High mag EP - BST or BCO?

[Planetesimal]

My best magnification right now is 125x on the TAL or 150x on the newt. I say "best" because the TAL 6.3mm plossl gives mushy views and likewise the SW 2x barlow is never anything but a waste of time... Actually I did try it once in the TAL star diagonal and the barlow nosepiece collided with the mirror!

So, I want to access the 180x - 250x zone, where I can get a bit closer to Jupiter on nights of good seeing, prise more detail out of the Lunar 100 targets, and split the tighter doubles (like Epsilon Lyrae, which I've yet to split with my current set-up). A 5mm EP would give me 200X in the TAL and 240X in the newt.

I've read John's BCO review and I'm convinced that, in the sad absence of the BGO range, one of those would be a good choice - although it looks like there isn't a 5mm in the range yet. Also, I'm not a big fan of the "pinhole" design and restricted eye relief you get with the orthos. I get on well with my BSTs, particularly given the large window of glass you get to look through, so I'm tempted to just add to my BST collection and be done with it.

However, as the prices are pretty much the same, and there's a chance the BCO might win on contrast, it's not a clear-cut decision... Can anyone help me part with my cash in a sensible manner?

[Spec-Chum]

Tough call.

If comfort and eyerelief is king then BST but if you want the best possible view without breaking the bank then Ortho.

Tiny eyerelief doesn't bother me all, so my choice would be the BCO.

For the record, I actually prefer my 12.5mm Circle T otho to my Meade 14mm UWA for the moon. The views are about as sharp as each other but I weirdly find the UWA distracting and prefer a narrower FOV when viewing the moon. I'm odd like that...

[The Flinty Fox]

Have no idea about the BSTs but I do have the 6mm BCO which has given me some very nice views of Jupiter.

As for eye relief I did'nt find it a problem on the planets and doubles, but it was a slight problem on the moon in trying to get the entire fov in without causing to much vibration. Will try again tonight, if weather is good. The eye shield can be removed which I think will help so will try that also. Still a bit new to this so hope that helps.

Paul

[nightfisher]

If you dont wear glass`s look out for a 5mm circle T ortho to use on good nights for high power, i bought the 5mm and im surprised at how easy it to get on with

[John]

For what it's worth, and from more extended use on some tough targets, I now feel the BCO 6mm is optically pretty much on par with the BGO 6mm. On finish and build quality the BGO takes it but the larger, raised eye lens of the BCO does make looking through it easier, even though the eye relief is no more than the BGO. The additional field of view of the BCO, though not all sharp, does help with finding and framing objects too.

[Planetesimal]

If you dont wear glass`s look out for a 5mm circle T ortho to use on good nights for high power, i bought the 5mm and im surprised at how easy it to get on with

I'll keep an eye out... It will come down to whether I can be patient enough to wait until I find a good ortho or if I crack and just order something that's instantly available!

[Naemeth]

Go for the BCO if eye relief doesn't bother you. An ortho nearly always beats any other eyepiece on planets if eye relief is no concern. They are cheap to make, have a small number of elements (usually 4 so less light loss) and are usually made to be very sharp. If you can get one, a Vixen NLV 5mm would be great, but it might be quite difficult to get used, and is expensive new!

[The Flinty Fox]

Just been out trying the 6mm bco with and without eyeshield and I think I prefer using it with the eyeshield on. You can get a little closer with the shield off but I find it easier to use with it on.

Personally I don't find the eye relief a problem and am quite happy using it and the views do make up for it anyway.

As I said in another thread it seems that both the 6 an 18mm bco (to me anyway) do seem to give slightly better contrast than my 10mm npl.

Paul

[The Flinty Fox]

In fact the 18mm bco gives noticably better contrast at least to me.

[John]

Just been out trying the 6mm bco with and without eyeshield and I think I prefer using it with the eyeshield on. You can get a little closer with the shield off but I find it easier to use with it on.....

Yes, I found that too. I usually fold the "wing" piece down but I prefer to have that soft ring of rubber around the rim of the eyepiece to snuggle my eye socket up to.

It would be nice if Baader could supply just the rubber ring without the "wing" for those of us who like it that way

I also agree on the 18mm Baader CO - to me, it's light throughput was better even than the 18mm Baader GO.

Despite their simple presentation, the more I use the Baader Classics, the more I'm liking them

[Planetesimal]

Yes, I found that too. I usually fold the "wing" piece down but I prefer to have that soft ring of rubber around the rim of the eyepiece to snuggle my eye socket up to.

It would be nice if Baader could supply just the rubber ring without the "wing" for those of us who like it that way

I also agree on the 18mm Baader CO - to me, it's light throughput was better even than the 18mm Baader GO.

Despite their simple presentation, the more I use the Baader Classics, the more I'm liking them

Okay John, I'm convinced. It's time for me to step into the world of the ortho... 6mm Baader Classic despatched from FLO and winging its way to me now!

[Stargazer_00]

I'd bring this right back to your comment about "mushy views". I would describe everything with an exit pupil smaller than 1mm as "mushy" so I dont magnify below that.

no matter the quality of the eyepiece you buy the exit pupil will remain constant for the magnification in your scope.

Putting some numbers on it your Tal 100 RS reaches 1mm exit pupil at 100x magnification and your 150PL will reach 1mm exit pupil at 150x magnification.

If it isnt obvious from the above statement, exit pupil is calculted by: diamater of clear aperture (mm) / mangification = exit pupil (mm)

I think under 1mm you will start to notice defects on your own eyes, personally I see alot of floaters at 0.5mm exit pupil and i perceive these views as dim, "mushy" and really unsatisfying. As soon as I get to 1mm exit pupil I see no floaters, good contrast and detail. Magnification is nothing if the view is rubbish.

[Planetesimal]

I'd bring this right back to your comment about "mushy views". I would describe everything with an exit pupil smaller than 1mm as "mushy" so I dont magnify below that.

no matter the quality of the eyepiece you buy the exit pupil will remain constant for the magnification in your scope.

Putting some numbers on it your Tal 100 RS reaches 1mm exit pupil at 100x magnification and your 150PL will reach 1mm exit pupil at 150x magnification.

If it isnt obvious from the above statement, exit pupil is calculted by: diamater of clear aperture (mm) / mangification = exit pupil (mm)

I think under 1mm you will start to notice defects on your own eyes, personally I see alot of floaters at 0.5mm exit pupil and i perceive these views as dim, "mushy" and really unsatisfying. As soon as I get to 1mm exit pupil I see no floaters, good contrast and detail. Magnification is nothing if the view is rubbish.

Fair enough, I think high mag will be used relatively rarely, but it would be nice to have the option when seeing and circumstances allow. For example at the moment with my 8mm EP the best mag I can get on my TAL is 125X, which means I can't resolve tight binary pairs and Jupiter is just a bit too small for comfort. A new 6mm EP will give me 166X in the TAL, which is similar to what I currently get with the 8mm from the 150PL, and I think that's a reasonable level of magnification.

Plenty of people seem to get on fine with their orthos at high mag, and I won't know whether it works for me until I try... Ultimately the great thing about this hobby is you can sell stuff on if it doesn't work for you!

[Stargazer_00]

Eyepieces are a very personal thing I just wanted to highlight the importance of exit pupil was all. My Own preference of 1mm as the smallest exit pupil I enjoy is just that, my preference. You may get on just fine at 0.5 mm this is recognised as the smallest practical size though

[John]

From my experience, I've found that I use 150x-170x often with my 4" refractor and 200x reasonably often on the right targets under the right conditions. With 6" scopes I've owned I'd up the above values to 180x - 240x again dependent on targets and conditions.

[andrew63]

i think 166x under good seeing will give you some fine views of jupiter and saturn for that matter in the 4". The 6mm ortho. should be an ideal choice - more of a 'punchy' view than through a BST and similar types.

andrew

[Planetesimal]

Thanks Andrew - excited now! Shame I didn't have it for the last 4 nights, the longest run of clear nights since I started observing!

[nightfisher]

when i got my 5mm ortho i was amazed at how good it performs in the tal, so i now have a 4mm ortho on its way, this will give x250 in the tal, but only on really sharp nights

[andrew63]

when i got my 5mm ortho i was amazed at how good it performs in the tal, so i now have a 4mm ortho on its way, this will give x250 in the tal, but only on really sharp nights

A 4mm ortho ! my giddy aunt - you are a stickler for punishment !

[John]

when i got my 5mm ortho i was amazed at how good it performs in the tal, so i now have a 4mm ortho on its way, this will give x250 in the tal, but only on really sharp nights

I think it's fun to have something a bit OTT to try out now and then and the 4mm Or's are not expensive. I was playing around with the Baader CO 6mm and the 2.25x barlow the other night on the moon. 596x and, unsurprisingly, not crystal clear by any means but a view that made me feel a tiny bit like the Apollo astronauts might have as they peered out the LEM windows as it neared the lunar surface

[Naemeth]

I think it's fun to have something a bit OTT to try out now and then and the 4mm Or's are not expensive. I was playing around with the Baader CO 6mm and the 2.25x barlow the other night on the moon. 596x and, unsurprisingly, not crystal clear by any means but a view that made me feel a tiny bit like the Apollo astronauts might have as they peered out the LEM windows as it neared the lunar surface

The Moon is one of those targets that can seemingly take any amount of magnification you throw at it. I've tried it at 325x and the view is fairly sharp. I might have to try it at 520x someday, although I don't think I could get any higher without a more powerful barlow .

[nightfisher]

I think it's fun to have something a bit OTT to try out now and then and the 4mm Or's are not expensive. I was playing around with the Baader CO 6mm and the 2.25x barlow the other night on the moon. 596x and, unsurprisingly, not crystal clear by any means but a view that made me feel a tiny bit like the Apollo astronauts might have as they peered out the LEM windows as it neared the lunar surface

I think i will only be using the 4mm circle t for star work, like the trapezium and trying for doubles that need high mag, maybe saturn will be okay on a really god night with it

[Planetesimal]

My first orthoscopic eyepiece has arrived!

The 6mm Baader Classic Ortho is as basic in construction as John said in his review - the important thing will be its performance. I had a quick go pointing the TAL at a tree in the garden to observe some insects and lichen, and compared the BCO with the TAL 6.3mm. The BCO didn't appear noticeably sharper under these conditions, but it was very much brighter, so I think that's where the difference will be more apparent on night sky objects. I'm looking forward to giving it a road test on the moon!

One thing I found is that the eyepiece end cap is really quite loose... it appears to be a larger diameter than the EP barrel to accomodate the rubber wing when folded down, but even so it's quite floppy. I might have to see if I have something that grips a bit better...

[Stargazer_00]

Make sure to use a filter, you dont want to go moonblind I was staring at the moon unfiltered the other day and when I backed off and looked around my left, dark adapted eye could see the entire garden (from moon light) and my right observing eye could barely see the telescope! everything else was black

Curious to see how it performs on Jupiter, if you could update tempted to pick up a short FL ortho now because of this thread.

I was going to get a 7mm Luminos for close up planetary work, would the glass in a luminos be as good as an ortho?

[Planetesimal]

Make sure to use a filter, you dont want to go moonblind I was staring at the moon unfiltered the other day and when I backed off and looked around my left, dark adapted eye could see the entire garden (from moon light) and my right observing eye could barely see the telescope! everything else was black

Curious to see how it performs on Jupiter, if you could update tempted to pick up a short FL ortho now because of this thread.

I was going to get a 7mm Luminos for close up planetary work, would the glass in a luminos be as good as an ortho?

I've not got around to getting a filter yet - but I don't plan on looking at the moon when it's full... Also, I find that higher mags reduce the level of light coming through so should be alright most of the time! Still, a Baader Neutral Density 0.9 filter is definitely on the future purchase list!

I'll do a little review once I've had a try on Jupiter, the moon and maybe some double stars (although I'm interested to hear how nightfisher gets on with a 4mm! ).