BEST spotting scope?

[dreever]

I think Bill said what he had was about 63X. If that's so I can turn my zoom down to about 63 the others can stay at 60X and the 85MM Zeiss perhaps turned down to match Bills since I'm not sure where that 85MM falls with the eyepiece set at 60. I'd guess somewhere around 65 or so.
I know Bill mentioned getting another eyepiece, but I don't know what he has in mind.
I'd like to try the fixed 7-XW and/or the 10-XW eyepiece on my big Pentax to see how much sharper they would be. Like I said though at about $320 a pop I think I'll just have to wait till I see someone with one on a Pentax and see if they want to do the switch comparison.

Danny

 

[tripcrow]

Looked through some spotters at today’s St. Thomas match. I honestly think the Celestron MAK130 as it came is better than my 50X Kowa TSN822M which I sold at today’s match.

At the match I borrowed an eyepiece from the Mifflin area gentleman that has the Meade 125 that got me to thinking on these astronomical scopes. His eyepiece was only a slight optical improvement over mine, Japan made Celestron eyepiece vs. China I think, and neither of us had anything less powerful than those 32,63X). The mirage was so bad today that it was very hard to see at 400 and my Weaver 36X because of its lower power was near as good much of the time.

While I know a variable is the way to go for a single all around piece. I’m now leaning towards a good single 40x power eyepiece just to deal with conditions like today. The 63X worked more than good enough under overcast skies while load testing 22 cals @ 400 meters Thursday evening. And I can’t imagine ever needing anything more powerful. The eyepiece really seems to be the weak link in the Celestron as it comes. I’ll try and make my mind up by Monday so the new eyepiece should be here Wednesday,

Dan., I’ll email you. I’m out of commission weekday mornings for the next 4 weeks babysitting while the wife teaches a couple summer classes. But I still may be able to get there for a little, while the kids are at swim practice. Depends on how my 6 yr old behaves. You forgot Steve and Gene’s Leicas which ought to be there Thursday also.

Edit: picked up a Celestron Ultima 100ED Spotting Scope 22-66x Zoom Eyepiece that hasn't ever been out of the box today in my Kowa sale deal and we could throw that in the mix too.

 

[patgblue]

Will add my two cents worth.Just received the celestron C130MAK.Nice cary case and nice looking unit.Not quite sure why the spotter on unit spots upside down but still reading about unit.C130MAK was 299. with free shipping.TeleVue click zoom 24-8mm and the Radian ERD-5.0 5mm,400x will arrive Monday.Price for lenses were 224. each and 8.00 to ship from Sun Adorama.com and they stated that I have 30 days to return the lens that doesn't work out.I will do testing late next week and give my report on spotter and my preference on lens.I have used most of the upper end stuff and am excited to see how a lower end" price wise" product will work.Seeing 6mm holes out to 600 or whatever it will do.I will do most of my testing @ 400yd.Will give report next weak.I will be needing a stand.Ewing, Ray-Vin, Davidson star-d, any one have any suggestions for the large heavy Celestron please post or email. Thanks Pat

 

[Fred Bohl]

Pat

I find the alignment scopes to be near worthless so typically do not bother with them. The inverted image is the normal view for amateur astronomers and is what you will get via the right angle eyepiece port,best for astronomy) so the alignment scope matches that view,same for either Meade or Celestron). For spotting scope use you need to use the erecting diagonal in the back port and flip the mirror down. With the eyepiece in the diagonal you will get an erect,conventional) image. Maybe it is just practice but I have no trouble finding the target without the alignment scope.

My lens testing has been done with both the C90MAK and C130MAK using my Sinclair International 06-3200 clamp to bench unit, a borrowed Ray-Vin Fstand free standing bench top stand and a nice stable Welborn tripod with a pan and tilt head. The best stability to date with the C130MAK,10 pounds with an eyepiece) has been with the Sinclair Stand clamped to the shooting bench. The Ray-Vin Fstand is good on a concrete bench but tends to move a little too much on a free standing wood bench. The photo tripod is fine for testing but not for bench shooting.

We only have one nearby 500 yard range so I have not been able to get there to test under good seeing conditions since starting the TeleVue with Dioptrx Astigmatism Corrector testing. They all,8-24mm, 5mm, 6mm and 10mm) work fine at 100, 200, 300 yards at local ranges under both good and hazy conditions for both the C90MAK and C180MAK. Mirage has been very bad with our hot weather after noon so over 200x then is tough. The only test I managed at 600 yards was a non shooting one from the tripod in the park across the street early one morning before a shower. With very good seeing and the C180MAK, 6mm holes were easily resolved at 200x, 250x and two just touching each other were resolved at 400x.

 

[Fred Bohl]

To further support Danny on the problem of eyepiece quality and its impact on comparisons, Take the two brands I have recommended, TeleVue and Vixen, if you were to compare the same focal length eyepiece of each in the same scope you would find the TeleVue to produce a better quality,sharper edge to edge, better color fidelity, and a little brighter) image, but it would have a larger field of view than the Vixen do to a different internal design. In our application the Vixen may provide a more useful image as the smaller field of view reduces the irrelevant data allowing the brain to concentrate its image analysis capability on the target image.

Re Field of View -- A larger objective does not necessarily yield a larger field of vision. For a given eyepiece and scope design, a larger objective will usually produce a smaller field of view.

Let us take Dan's two Pentax scopes from the review. If both used the Pentax XF Zoom,24-8mm). On the 80ED,focal length = 504mm) that eyepiece yields 21-63x and 108-57MOA field of view. On the 1000ED,focal length = 624mm) that eyepiece yields 26-78x and 90-48MOA field of view,Pentax specs).

If both were adjusted for 60x magnification, the field of view would be 98.4 MOA for the 80ED and 75.5 MOA for 100AE. Also note that the eyepiece focal length settings would be 8.4mm for the 80AE and 10.4mm for the 100ED. Further, the exit pupil size would be 1.33 mm for the 80ED and 1.67 mm for the 100ED. All of these yield higher effective resolution and improved target visibility.

 

[AckleyImproved]

I use a Zeiss 20-60X85 spotter, and all I can say is that I am glad that I spent the extra money.

At the time, I never intended to spend the amount I did, but after looking through numerous spotters, I settled with what I believe is the best.

It is very clear and sharp.. to the point like it does not feel like you are looking throgh a spotter.

I have looked through many a brand of spotter at comps, but I agree all the top end spotters really do have the edge!

Cheers
AI

 

[Fred Bohl]

Danny, Bill, and Pat

When I first replied to your query Pat, I was attempting to offer a solution to the part about "Is there such a thing as seeing 6mm holes at 500yrds?" and not attempting to offer the "top spotter".

Like all the choices we make in selecting equipment, the optimum,performance, usability and price) selection depends on the goal. If I were shooting Hunter Benrest,Max 6x scope) and thus needed a spotting scope every shot, I would probably select the Pentax 80ED based on the results from your review Dan. Since I typically use 36x scopes, I don't need a spotting scope out to 300 yards. However I want to see those 6mm bullet holes out to 500 and 600 yards under any reasonable conditions and out to 1000 yards under very good seeing conditions.

That is the territory of high resolution and high magnification. The required 100mm to 180mm objective diameters and 200x to 400x magnifications needed together with portability calls for another type of scope design. The optimal design for those specifications is the Maksutov-Cassegrain with its large apertures and long focal length for its size and weight.

Dan, your Pentax 100ED would probably do well in very good or better seeing conditions at 500 and even 600 yards if you could get the magnification higher. I would either use the TeleVue - 5X Powermate - 1.25" [TE-PMT-5126],$195 at OPT) with you zoom or the Vixen - 2.5mm Lanthanum LV Eyepiece - 1.25" [VX-3714],$100 at OPT) alone. IF you want to stay with the better quality Pentax lenses then I would use the Pentax - 2.5mm XO 1.25" Eyepiece [PE-XO2.5],$300 at OPT) as the XO has a narrower field of view,44deg) about the same as the Vixen,45deg) while the Pentax XFs match the TeleVue Radians,60deg) and XW series are even wider,70deg).

For target analysis higher magnification and narrower fields of view produce more useful images. When selecting lenses this should be considered in your selection.

I invite you to review and of course comment on my related paper at http://www.twincityrodandgun.com/PDF%20files/ScopeRes-Mag1.pdf and the calculator at http://www.twincityrodandgun.com/ScopeResCalc/ScopeResolution1.htm

 

[dreever]

Fred,
If I have this right you are suggesting for me to try a 2.5MM eyepiece on my PF100ED which according to my calculations would give 252X. This seems a bit excessive to me since I'd think the least bit of mirage would give you fits at that power.
Not to mention being very difficult to find the target in the first place which would be compounded in a Match situation when there would be twenty targets exactly alike side by side downrange where you'd have to rely on target number to find yours.
I agree in clear conditions you could score multiple bullet holes touching each other at that power, but wouldn't something more in order of 7MM @ 90X or a 5MM @ 126 be easier to use?
Currently in clear conditions I can see bullet holes clearly with my 12-42 Nightforce @ 500 meters in the white.
I'd love to give the gamut of eyepiece a try just to see what's what, but unfortunately I don't think that's possible. I may eventually plunk down the $$$ to buy another fixed power eyepiece, but I want to be darn sure I buy the right one the first time. Those Pentax XW's run $299-$320 which is a big chunck of change.

Danny

 

[jb1000br]

just the other day I could make out a cluster of shots,none touching) on clean, yet a bit wrinkly, white paper at 1025 yards with my Swaro 20-60x80 on full power.

Atmosphere was NOT ideal, but pretty good.

O yea, the holes were 6mm...

6.5 holes can be placed pretty well at this distance and condition, 6mm's you can see a cluster of them, but if there was one hole on the paper, I am not sure you could find it...

FWIW,
JB

 

[Fred Bohl]

Dan

I'll try to be more clear in my reasoning for the recommendation. Let us assume that your group is 0.25MOA. Now your PF100ED and zoom eyepiece yields 26-78x and about 90-48MOA field of view. Therefore, even at 78x your whole group,much less individual bullet holes) is 0.25MOA of 48MOA field or about 0.52% of the field,1 part in 192). For the Pentax XO 2.5mm eyepiece, FOV = 10.6MOA and 0.25MOA group is 2.4% of the field,1 part in 42). Or put another way your group appears about 4.6 times bigger and should also be 4.6 times easier to see.

As to usability, we use a post mounted Meade ETX 90 with a Vixen 6mm eyepiece that gives 208x for public use at our 200 and 300 yard targets. These have proven useful for nearly everyone under nearly all seeing conditions,excludes fog or the worst mirage).

While I have used 400x under good or better seeing conditions I will admit that as magnification increases, dealing with mirage becomes more difficult. Remember though reducing magnification does not reduce mirage it merely reduces the size of the motions while also reducing the relative size of your target.

For most people the challenge to successful use of high magnification in spotting scopes is learning to not touch the scope during an observation and if adjustments are necessary, make small changes, let go of the scope and wait for the motion to stop. At high magnification, relative motion between the target and the scope is often more of a problem than the mirage.

If you wish to retain the utility of having a zoom to cover a lower magnification to acquire your target then zoom - in to see your target detail, you could use the TeleVue 2x or 3x Barlows,very good) or even the 5x Powermate,excellent). With your zoom eyepiece. Those would give you ranges of 52x - 156x, 78x - 234x or 130x - 390x respectively. The Barlows will cause a small reduction in field of view and increase the eye relief but both may actually be improvements for the task at hand. The Barlows are $110 and the Powermate $195,at OPT) which is much less than fixed eyepieces.

Has this been helpful?

 

[Forum Boss]

Fred,

What do you think of the Celestron C5? Celestron claims it was used on some Space Shuttle missions. It comes with a 25mm eyepiece that is said to offer 50x. What eyepiece would you need for 70x?,Focal length is 1250mm). What would be a good brand eyepiece to buy?? Is the $630 C5 really any better than the $300,on sale) C130 Mak?

Link: http://www.opticsplanet.net/celestron-c5-spotter-spotting-scope.html

I understand your preference for higher powers, but for spotting a shooter at 600 and trying to catch any misses in the dirt, I think a 65-75x would be about right. Field of view is 53 feet at 1000 yards.

C5

C130 Mak

There is an interesting article on BetterViewDesired.com on Mirror scopes.

Link: http://www.betterviewdesired.com/Birding-Catidioptric-Scopes.php

I was surprised at this comment in the above article:

"How well do Cats [mirror scopes] compare to the best of the standard scopes? The answer, in general, is that Cats do very well... all of the Cats bettered the optical performance,resolution, contrast, color fidelity, and brightness) of the Nikon Fieldscope ED, the Reference Standard for 60mm scopes. When you move up to the 70-80mm refractor class, the question becomes more complex. Certainly the Questar, the Celestron C90 and the Celestron C5 offer slightly better raw optical performance,again: resolution, contrast, color fidelity, and brightness) than any of premium 77-80mm prismatic refractors,i.e., the Kowa 77mm Fluorite, the Bausch and Lomb Elite 77 ED, the Optolyth 80mm Fluorite, or the Swarovski AT80). [snip] The C5, with its huge aperture, provides truly exceptional, one could almost say "amazing," resolution, nearly 85 times that of the naked eye."

Interesting notes about resolution:

"In the field, at medium powers,40-60X), the C5 provides the kinds of views you have only dreamed about. It is one of the few scopes on the market that actually gives the impression of giving you a better view, brighter, richer, more detailed, at those powers than you get through your binoculars at 8X, and, as I said above, there seems to be no upper limit to the amount of detail you can see at higher powers. The C5 resolves finer detail than my test chart shows at 36 feet with the lines very sharply defined. There is little or no sign of the line blurring that results from abberations in the optical design. Outside, the C5 still resolves the finest lines on my chart at 66 feet, and might go a bit beyond. That translates to a resolution of .71 arc seconds, a fifth of a second better than theory, and more than twice the resolution of the best refractor that I have tested."

The article did mention that the image degrade slightly because of the 45° diagonal,mirror?) used to flip the image right-side up. Could that be the Achilles heel of these kinds of scopes?

 

[Fred Bohl]

Paul

The Celestron C5 could be an interesting choice for your application. The resolution is almost the same as the C130, it is about 4 lbs lighter, 5 inches shorter and will produce a brighter image,almost 50% brighter). These are the reasons that NASA selected and used it as a camera lens. For those that remember manual cameras the C5 is a 1250mm f10 design versus the C130 which is a 2000mm f15 design which makes the C5 faster,shorter exposure) as a camera lens.

For your 70x goal you would need an 18mm eyepiece such as the Vixen - 18mm Lanthanum LV Eyepiece - 1.25" [VX-3789],$120 at OPT) which would give you a 43MOA field of view. A more versatile choice would be the Vixen - 8-24mm Zoom Lanthanum LV Eyepiece - 1.25" [VX-3777],$150 at OPT) which would give you a range of magnification of 156-52x and 23-46MOA field of view.

My recommendation would be use the C130 with the same Vixen - 8-24mm Zoom Lanthanum LV Eyepiece which would give you a range of magnification of 250-83x and 14.4-28.8MOA field of view. This would be a 7.5-15ft field of view at 600yards and sufficient magnification to do some target analysis. Most performance for your dollars.

As to the comment about the "erecting diagonal" which uses a roof prism,like an SLR camera) not a mirror, the typical refractor spotting scopes use either a porro prism,bent or folded types) or a lens set,straight tube type) to produce an erect image. All these systems degrade the image by introducing more elements and distortion potential but this is in comparison to and astronomic telescope that does not use any of these as it does not provide an erect image,they need the least possible distortion so they forgo this nicety).

 

[Forum Boss]

Fred,

I've searched with Google and visited three telescope vendor sites. I can't find a C180. Is this a Celestron?

I find a Celestron C90 and C130, but nothing designated as a C180. Can't find a C180 on Celestron.com either...

link: http://www.opticsplanet.net/celestron-brand.html


What am I missing here.

 

[Fred Bohl]

Fred,

I've searched with Google and visited three telescope vendor sites. I can't find a C180. Is this a Celestron?

I find a Celestron C90 and C130, but nothing designated as a C180. Can't find a C180 on Celestron.com either...

link: http://www.opticsplanet.net/celestron-brand.html


What am I missing here.

Sorry Paul and anyone else. The only thing you were missing is the fact that I was typing that reply at two in the morning. I did mean the Celestron C130MAK. There is an old saying that I've just proved once again - you can't check your own work. I edited the offending post and hope I didn't waste too much of your precious time.

 

[Fred Bohl]

Pat,patgblue) and Bill,tipcrow)

Since you both seem to be following my recommendation for the Celestron C130MAK, I'm sort of cautiously awaiting your initial feedback. I do not recommend products or methods that I have not tried myself and usually not in a public forum until others have also tried it and also been satisfied. I skipped the third party testing here because of your query Pat.

Pat, I'm sorry to have sort of hijacked your thread. This is a subject somewhat dear to my heart. I do not have the hands on familiarity of you and Bill with the top conventional spotting scopes used at the range, but I do see the problems users at the local clubs and matches seem to be having with them.

My relevant background comes in part from being an amateur astronomer,familiarity with that type of equipment) and more importantly from my engineering career that included much involvement in optical sensing and machine vision systems and applications. Nothing teaches an appreciation of optics and image analysis like designing a system to look at rough castings randomly arrayed on a moving conveyor, analyze their orientation and position, guiding a robotic arm to pick up the casting, orient and load it in proper position in a machining center, then retrieve the finished part and load it an assembly fixture.

Because we all have such a fantastic vision system and the image analysis power of our brains, we tend to place unrealistic expectations on the manufactured optical aids that are so comparatively limited. By this I mean we tend to look through our scopes and expect to see not just the basic needed image data but also expect the image to be beautifully rendered.

My posts and recommendations are directed toward providing the equipment necessary to provide useful target data for a reasonable investment. It is the beautiful,but of little utility) image quality part that tends to elevate the cost of equipment and unfortunately also tends to be the focus of many evaluations/reviews. I'm a form follows function engineer - make the system perform the required function well then if there is budget left make it prettier.

 

[Forum Boss]

Fred,

I'm certainly not going to jump right into anything. I was initially hoping to get a Weaver ATX "loaner" for testing, but it has proven functionally impossible to communicate with Weaver by any means known to man.

That got me looking at the other mirror type scopes to see if they can really out-deliver conventional spotting scopes on a "bang for the buck" basis. I did see a couple astronomy forums where guys expressed a strong bias in favor of the Orion APEX 127 vs. the Celestron 130 Mak. The products look very similar however.

Here's a review of the Orion Apex 127: http://www.astromart.com/articles/article.asp?article_id=41

 

[Fred Bohl]

Paul

The Orion Apex 127mm is mid-way between the C5 and C130 in weight, length, and optical specs at 1540mm focal length and f/12.1 and with the Vixen - 8-24mm Zoom Lanthanum LV Eyepiece - 1.25" [VX-3777],$150 at OPT) would give you a range of magnification of 195.2-64.2x and 18.7-37.4MOA field of view. I can't offer you any personal or even second party experience with Orion products. I still think that the C130 beats both this one and the C5 for both usable magnification and bang for the buck, but you certainly have an array of choices.

 

[tripcrow]

Well so far for $300 and the dubious notoriety one’s bound to get carrying these 130 Celestrons around, I’d say “out of the box” you get something that’ll see holes at 400/500 yards better than $725 KowaTSN822M or $450 Celestron Ultima 100ED spotters, but not as good as a $700-$800 Meade 125 telescope or a $1100 Leica spotter. But I need more time and more eyepieces.

 

[Fred Bohl]

For those that seriously investigating the technical issues of scope and eyepiece specifications and selection, I offer the follow as an aid and reference.

Spotting Scope Optical Formulas

Magnification

Magnification = telescope focal length,mm) ÷ eyepiece focal length,mm)


Field of View

True field of view,MOA) = 60 x apparent field of View,degrees) ÷ magnification

Note: Apparent field of View is a characteristic of the eyepiece design and will be found in the eyepiece specifications. Typical values will be 45º,narrow), 60º,normal), 70º,wide) and 82º,ultra wide). The preferred range is 45º to 60º for spotting scope use.


Dawes Resolution Limit

Dawes resolution Limit,MOA) = 1.933 ÷ objective lens diameter,mm)

Dawes Resolution Limit,inches) = Dawes Resolution Limit,MOA) x Range,yards) x 0.01047

Smallest separation between features resolvable


Exit Pupil

Exit pupil,mm) = objective lens diameter,mm) ÷ magnification

or

Exit pupil,mm) = eyepiece focal length,mm) ÷ telescope f/#


Focal Ratio

Focal ratio = f/# = telescope focal length,mm) ÷ objective lens diameter,mm)


Importance of MOA units

The normal or median human visual resolution limit is 1 MOA,minute of angle). This is also called normal visual acuity when use by your eye doctor. On the typical Snellen eye chart, the 20/20 line,20 foot line in USA) or 6/6 line,6 meters in the rest of the world) was designed to be readable with a visual resolution or acuity of 1 MOA. The other lines characters are scaled accordingly.

Caution! --- The formulas above are consistent with the definitions of the terms. However the results obtained are only as accurate as the input data. Published specifications for telescopes and eyepieces are usually design values not measured from production parts and are commonly rounded to whole numbers.

 

[Fred Bohl]

Bill,tipcrow), Pat,patgblue) and Paul,Moderator)

You may want to get in touch with local Astronomy clubs to see if you could borrow some eyepieces for testing/tryout. That is common practice at many clubs and star parties because of the costs "try before you buy" is the way to go. Most of the eyepieces I have purchase were after trying them via loan from another user. Since you are doing daylight trials you would not be interfering with the owners use of his eyepieces so they may be even more willing than usual.


Paul

Give yourself a break, hop on I5 and go down for a visit to Oceanside Photo and Telescope, commonly known as OPT, located at 918 Mission Avenue in Oceanside, California approximately 200 yards west of the I-5 freeway, right on the northwest corner of Mission Avenue and Horne Street. Or at least contact them at 800-483-6287 or 760-722-3348 or opt@optcorp.com. Ask for Craig Weatherwax, Owner of OPT.,Available Monday - Thursday craig@optcorp.com). Craig can give you help on both scope and eyepiece selection and has demo stuff in the store that he would probably let you tryout,maybe even loan to you for a trial for an article on the site with proper credit). Tell him who sent you and show him this thread,with all my free plugs). He will either welcome you or question your dubious selection of acquaintances and throw you out.