Why? Well, first of all, my 30-mm Ultima is really a lovely eyepiece, and getting something of equivalent quality with a 68-degree FOV is not cheap at all. But a 24-mm wide-field is better - and more expensive.Įvery year for the last 5 years at least, I've pondered buying a 24-mm widefield and rejected it. A 32-mm Plossl is cheaper - and just fine.
So I'd say it's strictly a tradeoff of cost versus function. However, going to 3.3 mm will make an immediate and obvious difference in how many stars you can see, how well you can separate star pairs inside clusters, and in your ability to see faint nebulosity.Īnd while I agree that once the AFOV gets too big, it's hard to take the whole thing in, I find that 68 degrees is just on the edge of what I can meaningfully process at one time.
4.3 mm is a very nice low-power exit pupil - no complaints at all. I guess many times I really don't want to feel like I'm "in" something but prefer to hover above it.that old seeing the forest from the trees thing.Īctually, though I'm by no means one of the wide-field evangelists - rather the opposite if anything - I don't agree that the difference is strictly, or even primarily, aesthetic. I myself have both, but if pushed to keep only one, it would be really hard choice, but would probably opt for the 32 as it makes study of some things just plain easier - plus on things like Pleiades I personally would find the 52 deg tfov better than swimming around in a 70 or 80 or 90 deg afov as it lets me "feel" the relationship of the stars to each other better. If I'm scanning the scope around a rich star field and want that "Sunday drive in the country" feel, then the 24 wide field is the better choice. I find that if I am actually going to seriously study a star field, then the smaller afov is a better choice. If all you are after is the widest TFOV you can get, then the easy answer is a nice Plossl. So the decision comes down to aesthetics only IMO and does a nice 52 deg afov satisfy you. IME a 4mm exit pupil will give a nicely dark background and moving to a 3mm exit will not really change it all that much. Thank you BillP for the detailed explanation.Now i know what to expect.For relatively small 110mm f7.3 newtonian reflector is there any sense to buy for example 24mm 68 deg wide eyepiece to reach the maximum tfov of 2 degrees or i can just buy 32mm plossl for that goal?įor these 2 EPs, the 32mm will give you about a 4.3mm exit pupil and the 24 will give you around a 3.3mm exit pupil. Similarly at times my 40 Paragon shows the target best, at other times the 56mm Plossl does a better job (including aesthetically). For example, at times my 24 wide field will be best, at other times the 32mm Plossl shows the subject better. In my personal experience over the years, I have found that while wide fields are certainly beautiful to observe thru, depending on the target and the sky conditions, they don't always provide a preferred view of the target. So bottom line, your results will definitely vary (and sometimes substantially) over what the picture shows for things other than relative magnification differences, and of course whether you use a wide field or mid-sized afov EP for a particular target it will depend on your intent on the observation as to which will be the "best". I also worry that the color saturation and star point sizes are magnified in the picture example referred to whereas this will not occur to the same extent in reality, again being highly dependent on the resulting magnification that a 13mm will provide in your scopoe to show an actual increased star point size. A 13mm EP in my f/10 C8 will show such a magnificently dark background. Any 13mm EP in my 10" Dob in my Mag 3.5 skies will not show a dark background like the one pictured. The 52 deg fov will be easier to "study" the fov with more direct vision and will also show the image in a more orthogonally correct orientation as the 52 will have little or no apparent rectilinear distortion whereas the 82 deg will shift positions of stars in the periphery in order to maintain a focused star point.Īs far as the background darkness, IMO the picture referred to is misleading and is highly dependent on the scope used. The 82 deg fov will be more immersive of course and require you to use a lot of peripheral vision and/or looking around to take everything in. Same view, one just magnified more and spread over larger afov. You are correct, for any given scope the 1.25" 52 deg 32mm EP will produce the same TFOV as the 2" 82 deg 20mm Nagler.
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