A little help and advice

[xanthiax]

Hi All,

Ive done my research read the forums thought I knew what I wanted, read some more and confused myself!!

Ok, a bit of a two parter:-

I have my heart set on a skywatcher 130p 600mm.

Then I found a 130pm for the same price 900mm

This is where I get a litte lost. I know use use the focal lenth to determine magnification with eye pieces. (im sure thats a very basic understanding at best)

Id it important for any other reason? for the same price I might as well get the motor version. They both have a 5.1 parabolic mirror.... am I understanding this correctly?

Secondly.. this is where the over research has blinded me...

People seem to be recommending dobs over these skywatchers.

Why? Is the quality that much better for the dobs? I enjoy the learning curve so the eq2 mount doesnt scare me and I will eventually hook a dslr up to it.

What are your suggestions? Stick with the 130pm or reconsider?

Kind Regards

Martin

[YKSE]

Hi Martin, welcome to SGL

130P with 650mm focal length(fl) has parabolic mirror, while 130m with 900mm fl has spheric mirror, therefore the long fl.

I had 130P with 650mm focal length on EQ-2 mount as my first scope. The mount was barely stable for visual, It'll be too wobbly for a dslr, 130m would be more instable than 130P because of its longer tube length.

The general recommendation of dobs over these two are that dobs offer more aperture for the same amount of money.

If you're not shy of buying used telescopes, the used market, .e.g. here

http://www.astrobuysell.com/uk/propview.php

offers even better value for your money.

[xanthiax]

Hi YKSE,

The listing did say 900mm and 5.1 parabolic mirror. . Is this maybe a mistake? There was an faq which confirmed the parabolic mirror.

What difference im I going to get between the 600 & 900?

Can dslrs be attached to a dob?

Im not afraid of second hand so I will have a look on the link provided.

How'd u rate the 130?

[Zuben Elgenubi]

Hi and welcome to SGL 

The scope with the shorter focal length - 650mm - will give slightly less magnification and a wider field of view for a given eyepiece. 

People tend to recommend dobs as they offer the maximum aperture for a given budget and are very simple to use. You can attach a DSLR to most dobs, but don't realistically expect to be able to photograph much more than the moon.

I've never owned or used the 130P but they seem to have a good reputation.

[RichM63]

The "p" denotes parabolic mirror. According to the spec's for both models on Telescope Service both SkyWatcher models have a parabolic mirror, which is good, but the Celestron model has a spherical mirror which is not so good.

TS practial information: the advantage of a parabolic main mirror

Left picture:
A spherical mirror (as often used in cheap telescopes) does not focus the light in one point. Weak, undefined pictures are the result.

Right picture:
A good parabolic mirror gathers all light rays in one point. The overall picture quality increases by the pinpoint sharp and full of contrast images.

I reckon you would be happier with the 600 at f5, I have the 750 at f5 and find it great on distant objects DSO.

Your problem will be with the EQ2 mount, it will prove to be too feeble with a heavy DSLR + telescope, but you could always use it with just the camera and a standard lens for widefield imaging, see some of the shots from Knight of Clear Skies.

A 'DOB' is just the slang term for Dobsonian Mount, it does not denote the actual telescope, although the standard use is for a Newtonian Reflector Telsecope.

DOB mounts are pretty cheap, thus most of your budget goes towards the actual telescope and not the mount as is the opposite with EQ mounts.

You can attach a DSLR to a DOB mounted telescope but you will not be able to track well enough for any kind of long exposure imaging.

Second hand can save you a few hundred, most quality telescopes will have been well looked after and are only offered for sale due to a change in circumstances, type of use, or upgrading. But I would always drive to the seller's place to view the equipment even if it means a whole day out. Fuel will be offset against postage and you have the benefit of looking after the kit in transit.

[YKSE]

Hi YKSE,

The listing did say 900mm and 5.1 parabolic mirror. . Is this maybe a mistake? There was an faq which confirmed the parabolic mirror.

What difference im I going to get between the 600 & 900?

Can dslrs be attached to a dob?

Im not afraid of second hand so I will have a look on the link provided.

How'd u rate the 130?

Yes, I saw the parabolic mirror claim on some web too. I can very well be wrong about it, but I'll not totally rule out the possibility that SW's marketing department just copy&paste something either. Best to call a supplier to find it out.

Both two have 1.25" focuser, so only 1.25" eyepieces can be used. The physical size of 900mm will be longer, the same eyepiece will give higher magnification in the 900mm than in the 650mm, while the 650mm gives you larger Field of View(FOV) in the low mag end, e.g, a 32mm plossl with 50 deg gives 32*50/650=2.46 deg, comparing to 32*50/900=1.78 deg in 900mm. For viewing large open clusters, such as M45, the 650mm will frame it much better than the 900mm one.

I don't do imaging, it seems to me that advices given above are bang on.

The mirror in 130P was good, I got over 50 Messiers with it when I had it for about half a year in my backyard. The focuser was nothing to write home about, a little hard for fine tuning, especially in high magnications. The collimation screws were not the best quality either, I crossed one, had to replace it.

[xanthiax]

Thank you all for your kind replies.

Just to push a little deeper then, considering the above. What dob telescopes should I be looking at budget off about 200 for a new one?

Assuming I can save a little second hand, what models should I consider?

If I want to go down the long exposure route with the dslr, taking into consideration the wall mount wont be good enough, what would you suggest?

Is photography worth it on entry level scopes.

Thanks for the help

[xanthiax]

Hi and welcome to SGL

The scope with the shorter focal length - 650mm - will give slightly less magnification and a wider field of view for a given eyepiece.

People tend to recommend dobs as they offer the maximum aperture for a given budget and are very simple to use. You can attach a DSLR to most dobs, but don't realistically expect to be able to photograph much more than the moon.

I've never owned or used the 130P but they seem to have a good reputation.

So, 900mm would be good for seeing craters on the moon?

how much different would it be with the 600?

Likewise, what would the downside be with a 900 looking at a dso?

Sorry for the 101 questions I just wanna make sure I know what im doing before I shell out on the wrong thing

[bingevader]

A dob 'scope for £200 would be this one!

Photography can be achieved on basic kit as long as you understand the limitations and have appropriate expectations.

Magnification=focal length of 'scope/focal length of eyepiece.

So, a 10mm EP will give a magnification of 90x in a 900mm 'scope and 60x in a 600mm 'scope.

The two 'scopes both have the same 130mm aperture, so there shouldn't be any difference in light gathering ability, but personally, I tend to find that less magnification is better on DSOs anyway.

I hope that helps!

[Hootsitabernacle]

you can def get a 2nd hand 8" dob for £200 and trust me when i say you will be blown away with the views!

[ronin]

To the upset of many if you want to go down the photography/imaging route then forget dobsonians.

They are not the set up to do any with.

If imaging - even simple basic images - is required then you are really looking at an EQ3-2 as an absolute bottom end choice - simply you can add motors to them. The EQ5 is a better choice.

Do not going assuming a visual set up will do imaging well, they can at times but not the best choice. What can happen is that it takes more time to get usable data when using a visual rig then when using a dedicated imaging rig.

[Zuben Elgenubi]

So, 900mm would be good for seeing craters on the moon?

how much different would it be with the 600?

Likewise, what would the downside be with a 900 looking at a dso?

Sorry for the 101 questions I just wanna make sure I know what im doing before I shell out on the wrong thing

I'm sure either scope would give very pleasing views of the moon and other targets also.

Have a look at a field of view calculator to compare how objects will look in the two telescopes:

http://www.12dstring.me.uk/fov.htm

You will need to switch to visual view, select the correct scope (there is no option for the 130/900, but you can change the focal length manually) and eyepiece - I think they are both supplied with a 10mm and 25mm, and choose the object from the menu. Remember though that most DSOs will not appear to have colour when viewed through the eyepiece.

[xanthiax]

A dob 'scope for £200 would be this one!

Photography can be achieved on basic kit as long as you understand the limitations and have appropriate expectations.

Magnification=focal length of 'scope/focal length of eyepiece.

So, a 10mm EP will give a magnification of 90x in a 900mm 'scope and 60x in a 600mm 'scope.

The two 'scopes both have the same 130mm aperture, so there shouldn't be any difference in light gathering ability, but personally, I tend to find that less magnification is better on DSOs anyway.

I hope that helps!

Thanks Bingevader,

Spoke to the wife (boss ) regsrding value for money and second hand gear.. I lost the 'discussion' im sure most men can relate (?).

The short n curlies. I can only buy new but I can go upto 300! Would you duggest anything different to your prev post?!

You have all been a massive help. I look forward to getting to know some of you better as well as astronomy.

I think I'm about ready to buy pending suggestions

All the best

[xanthiax]

you can def get a 2nd hand 8" dob for £200 and trust me when i say you will be blown away with the views!

Any suggestions?

[happy-kat]

Save a little of your budget for other related buys like one better eyepiece.

Also think about storage location and how far it is to move the gear to where you will observe.

As an example the views from the 200p on the dob mount are apparently great but the complete unit weighs 27 kilos so for some adding stairs or a tricky back into the mix is a no go.

[AndyWB]

Yes, storage location and portability are important things to think about. A 200p is a fairly large thing; the boss might not like it living in the corner of the living room...

[xanthiax]

I'm sure either scope would give very pleasing views of the moon and other targets also.

Have a look at a field of view calculator to compare how objects will look in the two telescopes:

http://www.12dstring.me.uk/fov.htm

You will need to switch to visual view, select the correct scope (there is no option for the 130/900, but you can change the focal length manually) and eyepiece - I think they are both supplied with a 10mm and 25mm, and choose the object from the menu. Remember though that most DSOs will not appear to have colour when viewed through the eyepiece.

[xanthiax]

Lol fail on the quote.

This site was incredibly helpful. Saved for later

Unless anyone has more suggestions i will be going with the skywatcher skyliner 150p dob.

My understanding thus far. I will be able to see most things with realistic expectations

I can mount a dslr however tracking is a no go. My only option is moon snaps

150mmp mirror is best on my budget n should fit in my car.

Missing anything?

Sold on 150p?

[RichM63]

My only option is moon snaps

Not so.

There are many methods that can be employed for capturing short exposure frames (20 seconds) and stacking them together, or using a webcam and taking a video and then stacking that to create an image.

Its down to how creative and how much effort you put in. You won't obtain the images that a dedicated rig will acheive, but you should be able to create something that pleases both you and us.

[ollypenrice]

What doesn't seem to have been said about the Dob mount is that, as well as being the cheapest for visual use, it is also in many ways the best. The equatorial imposes all sorts of complications and contortions on the visual observer. It can also be very vibratory and flimsy if underspecified and only the better ones really work for long exposure photography. The great thing about webcam photography of the bright solar system objects is that the tracking can, in effect, be done retrospectively by stacking software.

Olly

http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/22435624_WLMPTM#!i=2266922474&k=Sc3kgzc

[xanthiax]

Not so.

There are many methods that can be employed for capturing short exposure frames (20 seconds) and stacking them together, or using a webcam and taking a video and then stacking that to create an image.

Its down to how creative and how much effort you put in. You won't obtain the images that a dedicated rig will acheive, but you should be able to create something that pleases both you and us.

Well i have to say, that is pleasing news indeed. My wife is into photography so in essence, the reason behind this is so that both of our interests align in some form.

I won't ask at this stage how this is done, id assume a few hrs on google will clear it up somewhat.

I will of course post everything here for people to look at once up n running.

As a final note, if there are no other suggestions on which scope to get by the end of the day, I will assume i'm on the right track n commit to the skyliner 150p

[xanthiax]

What doesn't seem to have been said about the Dob mount is that, as well as being the cheapest for visual use, it is also in many ways the best. The equatorial imposes all sorts of complications and contortions on the visual observer. It can also be very vibratory and flimsy if underspecified and only the better ones really work for long exposure photography. The great thing about webcam photography of the bright solar system objects is that the tracking can, in effect, be done retrospectively by stacking software.

Olly

http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/22435624_WLMPTM#!i=2266922474&k=Sc3kgzc

Wow. Olly, they're some great photos. Are they all yours? What setup are you using?

[happy-kat]

By what I have read the 150p skyliner is great for visual observing.

Have you searched to see what images have been taken with using it?

[xanthiax]

Zuben posted a website to compare with. Assuming it's relatively axxurete i will be more than happy for. Starter scope. Would need a 3 bedroom house for anything bigger

[xanthiax]

I have an emergency!! I have just found Skywatcher Explorer 150P EQ3-2.

Is this mount good enough or should i still stick with the dob skyliner 150p?

They seem to be relatively similar scopes?