Someone Please Explain

[Refractordude]

A reviewer of the Starguider 12mm used a cheapo barlow lens that improved the image at a higher magnification. Thanks to you all

[notFritzArgelander]

Easy. A cheap Barlow slows the convergence of the light cone from the objective. So instead of an f5 (which requires a highly corrected eyepiece design that is costly) the scope becomes an f10. An f10 is much more forgiving of eyepiece designs that are not highly corrected.

Many highly corrected designs BTW use a Smythe lens group up front that kind of, sort of acts like a built in Barlow.

The disadvantage of using a Barlow this way (or a Smythe lens in a more advanced eyepiece design) is more lenses. This results in losses of image brightness (absorption in glass) and loss of contrast (more scattered light from additional lens/air surfaces).

Hope that helps.

[Lady Fraktor]

At f/10 it would have to be a poor design eyepiece not to operate reasonably well. (Meade MA and Celestron Kellner come to mind)
It is an honest review of its performance at f/5, and not using it as a 6mm.
There are many high quality eyepieces that are designed to work best at f/7 and slower but suffer when used in faster telescopes.
A well made symmetrical (Plossl) will give a good view at f/4 if you do not mind the 50° AFOV

[Juno16]

I have the Starguider 12mm and 8mm and they work quite well in my f7 scope considering they are inexpensive eyepieces. They do cheapo barlow nicely on bright targets like planets and brighter double star pairs.

Thanks,
Jim

[Refractordude]

That being the case. I could use a Meade 4000 56mm plossl with a barlow on a f5 telescope, and have Tele Vue like edge correction.

[notFritzArgelander]

That being the case. I could use a Meade 4000 56mm plossl with a barlow on a f5 telescope, and have Tele Vue like edge correction.

Maybe not. You are using "word logic" only which can be misleading. There is no "optics logic" reason why it wouldn't be worth a try, though.

How might things go wrong compared to a 27mm TV Panoptic?

Well you are essentially designing your own system so it might not be as well integrated as a single TV. Coatings might be very different. Control of scattered light and contrast might suffer.Certainly the AFOV would be smaller.

I'd rather use the 27mm Panoptic, myself.

[Refractordude]

That being the case. I could use a Meade 4000 56mm plossl with a barlow on a f5 telescope, and have Tele Vue like edge correction.

Maybe not. You are using "word logic" only which can be misleading. There is no "optics logic" reason why it wouldn't be worth a try, though.

How might things go wrong compared to a 27mm TV Panoptic?

Well you are essentially designing your own system so it might not be as well integrated as a single TV. Coatings might be very different. Control of scattered light and contrast might suffer.Certainly the AFOV would be smaller.

I'd rather use the 27mm Panoptic, myself.

Not only designing my own system, but such a combo might be hell on a focuser.

[Lady Fraktor]

Yes some eyepiece/ barlow combinations can be quite hard on stock focusers

[notFritzArgelander]

Reminds me of stacking a Paracorr and eyepiece on my f4 Newton.

No diagonal though!

[Refractordude]

Yes some eyepiece/ barlow combinations can be quite hard on stock focusers
Watch your eyes.jpg

This combo might be shorter and half the price of a Panoptic 27mm.

[Lady Fraktor]

That would be the more economical solution!

[notFritzArgelander]

Yes some eyepiece/ barlow combinations can be quite hard on stock focusers
Watch your eyes.jpg

This combo might be shorter and half the price of a Panoptic 27mm.

That would be the more economical solution!

Well you are all welcome to your economies. I'll stick with my Panoptic 27mm because to my eyes It's much more pleasing.

I've played with Barlows and less expensive eyepieces like the Baader Hyperions for a 70 degree AFOV and I'm having none of it.

1) I know that even when I Barlow up a TV Panoptic there is a loss of contrast compared with a TV Delos or (even better) an Orthoscopic. I almost never use a Barlow any more because they always seem to lose image quality.

2) The only thing that can tempt me away from the TV Panoptic and Delos for my Z12 is possibly the Pentax XWs or something similar.

If it pleases you to save money that way fine. Tried it. It's definitely not pleasing to me.

[Ylem]

Interesting thread, I do not own a Barlow. But have always wonder if there would be any advantage in using one in an ST80?
Would there be any advantage to Barlowing a 20mm EP over just using a 10mm EP?

[notFritzArgelander]

Interesting thread, I do not own a Barlow. But have always wonder if there would be any advantage in using one in an ST80?
Would there be any advantage to Barlowing a 20mm EP over just using a 10mm EP?

It depends on what you want, what are your requirements"

If you are worried mostly about cost and eye relief then great! Go for it!

If you want the best quality image and to improve your observing skills? Nope. The images will deteriorate slightly. If getting the most out of your Mark I eyeball, no again. It's like playing a musical instrument, you need to practice on a good enough axe that allows you to improve your skills. You can stop your observing skills from developing by using less than stellar gear.

Would you give a cardboard violin shaped object or guitar shaped object as encouragement? I wouldn't.

[Ylem]

Interesting thread, I do not own a Barlow. But have always wonder if there would be any advantage in using one in an ST80?
Would there be any advantage to Barlowing a 20mm EP over just using a 10mm EP?

It depends on what you want, what are your requirements"

If you are worried mostly about cost and eye relief then great! Go for it!

If you want the best quality image and to improve your observing skills? Nope. The images will deteriorate slightly. If getting the most out of your Mark I eyeball, no again. It's like playing a musical instrument, you need to practice on a good enough axe that allows you to improve your skills. You can stop your observing skills from developing by using less than stellar gear.

Would you give a cardboard violin shaped object or guitar shaped object as encouragement? I wouldn't.

Yeah, that's what I have kinda thought. Hence I have never had a Barlow

[notFritzArgelander]

Interesting thread, I do not own a Barlow. But have always wonder if there would be any advantage in using one in an ST80?
Would there be any advantage to Barlowing a 20mm EP over just using a 10mm EP?

It depends on what you want, what are your requirements"

If you are worried mostly about cost and eye relief then great! Go for it!

If you want the best quality image and to improve your observing skills? Nope. The images will deteriorate slightly. If getting the most out of your Mark I eyeball, no again. It's like playing a musical instrument, you need to practice on a good enough axe that allows you to improve your skills. You can stop your observing skills from developing by using less than stellar gear.

Would you give a cardboard violin shaped object or guitar shaped object as encouragement? I wouldn't.

Yeah, that's what I have kinda thought. Hence I have never had a Barlow

I have Barlows and I've done tests. I might use them again if I ever do any lunar or planetary astrophotography other wise no. If you're on a tight budget you'll be giving up a little on performance. Each of us needs to decide what fits our requirements.

[Lady Fraktor]

Yes some eyepiece/ barlow combinations can be quite hard on stock focusers
Watch your eyes.jpg

This combo might be shorter and half the price of a Panoptic 27mm.

That would be the more economical solution!

Well you are all welcome to your economies. I'll stick with my Panoptic 27mm because to my eyes It's much more pleasing.

I've played with Barlows and less expensive eyepieces like the Baader Hyperions for a 70 degree AFOV and I'm having none of it.

1) I know that even when I Barlow up a TV Panoptic there is a loss of contrast compared with a TV Delos or (even better) an Orthoscopic. I almost never use a Barlow any more because they always seem to lose image quality.

2) The only thing that can tempt me away from the TV Panoptic and Delos for my Z12 is possibly the Pentax XWs or something similar.

If it pleases you to save money that way fine. Tried it. It's definitely not pleasing to me.

I only said it was economical, not that I would do it myself

[notFritzArgelander]

This combo might be shorter and half the price of a Panoptic 27mm.

That would be the more economical solution!

Well you are all welcome to your economies. I'll stick with my Panoptic 27mm because to my eyes It's much more pleasing.

I've played with Barlows and less expensive eyepieces like the Baader Hyperions for a 70 degree AFOV and I'm having none of it.

1) I know that even when I Barlow up a TV Panoptic there is a loss of contrast compared with a TV Delos or (even better) an Orthoscopic. I almost never use a Barlow any more because they always seem to lose image quality.

2) The only thing that can tempt me away from the TV Panoptic and Delos for my Z12 is possibly the Pentax XWs or something similar.

If it pleases you to save money that way fine. Tried it. It's definitely not pleasing to me.

I only said it was economical, not that I would do it myself

Once again I get to play the socially inept curmudgeon. Well that's reassuring.

[Bigzmey]

Yes some eyepiece/ barlow combinations can be quite hard on stock focusers
Watch your eyes.jpg

This should work well in ST80.

[Bigzmey]

The trick is valid, but nothing good comes from using a cheap barlow. I would either scout eBay or classifieds for older made in Japan barlows, or pay a bit more and get Baader Q-barlow. Coincidentally TV barlows are on 10% sale now. This is as good as it gets for TV.