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emadmoussa

My back may change my mind?

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1 hour ago, emadmoussa said:

A 14" Dob, according to her, is too big and looked like R2D2.

So to look like R2D2 is not a good thing??!

Sheesh...

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12 hours ago, RobertI said:

Very interesting, I don't want to stir up a hornet's nest, but should Emad be considering an ED100 instead of an 8" SCT then? :evil:

Equally I'm not trying to stir anything up here. It was an interesting project with surprising results. All aspects were covered including varied seeing conditions on different nights etc.

Anyway. Yes I feel advice maybe a ED120 lets say would be nice instrument to sit along side the 300P

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7 hours ago, emadmoussa said:

Would anti-vibration pads help? 

I think they would be a worth while extra if you're on decking. There used to be an ebay shop that sold them pretty cheap, might be worth a search.

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3 hours ago, Lockie said:

I think they would be a worth while extra if you're on decking. There used to be an ebay shop that sold them pretty cheap, might be worth a search.

I think I'll wait and see how the mount acts on the decking. I'll figure something out. 

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Out of interest, how far from the ground is the 14" eyepiece? When pointing straight up at zenith, I mean. 

Edited by emadmoussa

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On 17/08/2018 at 12:12, alanjgreen said:

Emad,

Personally, I cant see the point of owning an SCT & a big dob as they are both long focal length.

Better to get the big dob and a 100mm frac on a lightweight mount (AZ5 GTI for example). Then you get two COMPLEMENTARY scopes.

If you want a small SCT then I would also consider the CPC800 (they are great scopes with better focuser than Meade), one just came on astrobuysell for less than 1K with loads of extras too.

But if you want the big dob then do consider a frac to go alongside it!

Alan

I agree with this, an 8" is still a big lump. I rarely use my C8, my 14" dobsonian is actually faster to set up compared to a c8 on an eq5. When its a light grab and go session Ill pick my st120 or mc127 over the c8 as they are easier and quicker.

A 14" is going to be quite physical to set up and move. I have a solid tube orion optics 14" dobsonian and I set it up on my own but whilst it doesnt take much time it does take some strength. I use a loop to let me carry it by myself without bending my back (the yellow strap in the picture). Carrying it out anywhere around the house is relatively easy but a recent meeting where i  had to carry everything about 100m from the car left me feeling the next day  like I had been wrestling with a bear !

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I'd try higher power observing from your decking with whatever scope you can before investing in anything larger / longer focal length.

 

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2 hours ago, John said:

I'd try higher power observing from your decking with whatever scope you can before investing in anything larger / longer focal length.

 

Seconded. Motion carried... :thumbsup:

On occasions, when wanting to have a peek at Venus, I'm obliged to set up on our decking because of angles and foliage etc.

Whether with the refractors or the SCT, the vibrations, no matter how careful we have tried to be, detract from the experience to the point I no longer bother...

I would urge you to somehow try observing from the intended location as @John suggests before sinking too much cost into new purchases. If you're happy with the solidity of your decking that'll be fantastic. But I share his concerns...

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5 hours ago, John said:

I'd try higher power observing from your decking with whatever scope you can before investing in anything larger / longer focal length.

 

I currently use large bins, on a weak camera tripod, I get more vibration from the breeze than from the decking surface. The decking is about 4 years old and feels quite solid underneath your feet. 

Not sure how I can test it while I don't have a large scope. But, would it matter really if I don't observe at high mag? Then, there's the fact that I observe sitting and don't move around that much. I remember I used to observe from the upstairs office window and whenever the wife walked in, I could see the image shake. And that was lunar observation at somewhat high mag. One thing for sure, our decking a lot more solid than the upstairs floor.  

The way I see it, a bit of vibration is perhaps more important to imagers than it is to visual observers. If the vibration settles down fairly quickly, as the case with my current decking, then I don't know how that could be a big deal. That being said, I'm not sure how a heavier scope would respond. 

Edited by emadmoussa

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5 hours ago, John said:

I'd try higher power observing from your decking with whatever scope you can before investing in anything larger / longer focal length.

 

By high power, do you mean something over 200x mag? 

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9 minutes ago, emadmoussa said:

But, would it matter really if I don't observe at high mag?

You'll be fine at low mag Emad, I used to obs from my deck all the time. High power can get interesting, but its still works somewhat- just dont move!

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8 minutes ago, jetstream said:

You'll be fine at low mag Emad, I used to obs from my deck all the time. High power can get interesting, but its still works somewhat- just dont move!

I rarely observe planets, so there's no need for high mag. However,  the guys here made me a bit paranoid :) that I had to conduct a test. :)  I put a glass of water on the decking and stomped  around it. The water didn't move the slightest, which I think is promising. 

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if you don't observe at powers much above 150 or so then it may not be an issue. When I'm using 250x or more I can see vibrations from my movements even with the scope set up on my lawn or patio so I try to move carefully, if I have to, when actually at the eyepiece.

 

 

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34 minutes ago, emadmoussa said:

I rarely observe planets, so there's no need for high mag. However,  the guys here made me a bit paranoid :) that I had to conduct a test. :)  I put a glass of water on the decking and stomped  around it. The water didn't move the slightest, which I think is promising. 

It makes sense to take in everyones opinion in my opinion :grin:

From my former town location I could split Pi Aquilae with the VX10 from my deck.... lets face it though, if higher mag stuff prevails wheeler 'er  down the ramp. Low mag observing is no problem from a deck, I do it here once in a while too.

How dark is your sky Emad?

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1 hour ago, jetstream said:

It makes sense to take in everyones opinion in my opinion :grin:

From my former town location I could split Pi Aquilae with the VX10 from my deck.... lets face it though, if higher mag stuff prevails wheeler 'er  down the ramp. Low mag observing is no problem from a deck, I do it here once in a while too.

How dark is your sky Emad?

It'd say fairly dark, except the West, towards the city of Manchester about 15 miles away. I get a hint of orange near the horizon. East, South, and North are mostly countryside. My house is less than a mile away from the Peak District national park to the East and North East. I can see a hint of the Milky Way at zenith. 

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Sounds good, being able to see the Milky Way opens up many opportunities with a scope. I shall have to google the park and then Blue Marble it as I'm not sure where it is.

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11 minutes ago, jetstream said:

Sounds good, being able to see the Milky Way opens up many opportunities with a scope. I shall have to google the park and then Blue Marble it as I'm not sure where it is.

Downside though, we get tons of clouds. I haven't seen a single star for about 10 days now. 

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I found the park on the Blue Marble and I've observed from similar skies. The Marble shows a similar darkness in the interior of the park to a place I've used which would zenith SQM up to 21 mag, so my guess is that if you take a short trip the sky there would be anywhere from 20.5-21 mag, which is very nice. My guess is your home will go 19-20 or a bit more.

I would pick a scope that loads easily into a vehicle... you know a good 12" is no slouch and some friends use a VX14 which are VG.

 

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1 minute ago, emadmoussa said:

I haven't seen a single star for about 10 days now

I feel your pain lol! The forest fires 800 miles away have wrecked the skies here, nothing but haze and health alerts. bottom line- no stars.

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3 minutes ago, jetstream said:

I found the park on the Blue Marble and I've observed from similar skies. The Marble shows a similar darkness in the interior of the park to a place I've used which would zenith SQM up to 21 mag, so my guess is that if you take a short trip the sky there would be anywhere from 20.5-21 mag, which is very nice. My guess is your home will go 19-20 or a bit more.

I would pick a scope that loads easily into a vehicle... you know a good 12" is no slouch and some friends use a VX14 which are VG.

 

I'm almost exclusively a backyard observer. Don't drive! ;)

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I've had four Meade SCTs and, like Peter, have never noticed any issues with coma. In the present 14 inch I use, by default, a 26 Nagler and a 13 Ethos, both giving a stunning result.

I really don't think a long effective focal length is going to work on decking. That alone would scotch the 12 inch SCT for me. I'd be looking at keeping down to 50x or maybe 80x if you held your breath. Being seated at the EP would probably make a big difference.

Olly

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I am kind of surprised  your opting for a large SCT Imad given you history with them ?  IE. Cooling, dewing up, portability .... just get a Tak and be done with alll the messing about...... ?

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Re 'high power' magnification: if you go for a 14" dob, you may well find yourself enjoying pushing 300x or more on planetary nebulae :) The bigger aperture will allow you to up the mag with the likes of an O-III in place, and tease out finer detail & structure.  So deck stability could be an issue.

Edited by niallk

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