Masuyama 60mm

[25585]

FLO selling these Japanese eps. 

The 60mm, longest fl yet, would seem good for long fl scopes such as maks & cass. AFOV not much but lowest magnification yet. 

Has anyone tried the 60 in any scope? If so how are they for faster f ratios?

[John]

I might be mistaken but I can't see why anyone would invest nearly £600 in a 60mm eyepiece to use in a scope faster than F/10

Celestron used to market 45mm, 60mm and 80mm Ultimas which I believe were aimed squarely at their bigger SCT models:

https://www.astromart.com/classifieds/details.asp?classified_id=851195

There have always been rumours that these were made for Celestron by Masuyama, back in the days when Celestron used really top quality 3rd party manufacturers.

 

 

 

[Louis D]

If you want long focal length eyepieces to experiment with, try some of Gary Russell's long plossls.  He might ship out of the US.

[jkwhinfrey]

He’s said that he won’t ship outside the US in the past. I don’t know if that’s changed, but he found it to be too much hassle from his location apparently, which is fair enough.

James

[25585]

The Astromart is ConUS only as well. 80mm!

[Alien 13]

You can always play with a camera lens as an eyepiece to see if longer fl suits..

Alan

[John]

27 minutes ago, 25585 said:

The Astromart is ConUS only as well. 80mm!

Many US based sellers seem to stipulate that. I've found the occasional one prepared to ship but not many.

Siebert Optics in the USA make observatory eyepieces which go up to 110mm focal length and a 4.3 inch format. Really big stuff for really big scopes !:

http://www.siebertoptics.com/SiebertOptics-eyepieces-observatory.html#4 Eyepieces

[25585]

I find it puzzling that commercial long fl scopes like maks & scts are restricted to 31.7mm fit eps without vignetting. Thinking of the Skymax 180 for example, as much specialist through design undersight as through long fl for high mags. 

To some extent Meade & Celestron likewise on the 8 inchers. 

Opening up a scopes design to allow wider field/lower mag seems to make sense to me. Most innovation seems toward imaging or optics for large apertures & small f ratios. 

[Peter Drew]

11 hours ago, 25585 said:

I find it puzzling that commercial long fl scopes like maks & scts are restricted to 31.7mm fit eps without vignetting. Thinking of the Skymax 180 for example, as much specialist through design undersight as through long fl for high mags. 

To some extent Meade & Celestron likewise on the 8 inchers. 

Opening up a scopes design to allow wider field/lower mag seems to make sense to me. Most innovation seems toward imaging or optics for large apertures & small f ratios. 

Not a problem if you don't mind a large central obstruction, you just need a bigger hole through the primary mirror and a larger diameter baffle tube in a Mak or SCT and you could use 2"+ long focus eyepieces. The usual trade-off with catadioptrics. 

[25585]

Smaller aperture longer fl scopes to take long fl eps best are refractors I guess then. Just pricier. 

 

[Louis D]

11 hours ago, Peter Drew said:

Not a problem if you don't mind a large central obstruction, you just need a bigger hole through the primary mirror and a larger diameter baffle tube in a Mak or SCT and you could use 2"+ long focus eyepieces. The usual trade-off with catadioptrics. 

And a lot of folks don't realize that larger central obstructions lead to poorer contrast because more light gets tossed into the outer diffraction rings.