24mm eyepieces lowest power useable on f4.7?

[Tot]

I have a 24mm Hyperion which I love on my 10" Dob if that's any help :-)

Thanks. Seems some folk say one of these would be good, others say avoid. Thought that might be the case. :-)

[John]

Ok, so I'm best not to go overboard, going much beyond 20 - 24mm, as here is light polluted? If I went to 30mm I'd have a wider view but things would looked "washed out"? My compromise then might be a 24mm, wide view but not troubled by LP so much?

My 21mm gets more use than my 31mm for this reason.

I still like to have both though for the nights when the longer focal length can do well.

[Tot]

Hyperions are no good at f/4.7, they will be fuzzy at the edges.  I am in favour of the ES82 series 24mm, this will be great in your f/4.7.

Thanks for the advice. If funds allow I'm probably going to get an ES82 24mm. I want wide, but not so much that LP becomes a bother. Plus I have to think about weight of the eyepiece, too. The 24mm seems about right, I think.

Thanks for all the replies, advice and comments. So much to learn.... Any other people who want to add their experience or opinion please feel free.

Tot

[swamp thing]

Steve.

Yes good point. It is a big beast. But, if you want big wide quality views for aprox £200. You've got to accept some compromises.

I'm getting it because I'm after the context and multiple objects. For a quick swap in and out eyepiece, then 24mm 68° or a slightly shorter 82° will do the job.

Paul

Indeed Paul.

Don't get me wrong the big wide 30's are excellent eyepieces. I love mine despite Calvin (estwing) tempting me with his wonderful Ethos 21, that I simply cannot afford.

I just tend to recommend a more all round low power eyepice first. As John says, the big wides can become washed out if the sky is a polluted one.

For a newbie I'd put my money on a 20-24mm first. Then later if finances permit get the big lump. I think when using my 10" Dob the big wide only gets used on about five objects. For these objects and when used at dark skies the big wides can be stunning.

[Charic]

Hoping to get a 254mm (10 inch) , f4.7 dob reflector soon. Hoping to see wide-field views of clusters etc. I'd like the widest field of view my budget and scope will allow. Would a 24mm eyepiece be the lowest power to use? I'd love to get huge wide fields as with TV Delos and Ethos, but my budget for this eyepiece is around £150. Thinking maybe Hyperion? Any help much appreciated.

Tot

Tot  According to calculations? your 10" and your age ( exit pupil size @ 6mm ) could suggest a 28mm Eyepiece as your lowest power giving 42x magnification. The wide-field views dependent on the chosen parameters of the eyepiece?

You can often exceed the calculations/theories a little, when conditions allow.

[Charic]

No you are not wrong. The exit pupil of a 40mm eyepiece used in a f/4.7 newt (8.5mm) is way to big and you are wasting light. There is also a chance you'll start seeing the secondary shadow when viewing bright objects. TBH you can get wide enough 32mm eyepieces to get any object you want in a 10" f/4.7 newt.

Are you really wasting light? The image is as bright as it can possibly be for the eye, so no light lost. I believe in reality you are  actually wasting aperture, as you cant use the full exit pupil. If this means the same thing, I'll stand corrected.

My information is from a quote by Al Nagler

[swamp thing]

. If this means the same thing,

It does.

[jetstream]

The ES 82's are very good Tot, they do have a recessed eyelens that not all get along with. For my conditions this is an asset as they seem fog/frost resistant. These EP's come close to "Nagler" performance IMHO. The Luminos with its cool tone comes close too, but with a bit of astig showing at the very edge in fast scopes, mind you this EP has a the widest TFOV of any EP in its class.

[Polar Bear]

I use a Panaview 32mm with my 1200mm F4.7 Skywatcher and think it is a good EP for the price and will not upset the balance of your dob too much.

It is not sharp edge to edge but you get what you pay for. RVO are selling them at £78.50

With your change I would invest in a good 5mm or 7mm Japanese Orthoscopic for Planetary viewing.

Paul

[Tot]

I use a Panaview 32mm with my 1200mm F4.7 Skywatcher and think it is a good EP for the price and will not upset the balance of your dob too much.It is not sharp edge to edge but you get what you pay for. RVO are selling them at £78.50With your change I would invest in a good 5mm or 7mm Japanese Orthoscopic for Planetary viewing.Paul

Thanks for the info. I have some planetary eyepieces already so will see how they are with the dob. If money won't stretch to the ES82 24mm for my low power I'll take a look.

All of this of course depends entirely on my successfully robbing a bank. Or two. :-)

[Pankaj]

I have a 10" reflector. I think you shouldn't go beyond 30mm. Calculate the exit pupil. 6-7 is suitable for young eyes. If you are above 40 years,  either restrict exit pupil to 5 or confirm with your eye specialist.

My experience would suggest to be within 30mm with 62degrees to 82degrees AFOV of the eypieces.

By the way, with a 25mm, 10" aperture in a really dark & pollution location, will still give you that 'awesome feel of putting your head in a bucket of stars.'

Cheers...enjoy your 10" !!