4 replies to this topic

[Kruegon]

This is a dual post from Cloudy Nights. Figured I would ask in both to see what info each site has to offer.

I just finished reworking an ETX-60. Nice and clean now. The focuser is still a but stiff, but workable. Never did figure out how to get the focuser knob out. I still need the 6AA battery pack to test everything out properly. But in manual use, the terrestrial images are very clean and sharp. So here's a couple of interesing questions. 

 

First, it's listed as a refractor. However, the battery door has a factory sticker on it saying it's a Mak-Cass. While it does use the mechanics of a Mak, it's optical setup is clearly a Refractor. Was this a misnomer or a marketing scam? Or does it's odd design make it some form of a Mak-Refractor? Or is it something else all together?

 

Second, it's a  60mm/350mm f/5.8 Refractor. This seems to be true when using the built-in 90° position. And 700mm when using the built-in barlow in the 90°. However, when using the accompanying 45° prism, the FL changes to 525mm. And adding a barlow, obviously 1050. Not only does this bring the scope up to a much more usable level, but quite impressive for such a compact GoTo setup. The linear distance from objective to eyepiece doesn't seem much different. Certainly not 175mm different. How does the magnification change so drastically between the two positions? Did I miss something?

[MistrBadgr]

I am not sure, but it sound like there is another lens in the way for one of the directions.

 

Bill Steen

[MistrBadgr]

Forgot to comment about the Mak-Cass markings.  Some of the parts from one model of scope to another are the same.  That door is most likely one of them.  The ETX 90, a Mak-Cas was introduced first.  I believe the refractors came out later.

[Kruegon]

Got home late yesterday. Here's the door cover. Obviously someone messed up in printing, they don't know what they are selling, or it's a marketing scam. Either way, it's a misleading bit of info.

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[Kruegon]

I am not sure, but it sound like there is another lens in the way for one of the directions.
 
Bill Steen

You're right. The 45° has a built-in barlow that I had missed. I'm not a big fan of them controlling how I see. If I want a barlow, I'll put my own in. Plus, I don't like how it presents astronomy products to the general public. Simplicity is nice, but newcomers often expect it to be that easy all around. I much prefer cheap parts to built-in. At least with cheap eyepieces and barlows, they know the pieces. We can help them get better parts, but explaining they need more parts that they don't know about can make it seem more expensive than it is.

I found an adapter ring that fits the threads on the 60. It converts them to match a Mak/SCT threads. This way I can get a better diagonal and use a higher quality barlow. Not to mention that it will allow a T adapter for some photography. But baby steps first.