eyepieces for LX200 ACF 10"?

[Emmanuel Marchal]

Hi

I've recently bought a Meade 10" ACF (F/10). It came with the Meade microfocusser and the original 1.25" diagonal. I don't have any eyepiece yet. But I know I want nice ones (as I learned about the need for them in my previous scope).

To start, I'd like one EP for DSO wide field (or as much as the meade can achieve and one for planetary at high resolution. I think of then completing with a barlow which I could use for imaging. I wondered about upgrading the diagonal to a 2" one

I went to one astro shop where I was recommended the following

William Optics 2" diagonal and WO 2" 40mm EP

Planetary setup: Televue Delos 10mm

I was then recommended a Televue Powermate 2" 2x for imaging planets, which could also be used to turn the WO 40mm into a 20mm.

Has anyone tried any of these on such an OTA? I imagine these aren't light. Will the microfocuser support the weight?

Or what other EP would you recommend?

Clear skies!

[alan potts]

I have the 12 inch of the same model, I would think much of the works are the same. I put eyepieces weighing in at over 1kg, a Moonlite focuser and a TV diagonal, the scope handles this without a problem though I fitted a balance system to be on the safe side.

I am not sure about the 10mm Delos, yea it is a fine eyepiece, I used to have one, but it will give you x252 and for me that is a bit top end for regular use, I would have thought 12-13mm should be your top end. I don't like using large eyepieces in a powermate and I know a few others on site that also dislike this, individual eyepieces will always be better at the long end. I find say using a 20mm to obtain 10mm much better. You can always use a reducer to make the scope F6.3 to get your maximum FOV, I knocked up a review on this which is further back in this section, I posted it about 5 weeks ago, it is worth a read.

Powermates are superb but that will only give your scope F20 for plantary photography, I always thought you should be F25-30 but I am no expert on this.

Alan

[Emmanuel Marchal]

thanks for the comments. very useful.

I was indeed wondering if 250x was too much for our turbulent skies. Good to know. By the way, I was wondering about the maths behind the maximum magnification a scope can support based on the sky turbulence. Would you know if there is such a thing?

I couldn't find your review on focal reduced. I'm new to the forum so i probably don't know where to search ;(

Best

manu

[alan potts]

I will try to find it and send a PM to you so you can have a look. I do not know of such maths as conditions are so changeable. The other night on only X120 almost all the craters on the moon disappeared, the seeing was so bad, which is very unusual for me.

Alan.

[Laurie61]

Hi, you could Barlow a 40 mm but it may result in a lot of eye relief which can make eye placement more difficult. As Alan says there are no maths for sky turbulence as there are so many contributing factors. There are sites that use info from weather models to give a prediction of seeing conditions for astronomers like this one  http://www.meteoblue.com/en_GB/weather/charts/seeing/stafford_gb_26084   

The rule of thumb for max magnification on many nights is 200x but you will get a few nights a year which allows more. I have a 9 mm ortho for the C 11 and a 6 mm spl for my OO scope which gives me around 300x . Something you have to be aware of is the exit pupil generated, if you have older eyes you may not want to go much below 1mm as you can start seeing eye floaters which can be annoying. An eyepiece giving the same mag as the aperture of the scope, in mm, gives you a 1 mm exit pupil. For your scope this would be a 10 mm eyepiece and give 250x       

[Emmanuel Marchal]

Hi, you could Barlow a 40 mm but it may result in a lot of eye relief which can make eye placement more difficult. As Alan says there are no maths for sky turbulence as there are so many contributing factors. There are sites that use info from weather models to give a prediction of seeing conditions for astronomers like this one  http://www.meteoblue.com/en_GB/weather/charts/seeing/stafford_gb_26084   

The rule of thumb for max magnification on many nights is 200x but you will get a few nights a year which allows more. I have a 9 mm ortho for the C 11 and a 6 mm spl for my OO scope which gives me around 300x . Something you have to be aware of is the exit pupil generated, if you have older eyes you may not want to go much below 1mm as you can start seeing eye floaters which can be annoying. An eyepiece giving the same mag as the aperture of the scope, in mm, gives you a 1 mm exit pupil. For your scope this would be a 10 mm eyepiece and give 250x       

Thanks Laurie

I didn't know about meteoblue.com. Nice one. I've been using http://7timer.y234.cn/V3/index.php?product=astro&lon=0.16204833984375&lat=51.27566243415853〈=en&tzshift=0 in the past which gives a neat summary.

Learning a lot here. I never heard about the eye floaters. Is this what looks like little bubbles slowly cruising in your field of view?

I've got my old 0.965" eyepieces, Ortho 5, 6, 9, 12.5, an Carton Erfle 20mm-c and some K and AH 40mm. Yesterday, I tried the 5mm, 12.5 and 20mm on the moon and Jupiter. The 20mm is by far the piece EP I have and it gives a nice view. the 5mm was clearly a stretch but quite interesting as jupiter was taking a good 20% of the FOV.

Anyway, experience certainly matches what you are recommending as far as going for 250x.

I think I will settle on a 10mm and a 40mm or something like that and then over time, maybe add a midrange, ie 20/25mm.

Still need to figure out which model i should go for. Not many LX200 10" ACF I could find so for. Alan is pretty close with his 12" though.

Thanks a lot for your advices

manu

[Emmanuel Marchal]

To finish this thread, I ended up buying the kit recommended by my local dealer.

William Optics 2" diagonal and WO 2" 40mm EP

Planetary setup: Televue Delos 10mm

I can report I am very pleased with both eyepieces and the diagonal. The 40mm might be on the edge of low magnification (close to see secondary black spot) but stars are pin point sharp and view of M42, M1 and a few other objects I've looked at so far are really stunning. M42 shows nice green veils with excellent seperation of the 4 central stars. The nebula arms are very well defined, even from where I observed (Sevenoaks, Kent) where I estimate visual magnitude around 4.5.

The 10mm Delos on the moon and Jupiter is also very impressive. Given the local turbulence, 250x remains ok but on the limit.

Anyway, I'm now setup for visual. I'm soon going to try planetary photo with liveview imaging on eos 500d.

Last night I watched Io exit the front of Jupiter and I now can't wait to properly capture this kind of moments. Attached is a simple shot made with my mobile of the live view on the camera screen.

Clear skies.

Sent from my iPhone using Tapatalk

[michael.h.f.wilkinson]

Nice initial collection, both EPs are probably keepers. I always find using a Barlow for visual a bit cumbersome, so have gradually filled up gaps by dedicated EPs. If you run into that problem, I would suggest the MaxVision 24mm 68 deg (or the 82 if you can stretch to that) as an intermediate EP. The MaxVisions are near TV quality for very, very reasonable prices

[Emmanuel Marchal]

thanks for the advice Michael