Celestron Trailsetter 100 & M2 100ED (1 Viewer)

Might as well start a thread. I own both w/Trailseeker also incorporating the 45* angle for use by 1 1/4" eyepiece. They both came w/8mm-24mm/67-22X zoom though the M2 is substantially larger.

Both are doublet 540mm f5.4. I've complained that the Trailseeker only resolves to 45X. After that it begins to lose fine detail whilst blurring slightly at the same time.

The 100ED will resolve through the 67X w/no noticeable degrade of resolution. I bought a Celestron Luminos ocular in 7mm/77X and 15mm/36X and they both worl very well in the M2. I haven't tried either in the Trailseeker though would expect the 36X to work great and the 77x to have issues.

I've been told via PM that this is normal. I find this somewhat unsettling as I knew the cheap toy spotters < $100 would have such issues, but since even the Trailseeker touts a new price pushing half a grand I expected better.

I certainly did not believe that it would only resolve half of the available zoom. That within itself is somewhat of a travesty. If you are going to fall on your face at 45X then you should offer no more than 48X on a zoom at this price.

Anywho, I've ordered a Meade 5000 UWA 82* 5,5mm/98X and a Vixen LVS 45* 4mm/135X that should arrive Friday. I guesstamated after the rock solid resolution of the moon at 77X that 98X would produce similar though dimmer results.

I hoped against hope that w/the Vixen's exotic glass and small field that I might coax a decent enough view to poke around the moon. The new Vixen was only two dollars more than the 5K UWA, so the deal trumps all. HA!

We'll see as 135X is a lot to ask. At least it might help me decide if there's any hope at dropping only to 4.5mm/120X. I do not see a 4.7mm/114.9X Ethos SX in me future.

The most disturbing thing concerning the view w/Trailseeker is that neither the vendor nor Celestron stepped up to the plate and said, "Oh that's normal only to resolve to 45X on the 100mm Trailseeker.

It was a demo w/one year warranty for three & half bills, so it isn't as if I bought it new. It can still be used for soaring byrds as that's what the 15mm/36X was intended for even though after practicing I've been considering 45-49X/12mm-11mm as an upper limit on the wing. Not that I could swing 100* eyepiece though every little bit helps.

I bought the previously owned M2 sight unseen w/nary an inquiry to the seller.

So far so good.

ETA: I went ahead an ordered a Meade 07730 Series 5000 HD-60 4.5-MM/120X. Perhaps if the 135X doesn't work out this one will.
Anywho from the current 77X 82* to 98X 82*, 120X 60* & 135X 45* I should be able to determine the highest possible power that I can live with for day and/or night viewing.

I might end up where I was going to start at 6mm/90X.

Trailseeker 100mm & Regal M2 100ED

Regardless of previous title faux pas the more modest scope is a Trailseeker. Though at any given time I will interchange Trailsetter/Trailblazer w/equal enthusiasm.

Waiting on the Meade 5000 4.5mm I heard a vehicle pulling away. I go to the door to peek out and there's a package. Eureka! I open it only to find out that it's the Vixen SLV 4mm 50* a day early.

Rather odd using the 7mm/77X to locate a target, but nonetheless I carried on. Once the T-bar was found and centered I swapped w/4mm. Maybe not parfocal though surprisingly close from Celestron to Vixen.

Going from 77X to 135X provided a noticeably larger picture. I could still see the fine points of detail, yet I had to work a bit harder. I'm looking through a glass paned door from inside, but to be fair I did the same earlier w/77X.

Sun is out and all I see in focus is the top of the T-bar and shimmering heat waves of greater intensity. After a while a large cloud shades the sun and I saw all the detail from 77X and, due to the larger picture, a bit more.

The higher mag view doesn't have as good of contrast/colour or brightness, so the overall view doesn't appear as clean, but the detail is there and enlarged offers a bit more to peruse.

I know that a 100mm objective does not render any more resolution from 77X to 135X. However, the larger picture afforded a view of that detail that was unobtainable at 77X. So it can't, yet it does.

As well the fine tuning knob at 135X is not quite as fine. It seems easier to get close and compare how the two focus knobs align. Make adjustments from that and then take a peek. This tripod allows a bit of movement/vibration. Where at 77X I could rest the ocular against me nose and adjust focus this 4mm eyepiece is not so receptive.

If this isn't the practical limit on magnification it cannot be far off. I'm sure attempting to frame/maintain the moon, even w/fluid head, will be a mite tricky. Still, I'm anxious to take that view along w/Jupiter and Saturn.

And I'm curious how 98X & 120X look. Anywho, for what it's worth I'm impressed w/lowly Celestron top of the line scope.

The Trailseeker on the other hand only makes it to 45X before diffusion rears its ugly head. According to my research that's about where an 85mm should reach if there were no issues within the optical train.

As a demo, $350, the price was right. It does also accept 1 1/4" eyepieces. I just cannot go past 12mm/45X. I could use it for soaring byrds. I've become fairly proficient at 36X, so I'm sure I could squeeze in another nine power or merely live w/36X.

I do not agree w/guarantee that amounts to send it back and we'll try again if we have another demo. Otherwise we'll refund you after grading the wares and determining how new it still looks. What?

And I'm still waiting to hear back from Celestron.

I'm not holdin' me breath ...

you seem to bemoan the trail setter not being able to take magnification, but it is a short fast f/l achromatic refractor -grab any of the astro refractors with normal achro obj. & they will all show a kaleidoscope once you increase mag on the right object. they are wide field instruments only

i think you'll be more happy with the meade, than the vixen, i find the claims of exotic glass don't do much at the eyepiece & the narrow field will have you looking for something else

It is just as short & fast f5.4 as the Regal in which I have no issues. The ED glass lays claim to better colour representation though no allegations of improved resolution.

According to this link:
http://www.twincityrodandgun.com/docs/ScopeRes-Mag1.pdf

100mm objective should resolve unto 51.7X before merely magnifying the same resolution.

The Trailseeker was only one sample. However, it fell short and I find that unacceptable.

The Vixen SLV at 50* showed good lunar detail. As I recall the moon fairly well filled up fov. The two Meade eyepiece barrels are slightly larger in diameter requiring slow insertion, to equalize pressure, plus the shoulder on the safety channel on them match up w/compression ring in the focuser. This results in the focuser wishing to "spit" the bit. I can hold it w/one hand and tighten w/other, but it isn't as silky smooth an operation as the Celestron or Vixen eyepieces.

Still, I ordered another Meade in 10mm 100* MWA weighing in at one lb. I'm going to try it on feeder watch. Ever so roughly a 100* can go 3mm in a shorter fl and have the same fov. I pick up 18X and only give up the dif in 13-15mm 82* fov.

One thing I've noted on eyepieces is that it seems, due to the lower power of the short fast scope, that I'm nowhere near the eyepieces limit. Perhaps combined w/only a 100mm objective I do not FC that others report. I'm sharp to the edge and in focus across the board.

Next week I'll know if the 100* 10mm/54X presents the same.

Hi Nixterdemus,

as I tried to explain in my PM, axial CA will also limit effective resolution since different wavelengths are going to be sharp at different focus points. For low magnifications the depth of field will make up for that and the image looks sharp. At higher magnifications depth of field gets thinner and thinner and there will be no focus setting which has all wavelengths inside the depth of field.

In order to avoid this you could either use a slower instrument, thus increasing depth of field, or use low dispersion elements like ED glass or CaF2 in order to decrease axial CA (actually all CA but the transverse part is just cosmetic).

Your trailseeker would be a great instrument with no noticeable CA if it was f12 or so. Unfortunately this would mean it was a bit over 1m in length...

Joachim

So, dead center at approximately 100 yds, under canopy, through a 100mm doublet objective consisting of plain jane glass I should lose resolution on a mark no larger than the size of a BB upon reaching 45X?

I could not find any real reviews on line on the Celestron Trailseeker scopes but I just purchased the Trailseeker 65mm out of curiosity for $122 shipped to test some low magnification eyepieces. Just checked the sellers website, now the price is $224. looks like someone might have screwed up in advertising. I do not expect much.

The straight scope can be found considerably cheaper at time Vs. 45*. Demo/used-returned offers value as well. For the price you paid I do not see how you can go wrong.

Hi,

the 65mm model offers up to 45x with the zoom and should be ok at that magnification. If you can get a fairly wide angle 12 to 14mm astro EP used, that would give a nice wide field at around 30x.

Joachim

65mm tops out resolution at 33.5X anything above that is merely enlarging that view, so the "best" power is always subjective.
The focal length is around 400mm & 12mm eyepiece would be 33.33X. The Meade MWA 100* 10mm as I have would yield 40X which is 6.5X over the highest available resolution of a 65mm objective.
At 170 clams it might be a bit pricey.
The more modest Celestron Luminos 15mm would be 26.66X. It claims 82* though some have measured 72-74* & that's still considered wide angle. Around 3/4 of a C-note on sale. A lot of bang for the buck. Luminos also comes in 10mm though I do not have that one.

As always YMMV...

Nixterdemus said:

65mm tops out resolution at 33.5X anything above that is merely enlarging that view, so the "best" power is always subjective.
The focal length is around 400mm & 12mm eyepiece would be 33.33X. The Meade MWA 100* 10mm as I have would yield 40X which is 6.5X over the highest available resolution of a 65mm objective.
At 170 clams it might be a bit pricey.
The more modest Celestron Luminos 15mm would be 26.66X. It claims 82* though some have measured 72-74* & that's still considered wide angle. Around 3/4 of a C-note on sale. A lot of bang for the buck. Luminos also comes in 10mm though I do not have that one.

As always YMMV...

Click to expand...

Nixderdemus,

Telescope resolution should not be directly compared to the convention of 20/20 eyesight acuity corresponding to a resolution of 60 arc seconds. Eyesight acuity is based on the separation of lines per mm on the Snellen eye chart. Telescope resolution is based on the separation between the centers of two Airy discs which is essentially the same as line pairs per mm rather than lines per mm. 20/20 vision measured the same way as telescope resolution is 120 arc seconds, not 60. So, a person with 20/20 vision would need at least 67x to see the smallest line pairs resolvable by a diffraction limited 65mm scope.

Henry

henry link said:

Nixderdemus,

Telescope resolution should not be directly compared to the convention of 20/20 eyesight acuity corresponding to a resolution of 60 arc seconds. Eyesight acuity is based on the separation of lines per mm on the Snellen eye chart. Telescope resolution is based on the separation between the centers of two stars which is essentially the same as line pairs per mm rather than lines per mm. 20/20 vision measured the same way as telescope resolution is 120 arc seconds, not 60. So, a person with 20/20 vision would need at least 67x to see the smallest line pairs resolvable by a diffraction limited 65mm scope.

Henry

Click to expand...

Henry,
Always a pleasure to glean a mite from your expertise.

" So, a person with 20/20 vision would need at least 67x to see the smallest line pairs resolvable by a diffraction limited 65mm scope".

Is this to say that ever so roughly the resolving power of a refractor is at least 1X per MM of objective?

I realize that in modest scopes the optical train may be the limiting resolving factor instead of/before diffraction.

Perhaps I misinterpreted this chart that I found which seemed to me to say that resolving power was limited to just a hair over half the size of objective.
Though one could continue to magnify the image beyond that point there was for all intent & purpose no more detail to be resolved.

http://www.twincityrodandgun.com/docs/ScopeRes-Mag1.pdf

Nix,

Sorry for the delay in responding. I had hoped to make it easy on myself by linking to a source that explained everything, but I can't seem to find one that addresses the issue directly.

I think it might be easiest to just compare how resolution (or acuity) is derived from the "tumbling E" eye chart compared to how resolution is derived from the USAF 1951 resolution chart, which uses similar looking elements.

20/20 vision on the "tumpling E" is similar to 20/20 on the Snellen chart. The 20/20 line of tumbling Es and the 20/20 Snellen "optotypes" have the same apparent angular size when viewed from 20' (5 arc minutes x 5 arc minutes). The black lines that form them appear to be 60 arc seconds wide. So, on both charts 20/20 acuity means resolving lines that are 60 arc seconds wide and (on the tumbling E) separated by 60 arc second gaps. If those same lines and gaps were expressed as line pairs (the distance between the centers of adjacent lines) 20/20 would be 120 arc seconds rather than 60.

The USAF 1951 resolution chart is used to convert the smallest line pairs per mm visible in a telescope at a certain distance to resolution in arc seconds. It could be used just as easily to convert lines per mm to arc seconds, but line pairs are used instead to conform to the practice in optics of measuring resolution as the separation between the centers of a pair of Airy discs.

The confusion comes when these two different ways of expressing the same thing are inadvertently mixed, as in the article you cited.

As for how much magnification is needed to see the smallest line pairs resolved by a telescope. That would be the observer's eyesight acuity in arc seconds divided by the scope's resolution in arc seconds (both must be derived from line pairs). So, a person with 20/20 vision (120 arc seconds) would need 67x to just barely see the resolution of a diffraction limited 65mm scope (1.78 arc seconds).

Henry

Thanks again Henry.
I had another rambling, confusing response, but to cut to the chase. Due to the chart on page 4 of the pdf link mixing values all I need to do is double what is listed as match magnification, ever so roughly, to have the magnification required to see the resolution of a diffraction limited scope if viewed w/20-20 in the corresponding objective size.

If so then a 60mm objective would require 62X, 85mm 88X, 100mm 103.4. And, more or less, any magnification past those no longer resolves greater because they all have reached their limit though I may continue to enlarge that view w/more magnification.

Now, an individual w/20-20 through a 65mm scope at 67X can only read the eye chart up to a certain distance.
And all things being equal a larger objective would allow the chart to be read at a greater distance.

I hope or I'm throwin' in the towel.

Hi,

thanks to Henry for answering a question I asked myself too... Regarding that article from the gun nuts... it gets a few things wrong, I'd say.

So with your 65mm scope at 67x mag and 20/20 eyesight you should be able to read the test chart at 67x the normal distance of 20 feet... that is if the scope is a diffraction limited or better.

Joachim