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Who uses their refractor without a diagonal?


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Next session, I am going to try this. Just interested in who does this, and why.

Just to verify: this does give newtonian image orientation, correct? So you need to reverse direction on both axes when hopping or tracking?

:happy11:

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I've absolutely no idea about the strehl of the FC100D series. Tak seem to leave it to the individual, or indeed the forums to debate.  The SW 120ED's are superb scopes, of that there is no doubt

A Pirate?

I have tried it a few times.  I think there is an improvement in the image seen in the eyepiece, in particular less scatter, which improves contrast (its not huge, but noticeable) but at remotely high

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Always use a diagonal with my fracs. Happy to adjust when using the dob.

Only time that I don't use a diagonal is when initially checking collimation or optical axis alignment.

Good luck with the experiement Mike :smiley:

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Just to expand on why I would consider this at all. I actually prefer correct-image views, and have a very nice amici prism diagonal for this. But what if I didn't, and there was not one to be found? If I was resigned to not having correct image, then why put a diagonal in the path at all? I have yet to try a newtonian, but if all of those who use and love them can cope with the rotated image, then why not? Granted the mount will have to be a bit higher, but otherwise?

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3 minutes ago, Alien 13 said:

The view will be the same as a straight through finder so it could be easy to adapt if you use both.

Alan

Hadn't thought of that. Have yet to try a straight through finder, as well.

:rolleyes2:

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I have tried it a few times.  I think there is an improvement in the image seen in the eyepiece, in particular less scatter, which improves contrast (its not huge, but noticeable) but at remotely high altitudes it becomes quite uncomfortable and my neck is good a holding a grudge so I do not really do it.  Just an occasional experiment.

However, if I had one of these I might consider it more often!

58f62c39c1792_StarChair.thumb.jpg.df8217951790746f0ce704aa7a1e8f52.jpg

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5 minutes ago, DirkSteele said:

I have tried it a few times.  I think there is an improvement in the image seen in the eyepiece, in particular less scatter, which improves contrast (its not huge, but noticeable) but at remotely high altitudes it becomes quite uncomfortable and my neck is good a holding a grudge so I do not really do it.  Just an occasional experiment.

However, if I had one of these I might consider it more often!

58f62c39c1792_StarChair.thumb.jpg.df8217951790746f0ce704aa7a1e8f52.jpg

Agreed, it would be a sedentary affair, as with binoculars on a deck chair. We'll see how it goes.

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Apparently straight through viewing is popular in Japan. Don't know why this is but Japanese scopes are usually supplied with extension tubes which allow eyepieces to come to focus without a diagonal. My Tak and Vixen have this facility.

I'm getting curious now. I'll have to extend the legs on my Uni 28 tripod and give it a go !

 

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3 minutes ago, John said:

Apparently straight through viewing is popular in Japan. Don't know why this is but Japanese scopes are usually supplied with extension tubes which allow eyepieces to come to focus without a diagonal. My Tak and Vixen have this facility.

I'm getting curious now. I'll have to extend the legs on my Uni 28 tripod and give it a go !

 

That's the spirit!

:icon_biggrin:

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8 minutes ago, Dave In Vermont said:

I suppose that if I had the scope pictured below, it would be more doable.

Otherwise I'd need to start practicing Yoga.....

Dave

 

57a3d80627cac_ScreenShot2016-08-05at01_02_48.png.58b19bc3f2d4958befaab1ea10dc7d75.png.97bf1597ead2b5e9b47ea7feb8737e7c.png

 

And how about with your Mak?

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Of my scopes, the Vixen 102mm F/6.5 seems the best candidate for this. The eye lens of the eyepiece is around chest height at that angle. I'll give it a go tonight if clear :icon_biggrin:

P1050198.JPG

P1050199.JPG

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3 minutes ago, Dave In Vermont said:

With my Mak?! Let's see here.....

1. Build 7-foot pier to hoist it up high on.

2. Find a Dentist's Chair.

Piece o' cake!

Dave

Yes, yes, just thinking you could try it on Jupiter seated behind the Porta, just for the hell of it.

I can see you building your own dentist's chair, but I stray from the point.

:icon_biggrin:

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Actually it will be interesting to check out some double stars with the scope in this mode and compare the views with old records such as these from 1855:

 

smithsastro1855.jpg

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I recall Sir Patrick showing us his first scope, a 3" frac, lovely brass job, that one also didn't have a diagonal. Made around 1910.

:rolleyes2:

Things have moved on, but still, if he could make it work and map the Moon...

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19 minutes ago, John said:

Of my scopes, the Vixen 102mm F/6.5 seems the best candidate for this. The eye lens of the eyepiece is around chest height at that angle. I'll give it a go tonight if clear :icon_biggrin:

P1050198.JPG

P1050199.JPG

That setup is just so nice.

:happy11:

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Mind you, this 1990's Japanese postage stamp seems to disprove my theory regarding Japanese observers viewing straight through (I'm just going to slip into my Kimono):

 

 

jpnstmp1.jpg

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