Eyepieces again

[black5f]

A question thats been asked many times before... SW 150p with single speed crayford. Really very pleased with this. The supplied eyepieces (10 and 25 and barlow) all seem to me to give the thrill I wanted on the planets. I've been mucking about with imaging. Gave up on my webcam (a £10 one) for the moment, works but, frankly it's just too cold to fiddle with a laptop coverd in condensation in gloves. Very pleased with my 1000D results and just starting to get the hang of registax while I'm thawing!

I find the (lower price!) optics though could do with improving as this is noticable when imaging. 150x seems to be doable but getting a lot of CR on bright things (colomationvery good... home made laser). I've looked at sets but realy want a 5mm eyepiece for both eye and imaging. The 1000D hanging on an 10mm eyepiece projection rig plus barlow does work but the overhang needs shortening for the focus to work better. I'm really thinking of 4ish mm and 6ish mm for a 750mm scope for both eye and imaging, 150x seems to be the limit on image clarity vs mag. Does anybody have any recomendations or experiences in the £60 a piece budget range? What should my expectations be? I'm tickled pink with my images but could do with more contrast on the planets.

Jupiter | Flickr - Photo Sharing!

and

moon_2 | Flickr - Photo Sharing!

[Adrian]

Hi

The TMB designed planetary eyepieces are well regarded and can be got for under £40 on ebay 1.25" 5mm 58 Degree TMB designed Planetary eyepiece on eBay (end time 29-Nov-10 19:21:46 GMT). They also do many other focal lengths.

You may be able to get a second hand Baader Hyperion 5mm eyepiece in that budget - these have a built in screw thread that you can get a T-adapter for eyepiece projection photography. They are generally well regarded eyepieces, and can be altered to make different focal lengths too (the 5mm can be made into a 4mm, 3.2mm and 2.6mm using extension rings). Have a look at them on the FLO website linked at the top of the page.

Cheers

AD

[black5f]

Hi Adrian

Thanks for the reply. The TMBs are tempting but you have drawn my attention to the Baader range. I didn't realise they could be modified like that so a big thanks. 5mm would give me a very good quality EP with the option to go a little higher mag on those special but few clear days. I know whats going on my Xmas list!

You do realise though that it's going to be thick cloud now for several months ;-)

Cheers Tom

[Adrian]

I was going to put the two fine tuning rings on my Christmas list, but at the moment the 8mm is just showing me how bad the image produced by my scope is - I don't need to magnify that any more:icon_eek:

I picked up mine for £50 second hand. Now for a scope to go with it

[black5f]

I got the 150 OTA and now will break the news to SWMBO that I want to spend nearly as much on an eyepiece! A self inflicted arms war when I find I really need a 250pds and a new mount to compliment the EP! Tom

[Moonshane]

I am surprised you are not getting a good image with this at 112x magnification. if the seeing is OK I'd expect maybe 150x should be OK and maybe even 170x.

are you letting the scope cool for maybe half an hour to an hour before use?

also, it may need collimating? both of these will make a substantial difference to the view.

[sixela]

I find the (lower price!) optics though could do with improving as this is noticable when imaging.

Check usual suspects:

-Collimation (often a laser collimator's return beam is a bit unreliable - check with a collimation cap or Cheshire with pupil at the focal plane!). Double check with a star test -- the centre spot might actually not be centred well.

-Thermal management. Is the mirror cooled? Do you have a fan?

-Pinched optics. Sure the primary clips aren't tightened down?

Other that that, the art of focusing when doing planetary imaging is a difficult one, especially on an f/5 scope. Your eye can accommodate for a different focus, but the photosensor can't.

But visually, you should get good images up to 230-250x, at least in brief moments of good seeing (you do need patience!) on nights that aren't too bad, provided you control what's written above well.

Provided, of course, you don't observe over e.g. a neighbour's warm roof or a chimney, or worse, observe from a room through a window! Because if you do, you'll never get good seeing.

[Moonshane]

Provided, of course, you don't observe over e.g. a neighbour's warm roof or a chimney

I suspect this is the most common cause of poor seeing and the one least often considered as the cause. my garden is surrounded by houses and therefore it is hard to avoid looking over rooftops and I think this is what creates poor seeing for me in a number of cases.