are plossl eyepieces good

Since it's such a popular eyepiece and allows for quality, planet-viewing, that makes it a great instrument for attracting newcomers to the hobby, especially children. I did sell them all when I adopted Dioptrx, and the Naglers are amazing! I was just wondering if plossls are still worth it or should get a better eyepiece in a 30mm range. I also just bought the Celestron Starsense 102mm refractor (650mm focal length, f/6.5) as a first scope for me and my kids. I had a newer - purchased in 2016 Meade 32mm (white lettering) that was no better than the older 32mm 4000. Now here is something that some of us classic scope nuts know - there are plossls, and there are plossls. If you do choose to go with a Plossl eyepiece, I highly recommend spending some extra cash to get yourself a decent good quality branded Plossl eyepiece rather than going for a cheap, generic eyepiece which is a Plossl only for the namesake. Now we just divide it up and fill in some sample focal lengths. Here we have very good eyepieces with some extra features. The Plossl eyepiece is a four-element design consisting of two doublets. Celestron - 1.25" Eyepiece and Filter Accessory Kit - 14 Piece Telescope Accessory Set - Plossl Telescope Eyepiece - Barlow Lens - Colored Filters - Moon Filter - Sturdy Metal Carry Case. I have an SCT and my eyepiece case only hasPlssls (and one Ortho) in it. . Features : 5 superior-grade Plossl eyepieces: 1.25-in, 4-element design with a 52 AFOV (32mm has 44)4mm, 6mm, 9mm, 15mm, and 32mm . There is one aspect in which a Kellner can actually outperform a Plossl: eye relief. . Not only is it good to share the experience but you can get first-hand advice on things like diagonals and may even be able to try one in your scope to see if it makes a difference. I can say that most of my plossls have been replaced by other eyepieces for various reasons. https://telescopicwatch.com/best-barlow-lens-and-how-to/, Celestron 8-24 Zoom Review With a refractor, SCT or MCT, it is usually better to get a correct image diagonal than a correcting eyepiece. Meanwhile, Plossl eyepieces are much more common and easy to find. ES 82 degree series plus 1 meade uwa @20 mm with 1800 focal length optical tube lowest mag 51 x / highest mag 300. Each eyepiece gives you a unique magnification based on the formula listed at the start: Why do you need more than two eyepieces? I possess an embarrassing array of fine eyepieces with names like Ethos and Nagler and Delos. They are also good for those who have astigmatism because they are designed to be more forgiving with eye placement. We may earn commissions by recommending products on this website. Hi Ed, For astronomical observations, such as viewing craters on the moons surface from Earth, high-magnification models are preferred because they offer more detail. So, I think it worth your while to try the Plssls. SVBONY Direct . These are effectively simple designs like Plossls, Kellners, Konigs, and RKEs, with long focal lengths, that have a lens included to increase their focal length. NEW. Was $38.99 - $99.99 Now $31.19 - $84.99 Compare Orion Edge-On Planetary 1.25" Eyepieces At 32mm, a Plssl will give you as wide a field of view as any 1.25mm eyepiece can. The difference isnt that severe, and I often track more often than is strictly necessary to keep the object centered anyway. That is why I suggest, if you can use 2 eyepieces, you will want one or two low power wide view 2 eyepieces. Lower power almost always looks better than higher power. In order to help you narrow down your choices, weve created a short guide that can help you figure out what the best viable option is. As we go along, I will refer back to these, so dont worry if you cant answer the questions or understand the formulas now. This may be enough for many eyeglass wearers. Super Plossl eyepieces are generally a little smaller than this at around 16-20 mm in size, which is why theyre sometimes referred to as wide-angle or low power plossls. For the $66/$42 of these kits, you can get one or two decent eyepieces (depending on where you buy). If you want to buy him $200 eyepieces so he can grow into them, that works. And remember, when all else fails, read the instructions. In 1849, Carl Kellner invented the Kellner eyepiece, which is essentially a Ramsden eyepiece where one lens has been replaced with an achromatic doublet made of two different types of glass. I have seen elsewhere discussions about the exit pupil of eyepieces. A zoom eyepiece works like the zoom lens on a camera. A Barlow lens will not reduce the CA in a low FR achromat refractor so to speak of it changing the focal ratio would, I think, introduce confusion in most situations. A good modern eyepiece like a BST starguider 12,8 and 5mm are excellent eyepieces. I have a 4 element (traditional) and a 5 element 32mm Meade, both from the same era in Japan, and the 5 element is much better by quite a bit. Now we can establish a target magnification range. It costs three to four times as much as the Celestron Zoom, but if you have the budget, this is the one to get. Which is Stronger? Nothing will stop you from trying to go higher, but in all likelihood, the image will be poor and not worth the cost of eyepieces to achieve it. Poorly chosen eyepiece might give you poor experience and sometimes even make stargazing difficult. These sport a 60-degree apparent field of view, about a 20% wider apparent field of view than Plossl eyepieces. They all work, but as you go up in price, you gain features or performance or both. The Expanse is a lens that provides an extra sharp image, and it also has a wider field of view compared to the Plossl eyepiece. No, adapters are not needed but they may come in handy when you want to change the focal length or add other lenses such as filters or Barlow lenses. Read our full affiliate disclosure here. a breath of fresh air! Both will provide the same magnification. Even when I upgraded to a 6mm Goldline, I kept the Kellner around because of pretty annoying kidney-bean blackout issues on the Moon with that eyepiece. But you need to know, first, if you will be wearing glasses when you observe. The magnification and field of view is the same as a 10 mm eyepiece (AFoV being unchanged) in a 600 mm telescope but the eye relief is that of a 30 mm eyepiece. I have to say that your questions are answered in the article. Are plossl eyepieces still worth it? To estimate the highest practical magnification for your telescope, you take the aperture in millimeters, mm, and multiply it by two. By having a range of magnifications, you can optimize the image, which means you need more eyepieces. What happens if you use an eyepiece that has a the wrong exit pupil? Higher than 3X is usually reserved for astrophotography. It had one of the best fields, edge to edge, in my SCT that I've ever seen. Save my name, email, and website in this browser for the next time I comment. This general purpose design gives good colour correction and an adequate feld of view at reasonable cost and they are often bundled with new telescopes. In retrospect, I should have included Tele Vue. 30 = 60 = 1.3 I had a bino pair of TV 20mm Plossls, very fine for high power planetary observation with my long focus 8" Mak, then I also bought the older TV 21mm Plossl, after trying the 21mm I sold the more recent 20mm. Plossl eyepieces have an eye relief equal to about 80% of their focal length. Etc.? Another really helpful article, Ed. They also offer a generous 16 mm of eye relief which is most important in the shorter focal lengths. This is the link to the one I plan to buy as I know some others come with add ons: https://www.rothervalleyoptics.co.uk/baader-hyperion-mark-iv-8-24mm-universal-zoom-eyepiece.html, Thats great you had an XT8i that makes me feel confident I got a good telescope . We will use 10 mm as the eyepiece focal length, but we will look at three different 10 mm eyepieces, each with a different apparent field of view, AFOV. Warranty Limited Warranty against defects in materials or workmanship for one year from date of purchase. Get to know more about us here. Great article on eyepieces but I am still undecided exactly what eyepiece & Barlow to buy and from where since some buying sites dont provide all the info you cite in your article. If you don't like the reflections, there really aren't many other budget options at its focal length beside a Plossl which will be super uncomfortable to use, or spending over $100 for something like a Meade UWA. This eyepiece was even better at correcting false color fringing, but because of internal reflections, the glare was even worse. The Plossl design has become the mainstay of the modern ocular business and probably represents the best value in terms of performance and price, especially in medium and long focal lengths. But in this scope, the 32 mm doesnt work well. This eye piece provides the maximum true field of view in the 1.25 inch format. The image quality is very good and the additional field of view and longer eye relief makes them very comfortable to use. When discussing eyepieces, you will hear people comment on how well the eyepiece is corrected. Apparent Field of View: This is a measure of how wide a view the eyepiece will provide as compared to alternate eyepieces. In the box you'll receive 5 1.25 eyepieces at following sizes, a 32 mm Plossl Eyepiece, 17 mm Plossl Eyepiece , 13 mm Plossl Eyepiece, 8 mm Plossl Eyepiece, 6 mm Plossl Eyepiece, a 2X Barlow Lens 1.25. A Televue Plssl may be better than a generic one, but the difference is probably not worth the additional cost. People may have heard, and rightly so, that Huygens or Ramsdens are crummy eyepieces and that they should get a Plossl instead, and they may believe the same applies to Kellners, but the truth is that Kellners are often good eyepieces. Divide that by the magnification of that eyepiece in that scope. Even though the design has existed for more than a century, it has stood the test of and is still today the standard against which other eyepiece designs are measured. Stargazing Help is a participant in Amazon Associates program. My own lineup (with a C8) is 32mm Plossl, 18.2mm DeLite, and 10.5mm Pentax (the last one not chosen to match, but rather because it belonged to a deceased friend). Plossls provide very good eye relief for eyeglass wearers in focal lengths of about 25mm and longer. no caps come in bolt case. We often end up spending more on eyepieces than we did on the telescope. . Question: would it perform well with 1.5/2x and 3x Barlows? A 20mm Plssl is probably worth it, if for no other reason than to compare the views it gives to the 21mm Hyperion you have. A 6mm Plossl has a tiny eye lens. Edited April 23, 2010 by russ teh_orph Members 28 198 Author They have decent eye relief and little curvature of field. A Televue Plssl may be better than a generic one, but the difference is probably not worth the additional cost. There are three types of Plossl eyepiece: the regular, Super, and Orthoscopic. I havent been into the hobby for long but my experience is in line with whats been said. This four-element Plssl design is the most popular eyepiece optical design that gives you excellent image quality, good eye relief, and a 50 to 56 degrees apparent field of view. Explore Scientific 68 34 mm or ES 82 30 mm would also be good choices at a significantly higher price but with better edge correction. Using this approach, you would buy a 2X Barlow and hold off on the 4 mm and 3 mm to see if you can reach these magnifications often enough to justify buying an eyepiece. But dont fear that you will waste your investment as eyepieces are standard sizes. I just added the 4.7 mm. Modified vs Unmodified DSLR Astrophotography: The Ultimate Showdown! We also joined our local Astronomy Club and look forward to joining others under the night sky when the opportunity presents itself again. https://www.amazon.com/s?k=Orion+Q70&ref=nb_sb_noss_2, Understanding Telescope Eyepieces- There are recommendations, based on budget, I took notes and now can shop with confidence The magnification range that is appropriate to your scope. Nice, thank you again for the additional inputs. Over time, you may wish to add a specialty eyepiece here or there, but I would not make that a priority until you have filled out your magnification range. Look those up, seeing and transparency in the context of astronomy. Typically, these will be 25 mm and 10 mm or something close to that. Can you give me any specific recommendations on what to buy and from where? Here we focus on becoming a knowledge hub for astronomy and astrophotography enthusiasts. The Plossl eyepiece has 4 lenses, consisting of 2 identical double lenses. Plossl eyepieces are often included in better telescope packages as the starter eyepieces. Celestron Omni Eyepieces: The Omni series is the most economical eyepiece offering from Celestron. Hi, I have recently bought a Orion XT8 and am trying to work out which eyepieces to add to what is provided with the scope. But what are the other differences? But just because an eyepiece is 2 doesnt mean it has a wider field of view than one that is 1.25. A Plssl is probably as good as any 32mm eyepiece in a 1.25 inch focuser. Best suited for telescopes with f-ratios f6 or slower. This type of eyepiece provides you with wide-field views without any distortion due to its use as an achromatic lens system which reduces chromatic aberrations by combining two lenses made from different types of glass materials together on each surface. Plossls are available from many suppliers in a wide range of focal lengths in 1.25 and 2 sizes. Other eyepieces of more advanced design can have better eye relief and field of view. Are Plossl eyepieces good? But those EPs mentioned were all great too! a Celestron 8-24 Zoom with a 2x Barlow We are a reader-supported organization. For our experience level, would you recommend changing anything right now? These are the best in optical performance and build quality. EP-mm = magnification = afov OHHH, now i get it! Perhaps you should seek out help from your local astronomy club. Again, I only do this for my low power wide views. In my opinion, you do not. Depending on your budget, if you only have limited funds and are just starting to fill out your eyepiece collection I would go with the zoom, then zoom with Barlow. Here we get into the BMW, Cadillac, Porsche, and Ferrari of eyepieces. If you were considering a Super Plossl made by an entry-level brand, just use those extra funds to instead get a regular Plossl made by a more reputable manufacturer. Elena is a Canadian journalist and researcher. As for tabletop scopes, dont forget that you need a table, stool, or bench to place them. Sorry but I am not offering a configuration and pricing service. When I had a 6mm Kellner, I found the eye relief annoyingly short, sure, but when compared to the 6mm Plossl that often comes with eyepiece kits, it was luxurious. FOR SALE! Number of Lenses. To determine a magnification range, we will start with the aperture of the telescope, the size of the front lens, or the mirror in the back. The only one not in the article is the Orion Q70 which is available in 38 mm, 32 mm and 26 mm. In simple terms, high focal ratio scopes, say those over F6, tend to be less demanding on eyepieces than those below F6. What diameter eyepieces will my telescope accept? Low focal ratio scopes deliver the light rays to the eyepiece at an ever-increasing angle as the focal ratio number goes down. You can do that by using this long focal length eyepiece. In some cases, an object is so large (i.e., the Moon, the Pleiades, the Orion Nebula, the Andromeda Galaxy) that a narrow field of view can only show you part of the object, whereas a wider field of view could show the whole object at the same magnification. A Kellner eyepiece has 1 double lens and 1 single lens. And new proprietary designs come out from time to time. Plossl telescope eyepieces are the most popular type of eyepiece on the market. A very good quality eyepiece for a reasonable sum. In this case, I am going to define this by the focuser and eyepiece size. They have a narrow AFOV but have a reputation for being very sharp.. The downside to this type of lens is that they can cause chromatic aberration which creates colored spots around bright objects such as planets or stars due to the different wavelengths not going through equally. All registered. Because of this setup, you might also hear a Plossl eyepiece referred to as a symmetrical eyepiece. The focal length range for 1.25 Plossls is about 6mm to 45mm. Best Telescopes For 10 Year Old Kids: Reviews and Buying Guide, The Complete Guide to the Planets You Can See With a Telescope, The Best Barlow Lenses: Reviews and Buying Guide. OK that makes sense, many thanks. Second? (Focal ratio is a term that refers to the telescopes focal length divided by its aperture. In my opinion, there are no wrong exit pupils. If you were considering a Meade Super Plossl, in that case just get the regular one also by Meade. Interesting points Philip. They deliver sharp images in almost all telescopes. If you look up transparency and seeing in the context of telescopes you can learn more about how atmospheric conditions will affect what magnifications you will choose on any given night. However, if you want to optimize your viewing experience, youll need to invest in a better-quality eyepiece. So you would have to test the set to see the actual result. What follows are specific eyepieces that I have tried, own, or have read so many good reports about that I feel very comfortable recommending them. They are 82-degree AFOV eyepieces. Do you need a 10 mm planetary and a 10 mm DSO eyepiece? The "sharpness" you are seeing may well be better explained by the focal length of the ep than the quality of Plossls in general. Kellner eyepieces work perfectly with small and medium-sized telescopes. Many compare these favorably to eyepieces that are much higher priced. I cant answer that specifically as I have no experience with that eyepiece in that scope. While many people will stay with and add Plossls to their eyepiece set, I would recommend not going below 10 mm focal length as the eye relief gets quite short. I have just one Meade product currently and that is a series 4000 1.25 inch UHC type filter which I use for outreach. Very worth it for me, as I like to use bino-viewers. The Big Bang Optics participates in the Amazon Services LLC Associates Program, which is an affiliate advertising program designed to provide a means for websites to earn advertising fees by advertising and linking to amazon.com. A standard Plossl eyepiece is typically between 20mm to 25mm but can range anywhere from 15mm up to about 40mm in diameter. So, even if you have a Maksutov-Cassegrain scope, you should get a good experience from this eyepiece. Quality this good usually costs a lot more. These are highly sought after ep's, and hold their value well. Even though there are more sophisticated types of EPs, Plossls hit the right spot between high-quality optics and price. Why not go back to the people who sold you the scope and get their help. As to a more immersive experience, yes, I would say a wider FOV does provide a more immersive experience. Plossl eyepiece is one of the reasonable options when it comes to telescope eyepieces for stargazing or astronomy. The result in magnification is the same and the eye relief associated with the eyepiece is retained or, in some cases, actually lengthened a bit. You have a very wide choice of brands and styles to choose from. You alluded to them, but you never mentioned Tele Vue. Look at the apparent field of view specs and understand what this means for the field of view. How does that field of view impact the viewing experience? All focal lengths offer 50 field-of-view except the 40mm which offers 42 So we say that an F5 scope benefits from better corrected eyepieces more than the F10 scope. i did buy an astro-tech 3.2 paradigm ed from a cloudynights.com forum member. I currently own a Mak127 ( that can't use 2"eyepieces) and a 80ED ( that one can hold 2"eyepieces). Plossl eyepieces have wider fields of view than Kellners. It offers good color correction and high-contrast images. While I also have the Baader Hyperion Zoom, mentioned later, I continue to make use of the Celestron, especially in my smaller scopes. Eye relief is the distance from the eye lens to your eyeball, and the higher the better (within reason). Not everything in the sky benefits from high magnification. Omni 12mm Eyepiece - 1.25" Learn More. No surprise there. Despite the narrow field of view and short eye relief, it showed shockingly good views of Saturn, Jupiter, and even the Moon. This can be very helpful for star hopping. If you want to observe the fine details of a specimen, Plossl eyepiece has a higher magnification than an ocular with lower lenses. (Svbonys Plossls, for example, are optically identical to Orions Sirius Plossls). Every new skill takes time. They also offer more eye relief than Plossls at the shorter focal lengths. With an f/10 telescope, Plossls are as sharp as any other kind of eyepiece of the same focal length. But I think you will feel more confident about your purchases and be less likely to be disappointed if you read through the guide. Or is this overkill and am I better off saving money and going forward something like the Celestron Zoom? I do not miss beating my eyelashes against a 9.7mm Meade Plossl that I used to own. With your glasses on, you simply cant get your eye close enough to an eyepiece that only has 10 mm of eye relief. But are they really? That's hard to beat IMO. Another useful aspect of a wider field of view is that, assuming the entire eyepiece is sharp enough to show good images right to the edge, you dont have to nudge the telescope to track the rotation of the Earth as often with a Plossl (50 degrees) compared to a Kellner (40 degrees). If you read the article you know how to calculate the magnification and field of view. But the longer FL units are certainly useful. Plossl eyepieces have an eye relief equal to about 80% of their focal length. Under my sky it was rare that I would be able to get over 225X and still maintain a good quality image, except on the Moon. The third choice of eyepieces is the Orion 12 mm Sirius Super Wide Angle Correct Image Eyepiece. Can you suggest the total . Since each eye has a different focal point, I suspect pulling the eyepiece out until reaching focus and then tightening the set screw. A 10mm or shorter Plssl is probably not worth it unless you want to see how you personally cope with short eye relief. Explore Scientific recently extended this offering by adding a series of 82 degree eyepieces labeled LER, or Long Eye Relief. Some include: Parks Gold Series, Celestron Ultima's, Meade Series 4000 Super Plssls (depending on year / origin / style) and a few others that I don't remember. Your email address will not be published. The price can run to over $1000 per eyepiece. These are the workhorse eyepieces of today. I must say Im quite confused about eyepieces. Save my name, email, and website in this browser for the next time I comment. And since this article is intended as an aid to beginners rather than a rigorous optics lesson, I think the context I provided works well enough. I beleive this is the same as they ones you asked about. A Kellner eyepiece has 3 lenses, while a Plossl has 4. Many thanks, Sophie. I have not had an opportunity to test it yet but the general discussions have favorable. As the clear cut worlds best eyepiece manufacturer, their name should at least be mentioned in an article like this. Plossl eyepieces are perfect for astronomical viewing because the field of view is wider. Orion Q70 38 mm works well. I would recommend the Orion Q70 series over that. It costs a lot to get that last 10% of performance. You mentioned regarding ORTHO eyepieces: Excellent specialty eyepieces, usually for planets. there are of course options to plossls which are about the same prices as GSOs such as the BST Discoveries and TMB type eyepieces (new from Skies the Limit on Ebay) which have a wider field and better eye relief than plossls and are probably as good as most things non-premium. A long eye relief is also important for those who wear eyeglasses at the eyepiece, whether thats a member of the general public at a star party or an astronomer with astigmatism, which, unlike near- or far-sightedness, cannot be corrected with the telescopes own focuser. Your email address will not be published. In this article, were going to talk about what is a Plossl eyepiece, what are its components, how do they work, how many types are there and how youd buy a good Plossl eyepiece. Hi - I bought these from another AM'er 1 year or so back, thinking I will get into visual astro, But never found the inclination, So here it is for sale 9mm Nagler type 6 mint with box and caps,16mm Nagler type 5,optics are exc. With a 130mm-F5 I would use a Plossl 32mm for its low-mag-wide-view. The design of a Plossl eyepiece consists of an objective lens with one side that is convex (wider than its length) while the other side is plano-convex or flat in shape. I believe the 5000 UWA's are good as well. Kellners can be as little as half the price of a Plossl in the same focal length, but they are generally very comparable, especially in recent years as telescope prices have fluctuated in response to changing supply chains and demand. Be sure to read the following as you consider your eyepiece purchases. Ive read, and re-read, and re-re-read this page. The components of a Plossl eyepiece are the two groups of lenses. If that is the case, it will give me another reasonably good, inexpensive zoom to recommend to beginners. Celestron's 4-element Plossl eyepiece features include blackened lens edges to minimize internal reflection and maximize contrast, fully multi-coated optics for maximum light transmission. In the world of eyepieces, when you want the very best, turn to Tele Vue, but be prepared to pay a truly premium price. This number can range from 30 degrees to 120 degrees. When I started, I purchased less expensive eyepieces to learn about them and how I would use them. By correcting for aberrations, the field of view of these eyepieces could be much larger than the soda-straw field of view in a Ramsden or Huygens, around 40 or perhaps up to 50 degrees. They are all 4-element Plossl eyepieces, and most have a 52-degree field of view that is common to the Plossl design. Eye relief of less than 10mm gets really uncomfortableyou tend to rub your eyepieces against the eyepiece or lens, and you have to hold your eye at just the right distance to keep from touching the lens. For modern eyepieces, the differences between Plossl and Super Plossl is going to depend on the manufacturer. Omni 40mm Eyepiece - 1.25" Learn More. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Our team of experts has reviewed and ranked 180+ telescopes based on price and quality. If we look at the range I provided above, we see that we could replace several eyepieces with one zoom. I once had to use a 6mm Plossl to attempt to perform a star-test collimation for a telescope at the observatory. The image will be reversed left to right so you will need to get used to that. You could base this on 3, 4, 5, 6 or more focal lengths/magnifications. One of the main drawbacks of this eyepiece, though, is the eye relief. Some optics brands have taken the next step and launched some eyepieces they have labeled as Super Plossl. Kellners are often sold with cheaper, even more entry-level telescopes than Plossls. So plan this into such a purchase. For me personally, even though I don't use glasses to observe, I still don't want to dig out the view through a plossl or ortho eyepiece which tend to have short eye relief. Very often, those eyepieces will be in the outdated 0.965 format rather than the modern 1.25 or 2 diameter barrel format. So its best for use during duller times when there isnt much brightness visible. Again, it only costs $30 to $40 to find out, so the education is not that expensive. But your point is well taken. My Barlow is a 2X with a removeable Barlow element that can be screwed right onto an eyepiece giving a 1.5X effect. A Plossl eyepiece has a lens thats plano-convex, which means it is flat on one side and convex on the other. https://www.amazon.com/Explore-Scientific-68%C2%B0-40mm-Eyepiece/dp/B007LMG3F6/ref=sr_1_1?dchild=1&keywords=explore+scientific+68&qid=1606584676&sr=8-1, Thanks for your reply, I think I will go for the Orion Q70 . The original Meade 5-piece Super Plossl hasnt been in production for decades and at this point is more of a collectors item than a high-performance eyepiece. If I had to give them all up and keep only one eyepiece, It would be the BH Zoom. This is perfect for a 25mm Plossl (an extremely common standard) and downright luxurious with a 32mm Plossl, but when you get below about 12.5mm or 10mm, it can begin to get difficult to use. The eye relief is the distance between your eyes and the eyepiece where you are able to view the whole image comfortably. Does this sound like something you would recommend based on the telescope I have? Free shipping for many products! If you are going to wear your glasses when you observe, you want at least 18 mm of eye relief and 20 mm is better. Gold Line eyepieces also offer better eye relief than Plossl eyepieces, especially at the shorter focal lengths.