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Old Oct 8, 2005, 1:11 AM   #1
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Let me explain a little about my situation. I work on the east coast, on two inland bays, that are connected together to form one body of water. For practical purposes, the longest stretch of water that I would need visually scout would be about 8 miles. What I need to do is this: Let me use a liscense plate as the objective in each case since it is similar in size to what I'd actually be viewing. I will not be needing to take pictures with this scope, only to view a target and maybe get closer. I'll be using this scope sometimes from a boat (only a little choppy on occasion) and sometimes from shore. What I'll do first is scour the whole body of water until I happen to spot the objective, then I'll zoom in on the objective and examine it more closely through the scope.
Now let's say that there are two liscense plates, both standing upright and visible, about a foot or two above the water line. One plate is only one mile away and the other is eight miles away. I'd like this scope to enable me to view both of the plates so clearly that I can read off the numbers of each plate.
So what I need is a spotting scope, binocs, or whatever else is best suited for this type of viewing at the most affordable price. I'd not be using this scope for eight hours a day. When I did need to use it, I would probably only use it for a half hour at the most. After searching the internet and learning a little about binocs and scopes, I'd be willing to sacrifice weight for viewing quality. Viewing quality would be the most important feature of this device (that, and being able to keep the same viewing quality from one to eight miles in distance). I welcome any input, advice, suggestions, links, etc. from anyone who has the experience to know what kind of optical device & specifications I should be looking for.
Just from owning a relatively cheap pair of binoculars (Jason model# 1113f, mercury 10 X 50, field: 288ft at 1,000yds, fully coated optics), and from what I have learned from the internet I THINK that I am looking for the following specs but I'd like some experienced opinions to what I need or if I'm even on the right track with the specs below:

One mile = 5,280 feet = 1,760 yards. The two example specs below are just my assumptions of what I might need.

10 mile binocs: 10 X 1760 yards = 17,600 yards. 176 X 50 = 17,600 yards away looks like 100 yards away.
(field of view at 1,000 yards = 20 feet, this is too small??)

8 mile binocs: 8 X 1760 yards = 14,080 yards. 140 X 50 = 14,000 yards away looks like 100 yards away.

NOTE - for an optical device that is able to view 8 miles away in some detail, I'd probably want a bigger field of view than a 50mm objective lens

Thank you very much for your input on this matter.

Sincerely, Steve
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Old Oct 8, 2005, 8:21 AM   #2
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Steve:

I am no optics expert by any stretch of the imagination.

But, have you looked through more powerful scopes while trying to hold one steady (espcially on an unstable platform like a boat)?

With a narrow angle of view, it's pretty tough to findwhat you want and hold a scope steady on it, even with a stable platform, much less without one.

Most scopes and binoculars will publish their angle of view and/or field of view at a given distance (most often 1000 yards), and the objective size doesn't necessarily mean anything (i.e., a larger objective and associated aperture is needed to let in more light, not necessarily to give you a wider angle of view).

It's been my experience that anything that's much more powerful than what you're using is going to be very difficult to hand hold, but you'll want something of higher optical quality to make the image clearer and brighter (prism type, optical quality, coatings, etc.), especially in less than optimum lighting conditions.

Also, you'll need to be viewing from a distance of more than 40 feetabove the water, just to see 8 miles (unless what you're viewing is higher up off of the water). If you're looking at some bouy marker or something, it's not going to be higher up.

You'll need a pretty powerful scope just to be able to readnumbers from a license plate at one mile, much less 8 (even if you could get high enough to see that far), and unless the platform is stable, I just don't see how you'd manage it, even if you could finda scope that's powerful enough and bright enough to do it at a price you could afford and a size thatyou could live with.

There is a reason that you see heavy pedestals acting as a platform for some of the larger binoculars you see (look at the ones on U.S. Navy vessels as an example, and those are nowhere near as powerful as what you're looking for).

2o feet field of fiew at 1000 yards? No way you're going to be use something like that thing on a non-stable platform, if you could even find something that good (not to mention it's size and/or weight to have any chance of seeing a bright image with it with decent optical quality).

Heck, some of the spotting scope manufacturers that have lenses that act like a 1900mm lens on a 35mm camera from an angle of view perspective, try to impress by letting you know you can read license plates at one mile away, and you want to read them at 8 miles away, from a non-stable platform?

Again, I know just enough about optics to be dangerous, and perhaps some of our more knowledgable members may tell me I'm nuts.

But, I just can't see it, even if you had some form of stabilization (and some binoculars, etc. do now).


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Old Oct 8, 2005, 3:18 PM   #3
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I own one of the best commercial available spotting scopes made.
http://www.bhphotovideo.com/bnh/cont...goryNavigation
Swarovski ATS-80 with a 20-60x eye piece.

It couldn't do what you want. You've got curvature of the earth issues at 8 miles that will cause you some trouble I bet (which Jim covered.)

There is no way you'll find a pair of binocs that will do 8 miles and use it to read something that small. 1 mile is going to be hard enough. You'll see the object (if it's tall enough, or you're high enough) but you won't be able to read something the size of a license plate I don't think.

You're only chance will be to use a telescope that works for terestrial use. They won't be water proof, they won't be designed for easy carrying, but they will probably be very cheap (compaired to spotting scopes, mine costs around $2,500.) And you can get them with staggering magnification. You don't be able to use it on a boat, because no boat will be steady enough for you to read something in the view. I have that problem even with my spotting scope, and the telescope will be more powerful then them.

You could look into binocs that have built-in image stabilization. I know some people love them (Canon makes some.) But I don't know if they would be powerful enough.

If you need to do this near dawn and dusk, or in low light, that will cause you even more problems because it will be harder to resolve details.

Eric
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Old Oct 8, 2005, 11:17 PM   #4
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Thanks JimC and eric s. I didn't even think about the "curvature of the earth" issues, thanks for pointing that out. It looks like I'll have to do my scouting from shore, maybe one day a week. And it looks, so far, like I'll want a telescope that can be used for terrestrial applications. I do have a very cheap telescope now. It's a bushnell, one of those plastic things that I got free for redeeming a bunch of upc's. It works good enough to give me hope. From shore, I can spot a fellow clammer or fisherman about two miles away but, with the cheap lenses, most times I cannot tell whether it's a clammer or fisherman, let alone if they are catching a decent amount of clams or not (that's my main objective, to find out where the best clamming spots are). It's a Bushnell, Deep Space Series, 420 X 60 Refractor Telescope, model 78-9512. The objective lens is 60mm, it has a little tripod (I mostly use it from shore in the back of my truck). It comes with a 20mm eyepiece, a 5mm eyepiece, a 1.5X erecting lens, and a 3X barlow lens. So far, I've only been able to spot other objectives far away on land with the 20mm eyepiece attatched to the 1.5X erecting lens. I think I'm going to get something that is 3 times as powerful as this setup, but with better optics, etc. First, I'm trying to narrow in on exactly what I need and then I'm going to try to experience it first hand before I actually make a purchase. It'll probably be a small fortune but it'll end up saving me time and fuel in the long run. Thanks for all your replies and I welcome anyone else to chime in as well. Thanks alot guys! Steve
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Old Oct 9, 2005, 9:02 AM   #5
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I couldn't figure out what you were trying to accomplish. My imagination was going from a Military/Shoredefenseapplication to a terrorist application (hoping it wasn't the later).

You want to see where the best fishing spots are, huh? ;-)

There can be a big difference in Optical Quality between scopes, binoculars, etc.

Although it's not the same thing, there's a saying down here "in the South" (and probably elsewhere, too). It's better to have a $500 scope on $50 rifle than a $50 scope on a $500 rifle. ;-)

Perhaps that's an exaggeration (depending on the quality of the scopes and rifles involved), and there is more to it with a rifle scope (not only optical quality and things like contrast and brightness, but usable eye relief, type of adjustments and not having any "drift" from where you've got the windage/elevationset,etc.). But, there is a lot of truth to that. You're just throwing away your money on most of the cheap ones.

You see the same thing with cameras, too. Someone will buy the latest and greatest (and oftenexpensive)Digital SLR and then buy a cheap lens for it, complaining about the quality of the camera because their images are coming out soft andthe camera can't "see" to focus in less than optimal lighting.

FWIW, I bought about a dozen pairs of binoculars some years back as Christmas presents. These were all cheap binoculars at bargain basement prices (closeouts on brands that were cheap to begin with). Some wereunder $10 on sale. But, I figured they'd make good Christmas presents for the younger kids, grandkids, nieces and nephewsthat we were buying presents for. LOL

I bought several different kinds, and to my surprise, some weren't too bad (even though they were very inexpensive). But, that's the exception versus the rule.

I got them all from Sportsmans Guide via some of their "Daily Specials" around the Christmas season. Sometimes you'll see items they have left in small quanties liquidated this way at a fraction of their original prices. I used to do all of my Christmas shopping there (so my relatives all have lots of camping/fishing/hunting related gear they've received from me over the years for Christmas, not to mention clothing like boots, jackets, sweaters, shirts, etc.). ;-)

They have very high quality optics (Ziess, Swarovski, Steiner, etc.) as well as the "mid range" brands like Nikon, Burris, etc.), and the cheap stuff with brand names you've never heard of (and you often see the same cheap optics being sold under multiple brand names).

Just like camera lenses, some scope manufacturers tend to have a wide variety of optical quality available within theirproduct line, too. Their low end may be junk, but their higher end may be OK.

Here is a "no name" pair of Binoculars that are about 3 times as powerful as the ones you are using for $59.95, and they have zoom (which can be abad thing).The view probably looks like a pair of $59 binocs, too. ;-) You never know about these things, though.

http://www.sportsmansguide.com/cb/cb.asp?a=226228

Here's a pair for only $29.95:

http://www.sportsmansguide.com/cb/cb.asp?a=160687

Heck, I even see some Binoculars with the amount of power you're looking for (and even the zoom you seem to want, since you mentioned "zooming in"). Here's an example with a 21 feet Field of View at 1,000 yards:

http://www.sportsmansguide.com/cb/cb.asp?a=207032

But, the optical quality probably leaves a lot to be desired (especially since it's a zoom lens design), and I wouldn't want to try and hand hold something like that.

Here's another similar pair (same field of view at maximum magnification), with a larger objective, too. 3mm eye relief? I hope that's a misprint and it's really 13mm (but you never know about these things). LOL

http://www.sportsmansguide.com/cb/cb.asp?a=198671

Here's another one with even more magnification (and some seem to have the BaK-4 Porro prisms, which are supposed to be better quality compared to the Bak-7 desgin).

http://www.sportsmansguide.com/cb/cb.asp?a=220762

Personally, I wouldn't eventhink about buying anything like these for critical applications, unless I had tried them and compared them to higher quality optics.

You'll find a lot of junk around, with specs designed to sell them to people that think "more is better" (even though the optical quality may stink, and the liikelyhood of them being very usable "hand held" is virtually nill for many uses).

You'll see an "Optics" Category here, where you can select the type you're looking for at the top of the page:

http://www.sportsmansguide.com/brows...amp;bt=N&s=

You also see more stuff in the "daily specials", and can find stuff in the individual catalogs that is missed by the search engine. You also sometmessee the exact same item at different prices (sometimes with huge differences), depending on the catalog you're looking in. The search engine isn't going to find the lowest price for you. ;-)

The last scope I bought for myself was a long eye relief Burris with a whopping 2x power rating, using a custom "ahead of the bolt" scope mount on a modified "heavy" target barrel.

I've got more powerful scopes. But, my point is, you don't want any more magnification than you really need. Otherwise, they're just more trouble than they're worth trying to find your target with one and hold it on it for the shot (especially hand held), even if they are of good optical quality.

Trying to use one of these high powered pair of binoculars from a boat, even if by some fluke the quality is acceptable? Not me. ;-)

OK... enough rambling.

Hopefully, since this thread is now in the Digiscoping Forum, you'll get some suggestions from members that know a LOT more about optics than I do.

Eric probably has the right idea (a more powerful telescope) for your type of application (just not from a boat). LOL


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Old Oct 9, 2005, 6:42 PM   #6
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Ah, so you're trying to spot boats. That is another matter entirely. I still don't know if you'll be able to see them at 8 miles, but they are much bigger than license plates!

Lin Evans, who runs this part of the forum, is a fan of this older model telescope:
Meade ETX-90 (90mm)

I don't know how good it is, but I have faith in him that he wouldn't suggest it if it wasn't fairly good, easy to move around and easy to setup. He has suggested the price is around $200, which isn't too bad.

One thing to know is that the eye piece matters as much (if not more) than the telescope. So make sure you are getting the right (powerful enough, good enough quality) eye piece. It is my understanding (correct me someone!) that it is the eyepiece which really gets you the optical power. The telescope is a fixed power, and the eye piece adds magnification to give it the real reach.

I currently own (I was given as a present) a pair of Swift Audubon "Wide Field" binoculars. They are not cheap, but not "high end" by binoc standards. They cost around $300 or so. I find them to be very good:
http://www.bhphotovideo.com/bnh/cont...ughType=search
You can certainly get better, but I've been happy with them and recomment them to others. The company has also been good to me in the few repairs I've needed.

Eric
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Old Oct 11, 2005, 12:52 AM   #7
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Thanks for all the info. I'm saving all the responses, links, etc. in a text file. I was looking at a map of the bay and I've refigured that if I can see if a wading clammer (one who is overboard with a hand rake) is consistently pulling up a basket that is at least half full at four miles away, this would satisfy me. I also tried using my cheapy telescope without the tripod but more or less aiming it like a rifle. I wouldn't want to do that for too long. I think I'm going to fashion a monopod stand that swivels, that I can stab in the sand when I am wading for clams in the water and need a closer look at something. Right now, I am learning a bit more about eyepiece lenses, like how to figure out which sizes would probably work best with whatever objective lens size, focal length, and distance that I'd be working with. I also found that using the diagonal mirror helps image quality (in one case anyway) even though it doesn't magnify the image any more than without it.
My current puzzle is that I am not sure if I am understanding the numbers enough to make at least an educated judgement on size upgrading. For example, here's what I've got now:

420mm X 60mm refractor telescope
20mm & 5mm eyepieces, 1.5X erecting lens, 3X barlow lens
Objective lens = 60mm
Main tube focal length = 700mm (this is what the book says)
Aperture = 60mm
Focal Ratio = 11.666? I calculated myself?
Exit pupil = 60? I calculated myself?

I like its overall view best with the 20mm eyepiece and the diagonal mirror (about 35X magnification). Just using my limited intuitive understanding of the specs, etc., I've been trying to come up with what would (in theory) give me a view four times as strong. So far, I've come up with:

Magnification = 140 X
Main tube focal length = 2,800mm (or close to it)
Field of view = (enough to see a person clamming at 4 miles)
Eyepiece = 20mm (just a comfortable / reference size)
Objective lens (aperture) = 80 - 100mm
Focal ratio = 28 (I think I'd want this number to be smaller, thus, more effective optics??)
Exit pupil = 100?? (I don't think this is the correct number based on the data above scaled up four times as strong, I've read that an exit pupil of around 7mm might work best because anything more might be lossed and not processed by the human eye?)

That's what I come up with based on what I've been reading so far. 140X doesn't seem too far fetched. 2,800mm main tube focal length seems a little bit like science fiction. I think I messed up calculating the focal ratio; one site said that all else being equal, a ratio of 6 is better than 8 and 12 is about a medium range. I also think I miscalculated the exit pupil (I don't really know what that is anyway, I only know that when you look through the scope, the view is either good or bad). I'm also looking to see if I can buy eyepieces near where I live. They shouldn't be that much and I figured out that a 7mm or 8mm EP with the 1.5X erecting lens would probably do me fine. Either way though, I'm hooked on learning about the numbers and actually doing the scoping thing. Soon, I hope to start getting first hand glimpses through some scopes that will help me out next spring when everyone starts clamming again. I'm going to check out the Meade ETX-90 and some others by Orion, Celestron, and Questar, & any others that I can get my hands on.
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Old Oct 11, 2005, 11:22 AM   #8
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Although you've probably already thought of this, it sounds like you really need to take weather proofing seriously. I know that most/all spotting scopes (used for birding, but other things too) are weather proof. I know that my Swarovski is. I bet that most of the telescopes are not. So make sure you check on that.

Obviously it has to have enough reach or it won't fit your needs. But you'll be using it in an environment that most are not intended for. So you might want a good pair of powerful water proof binocs (maybe image stabilized, but that requires a power source which can run out) that you can put on a monopod of some kind. That you'll use on the boat or in low later. And the spotting scope or telescop will be for land use.

Just a thought.

Unfortunately I can't help you very much about the optics. I know very little about that area. I would like to think you could find something out on other web sites. Maybe even the scope maker's web site. Personally, I'd think they'd want an informed public... then they'll buy what they need, be happy with it and speak well of them. Word of mouth is powerful.

Eric
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