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Equipment Discussions >> Binoviewers

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A6Q6
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Reged: 05/31/11

Loc: Stroudsburg,Pa,U.S.A
Re: Final apeture reduction measurment for EdgeHD 8" new [Re: Eddgie]
      #6135305 - 10/13/13 04:00 PM

Eddgie, tell us you didn't get rid of your C14!

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Eddgie
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Re: Final apeture reduction measurment for EdgeHD 8" new [Re: HowardK]
      #6135447 - 10/13/13 05:28 PM

That is a pretty big difference between my scope and your scope.

I was under 6.5" with a baader Clicklock and standard 2" diagonal, but no filter switch, and also using a scope with a longer light path than the Mark V.

Again, perhaps there is some difference in our scopes that is making mine work differently.

If you could make the light path measurements and double check that you did the measurement at low power at infinity focus, I would really appreciate it.

Perhaps there is something in my scope that could be changed to improve it.

Again, this is why I encourage people to measure though. You don't really know what you are getting until you measure.

7" is not bad for having a reducer. Still a 34% light loss though, and if you can shorten up by 50mm, that will put you at 7.5", which is only a 15% light loss, that still gives a 20% improvement.

20% is only very moderate improvement though, so if you are happy with it, it may not be worth dumbing the 2" diagonal. Only you could say.

You might though want to do the math to see how using the Mark V with 24mm Panoptics or 35mm Ultimas might work out.

You may find that the power is not all that different and that you can get almost as wide a field at a bigger exit pupil when you factor in the light loss.

But this is academic really. If you are happy with the way it is, there really isn't any need to do anything and you can simply enjoy it the way it is.

I am curious about the disparity though. I would have calculated well under 7" of aperture based on my own configurations.. If your measurements confirm your original readings, then there must be an issue with my scope.


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Eddgie
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Re: Final apeture reduction measurment for EdgeHD 8" new [Re: A6Q6]
      #6135464 - 10/13/13 05:38 PM Attachment (15 downloads)

C14 has passed to a new owner.

I love it and enjoyed it for many years, but had been waiting to buy a Go-To dob.

The CGE 1400 was simply getting to much to move in and out, and it took too much room to leave on my covered patio.

The new scope has a very small footprint and can be left on the patio in a sheltered corner and deployed in a couple of minutes with a hand truck. So, 12" stays outside 24/7. CGE on a cart would have been to big.

The other factor was that I simply could not get much true field using binoviewers and the 12" dob is far better in that respect.

The primary driver though was the desire to simplify the setup routine and the 12" has been simply fantastic from that standpoint.

So, was time.

The 12" is of course giving up a little light, but I get a much wider field of view, so I am happy with the trade.

Been revisiting a lot of targets. Globulars are not as good, but most other targets are still very satisfying.

Have not really had much chance to do planets or the moon but seems like it will be good enough.

Edited by Eddgie (10/13/13 05:40 PM)


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REC
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Reged: 10/20/10

Loc: NC
Re: Final apeture reduction measurment for EdgeHD 8" new [Re: Eddgie]
      #6136738 - 10/14/13 11:41 AM

Nice pic of your new scope! Where do you observe from, backyard area and if so, what is your LP level there, red, yellow zone type of sky?

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Eddgie
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Re: Final apeture reduction measurment for EdgeHD 8" new [Re: REC]
      #6136915 - 10/14/13 12:56 PM

I am in Austin Tx about 4 miles north of downtown, but central neighborhood.

Lot of tree canopy, but still most nights VLM is 3 or 4 if I am lucky.

But I do an enormous amount of observing in terms of catalog objects. Brighter galaxies only, but tons of planetary nebula, Globulars, and clusters and doubles and most of these are still really excellent.

Of course better under dark skies, but the nearest dark sky observing site (where the skys are really black and you won't get shot at for being on the edge of someones private property... Yeah, this is Texas and they $**T like that here) is 70 miles away.

But the scope has been working great. It is a heavy sucker, but I can move it on a hand truck and the alignment is really fast because you don't need to do any kind of home position. I really like that.

And if you only want tracking, you really don't even need to use a star!

Sweet.

Once I got past the weight, I was really happy with the telescope and Go-To, and it is great with the Binoviewer and 1.7x coma corrector. I can't use to low a power anyway because the sky washes out, so is working fine.


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A6Q6
professor emeritus


Reged: 05/31/11

Loc: Stroudsburg,Pa,U.S.A
Re: Final apeture reduction measurment for EdgeHD 8" new [Re: Eddgie]
      #6137123 - 10/14/13 02:07 PM

Well, I'm very sad to see you part from your C14, for me its like when Erik Bakker over on the Questar forum, sold his Questar 7 and now uses a 16" dob. I always liked the fact that you could speak from a position of authority when people talked about the C14 vs 6" APO . I hope when you start L&P observing that those Orion optics hold up. But you can always send them out to have them reworked.

Edited by A6Q6 (10/14/13 02:09 PM)


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Eddgie
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Re: Final apeture reduction measurment for EdgeHD 8" new [Re: A6Q6]
      #6137525 - 10/14/13 05:28 PM

I had budgeted to have the Orion mirrors refigured if they were at the lower end of the quality spectrum, but they were better than that, and if fact, I would say pretty decent. The secondary breakout is fairly well balanced, and there are no zones, no sight of turned edge.

I am sure everyone would be curious about why I sold the C14 and kept the 6" APO.

I was going to sell the AP, but my assistant astronomer really balked. She remembered how much I wanted it and thinks it would be a mistake to sell it.

Have not used it in a year though. If it fits in the field, I prefer the EdgeHD 8" because it goes a tiny bit deeper and has the same excellent off axis performance and it is a lot easier to get out of the door.

I have considered putting the 6" APO on a DM6 or something to make it easier to use, but I am not so much into low power scanning.

So, will keep it for the time being, but I suspect its days might be numbered.

I am really enjoying the ease of getting the 12" dob on to the firing line, and once I get a coma corrector for the 31mm Nagler, I simply can't see myself using the 6" APO again. The 6" dob with the 31mm Nagler will have only a little narrower field of view, and a lot more horsepower.

But I still might keep the refractor. It will be the only AP scope I will ever own, and it really is a lovely telescope to use if you can be happy with 6".

I am lucky to own one telescope that is pretty much perfect at everything it does. 6" Though. 8" would have been better.. LOL.


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REC
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Reged: 10/20/10

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Re: Final apeture reduction measurment for EdgeHD 8" new [Re: Eddgie]
      #6137566 - 10/14/13 05:52 PM

You sure make the most out of this hobby even in a limited sky....what dedication! Yeah, I really enjoy your enthusiasm in your posts and have learned a lot especially in the world of binoviweing, you help a lot of people out and seem to be able to enjoy it as well:)

Clear skies to you


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HowardK
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Re: Final apeture reduction measurment for EdgeHD 8" new [Re: REC]
      #6137583 - 10/14/13 06:03 PM

Yup

I also get a lot out of Eddgie's posts on all forums he is at large on.

Very knowledgeable and prolific


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Eddgie
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Re: Final apeture reduction measurment for EdgeHD 8" new [Re: HowardK]
      #6137873 - 10/14/13 09:18 PM

Too much. I need to cut back.

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Mark9473
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Re: Final apeture reduction measurment for EdgeHD 8" new [Re: Eddgie]
      #6138499 - 10/15/13 08:19 AM

Put a Herschel wedge with binoviewers on that 6" AP, Ed.

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Erik Bakker
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Re: Final apeture reduction measurment for EdgeHD 8" new [Re: A6Q6]
      #6138653 - 10/15/13 09:46 AM

Quote:

Well, I'm very sad to see you part from your C14, for me its like when Erik Bakker over on the Questar forum, sold his Questar 7 and now uses a 16" dob.




I am sorry about that

Love my MW 16" f/5 though, it is a big step up from the wonderful Q7 in planetary observing and has it's own superb user friendliness


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A6Q6
professor emeritus


Reged: 05/31/11

Loc: Stroudsburg,Pa,U.S.A
Re: Final apeture reduction measurment for EdgeHD 8" new [Re: Erik Bakker]
      #6138898 - 10/15/13 12:06 PM

Hi Erik, I know you and Eddgie wouldn't settle for anything less, and I know you have to move on. But the Q7 & C14 are scopes that many people who have been in the hobby a long time have admired, and for whatever reason, couldn't have. I will still always enjoy what you guys post.

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Eddgie
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Re: Final apeture reduction measurment for EdgeHD 8" new [Re: A6Q6]
      #6138985 - 10/15/13 12:47 PM

Well, just because we have changed scopes doesn't change our experience with them.

And new scopes mean new insights.

For example, the 12" is not as comfortable to use as the C14, and the off axis performace even with a coma corrector is not as good as the 6" APO.

I have had Newts before too. My first large telescope was a Meade 10" f/4.5 Newt (GEM Mounted).

So, Newt is not new territory for me at all.

Changes sometimes result from change in requirements, thats all.

No reflection on the C14. I have seen more with it than all of my other scopes put togehter I suppose.

Seriously, I have viewed maybe 1000 different objects with the C14. Most so faint that I could barely see them.

But the 12" offers new possibilities, and will do things the C14 could not do.

Just a different instrument with different capabilities.

I always said that if I had an observatory, I would have the C14 in it, but I guess that is never going to happen.

And the convenience of the Go-To dob became compelling in my own case. I had waited for a well integrated Go-To dob, and I knew that when one came along I would buy it.

And it did, and I did what I had wanted to do.

Don't worry, be happy.


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HowardK
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Re: Final apeture reduction measurment for EdgeHD 8" new [Re: Eddgie]
      #6141244 - 10/16/13 04:36 PM

Eddgie....

Edge8" with baader 2" cliklok visual back, mk v binos on 2" diagonal with powerswitch and filter switch with the baader quick change lock on top as shown on my fotos gives...

178mm aperture in reduction mode
185mm aperture straigh thru mode

So straight thru i am at 7.3 inches aperture....not so great.

If i remove the whole 2" diagonal/power/filter switch thing and insert a baader zeiss prism diagonal into the cliklok visual back with its quick change lock on top and then clip on the mk v's .......i do get 200 mm aperture....or....the full 8"

Compromise then for me...

Live with a 7-7.3" aperture but being able to flick thru 3 magnifications without changing eyepieces or go the full 8" but only one magnification.

I do not really look at DSO's...from my backyard....more planet, moon and difficult double stars

What say you?


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Eddgie
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Re: Final apeture reduction measurment for EdgeHD 8" new [Re: HowardK]
      #6141330 - 10/16/13 05:19 PM

Well, getting 178mm is a lot better than I got with a 2" diagonal and a powerswitch binoviewer but I was also using a binoviewer with a 127mm light path. It all adds up.

So, the WO diagonal has indeed paid off for you for low power.

But as you can see, straight though, there was a penalty.

Still, you are doing better than I am because even with the 10mm SCT to T2 adapter, I am getting 200mm where you are getting 200mm with the Baader Clicklock.

I can only think that there may be some slight difference in our scopes to account for the .1" difference in aperture reduction that appears to be occurring.

Even with the Televue short adapter (30mm of light path) I was only getting 7.7".

Did you measure your light path? Just curious.

7.3" is a big hit. Only you can judge if it is meaningful enough difference, but for planets, I think you would do better to go to the BV/Prism You are loosing 22% brightness, which combined with the binoviewer dimming, is giving you about the same brightness as you would get with maybe a 6" telescope the same magnification, and the contrast loss is going to be a little more of course because while the aperture is reduced, the size of the secondary is not, so the percentage grows.

I am also again bit surprised by the fact that your aperture was only reduced by .3" with the low power arm.

I got .4" to .5" of loss depending on the configuration, but again, I was using a regular 2" diagonal and a binoviewer with a longer light path (The Mark V really is short considering the giant prisms being used, yes?).

Only you can really say for sure if the compromise matters. Your system is working a bit better than my system did, but as you can see, there is always some kind of compromise.

Again, your scope seems to be getting a bit better result, but I would really appreciate it if you could measure your light path. Perhaps I over-estimated yours. I think the diagonal your are using may be shorter than I would have guessed.

Again, thanks for the measurement.

And yes. All about compromise. But I totally get the desire to have the powerswitch.


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Eddgie
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Re: Final apeture reduction measurment for EdgeHD 8" new [Re: HowardK]
      #6141337 - 10/16/13 05:22 PM

Also, this.

What is the lowest power eyepiece that you use for low power arm? Are you using anything like 24mm Pan or ES???

I tried 24mm Hyperion in a powerswitch system and got pretty noticeable vignetting with the low power arm.

Would be good to know your light path...


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Eddgie
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Re: Final apeture reduction measurment for EdgeHD 8" new [Re: Eddgie]
      #6141345 - 10/16/13 05:27 PM

And one last thing.

Remember, when you put in the high power are, if you don't get too much power (which was a problem I had many nights) for planets, remember that you will pick up a couple of tenths of an inch of aperture because you have to move the mirror forward to re-focus.

You may want to measure it. This might mean that you have 7" for low power, 7.3" for medium, and maybe 7.6" for high, and 7.6" would not be so bad really for planets.

Again, one of the problems I had though is that if I went with a 20mm ES (no vignetting in low power) I would get too much magnification for most nights with the high power arm in, so I was forced to change to a 25mm pair anyway, which kind of defeated the purpose of the powerswitch.

But if you don't want to re-configure, putting in the high power arm and going to longer focal length eyepeices might be a good way to brighten the image and lower the power a bit, because you get back some aperture as well.


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Eddgie
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Re: Final apeture reduction measurment for EdgeHD 8" new [Re: Eddgie]
      #6141435 - 10/16/13 06:05 PM

And one more "one more thing."

The reason that I was hoping to get your total was to see is the .1" loss per 10mm figure is otherwise accurate.

If aperture reduction starts at 160mm (though it may be starting at 170mm on your scope), that would according to my estimate mean that your light path is 240mm (230mm if your scope is starting to loose aperture at 170mm).

By knowing the light path as exactly as possible, we can see if the 160mm figure I came up with is working.

Also, what eyepiece were you using to make your measurments?

I had .1" extra when I used 40mm Plossls because these have ffield stops very low in the barrel.

With the 24mm Hyperions, I go the most aperture reduction because the field stop is pretty far back in the barrel. I started using the 24mms for all measurements because it was the eyepiece I used the most.


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HowardK
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Re: Final apeture reduction measurment for EdgeHD 8" new [Re: Eddgie]
      #6141483 - 10/16/13 06:26 PM

Eddgie

I was using a pair of 16mm Naglers for the test.

I cant understand how to measure the diagonal light path or the cliklok visual back light path
Can u post a photo or diagram showing me please


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