My first orthos

MortonH · #1 05-03-2016, 01:45 PM

Yesterday I received an old Vixen Circle V 7mm. I'd never looked through an ortho before so was interested to see what it was like.

I knew the downsides by today's standards - short eye relief, small field of view, etc. but they're supposed to have high transmission and be very sharp.

I'd started off looking at Jupiter with a 7mm Nagler T6 in my Tak. Jupiter was still quite low so I couldn't push the magnification any higher. I was fairly pleased with the view and the first shadow transit was in progress.

I then swapped in the ortho and re-focused. Wow! This thing is very, very sharp!

In some parts of the FOV I noticed some glare. On closer inspection I discovered there appears to be some fungus inside the lens. If I de-focus the telescope it's like looking at plant cells under a microscope!

The fungus affects about half of the FOV but is concentrated to one side so I found I could rotate the eyepiece to position the fungus in the lower half of the field then position Jupiter just above it and still get a good view.

I'm going to sit the eyepiece in the sun for a while to attempt to kill off the fungus. I don't think it'll clear what's there but at least I can stop it getting worse.

Anyway, the fungus isn't the point of this thread. I'm very impressed with the sharpness of the eyepiece and it makes me wonder about getting one or two more.

gts055 (Mark) · #2 05-03-2016, 02:01 PM

Hii MortonH, try cleaning the elements. The eyepiece will disassemble quite readily, just make a note of the orientation of each element and use plain unoiled/scented tissue with blue windex and final clean with distilled water. Mark

janoskiss (Steve H) · #3 05-03-2016, 02:16 PM

Good orthos are very nice indeed. I used to own a bunch of UO HDs (which I see on the UO website are making a comeback maybe??). Down to 12mm they were super comfy, the 9mm was still not bad but borderline for me for eye relief. The 7mm (or less) I could never get used to. 12mm was my fave and used it barlowed for higher powers. (I'm not sure if I still have it or if I sold it. I should check the IceTrade archives. edit: I just rememered it got nicked at a music festival along with $500 worth of other EPs & things in a camera bag

)

These Fujiyamas are said to be very similar and price is very good at AEC esp considering the poor current $AU/$US exchange rate (if they actually have them in stock):

http://www.astronomy-electronics-cen....au/kkohki.htm

Fungus-free is always best.

I'd say have a go at pulling apart your EP, cleaning+sterilising the lenses and the EP internals and putting it back together. Orthos are simple enough to attempt such a thing.

MortonH · #4 05-03-2016, 02:30 PM

Quote:

Originally Posted by janoskiss

Good orthos are very nice indeed. I used to own a bunch of UO HDs (which I see on the UO website are making a comeback maybe??). Down to 12mm they were super comfy, the 9mm was still not bad but borderline for me for eye relief. The 7mm (or less) I could never get used to. 12mm was my fave and used it barlowed for higher powers. (I'm not sure if I still have it or if I sold it. I should check the IceTrade archives.)

These Fujiyamas are said to be very similar and price is very good at AEC esp considering the poor current $AU/$US exchange rate (if they actually have them in stock):

http://www.astronomy-electronics-cen....au/kkohki.htm

Fungus-free is always best.

I'd say have a go at pulling apart your EP, cleaning+sterilising the lenses and the EP internals and putting it back together. Orthos are simple enough to attempt such a thing.

The eyepiece barrel just screws off but after that I couldn't see any way to take it apart further. It doesn't seem to have the normal circular retaining ring you see at the bottom of most eyepieces.

I'll post a shot later (once it's finished sunbaking) and see if you have any ideas.

simmo · #5 05-03-2016, 03:35 PM

Nice one Morton.

Pity about the fungus. Hope you can clear it up.

I love my orthos and they are my main weapons in the dob. I find the detail stands out more as there is less light and distraction from surrounding objects.

Best thing the value is quite good to.

MortonH · #6 05-03-2016, 04:56 PM

Quote:

Originally Posted by simmo

Nice one Morton.

Pity about the fungus. Hope you can clear it up.

I love my orthos and they are my main weapons in the dob. I find the detail stands out more as there is less light and distraction from surrounding objects.

Best thing the value is quite good too.

Figured out how to take it apart and gave it a clean. Looks like I got most of it off. Will test tonight on Jupiter.

My initial impression was that he ortho was sharper than the Nagler on Jupiter and on a couple of double stars I checked out (Alpha Centauri and Acrux). Contrast may have been slightly better, or maybe that was just the sharpness.

I also compared it to my 15mm Ultrascopic and 12.5mm Ultima (both with 2x Barlow) and the contrast of the ortho was quite superior.

Do orthos play well with Barlows or do they lose something when you do that? I'd like one around 5mm but that would mean awfully short ER. More tempted to try a 9mm with Barlow. What do you think?

simmo · #7 05-03-2016, 05:42 PM

I'm not sure about barlowing Morton as I haven't used one so far. I have the 25, 18, 12.5, 9 and 6mm which is about all I need for our atmosphere here in Perth.

On average the 6mm only comes out on good nights and if you are unlucky an eyelash can ruin the view however I've only had it happen once or twice in a few years of owning them.

Seeing through the 6 to me is no harder than the others even though the glass is way smaller. Everyone is different though as you know so I think you will have to gauge that for yourself. If the 7 is manageable/comfortable for you then there is not a huge amount of difference to the 5 in reality.

If you have tracking then I would imagine using the ortho would be far easier as well.

ausastronomer (John Bambury) · #8 06-03-2016, 12:57 AM

Quote:

Originally Posted by MortonH

Do orthos play well with Barlows or do they lose something when you do that? I'd like one around 5mm but that would mean awfully short ER. More tempted to try a 9mm with Barlow. What do you think?

Hi Morton,

I have all of the UO HD orthos from 4mm through to 25mm. The 4mm and 25mm are series 2 HD's and recent additions, which I added last year when they were released. The 6mm, 7mm, 9mm,12.5mm and 18mm are series 1 HD's and I have had those for about 12 years. I had previously owned a full set of UO Volcano top orthos (4mm through 25mm) for well over 10 years. Notwithstanding that I have a case full of premium widefields, the orthos still see a good bit of use. I just love the clean clinical view they offer.

Most orthos are fairly similarly engineered and constructed for a given focal length and how they barlow is a lot more dependant on the focal length of the ortho and the specific barlow, than it will be on the brand of ortho. The shorter focal length orthos (12mm or less) will generally barlow very well in any high quality barlow. In many cases it can be an advantage to barlow a short focal length ortho because it extends the short eye relief. The longer focal length orthos (18mm and 25mm) can barlow very well in some barlows and not so well in others. Some barlows can extend the eye relief excessively making it harder for some people to find and hold the exit pupil (usually shorter barlows like Orion Shorty Plus, or Celestron Ultima) and some barlows with a narrow clear aperture (eg UO 2.8X KLEE) can cause them to vignette, notwithstanding that these barlows are high quality. I have found the Televue 1.8X and 2X barlows, as well as the 2.5X TV Powermate, work fine with the longer focal length orthos, as does the Zeiss, Baader, TMB and AP BARCON barlows. Any good quality 2" barlow, or powermate should work well also.

Cheers,
John B

MortonH · #9 06-03-2016, 01:58 AM

Thanks John. My Barlow is a Tele Vue 1.25" 2x so hopefully that's a good start.

MortonH · #10 06-03-2016, 02:16 PM

Used the ortho again last night on Jupiter. No ghosting or flaring so the clean was successful.

One weird thing was that off-axis performance was poor. Didn't notice that before. Then it dawned on me - I'd put the eye lens back upside-down

Just fixed it and tested on a distant street light and it is now sharp across the field again. Phew!

MattT · #11 06-03-2016, 05:27 PM

I have a set of UOVT Orthos except the 4mm is missing. What's the difference between them and the newer HD Orthos? I prefer the VT's from the ergonomic point of view...having only tried a newer 5mm flat top HD and VT together.

I do like the clean view of the Ortho's, no matter how narrow it is. Can fit the Jewel Box in the TFOV of the 12.5mm....what more could I want really?

I think you should get a few more Morton

Matt

janoskiss (Steve H) · #12 06-03-2016, 06:01 PM

Quote:

Originally Posted by MattT

I have a set of UOVT Orthos except the 4mm is missing. What's the difference between them and the newer HD Orthos?

Better lens coatings on the HDs but if you prefer volcano tops, the ergonomics, especially at short eye relief, will likely outweigh any advantages of the improved coatings. You may like to try HDs at 9mm up (definitely great from 12mm and up) and stick with the VTs for the shorter FLs.

MortonH · #13 06-03-2016, 08:42 PM

Quote:

Originally Posted by MattT

I do like the clean view of the Ortho's, no matter how narrow it is. Can fit the Jewel Box in the TFOV of the 12.5mm....what more could I want really?

I think you should get a few more Morton

Matt

A few weeks ago I bought a used but pristine 7mm Nagler T6 and it really impressed me. Sharp, bright and it seemed colour neutral on the Moon and Jupiter.

Last night I compared the 7mm ortho to the Nagler and also a 15 Ultrascopic with 2x Barlow. It seemed to me that the ortho was sharper and had better contrast, which was the same impression I'd had the previous night. I also compared the ortho and Nagler on some bright doubles (again, the same as the night before) and the ortho seemed to give tighter stars, but the seeing was too variable to make a definite conclusion.

I think I still prefer the Nagler on most deep sky stuff where the wider field gives a bit more context, but on small bright objects the ortho really delivers.

Yes, I need one or two more.

MortonH · #14 10-03-2016, 10:11 PM

Picked up a couple more but haven't been able to test them yet.

I now have:

Circle '-' 12mm (branded Celestron)

Circle 'A' 9mm (unbranded)

Circle 'V' 7mm (unbranded)

MortonH · #15 27-03-2016, 10:41 AM

I just acquired a number of eyepieces being sold by someone getting out of the hobby. One of them is a Carton 6mm ortho and it's a cracker. Mint condition and very sharp. Had some great views of Jupiter with it on Friday night.

Usually I see orthos described as either 'volcano top' or 'flat top'. This one is kind of a hybrid so not sure what to call it. But it works well and is comfortable to use.