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Is there a law of diminishing returns on eyepieces?


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12 minutes ago, Stormbringer said:

Funnilly enough it was my 1st slr as well and yep the lenses had Carl Zeiss written all over them .

The closest thing to that example I can think of are vintage microscope eyepiece collectors who buy old eyepieces cheap off of ebay and other sources to try them in telescopes to see if there are any hidden gems from the past.  In slow scopes, some of the well known brands of the past did produce quite good eyepieces as I recall from online discussions and articles.  However, it means buying dozens of mediocre ones to find them.  Several modern Zeiss microscope eyepieces are known to be exceptional in astronomical usage, but they are no bargain unless you can find them used for cheap.

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12 hours ago, JOC said:

I started with a Praktica manual camera years and years ago, For about the last 8 years I have owned my Canon DSLR with Canon lenses.  OK, so the Praktica was a film based SLR where as the Canon is a digital job, but if I am being honest I haven't noticed a wholesale improvement in the quality of pictures I am able to take.  Whether this has anything to do with the fact that the lenses were reputed to come from the Carl Zeiss factory I don't know, but for a budget camera my lenses seemed very high quality.  I wonder how may budget eyepieces actually have high quality glass in them that we just don't know about.

Well, I owned an analogue Praktica as well as an Asahi Pentax in the early seventies and eighties and tried to do astro-imaging with them with deepcooled film... What a disaster ...! And how painfull (literally)
When the digital age arrived I was very happy the days and frustrating experiencesof looking through a guider eyepiece for god knows how long and afterwards finding out I did something wrong, were gone. 
After experimenting with DSLR's for a while I switched over to dedicated mono CCD camera's and a whole new world opened up for me.

So don't talk about "those good old days" cause they were not. Apparantly you forgot about all the other 'features' of those camera's... like high costs, no processing possibilities, faillures... but then again... Time heals wounds quite fast!
Memory seems to be subjective for the good things to remember and looks at most things through pink (sometimes dark) glasses.

'Great pics' nowadays is very very different from 'great pics' back then... but maybe you remember the words, not the pics...

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Waldemar, just for the record I don't think I am harking back to the good old days of film based cameras.  What I thought I was suggesting is that it is sometimes possible to purchase a budget item and find that you can get surprisingly good items with good pedigrees that you might not expect to obtain for the cash expended.

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8 hours ago, JOC said:

Waldemar, just for the record I don't think I am harking back to the good old days of film based cameras.  What I thought I was suggesting is that it is sometimes possible to purchase a budget item and find that you can get surprisingly good items with good pedigrees that you might not expect to obtain for the cash expended.

Look at the guys who invented the digital camera. It took 30 yrs in the making, but they were awarded full recognition (and a nice cash prize) for their contributions to photography, just this week.

I agree with the above (in all aspects), expensive doesnt always have to mean "best". Budget products can deliver amazing results. It boils down to expectations.

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2 minutes ago, LukeSkywatcher said:

expensive doesnt always have to mean "best". Budget products can deliver amazing results

I'm still struggling to spend £23 on my next eyepiece? :happy9:
It will produce the goods, its probably uncomfortable due to its eye-relief, it just completes a set.

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13 minutes ago, LukeSkywatcher said:

I'm guessing its a Plossl

Its is.  The  Revelation 4mm. I favour the Revelations over all the other Plössls I have tested? 
Meade and Televue Plössls are no longer in my list/collection ( TV Sold, Meades pending!)

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23 minutes ago, Louis D said:

Has anyone tried mounting those older Zeiss lenses to modern DSLRs or astro CCD cameras?

The problem is often the fitting, but I do have a PB bayonet to cannon EF adapter.  Obviously you are reduced to treating things as manual lens (you lose the electronic control), and for this reason I have not given the adapted lens much use - it covers much the same focal length as my existing canon lens which does have the full electronic interface and so there has been little reason to use it.  However, in the spirit of this thread (which after all is of my own making), perhaps it would be a useful exercise to compare the two.  I'll liven up my long unused camera know-how brain cells and see if I can take some comparable shots using a manual set-up with the old Practika Zeiss lens and the modern Canon lens under the same settings and if I can get some I'll see about posting them so we can see any differences.

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1 hour ago, JOC said:

The problem is often the fitting, but I do have a PB bayonet to cannon EF adapter.  Obviously you are reduced to treating things as manual lens (you lose the electronic control), and for this reason I have not given the adapted lens much use - it covers much the same focal length as my existing canon lens which does have the full electronic interface and so there has been little reason to use it.  However, in the spirit of this thread (which after all is of my own making), perhaps it would be a useful exercise to compare the two.  I'll liven up my long unused camera know-how brain cells and see if I can take some comparable shots using a manual set-up with the old Practika Zeiss lens and the modern Canon lens under the same settings and if I can get some I'll see about posting them so we can see any differences.

i think that would be pretty cool and looking forward to results 

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3 hours ago, Charic said:

Its is.  The  Revelation 4mm. I favour the Revelations over all the other Plössls I have tested? 
Meade and Televue Plössls are no longer in my list/collection ( TV Sold, Meades pending!)

Revelation are not a bad brand. I have concerns about a 4mm EP and the eye relief. In this case its something like 6mm?.

I have a 4mm Celestron Omni which cost me about 70 euros. It also has 6mm eye relief. Ive used it exactly once.

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Its the same with the TeleVue 8mm, only six millimeters of eye-relief, the main reason I disliked the TV8 at that time, although looking back, not the best night to carry out a first light, though the 11mm was a little better on the night.

That said, TeleVue stop their range at  8mm, for practical reasons, and I thought I needed more magnification, at least to 6mm with a single  eyepiece, no Barlow.

I also wanted  brand specific from the start and selected Meade? but having tried  various brands, the Revelation Astro's ( assumed  GSO built?) suit me fine so far, and almost complete the set, if/when I need to sell? ( a bargain in a bundle ) :happy9: 

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So, I've often wondered about Barlows - I know it saves on cost because the one Barlow multiplies the magnification of all the eyepieces it is applied to so in theory you buy less eyepieces and cover as much magnification.  However, reading above, do Barlows affect the eye-relief of the EP they are used with or does the use of a Barlow allow the user to benefit from an, often favourable, eye-relief (which I understand as how close the eye needs to get to the EP) which often appears to be associated with the higher number EP's (lower apparent magnification).  i.e. does the use of a Barlow preserve the eye-relief of the EP it is being used with?  For some reason, if it does, I think that would surprise me.

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Original question was: top eyepieces in budget scopes? My answer is YES.

We have Sir Isaac, a 20 inch F4.1 here with basic optics* probably not diffraction limited. We don't use a coma corrector.  My default EPs are a 13mm TV Ethos and a 26mm TV Nagler. Nobody has ever asked for a CC but serveral have been surprised to discover that there wasn't one in the train already. Lots of far more expert visual observers than I have professed themselves perfectly happy with Sir Isaac and, in over ten years, nobody has ever complained. 

In my opinion the big scope is transformed by these high end widefields. In a Plossl, despite the small FOV, the edges make me feel physically uncomfortable.

Olly

* Well, the primary is 'basic' but the incomparable Ralf Ottow kindly made us a new secondary to his usual standard.

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10 hours ago, JOC said:

So, I've often wondered about Barlows - I know it saves on cost because the one Barlow multiplies the magnification of all the eyepieces it is applied to so in theory you buy less eyepieces and cover as much magnification.  However, reading above, do Barlows affect the eye-relief of the EP they are used with or does the use of a Barlow allow the user to benefit from an, often favourable, eye-relief (which I understand as how close the eye needs to get to the EP) which often appears to be associated with the higher number EP's (lower apparent magnification).  i.e. does the use of a Barlow preserve the eye-relief of the EP it is being used with?  For some reason, if it does, I think that would surprise me.

It's better than that JOC, a Barlow actually extends the eye relief of the eyepiece you are using. In shorter focal length Ortho or plossl eyepieces this can be very useful to go to higher powers whilst keeping them comfortable. I often use a good quality Barlow with a 12.5mm, 9mm or 7mm Ortho rather than use the shorter focal lengths. Barlows work by increasing the effective focal length of the scope i.e. they narrow the angle between the light rays making them closer to parallel so they also reduce certain abberations associated with faster scopes.

Tele extenders such as the Televue PowerMate work in a different way, maintaining the same light cone as was incoming so they do not affect the eye relief of the eyepiece being used.

The negative effective of barlows happens when used with eyepieces which already have a lot of eye relief such as a 32mm plossl. Using a Barlow pushes the eye relief out to a position where you have to hover your eye a long way from the exit lens which can be difficult and allow glare and reflections to spoil the view. In these cases, a PowerMate or equivalent is a better choice.

One thing that confuses me on the forum is people saying you can't use Xmm focal length eyepieces, or Ymm focal length is my favourite and recommending it without know the focal length and ratio of the scope being used.

A 4mm eyepiece in a smallish fast scope will be highly useable e.g. In a Televue NP101 which is 101mm with a 540mm, f5.4 focal length it would give a very useable x135 mag. In a 102mm f10 scope it would give x255 mag i.e. A good high power planetary eyepiece for steady seeing. In an f3.7 20" dob it would give x470, useable on rare occasions of excellent seeing. In the Infinity 76mm f4 scope referred to earlier in this thread it would, of course give x76, lowish mag, but probably higher than you would want to use and still be able to track easily. Finally in my old (no longer with me) OMC200 f20 scope, 4000mm focal length it would give x1000. Let's not go there!

So, I don't think you can ever just say a certain eyepiece is suitable or not without knowing the scope it is to be used in.

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  • 3 weeks later...

So lets go back to my comparison between my 10mm 'bundled' Plossl and my new (2nd hand) 'branded' 11mm TV Plossl using my 'uneducated' eyes - would you believe it took until last night to get a chance to size them up on the same object - that's how bad the weather has been.

So what would be a good object for a comparison - one I'm already familiar with so I used M42 for general viewing and the quality of that trapezium split.  Last night for an hour or so Orion blazed clear as bell and so I tried out both eyepieces.

The first obvious difference is that the focal point of both eyepieces was completely different - I have other eyepieces, a Celestron Plossl, the two that came with the telescope and I've tried some clone TMB Planetaries, if I swap one for the other in any combination (even from high to low magnification) I need very little adjustment on the focusser wheels until I used the TV Plossl - there was a huge difference in the adjustment required on the focusser and I was quite surprised at the difference that was needed.

So to look through - well up front I ought to say that I am clearly used to my generic 10mm Plossl.  However, I gave the TV Plossl a fair go and, I don't quite know how to describe the difference, but its almost as though it wasn't as easy to look through the TV.  In terms of quality there seemed very little difference.  The wispiness of the nebula background seemed similarly bright with both EP's, the trapezium split as well with both and the individual stars seemed as well defined.  I guess the TV should have offered slightly more magnification, but it wasn't hugely evident. 

I would have liked the difference to have been clear-cut, for the TV to clearly be the better choice and I was ready for that to be the case, but I have to say for the ease of 'looking' the generic 10mm has a lot going for it and out of the two, I wouldn't be concerned about using either one if I dipped into my lens box on a dark night, but I probably be glad if the generic appeared in my fist first.

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Interesting comparison.

I don't think you (or anyone else) should go looking for an obvious difference between 10mm and 11mm focal length as it will be imperceptible to host eyes and irrelevant when using two different manufacturers of EPs.

It would be interesting to hear about the results of the same comparison wth a target that would provide more obvious detail, such as the Moon or the cloud bands on Jupiter.

 

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18 minutes ago, DRT said:

Interesting comparison.

such as the Moon or the cloud bands on Jupiter.

I expect JOC would have liked to do that as well, if only the cloud bands on Earth would co-operate ? :D ,,, all in good time   due course I expect !

27 minutes ago, JOC said:

So lets go back to my comparison between my 10mm 'bundled' Plossl and my new (2nd hand) 'branded' 11mm TV Plossl using my 'uneducated' eyes - would you believe it took until last night to get a chance to size them up on the same object - that's how bad the weather has been.

Thanks for that, very interesting, I was wondering how you were getting on with the new toy. Shame about the Wx tho' ! I was thinking perhaps I had missed one of your posts !!

 

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You need to compare eyepieces over a number of nights, on a range of different targets, including some that are really challenging, under varying conditions and ideally in different types of scopes to really find out how they compare. Thats why, when doing reports on eyepieces for this forum, the lapsed time between me receiving them and me being able to post some sort of coherant report is usually months :rolleyes2:

Most eyepieces available today (across all price ranges) perform pretty well on axis. It's when you start carefully examaning what is happening away from that part of the FoV that differences start to be perceived, especially as the focal ratio of the scope starts to reduce.

My 1st decent 1.25" eyepieces were Tele Vue plossls which I purchased new back in the late 1980's. I think the focal lengths were 7.4mm, 13mm and 20mm. Initially I was disappointed that the views through them looked pretty much like what I was getting through my cheaper Taiwanese standard plossls. It took me many eyepiece changes and a few years of observing before I started to appreciate the qualities that the Tele Vue's delivered. Perhaps I was a slow learner !

Today the range of eyepieces available is much wider and the production quality of even the low cost ones is better so the performance "gap" between the premium eyepieces and the more affordable ones is even smaller, perhaps to the point of being indistinguishable much of the time ?

A great bit of advice was posted on here a while back by Michael  H F Wilkinson. It went along the lines of "the time to upgrade is when you try something else and see a difference that matters to you". Can't argue with that ! :icon_biggrin:

 

 

 

 

 

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Thanks for the comments all.  Yes, I would love to try it on more targets :-) SilverAstro has obviously read my other postings - Thursday night was my first night out since getting the new EP.  No moon to try and Jupiter I was lucky to even get a glance at.  I don't intend to give up with it and will certainly report back on its performance with other types of targets.  As I say I would certainly like to find that it was better if only because I might feel inclined to do some more shopping for a few more (it's always nice to buy new toys, but only if there is a point to them).  I only bought it because as a good price didn't break the bank and I thought it would be an interesting comparison.  More reports, when the weather allows, will certainly follow :-)

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21 hours ago, JOC said:

The first obvious difference is that the focal point of both eyepieces was completely different - I have other eyepieces, a Celestron Plossl, the two that came with the telescope and I've tried some clone TMB Planetaries, if I swap one for the other in any combination (even from high to low magnification) I need very little adjustment on the focusser wheels until I used the TV Plossl - there was a huge difference in the adjustment required on the focusser and I was quite surprised at the difference that was needed.

This is because most non-TV eyepiece focus at the shoulder rather than above or below it.  Most TV eyepieces by comparison focus 1/4" below the shoulder.  This is referred to as parfocal group B in TV parlance.  Most of their eyepieces, if they are in a parfocal group, fall into this group.  The Ethos line is all over the place focus plane wise by comparison.  Only the 17mm Nagler T4 focuses at the shoulder like most other eyepiece lines.  TeleVue has this information in the eyepiece dimension column F on their eyepiece specifications page.

The only possible reason I could come up with to put the focal plane 0.25" below the shoulder would be to make their group B eyepieces roughly parfocal with 2" eyepieces that focus at the shoulder when using a high-hat style of 2" to 1.25" adapter.  Anyone else have any idea why TV doesn't put the focal plane of any but one of their eyepieces at the shoulder?

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Louis D well at least there is an explanation - I thought I was possibly doing something wrong, or there was something amiss with the eyepiece, but from your information above it seems it was doing as it was designed to do.  Thank you for that!

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