f stop, or wide open. If you shoot wide open all the time, then you might want to consider that extra expense. On the other hand, if you shoot occasionally wide open, this lens (400) is great and I have liked shooting with it.
1140833
4.04 is from a specific vendor that I assume has worked something out with Amazon to be the default vendor for these glasses. If you look a little lower down you'll see where it says "New at $1.69" click on that link and other distributors will come up at a lot lower price. BTW if you want to buy some click on Aretex's link and order from me and I'll throw in a free pair of Radians Crossfire safety/sun glasses.