Spherical Aberration of Intraocular Lenses - PMC - spherical aberration

 2024-11-11 16:09:33

i would say it is more of personal preference really. Some like vulcano tops,some flat tops.Circle t`s came as vulcanos,Meade Rg`s same,Zeiss Zao 1 and 2,BGO,Astrotech,UO as flat tops.UO(university optics)where also made as vulcano tops.There where quite a few other orthos made under different brand names,like Antares,Celestron,Vixen etc.Orthos where and i think still are very popular for planetary observers.

Well there is nothing like an eyepiece contrast, Orthoscopic and Ethos, bit like chalk and cheese FOV wise. Having both I do like the wide field E's on the Dob for just the user friendlyness of them but orthos come into their own on the driven scopes with planets. In fact the only thing I am not over keen on is that tight ER on the 5mm, so I don't know what the 4mm will be like. I then only find this is time limiting as to how long you can use them.

You're in luck! They're on sale: http://www.firstlightoptics.com/japanese-made-eyepieces/hutech-orthoscopic-eyepiece.html

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Whatisobjectivelens inmicroscope

TeleVue claim: ‘Tele Vue Plössls deliver sharper images than any other brand of 4 or 5 element "Plossl" or Orthoscopic designs’ and though I don't deny their remarkable quality I couldn't detect any difference in sharpness between the Astro Hutech 18mm and the TeleVue 20mm.

I have a TV 20mm plossl which is a very good EP to me. I find 50 deg a bit claustrophobic though.. This is the reason why I don't go for the cheap bco. On the other hand, I'm a bit tempted due to the constant positive opinions by members.

Objective lenses are used in microscopy systems for a range of scientific research, industrial, and general lab applications. A microscope objective is typically composed of multiple lens elements and located closest to the object. There are so many types of microscope objectives available, choosing the right objective can help you produce good quality images at a reasonable cost. When choosing a microscope objective, we will need to consider a number of factors including conjugate distance, numerical aperture (NA), magnification, working distance, immersion medium, cover glass thickness, and optical aberration corrections. In this article, we will discuss how to choose the right microscope objective.

A dry objective is designed to work with the air medium between the specimen and the objective lens, while an immersion objective requires a liquid medium to occupy the space between the object and the front element of the objective for enabling a high NA and high resolution. Figure 4 shows the oil immersion objective, which can collect more light (i.e., have a higher NA) compared to a dry objective.

The optical aberration corrections determine the optical performance of an objective lens. According to the degrees of the aberration corrections, objective lenses are typically classified into five basic types: Achromat, Plan Achromat, Plan Fluorite (Plan Semi-Apochromat), Plan Apochromat, and Super Apochromat. Choosing an objective with a proper aberration correction level will help you build a microscopy system at a reasonable cost.

Whatare the 3objective lenses on a microscope

I was just saying that I feel 40-50 deg quite claustrophobic and therefore I feel that I would not appreciate them. Hence I prefer not to buy even the most affordable ones, the bco'. This is because I am not interested in having a large collection of tools, but just using a lot what I already have. This is a personal opinion and doesn't have anything to do with excellent eyepieces out there.

many might not see the need of the "cheap" orthos,despite some of the orthos are not that cheap and actually can cost even more then Ethos,but in my opinion,if you are after some critical detail on planetary or even a DSO object and dont need to see those extra degrees of FOV,nothing can beat a good old ortho and that has been conformed by many observers many times over.

Hi Gerry, I apologise, I should have clarified this better. I wasn't meaning that bco are cheap, likely not good. I know they are very very good, as one can read from your and other members' experiences.

The "volcano top" orthos used to be on the used market for rather low prices at one point which made them somewhat of a bargain. Their prices seem to have crept back up to closer to the more recent flat top designs now they are out of production.

Don't be fooled by the price of the BCO Piero, the glass in these things are superb as are the coatings. They give black and green more than a run for their money IMHO.... Sorry for the "heresy"

Types ofobjective lenses

On the other hand, Televue plossls are not true plossls (just as all the other nowadays' plossl), they're symetric doublet (achromat pair), and from the pictures in the middle of this page

As for the Pentax XO 5mm mentioned earlier.I do have one,it does deliver what it says on the tin and i have had some breath taking views with it,but as always there is a spoon of sand in this case its the eye relief of the Pentax XO. 3.8mm for 5 mm ortho is really tight.If you can live with that,you will be rewarded with some cracking views and i would love to see Pentax XO as a proper series of orthos and not only in 2 focal length`s. Would be prepared to pay the high price they demand,but this isnt going to happen sadly.

The 20mm TV Plossl was one of my favourite eyepieces until it essentially got replaced by a 68° 19mm Panoptic. My 8mm, 11mm and 20mm TV Plossls don't really see that much use these days but I think Plossls are still relevant depending on what you are viewing. For low power views of open clusters or objects such as M42 I sometimes prefer a 25mm Plossl over the 24mm Panoptic. I think the 50° FOV can be limiting although a lot depends on field stop and eye lens size. Plossls can vary a bit with this which is generally why I use TeleVues.

I don't understand why they lack popularity at times, the views they give are superb and the better the seeing gets the more they can pull away IMHO. I have no problem with a 5mm ortho in my truss dob , and the views are worth the nudging.

There are a few ortho's now on the market. I think they may be coming back into fashion. Talking of Celestron ortho's, I've never seen one, but I found this online:

We can see that for the focal ratio, Monocentric has best on-axis sharpness, ortho comes second, thereafter come achromat pair and könig.

On the other hand, Televue plossls are not true plossls (just as all the other nowadays' plossl), they're symetric doublet (achromat pair), and from the pictures in the middle of this page

Don't be fooled by the price of the BCO Piero, the glass in these things are superb as are the coatings. They give black and green more than a run for their money IMHO.... Sorry for the "heresy"

Many objective lenses are corrected for infinite conjugate distance, while others are designed for finite conjugate distance applications. Compared to infinite conjugate objectives which need a secondary lens (also called tube lens), a finite conjugate objective can generate an image of a specimen by itself. A finite conjugate objective, as shown in Figure 1, is a good, economical choice for a simple microscopy system.

There isn't a huge difference between the 18mm AH ortho and the 20mm TV Plossl in overall size. The TV is a little bit more expensive (a few pounds Sterling) but you do get a rubber eye guard, a rubber barrel grip and a tapered barrel safety undercut.

The most important parameter of a microscope objective is the numerical aperture (NA). NA measures the microscope objective’s ability to gather light and determines the resolution of a microscopy system.

Usually the working distance (WD) refers the distance from the front lens element of the objective to the observed object when the object is in sharp focus. Objective lenses with long working distance are needed for many scientific research applications such as atom trapping and analyzing fluid samples that require putting an object in a chamber. The resolution of a microscopy system can be significantly affected if the observed object is not placed on the designed object plane, especially for an objective with high NA.

I would like to think that Televue's claim are meant astigmatism suppression in the field (outer edge), especielly in faster scopes, since Televue has its patent in plossl design, USpatene4482217.

Objectivelens function

I would like to think that Televue's claim are meant astigmatism suppression in the field (outer edge), especielly in faster scopes, since Televue has its patent in plossl design, USpatene4482217.

If you really are a fan of orthos and have the cash to burn and can get your hands on Pentax XO,get it and you will love it.it is truly a magnificent eye piece.

Whatis the magnification of the ocular lens

NA is commonly expressed as NA = n × sinθa where θa is the maximum 1/2 acceptance angle of the objective, and n is the index of refraction of the immersion medium. The limit of resolution of a microscope objective refers to its ability to distinguish two closely spaced Airy disks. Resolution (r) = λ/(2NA) Where r is resolution (the smallest resolvable distance between two objects), and λ is the imaging wavelength. The higher the NA, the better the objective resolution.

Whatdoes the stagedo on a microscope

Don't be fooled by the price of the BCO Piero, the glass in these things are superb as are the coatings. They give black and green more than a run for their money IMHO.... Sorry for the "heresy"

The most common immersion media are air, water, oil, and silicone. Choosing the appropriate objective designed for your immersion medium will result in higher resolution images.

I think I've seen some of those. Some people prefer the volcano top with ortho's, although I suppose only the really short focal length ones really need it.

I found that the "volcano top" shaped orthos made it easier to access the eye lens of the shorter focal lengths. Optically the more recent "flat top" Baader GO / Astro Hutech / Fujiyama orthos show slightly less light scatter and a little more transmission than the "volcano tops" to my eyes but the eye lens can be hard to locate and hold (for me at least) in 6mm focal lengths and below. My scopes are undriven though, which might not help with that !

I honestly thought it was just advertising spiel by TeleVue. Although, the build quality of the eyepieces isn't in dispute. I thought a Plossl actually was an achromatic pair. I'm not that up on the history though. That link about optics is good though, I've bookmarked it. Thanks.

Infinity-corrected objectives are ideal for research-grade biomedical industrial applications especially when additional components (such as filters, dichroic mirrors, polarizers) are needed in the microscopy system. Adding optical plate components in the infinity space (shown in the Fig.2 labelled as “Parallel Optical Path) between the infinity-corrected objective and tube lens will not introduce spherical aberration, or change the objective’s working distance.

High powerobjective microscopefunction

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Objective lenses are used to magnify an image. In addition to numerical aperture, magnification is also an important parameter. The objective magnification typically ranges from 4X to 100X. As the image sensor size or eye observed area is fixed, the field of view of a microscopy system changes with the magnification of the objective lens. Typically a lower magnification objective lens will have a larger field of view and lower resolution, and a higher magnification objective lens will have a smaller field of view and higher resolution. The diameter of the FOV can be calculated by using the following formula: FOV= FN/Mag The field number (FN) in microscopy is defined as the diameter of the area in the image plane that can be observed through the eyepiece or image sensor.

We can see that for the focal ratio, Monocentric has best on-axis sharpness, ortho comes second, thereafter come achromat pair and könig.

Yeah, I really find Plossls less than 8mm hard work, I should imagine ortho's are no easier even with possible better eye relief. I suppose anything rare that comes back into fashion will command high prices.

No need to apologise Piero- they are cheap lol! and that is one of the beauties of them. I just wanted to emphasize the optical quality of these eyepieces. Orthos are definitely not for everyone and with the excellent widefields out there many don't see the need for them. BUT on nights of excellent seeing out they come or if we need to keep bright stars away from those cherished faint nebs...

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SO offers a wide range of objective designs, which provide various degrees of optical aberration corrections for supporting different needs, such as achromatic objectives (the cheaper objectives) for laboratory microscope applications and long working distance apochromats (expensive objectives) for biological and scientific research applications. We can help you choose or design a properly corrected objective lens for meeting your application requirements.