Pushing the mag

[sirmetin]

We have a 10" orion optics F4.8 Newtonian and have both the 6mm and 10mm Delos EPs along with a 24mm panoptic. The long eye relief of these is great becasue we both wear glasses. What would people suggest to get mags above the 200x limit of the 6mm we have atm?

[brantuk]

With a fast scope you want quality optics - the only thing really is a TV Powermate 2x. It's about the best "barlow" you can get. It's not so much of a barlow as it is a magnifier - you just can't see it in the light train

[sirmetin]

Was looking at the Nagler and Pentax XW both at 3.5 but ideally I think I need 4mm c340x vs 300x.

[Stephen]

I think you may well find that EP never comes out of its box. You would need absolutely perfect sky conditions to get much above 250x, let alone 300x?

[sirmetin]

So a 5mm could be a better target as a next step?

[NGC 1502]

So a 5mm could be a better target as a next step?

Yes I agree, a 5mm would get more use than a 3.5mm with your scope, and the 6mm you already have will be usefull more often than a 5mm.

I too have a 10" F4.8. It's kept well collimated, and I'm happy with 150 - 200x high power on most nights. Opinions will vary however.

If you get nice sharp views with the 6mm at 200x, it could be worth getting a 5mm for really good nights.

Regards, Ed.

[Chris H]

I have the same size scope to you and I have a Pentax XW 5mm which gives me x240 however it so rarely gets used that I consider it to be a waste of money. My maximum magnification usually tops out at x150 with x200 occasionally and x240 very rarely (3 times in last year). Just my 2 pence worth.

[John]

I have an Orion Optics 10" F/4.8 as well. I rarely use mine over 200x. Much more often 150x or 180x is as far as you can push while retaining sharp, contrasty images. I can't imagine ever using 300x or 340x with it despite having the eyepieces to deliver that.

[michael.h.f.wilkinson]

With my C8 I can on occasion go (well) above 200x. My Radian 8mm gives about 250x, and has been used quite often on Mars and the Moon. The 10mm does get used more, but I have also used the 14mm with TeleXtender (very like Powermate) to get 288x. A 10" scope should be able to handle more, but only on good nights. For detailed planetary work, it is good to have a fairly closely spaced series of EPs to match the conditions. A 5mm would certainly be useful, and maybe a 4mm as well. The Radians come in those focal lengths

[RikM]

I chose the Pentax XW 7mm over the 5mm for use in my 10" f/4.7. I would have thought your 6mm Delos would be just the ticket?

If you want to stick with TV, then a 4mm or 5mm Radian would probably be what you should look at.

[Mr Spock]

I used to have a 250mm f4.8 (Skywatcher) and my most used eyepiece was a 4mm NLV. Only 45° but 20mm eye relief and as sharp as an Ortho.

I also had a 6.4mm. It was good, but didn't bring out the detail like the 4mm.

Even in moderate conditions an experienced observer can be patient and skillful enough to take advantage of those fleeting moments where x300 is pin sharp.

[michael.h.f.wilkinson]

I used to have a 250mm f4.8 (Skywatcher) and my most used eyepiece was a 4mm NLV. Only 45° but 20mm eye relief and as sharp as an Ortho.

I also had a 6.4mm. It was good, but didn't bring out the detail like the 4mm.

Even in moderate conditions an experienced observer can be patient and skillful enough to take advantage of those fleeting moments where x300 is pin sharp.

Agreed, at those magnifications you do not get a sharp image all the time, you need to wait for the good moments. Patience has its rewards.

[rwilkey]

The 3.5mm is pushing it a bit, I bought the tall SW 3.5mm a year ago and have never had good enough conditions to use it at 285x or at 257x in my C100ED. I would never go below 5mm to be honest.

[michael.h.f.wilkinson]

The 3.5mm is pushing it a bit, I bought the tall SW 3.5mm a year ago and have never had good enough conditions to use it at 285x or at 257x in my C100ED. I would never go below 5mm to be honest.

But the 100mm aperture may limit that. A 3.5mm in an F/4.8 scope is not necessarily pushing it. A 5mm EP in an F/10 scope gives you the theoretical limit, as does a 2.4mm in an F/4.8 scope.

[rwilkey]

Hi Michael, doesn't work in my f/5 scope, just not a good marriage at all.

[michael.h.f.wilkinson]

Maybe the SW 3.5 does not like the wide light cone of a fast scope? I have used a 7mm in my C8 (same magnification as 3.5 in your F/5) under good conditions.

[Moonshane]

another thing to consider is balance. with a 2" powermate or barlow, the weight of this plus a hefty eyepiece may make it tricky to retain balance.

I tend to agree that at this sort of focal ratio, anything above 200x will be relatively scarce in our viewing conditions and you might be disappointed.

if you can readily afford another good quality eyepiece then perhaps a 5mm Radian would be a good choice as this will cetainly not upset your balance, has good eye relief and a 60 degree field.

all that said, I have eyepieces which give me magnification of up to 400-500x and use this regularly on double stars in my 6" f11 dob.

[rwilkey]

I am not sure what it is to be honest, and don't know the answer, it is an SWA with 70* fov, I go for wider angle at most mags, especially the higher mags.

[great_bear]

As I've mentioned before - on any reasonable night, I can get 240x - 300x without difficulty - but only for about 30 mins or so - at some point between about midnight GMT and 1am. After that, it's gone for good and there's no point shooting for it any further.

It's worth it though for those 30 special mins of Jupiter...

(this is in central London)