Starbase ortho Eyepieces

[chiltonstar]

There was a mini-review of these in October's AN, and although labelled as orthos, they seem to be symmetrical Plossls. Oddly, on the FLO website they come under Takahashi (really?).

Anyone any idea of how well they perform?

Why oh why isn't there a half decent 8mm ortho available? It is a good fl for my 180 Mak and although I have a BST 8mm, it is not up to ortho standards.

Chris

[John]

I've not used a Starbase ortho so can't comment on those but the older Vixen Orthos (engraved Or.) were often symmetrical plossls as well, having taken a few apart to clean over the years. They used to work pretty well.

 

 

 

[Stu]

1 hour ago, chiltonstar said:

Anyone any idea of how well they perform?

I think @IB20 has the 80mm Starbase scope and the ortho eyepieces so may be able to give some opinions.

[Stu]

1 hour ago, chiltonstar said:

Why oh why isn't there a half decent 8mm ortho available?

I know it’s not an Ortho, but have you thought about trying the Televue 8mm Plossl Chris? They are pretty sharp.

[John]

19 minutes ago, Stu said:

I know it’s not an Ortho, but have you thought about trying the Televue 8mm Plossl Chris? They are pretty sharp.

I had some of my best views of Saturn ever with an 8mm TV plossl and my old C8+

[IB20]

BillP has given a thorough review of the 6mm SB ortho here https://www.cloudynights.com/topic/722346-a-modern-classic-starbase-6mm-ortho/

Personally I really like the 6mm, I have used it in both my scopes (Starbase 80 and 8” dob) and have had great success predominantly with WL solar and double stars. I have the 14mm too but it’s a bit redundant because of the 13mm Delite. When I have used it I have noticed some field curvature around the edges. 

It’d be quite a good shoot-out between the 6mm BCO and 6mm Starbase but I haven’t felt the need to buy the BCO due to the Starbase ortho’s performance. 
 

 

[markse68]

2 hours ago, chiltonstar said:

and although labelled as orthos, they seem to be symmetrical Plossls.

I bought a Zeiss “Orthoskop Okular”microscope ep recently and when i got it was surprised to find it was a symmetrical “plossl” type ep rather than the Zeiss Abbe design we call ortho. 

Mark

[Mr Spock]

They may be good quality but they really shouldn't be calling them orthoscopics when they are clearly a Plössl variant.

[Knighty2112]

I got a 6mm Starbase from FLO. It works very well. Gives good contrast and sharp view across the fov, so pleased with it. Had it out on Jupiter and the moon last night for a while before clouds piled in, and got great views with it, even compared to my Baader Zoom and 4mm TV Delight.

[Louis D]

1 hour ago, Mr Spock said:

They may be good quality but they really shouldn't be calling them orthoscopics when they are clearly a Plössl variant.

If it gives an orthoscopic view (ie., without magnification distortion across the field), then the term orthoscopic can certainly be applied.  An Abbe orthoscopic is simply one design that gets you there.  As far as I know, these Starbase orthos have never claimed to be Abbe orthoscopics.  However, there are reports that the Starbase orthos actually have some distortion which would then call into question labeling them as orthoscopic.

[Don Pensack]

6 hours ago, chiltonstar said:

There was a mini-review of these in October's AN, and although labelled as orthos, they seem to be symmetrical Plossls. Oddly, on the FLO website they come under Takahashi (really?).

Anyone any idea of how well they perform?

Why oh why isn't there a half decent 8mm ortho available? It is a good fl for my 180 Mak and although I have a BST 8mm, it is not up to ortho standards.

Chris

Read this and the thread that follows:

https://www.cloudynights.com/topic/700422-starbase-orthos-first-light/

They are distributed by Takahashi in the US, which is why the association.

 

[Don Pensack]

1 hour ago, Louis D said:

If it gives an orthoscopic view (ie., without magnification distortion across the field), then the term orthoscopic can certainly be applied.  An Abbe orthoscopic is simply one design that gets you there.  As far as I know, these Starbase orthos have never claimed to be Abbe orthoscopics.  However, there are reports that the Starbase orthos actually have some distortion which would then call into question labeling them as orthoscopic.

Almost every "Orthoscopic" eyepiece has some rectilinear distortion.  The question is whether it can be seen or not.

People seem to like the Baader Classic Orthos, yet these have quite a bit of RD.

I really don't know why people object to a small amount of RD yet tolerate horrible astigmatism or field curvature.

It might not be orthoscopic, but give me an eyepiece without astigmatism and field curvature first, THEN think about how the distortion is viewed.

Plus, we see up to about a 7% level of RD as distortionless because of the nature of the eye.

 

By the way, it is usually the control of distortion that identifies the eyepiece as orthoscopic, i.e. no distortion of a square grid across the field.

Since that means near zero angular magnification distortion AND near zero rectilinear distortion, it means 40° fields or less.  Even 42° is pushing into distortion territory.

See:

Note that there will be no visible distortion if the curves are together and do not separate.

 

[chiltonstar]

Many thanks for the above very useful info and suggestions. Maybe I can persuade The Cat to buy me the TV 8mm for Xmas - after all I've just had to pay for her to visit the vet after she dined out on after sell-by date mouse!

Chris