Show Us Your Eyepiece Sets

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gfletcher
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Show Us Your Eyepiece Sets

Post by gfletcher »

Hi Guys

Well this is mine .
I think i am quite happy with this set at the moment.

Graham

Image
Meade LX 10 8" SCT OTA, HEQ5,
Celestron X-cel LX 7mm,9mm,12mm,18mm,25mm
Skywatcher Panaview 32mm
Revelation 2" 42mm
William Optics Binoviewer
William Optics SCT Crayford Focuser
Olympus 8X40 DPS I binoculars
Ender Of Days
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Post by Ender Of Days »

Here's mine .. Standard series 4000 super plossl set,

Image

6.4mm
9.7mm
12.4mm
15mm
26mm(came with scope)
32mm
40mm
2x Barlow
and the filters

I researched what I needed,but it was just going back and forth in and out and round my head :lol:
so I went for the box,I doubt Il be using the 6.4mm much but the lower end are superb,




JJ..
aint no speed limit where im comin from ..
lets hit the highway doing 69


ETX 125
Meade Series 4000 box set
David Frydman
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Post by David Frydman »

Dear JJ,
The 9.7mm I think gives 200x, which would be good for planets and double stars.
The 6.4mm I think gives 300x. On a really good night it might be worth trying it on epsilon Lyrae to look at the double double or on Mars.
A 7.6mm would be better giving 250x I think.

I used to enjoy using high magnifications for testing and to look at Jupiter's moons to see if I could see the actual discs.

With a 127mm Maksutov the focal length changes as you focus because the mirror and secondary gap changes, so magnifications vary somewhat.

Regards, David
David Frydman
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Post by David Frydman »

Actually the biggest change in magnification will be if you use a star diagonal.
I can't remember, but I think the 200x eyepiece will magnify approx. 220x, and the 300x eyepiece approx. 330x.

Even bigger changes occur if you use a terrestrial straight through prism, I think Questar had one and with such a small 89mm Maksutov the variations are much larger.

It is only with compound main mirror focussing scopes or those where the secondary is moved such as with photo mirror lenses that large variations in focal length occur.
With very fast mirrors like the Sigma 500mm f/4 not only are there drastic changes in focal ldengths but drastic changes in the image quality.

For most astronomers with medium or larger scopes the changes are not significant, although they should be noted, i.e. 'star diagonal used'.

Regards, David
Ambit Energy

Post by Ambit Energy »

WOW... what a set..!!

I just own 1 piece and not as good as that LOL.

I hope I can have like this too.. "Dreaming" ^_^







:lol:
Ender Of Days
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Post by Ender Of Days »

Just realised all they eyepieces are in the plastic covers :lol:
I don't leave them around the scope (although Ive just made a little table to hold 5 of them,that will fit under the scope)

Never thought of the FL changing due to focusing,a new one on me :shock: :)

I live and learn :)

JJ..
aint no speed limit where im comin from ..
lets hit the highway doing 69


ETX 125
Meade Series 4000 box set
mike a feist
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Location: Portslade, Sussex Lat 50deg 51min Long 0deg 13mins West
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Post by mike a feist »

Lots of eyepieces indeed! In my younger days (1960s) with 8" scope, the eyepiece (yes...singular!) that I used was a quarter-inch [=6mm] Ramsden, giving a magnification of x256. In retrospect not having a lower-powered eyepiece, say a half-inch [=12.5mm, giving x128] or even three-quarter-inch [20mm] was quite detrimental to seeing lots of astronomical objects, did I but know it. In fact, I rather unwisely sent away for a one-sixth incher [=4mm]. I mainly used to observe the Moon in those days.
I now only have three eyepieces, all of which I used on the PST....a Kellner 20mm, a 15mm (Plossl?) and a Kellner 12mm. The 15mm is most suitable for this.
All my observing instrument are basically "terrestrial" (binoculars, monoculars and spotting scopes) and have fixed or zoom eyepieces. maf
brian livesey
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Post by brian livesey »

I use TelVue Plossls from 32mm to 15mm, BAADER orthos from 12.5mm to 6mm, and a 24mm to 8mm zoom.
Ah yes, the old days Mike! Then, I had a few PRINZ Huyghenians, an old brass Symmetrical ( another name for a Plossl ) gun-sight eyepiece for sweeping and a binocular eyepiece. In other words, odds 'n' ends.
Ironically, given the exotic choice of eyepieces these days and their exotic prices, how many of them are used for other than casual skywatching?
Clear nights are at a premium in the North-West of England ( 70% cloud-coverage I've heard ), so, casual viewing is about all there is! Cloud gets channeled to us between the Welsh mountains and the Cumbrian fells. No wonder James Nasmyth. Isaac Roberts and Lassell fled the region!
brian
David Frydman
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Post by David Frydman »

As long as the eyepieces are parfocal or nearly so as they may be in the Meade set then the focal length of the Maksutov telescope or indeed a SCT will be almost constant for any particular observer.
This is as long as you use the same set up, i.e. straight through, 45 degree prism or 90 degree star diagonal. In other words, so long as you hardly change the separation between the mirror and secondary/corrector.
A similar situation exists in all scopes if you position a barlow lens at different locations. A 2x barlow could be 1.5x or 2.5x depending where the negative barlow is situated along the optical axis. It can also vary depending what eyepiece you use.
None of this really matters visually as long as use whatever eyepiece gives the best view.
However, it is a bit silly to give a magnification of say 227x when you have no idea of the actual telescope's focal length. 230x is more sensible even if it actually might be 220x or 240x. And the eyepiece itself may vary 5% from its marked value. My old Swift 4mm was actually 4.6mm and my original 6mm Ortho RAS thread eyepiece was actually around 7mm.
I told Horace Dall I had an ex gov. probably Barr and Stroud 20mm large Plossl eyepiece. He told me they were all 3/4 inch to high accuracy. He made his device for measuring eyepiece focal lengths to great accuracy.

With imaging the image scale will vary depending on the separation of primary and secondary, but this is completely changeable after capture.

I was looking at the Vixen 110L which seems to be a Cassegrain working at f/9.7 I think. It is light and has two ports, straight through and 90 degree. I don't know how this focusses, i.e. does the separation change between mirror and secondary, and I don't know if the light path is longer with the 90 degree port. If so the magnification will vary for the same eyepiece depending which port you use. It looks like a nice scope and not expensive.

The main reason the Maksutovs and SCTs change so much in focal length is that the main mirror works at about f/2.5 for the Mak and f/2 for the SCT. The secondary basically amplifies this 5 times making them sensitive to changes of separation.

Cloudy today.
Regards, David
David Frydman
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Post by David Frydman »

Looking at the picture of the Vixen 110L the arrangement of the flip mirror suggests similar path lengths with both eyepiece ports. It is when you add a star diagonal to the rear of a small compound scope that the focal length changes considerably.
At £195 it looks good value, i don't know if anyone has used one here.
It doesn't seem to have a standard tripod socket, which would suit me.

Regards, David
Sheffield Col
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Post by Sheffield Col »

Ender Of Days wrote:Here's mine .. Standard series 4000 super plossl set,

Image

6.4mm
9.7mm
12.4mm
15mm
26mm(came with scope)
32mm
40mm
2x Barlow
and the filters

I researched what I needed,but it was just going back and forth in and out and round my head :lol:
so I went for the box,I doubt Il be using the 6.4mm much but the lower end are superb,




JJ..

Hi, I have the same ep's Meade 4000, But I am still relatively new to astronomy. I bought Meade ep's because I thought Meade make good quality scopes, so it follows the ep's should be good as well. I have never had any other ep's to compare them with, so I dont really know if they are better. Have you been able to compare them against others? If so what do you think? I notice you are in Sheffield, So am I.
Ender Of Days
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Post by Ender Of Days »

The only one's Ive used to any degree before now were some old 0.75" ones from an old refractor,
needless to say the 4000's are stunning in comparison :lol:

Ive tried them all but not much due to the weather,but I do love the 40mm and the 32mm,and the one that came with the scope .. the 26mm,

I only went for them as all the info on eye pieces was getting a bit like over load,and it was simpler to buy them all rather than pick them one at a time,more expensive in the long run but at least I got them now :D

Im in North Sheff by the way,

JJ..
aint no speed limit where im comin from ..
lets hit the highway doing 69


ETX 125
Meade Series 4000 box set
David Frydman
Posts: 5366
Joined: Mon Jan 18, 2010 9:25 am
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Post by David Frydman »

Old astro eyepieces were 24.5mm or 0.965 inch from memory.
Microscope eyepieces were or are 23.5mm and when used with faster telescopes are usually not good.

Meade eyepieces vary from very cheap to very expensive. For instance their MA eyepieces are O.K. with slow scopes but not so good with fast scopes. Also the coatings are basic or poor on these whereas the expensive ones may be multicoated on every surface and the glass elements edge blackened.
So really one cannot say that a named eyepiece is always good with all scopes. Some are some aren't.

This also applies to other named eyepieces with many different designs sold under the same banner. In fact many eyepieces from different firms probably all come from the same chinese factory.

Best regards, David.
Ender Of Days
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Joined: Fri Oct 10, 2008 9:00 pm
Location: north sheffield
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Post by Ender Of Days »

David Frydman wrote:Old astro eyepieces were 24.5mm or 0.965 inch from memory.
I just checked,You are correct .. 0.965"
don't know why the figure came into my head,
Either way the 0.9 exit holes are just too small to look through for me,the best eyepiece I had was (iirc) 20mm,


JJ.. :)
aint no speed limit where im comin from ..
lets hit the highway doing 69


ETX 125
Meade Series 4000 box set
mike a feist
Posts: 3303
Joined: Sun May 11, 2008 6:11 pm
Location: Portslade, Sussex Lat 50deg 51min Long 0deg 13mins West
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Post by mike a feist »

The "old Japanese inch size" , I have heard then so referred........presumably because they were often supplied with Japanese cheap refractors until recently. maf
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