markse68

I couldn’t wait to try so went out last night for a quick first look at Jupiter with it.  Conditions weren’t the greatest with a bit of wind and a lot of whispy cloud Interrupting viewing but the seeing was pretty ok when the clouds parted. I compared it to these 2 10mm eps- the Parks Gold GS-5 and BCO. It seems if you use half a plossl you effectively double the focal length so the 10mm plossl became a 20mm Dollond. So I used my 2x Tal barlow with it. Barlowing  makes a lot of sense actually as the field curvature of the doublet is really bad and doubling the focal length of the ota helps a bit there.

so how was it? Well I don’t want to draw any conclusions after just one session in not the best conditions but what I can say is it was no slouch when it came to sharpness and contrast, revealing just as much detail as the other 2. Was it better? Not earth shatteringly if at all lol. I couldn’t really see much difference between any of them! But that in itself is kinda amazing- that such a simple lens can compete with a well regarded ortho in terms of sharpness and contrast! Of course that was only in the centre but that was plenty to view the whole disk at 160x- the edges dropped off a cliff with the moons blurring into smears) 

 The Parks Gold is interesting too- it seems to my eye to give a lower contrast almost pastel like view yet it showed as much detail as the others with a wider more comfortable afov!
 

It was “fun” using the Dollond though- on a rickety old dob in gusting breeze with a tiny fov 🤦‍♂️ I persevered but it wasn't ideal. On a driven mount or still conditions it’d be more usable. The afov wasn’t the biggest problem though- it was the eye relief that I found most troublesome. Unlike the orthos which can be a bit too close, this had huge eye relief- too huge really. It was quite tricky to hold your head just right without suffering blackouts and I thought at times kidney beaning! So not really a comfortable experience. 

I tried it with a 3x barlow against some 6mm orthos with similar results but the fov was sharper at the edges with the longer effective ota fl. but much more of a mare tracking targets!

(I also discovered that the CZJ 6mm ortho that came with my telementor despite more flare from older coatings showed I think more detail than the BCO 6mm 🤔)

Looks like we have a return to fine weather next week if nobody buys any new Astro gear! 😉🤞 so will give it more time in hopefully much better conditions then 😊

45 minutes ago, John said:

My OO primary cell could not be more ventilated really. There is a small fan there but I don't use it.

 

I use the one I built for my dob religiously 😂 I noticed last year that I was having terrible tube currents even after an hour of use leading to awful star tests like this. Probably not helped by the insulating properties of the pvc drain pipe used for the OTA. I get much better more stable star tests now after only a few minutes with the fan on full blast. Vibration doesn’t seem to be an issue though when I was trying to split Sirius I did switch them off for best stability. In my mind it’s been a very worthwhile upgrade. 
 

I did plan do do something similar to op when I designed my 12” dob (that I didn’t build ) using an aluminium baffle plate that’d serve to mask the mirror bevel and deflect the air flow- seemed a good idea at the time. But I didn’t build it yet lol. 

I will let you know how it goes Mike- I’m super intrigued myself. 

Surgery is done- very simple indeed. The idea is you use one of the plano convex doublets and invert it so the convex part faces the eye. The doublets strangely were  partially edge blackened so I fully blackened the lower one to use for this- the top one  having cleaning marks from its past life. I used some small o-rings to make up for the missing lens cos I was too lazy to make a proper spacer.

Looking through it at a bright led desk light it shows none of the usual hazy flare you get with a lot of eps as you move the light across the fov and it internally reflects.  The fov doesn’t seem all that small though only the central part will be usable.

Mark

I just looked up @Robs “new” Meade MA9 ep and came across a thread on CN where someone talked about converting one into a Dollond ep- an ancient super simple, highly compromised but apparently unbelievably sharp eyepiece.

so I went rummaging and found this old “junk” plossl and will take it apart later to create a ~20mm Dolland ep which I’ll try with 2x barlow next time I’m out- quite excited about it 😉 

They talk about sharpness and contrast that is a step up from the best orthos! And completely glare/scatter free! A poor mans monocentric apparently. Obviously the severe aberrations and very narrow fov make it pretty impractical but 😳 got to be worth a try I reckon

Anyone else tried this simple hack?

Mark

I can’t remember observing this before so probably haven’t but it was a great sight. I thought I could make out “something” on Jupiter’s disk approaching the limb at around 1am but the seeing wasn’t fantastic. But as it approached the limb it became more and more obvious a a brightening spot and as it touched the limb a swelling pimple which over the next 20mins or so elongated until separation. Just a moon passing in front of a huge planet but it was quite amazing to me and I’m glad I was there to see it  

4 hours ago, Captain Magenta said:

Now why don't I believe this for a single moment?

Get the two of us into a room together with any sort of astro stuff and tools, and woe betide any astro stuff lying around  . Just remains for @John to send either of us his 13mm Ethos for some improvements...

Seriously though, very interesting!

M

 

There is definitely an element of truth in what you say Magnus 😉 But I am a bit reluctant with optics as the moment you break that seal the dirt is in there and it’s practically impossible to get rid of it all without working in a vacuum which wouldn’t be much fun. 

6 minutes ago, John said:

Oh, that is very different then.

It's been a long time since I've had the 6mm so I could not remember what it looked like from beneath !

I wonder why the design was changed ?

I'll guess and say that the longish tube acts like a light baffle to keep stray light away from the optics.

 

That’s my thinking- plus looking at that pic from your old post the bore of the barrel was smooth too whereas now it’s grooved to form light traps. Now mine is matter too 😉

46 minutes ago, John said:

No harm in having a look to see if things can be improved a bit further

These are the 3 that I was sent to review:

Have they changed the design of the 6mm then ?

 

I could be wrong but the image of the underside of the 6mm in your early review showed a flush retaining ring like my 10 but my 6 is a longish thin tube? 

Yes a bit arrogant of me to presume I can improve on them- they’re almost certainly not as clean inside now 🤦‍♂️

But I figured they’re made to such a low cost and it’s a bit fiddly painting the edges of the eye lenses of the smaller ones so maybe that’s why they didn’t 🤷‍♂️ The stop on this 6mm isn’t very sharp either despite seemingly a different design to the one you reviewed John?

I’d never think of doing this with more expensive or complicated eps but these were pretty cheap- all bought second hand and I thought it’d be worthwhile seeing how they go together and if they could be “improved” 😬

Theyre all of similar construction with a screw in retaining ring holding the glass into a solid top housing from the bottom. They all have removable 1.25” nose pieces that make access easier and they were all finger tight. As expected the glass is the same idea in all 3 just scaling up with focal length- the 18 quite a chunk of glass

Interestingly the eye lens of the 18 was edge blackened but neither the 6 or 10 were. I blackened them. All the cemented triplets had lightly blackened edges- I left them alone.

 I dusted over the insides of the 1.25” barrels with matt black spray paint which maybe the most worthwhile “improvement” - don’t suppose it’ll make any difference for the 6 though as it has a longish snout extending the retaining ring with its own micro baffling that looked quite matt inside anyway.

If we ever get clear skies again it’ll be fun to see if it’s made any difference- I have a duplicate of the 10 so can compare. 

A piece of orange Formica 😊

On 06/06/2020 at 09:56, John said:

The 6mm is not quite as good as the 10mm and 18mm but still a comptant 6mm eyepiece.

Hi John, I recently picked up a 6mm BCO and reading up about it found your early review. I noticed your image of the inside of the barrel and it’s quite different to mine. Mine has a long thin central micro ridged tube containing the optics and field stop but yours looked to be mounted flush. Looks like an improved design- it must surely help with eliminating reflections from the glossy anodised barrel interior from getting into the lenses? Sorry if this is already common knowledge- couldn’t find anything about it.

Mark

Very interested to hear how/if the adc  helps especially on Mars Kerry

19 hours ago, ScouseSpaceCadet said:

Thanks and yes I'm aware of his site and arguably controversial views! 😉

Just looked him up- no idea what you’re suggesting 😉

What version of SkySafari are you using Sunshine? According to pro there was an eclipse of Callisto but it started a bit earlier- 1:15 am your time before the Io transit

By chance I noticed the clear sky last night around 2am and took my scope out to check the planets (and measure barlow focal plane offset for a new project I’m working on)

Wow! I kept saying wow- couldn’t help myself. Lucky there were no others around to witness... 😂

Saturn was stunning last night- the best I’ve ever seen. The rings gave it amazing 3D quality, Cassini division was sharp and clear and the banding on the orb delicate and beautiful

Jupiter didn’t disappoint either with a GRS transit starting as I set up and progressing for the couple of hours I was out. Plenty of detail in the belts with hints of curly detail. GRS was a lovely distinct orange and very clear. Seeing wasn’t that great actually with wobbly fluctuation but in settled moments it was very wow!

but the highlight was Mars. Till last night it was just an orangey diffuse blob but last night it was an orangey marble with dark x pattern and wearing a white beret and sporting a white goatee! I’m thinking it must be the increased albedo of the polar co2 ice that caused it but it was strangely elongated like it had a big cloud sat atop its head. Maybe it was just atmospheric distortion but it was still there as the sun started rising and it had gained some altitude. 

Anyway I didn’t see Mars last year at all so this is my best view yet and I’m liking what I see- it should only get better!

2 hours ago, John said:

Depends on the focal length of the barlow I think. Not a spec that is regularly published

 

After I wrote that I noticed Jupiter and Saturn in a clear sky so took the scope out to measure it- and oh boy am I glad I did as they were superb this morning! Best I’ve seen ever! So sharp and contrasty and the GRS obliged too! Clear banding on Saturn- so sharp and 3D. Mars wasn’t too shabby either- definitely some darker markings on the disk. Strangely elongated though- I wondered if it was atmospheric distortion but actually I wonder could it have been the polar caps just reflecting a lot more light causing the distortion? Definitely bright areas at the N and S poles- must be. Hopefully a taste of good things to come- so excited as the planets are already besting what I saw all last year

Back to the barlow thing though it’s a bit confusing. My Tal 2x didn’t change the focus just shifted the ep out 30mm- the length of its body. An AE 2x I also have shifted the focuser IN by about 7.5mm and the ep out the length of its body- 43mm. It’s too late (early) and my brains foggy so I’ll have to think what this means tomorrow 🤔

Btw, anyone any idea how much a 2x Barlow shifts the focal point or is that a complex thing to determine?

On 12/06/2020 at 13:22, CraigT82 said:

Yeah even with Barlow! At the time I had quite a tall focuser but now have a moonlite which has a much lower profile and I returned the mirror to its original position after fitting that. 

Hmmm, I’ve only got about 20mm inward focuser travel from focal plane so maybe 30 for some eps and I don’t really want to shift my primary- the secondary is on the small size already, so I don’t think either of these are going to work. 🤔 I’ve found and ordered some cheap prisms on eBay and have a cunning plan evolving....😉

21 minutes ago, CraigT82 said:

I can't comment on zwo vs Altair as never had my hands on the altar version (I think its the same as the omegon branded one?) but just to note that you can get more correction on any adc by increasing distance between prisms and eyepiece. A T2 extension between adc body and ep holder would be ideal but even just pulling ep out of holder a bit would give you a bit more correction if needed. 

On my fullerscope I had to move the mirror up the tube a bit to be able to focus with the adc in place. 

 

Thanks Craig- I saw you had the Zwo one. Did you have to shift the primary even with a Barlow?

Hi there, not sure if this is the right section but it’s for something I want to look through so hopefully it’s ok here. I’m about to pull the trigger on a “cheap” adc for visual and wonder if anyone has an opinion whether to go Zwo or Altair? They look similar but the Altair is a bit cheaper. Zwo claims 1/10 lambda finish on 2deg prisms, Altair doesn’t mention quality but their prisms are 2.5deg. Is there generally a quality difference between the 2 companies products? The Zwo cameras seem to get more mention than Altair but that’s likely more to do with image sensor etc- but engineering-wise, fit and finish? I doubt there’s anyone who has both their ADCs to compare so it’ll be very subjective I guess. The prism difference would mean the Altair could compensate for more atmospheric dispersion but would that be necessary for me looking at the planets from now on?

thanks,

Mark

Not Astro related at all really but it does have a nice lens  all the way from Belarus and much needed as I’m getting old... nice leather case too so I can carry it with me everywhere

1 hour ago, happy-kat said:

 

I've come across using Arduino code to manage tangent error.

These mechanical solutions are ingenious but isn’t this the better more modern solution? Or couldn’t you print or cut curved gear segment actuation levers @Chriske like the curved threaded rod in the other thread?

Looking forward to hearing your first impressions Baz- once the clouds clear! That’s a big step up in aperture! 

5 minutes ago, Jonny_H said:

This is what I am asking myself. To be honest I think it looks quite cool and it's different! As long as performance isnt impacted I'll be happy with it. But it begs the question as to why they are frosted in the first place!

Maybe they only frost the ones that get marked during the grinding/polishing and don’t look so good and those that survive in a pretty state get left. So your new one was handled better in the factory. Or maybe they got a new supplier of blanks 🤷‍♂️