views on this setup ?

[Mansnake]

Guys,

Iv'e been reading a lot on this forum (thanks to having time to save!) and now i'm in limbo !

originally i was going for a MAK 127 AZ Goto and doing webcam imaging, but now im thinkin maybe getting a better mount and scope to able to do DSO and planetary so i have the best of both.

So what can i expect from the following:-

Skywatcher Explorer 150P

Skywatcher EQ3 PRO Synscan GOTO

Will that mount take the weight of the OTA and a DSLR attached ?

any pointers welcome !

[greenninja]

I think it will take the weight of the 150 and be fine for viewing- but I'm not entirely sure it will have enough stability for long exposure imaging.

[RikM]

If you have a look at my deep sky album, all the older pics from M18 M82 and before were done with 150P, Canon 1000D and an unguided EQ3-2 standard version with dual axis drive motors. The info on each image should say what kit was used.

It is a good 'training' mount for deep sky imaging and I could get 60 - 90 secs subs unguided most of the time. With some of the DIY autoguiders being cooked up there should be some very nice images from this sort of set-up floating about. If you are wanting really good images though, you would be better with an HEQ5 or NEQ6 in the long run.

[Carbon Brush]

The general view on here is that a '150 atop the EQ5 is about the limit photographically.

EQ3 and 150 scope is going to fine visually though.

The AZ goto is of course out for long exposure due to field rotation.

The benefit of an EQ mount with RA drive is that you can change for a different scope, or camera + lens.

Just to add confusion. Have you thought about buying parts separately on the used market? An EQ5 driven + 150 scope would be a good photo package.

More confusion. An SW200P is not necessarily a bad planetary scope. I have had mine to 285mag (3.5mm FL EP) on a good night. Then swap for a long FL EP and you get the DSOs.

There is never an easy choice....

[Mansnake]

There is never an easy choice....

True indeed !

So many combinations.

The reason i said about the EQ3-2 is because its one of the cheapest Goto equtorial mounts.

Ive had a look on astro buy sell but its just one long list, unless there is a filter i cant see.

Is the SW150P quite portable ?

what to do.....what to do

Rik, ive just had a look at your deep sky album and WOW ! they are exactly the sort of image im after. The ones taken with the EQ3-2 are really good !

I think im sold on the SW150P on top the EQ3-2 Goto

[Mansnake]

Oh god.....i shouldn't keep reading this forum....

i now have another setup im looking into for DSO photography

ok so what about:-

Skywatcher Startravel 120

EQ3-2 Goto mount

Nikon D40 (my dads)

views ?

[Carl M]

You will get chromatic aberration with the startravel so wouldn't recommend for photography. I would go for the 150P personally.

[Mansnake]

Why would i get chromatic aberration and what causes it ?

[Probablynot]

And here's me with a SW150P on an EQ3-2, only two months old, now agonising about upgrading to a 200 on the Celestron CG-5 GT Goto!

It's what we all seem to do here!

[RikM]

Why would i get chromatic aberration and what causes it ?

Chromatic aberration is caused by the lenses in achromatic telescopes. They don't bring all the wavelengths of light to focus at the same point. Mirrors reflect light off the surface so don't suffer from CA. They suffer from coma instead (smeary stars in the corners).

[ollypenrice]

Why would i get chromatic aberration and what causes it ?

Lenses bend light. The different wavelengths of light bend differently, blue bending the most and red the least. This means they don't come to focus at the same point, so multiple lenses with different glasses are needed to bring them all to focus at the same place. Sophisticated imaging refractors have four lenses to make them 'apochromatic' - ie capable of focussing all colours to the same point over a whole chip. This is expensive. If the the compound lens has a fast F ratio it is even more expensive. The ST series have fast F ratios and two element lenses and low prices. This is, alas, no good for imaging.

On a simple unguided mount what you need above all is a short focal length. Weight is a minor issue beside focal length.

Olly

[Mansnake]

Ok i understand now, i had another read up of 'making every photon count'

So if i go for the SW150P would i have to use a coma corrector when using a DSLR ?

Also does anyone know the dimensions of the SW150P OTA ? i need to see if its going fit in my car ok.

I found a link to a telescope calculator page the other day while browsing the forum but forgot to bookmark it, does anyone know the link ?

cheers guys

[RikM]

A coma correct makes for nicer stars in the corners but it isn't necessary from the start.

The Explorer 150P OTA is 710mm long including dustcap and 280mm across as a maximum if you have the dovetail one side and the focuser opposite. Just the tube bit is about 180mm diameter. The OTA with rings and dovetail weights about 6kg.

This is FOV calculator I use Field of view Calculator<script src="title2.js"></script>

[Mansnake]

Thanks Rik that was exactly the link i was looking for !.

Just confirming that the dovetail is only need if using a guide scope ?

If i got a SW150P on a EQ3-2 Goto mount could i start taking long exposures straight away or do i need anything else

Ill be using my dads Nikon D40 to start with.

Cheers for all your help guys !

[RikM]

The dovetail is what connects the 150P to the mount. If you are getting the kit it will be included along with tube rings.

You will need a t-ring to connect the camera to the scope. The 1.25" EP adaptor screws in half to reveal a t-thread. You need to take the lens off the camera body, fit on a t-ring and screw it onto the adapter to fit it into the focuser.

A remote timer or laptop camera control software would be highly recommended.

I would also suggest a red dot finder or something to help with getting the right stars centred for your alignment.

[Mansnake]

Ah i see. cheers Rik.

Yea my dad has a remote timer for his camera so that will be handy.

Doesn't the scope come with a finder ? (6x30 finderscope). You mean replace this with a red dot finder ?

When using the DSLR i would focus once the camera is in place using the LCD screen on the camera right ? As im not sure if software will work with an Nikon D40.

Cheers

[RikM]

I use a red dot finder (actually a RigelQuikFinder) and then use the camera viewfinder to do the star alignment. This is just to set up your GoTo. You may be fine with the 6x30 finder. Give it a go and see how you get on.

Yes, focus using the screen on the camera. This is not easy. A Bahtinov mask will be a big help. Google it to see how to use it. Basically you point at a bright star and adjust the focus until all the diffraction lines line-up. Focus is most important. Lots of things you can fix in post processing, but if your shot is out of focus there is not a lot you can do about it.

[Mansnake]

Thanks for the info, ill have to invest in a red dot finder at some point.

When imaging Rik do you use a barlow at all ?

With this scope am i likely to get any decent views of Jupiter & Saturn etc... or is the focal length too small ?

Cheers