image scale porro vs roof

Guest · Posted: Sat Mar 11, 2006 1:06 pm Post subject: image scale porro vs roof

I got an roof prism spotting scope. Is there a difference in image scale (not FOV) between a roof spotter and a porro spotter? Also every time I zoom up the image is good, but I have to keep repositioning my eye with the eyepiece because iof the balckeing opf the edges. Can someone anyser these 2 questions please. Thank you Very Happy

opticsplanet.com · Posted: Sat Mar 11, 2006 1:21 pm Post subject:

Hi

60x is 60x, regardless of the optical system used to get it. Any instrument that offers 60x, will enlarge an image 60 times over normal.

Your second question is more a matter of the specific eyepiece you are using. Some eyepieces are very fussy about the positioning of your eye and even the slightest movement from the ideal position will cause the "blackening" you describe. if your eyepiece has an adjustable eyecup, try setting it at different positions to see if it helps.
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Guest · Posted: Sat Mar 11, 2006 1:30 pm Post subject:

Thanks I'm not sure if we are on the same track here. Let me try to explain. When I look through my spotting scope I can see more detail than my binoculars but the image is small (not talking about field of view). But when I look thorugh my 10x50 binoculars the image looks HUGE comapired to the scope. I can see more detail at a distance with the spotting scope, but the image in my brain is much bigger with the binoculars.. By the way the scope I am refering to is a Bushnell elite 20x60x70. Does this balckening out have anything to do with the eyepiece my bushnell uses? Do you think it will go away after I get to use the scope a little longer and get more familiar with using it. I hope this makes sense to you about the image scale thing. It's the best I can described. Your professional opinions are greatly apperciated thank you.

opticsplanet.com · Posted: Sat Mar 11, 2006 3:25 pm Post subject:

Hi

Not sure exactly what you are describing, but I suspect it is partly due to using one eye versus two eyes. Using two eyes with a binocular adds a 3-D effect that you do not get in a spotting scope. Using two eyes also makes for slightly better visual acuity since your brain is processing data from two sources. Lastly, using two eyes is a more natural way for the brain to process visual data, therby producing images that seem more comfortable.

Your binocular is also using different style eyepieces than your Elite. More sophistcated eyepieces, either on a spotting scope or binocular, produce more of that picture window effect - seems like you are up close looking through a window rather than back at the end of a tunnel, as things might appear in your Elite.

As far as the blackening, it is a matter of the eyepiece. Do you wear glasses when looking through your Elite? If so, the short eye relief on this model may be the problem. It will require precise positioning of the eye to see comfortably. Otherwise, it's just a matter of getting used to it.
_________________
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Your personal optics expert
Joanie (Jne) K
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Phone: (888) 263-0356
Fax: (847) 574-6820

Guest · Posted: Sat Mar 11, 2006 3:57 pm Post subject:

Ok let me try this. Say you take one of those cardboard rolls from a roll of toilet paper, close one eye, and look through it. This is similer to my scope . Now if I take a coffee can, cut the bottom out of it and look through with both eyes, that is what my binoculars look like compaired to my spotter. I just wanted to know if this "narrow effect" is because I bought a roof prism scope and not a porro. Sorry to be a bother but I know NOTHING about optics and this is the very first scope I have ever owned. But I do hope that my example with the coffee can and the cardboard roll gives you an idea of what I am talking about.

opticsplanet.com · Posted: Sat Mar 11, 2006 4:23 pm Post subject:

Hi

You are certainly not a bother and are always welcome to post here.

Yes, that is a good analogy and it is the result of both the eyepiece design on the Elite (a compromise to keep things compact) and using only one eye. I think you would gind this less of an issue on a spotting scope that used a very large eyepiece with a larger lens for viewing, a la the Swarovski, Zeiss, Leica and so on, but then you would not have such a nice slim scope. Best advice I can give is to go look through one of these premium scopes and see how it works for you.

Thanks for posting.
_________________
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Your personal optics expert
Joanie (Jne) K
http://www.OpticsPlanet.com
Phone: (888) 263-0356
Fax: (847) 574-6820

Guest · Posted: Sat Mar 11, 2006 4:44 pm Post subject:

Thanks for the reply. Unforntually I really can't afford a premium scope (sure would be nice) besides, I just got this bushnell. the only 2 scope's in my price range that I was willing to buy was the nikon sky and earth 20x60x80 and the celestron 20x60x80ed. I first eliminated the nikon because it's not waterproof, and the celestron becuase I didnn't like the build quality (IMHO felt cheap). My elite's build quality is very good. I REALLY DON't want to have to go back through all the trouble of sending the scope back, and getting another one that I don't like and having to send it back, etc, etc. I love the optics of this elite, i mean I really do, and if I knew for a fact that it is normal for a scope of this size, and price to have the "narrow view" then I would be happy. Even if I bought the Nikon or celestron would they have the same "narrow view" as the bushnell? If you told me to not worry, becuase almost all scopes in this price range, and size, all have the "narrow view" then I would be happy. I just want to make sure this isn't because my new scope is a Roof prism. The last thing i want to do is go through the aggervation of sending this scope back.

AstroBoy · Guest

Do you wear glasses?

You may be having a problem with eye relief. If you can get your eye close enough to the eyepiece, you shouldn't see that much of a difference. The farther your eye is from the eyepiece, the more constricted the opening will seem.

Guest · Posted: Sat Mar 11, 2006 8:57 pm Post subject:

no I forgot to mention i don't wear glasses. That's a good guess though. Thanks

GUEST · Guest

no I forgot to mention i don't wear glasses. That's a good guess though. Thanks Maybe Jonie will know the anwser to what I'm asking.

Guest · Posted: Mon Mar 13, 2006 3:06 pm Post subject:

Guest · Posted: Mon Mar 13, 2006 8:17 pm Post subject:

hi sorry if I am being a bother but the reason I keep asking this question is because I only have a few days left if i want to send back the scope. Sad

After that I will have to keep it.

AstroBoy · Guest

If you want another reply from Joanie, you may have to post as a new topic, as I think she assumed your question was answered and she moved on.

What does it look like if you use your binoculars and *close one eye*? Do you still have the impression that the opening is bigger?

Do the eyepieces have eyecups? If so, do the eyecups on the binoculars allow you to get your eye closer to the eyepiece than the eyecup on the spotter?