Best Cheap 150mm f/5 Reflector for Visual & Astrophotography

[Xzenotrex]

Hi everyone,

I'm looking at upgrading my telescope (I've currently got some rubbish small celestron) and for my budget I decided a 150mm (6 inch) f/5 newtonian would be best. I am looking at buying just the telescope, will get the mount seperately, and have a budget of up to £300, although less would be better.

I am wanting to do some visual and also some astrophotgraphy, probably of DSOs.

So far I have found a couple of scopes that looked good:

1. Skywatcher Explorer 150pds or 150p OTA (Around £289)
2. Bresser Messier NT-150S/750 Hexafoc OTA (Around £250)

Any reviews of these or other reccomendations would be greatly appreciated.

[vlaiv]

Hi and welcome to SGL.

If you plan on doing astrophotography, then get 150PDS or any other scope that has 2" dual speed focuser and optimized secondary mirror.

150p has smaller secondary mirror - which is good for observing (planetary especially - but if you are into planets, then 150mm F/8 version is even better) - but that is not so good as far as field illumination goes - more vignetting in your images that needs to be corrected.

Here is alternative:

https://www.firstlightoptics.com/ts-telescopes/ts-photon-6-f5-advanced-newtonian-telescope-with-metal-tube.html

Do factor in that you'll have to use very sturdy equatorial mount for astrophotography (at least EQ5 and preferably HEQ5) and coma corrector (you don't need one - but you'll want one).

For visual use - maybe make simple dob type mount for the scope - or alternatively put it on azimuth mount like this one:

https://www.firstlightoptics.com/alt-azimuth-astronomy-mounts/skywatcher-skytee-2-alt-azimuth-mount.html

It can also be used on something like AZ4 - but I think that you'll have issue of OTA hitting the tripod near zenith on that mount as scope tube is a bit on thick side.

(image taken from: http://www.waloszek.de/astro_sw_az4_e.php)

 

[Xzenotrex]

Thanks for the great reply, I'll look into that scope you suggested.

You suggested for me to make a dobsonian mount or use an altaz one for visual use, is there any reason why an eq mount wouldn't work as a mount for visual use?

[vlaiv]

46 minutes ago, Xzenotrex said:

Thanks for the great reply, I'll look into that scope you suggested.

You suggested for me to make a dobsonian mount or use an altaz one for visual use, is there any reason why an eq mount wouldn't work as a mount for visual use?

Not that it would not work - most people find it very awkward to use although some get used to it.

As you move the scope around the sky on EQ mount - Eyepiece position changes - it can be on one side and in next instant facing down towards the ground and so on.

Cure to this is to rotate tube every time you change position of the scope - loosen rings, rotate tube, tighten rings. There are specialist rings that let you rotate tube as well - but are expensive.

Refractors or compact scopes don't have this problem as eyepiece is at the end of tube not on its side - all you need to do is rotate diagonal mirror and you are good to observe.

Alt-az type mount - whether it is dobsonian or regular alt-az - just keeps eyepiece at same position.

In order to see how Eyepiece / focuser / finder can end up in strange positions - find some Youtube videos explaining operation of Newtonian scope on EQ mount.

[Xzenotrex]

Okay thanks for explaining that.

I looked into that TS-PHOTON telescope you suggested, and I realised it doesn't come with a dual speed focuser. I was just wondering how important this is and whether it would be worth it to buy the 150pds instead which comes with a dual speed focuser. Thanks!

[vlaiv]

6 minutes ago, Xzenotrex said:

Okay thanks for explaining that.

I looked into that TS-PHOTON telescope you suggested, and I realised it doesn't come with a dual speed focuser. I was just wondering how important this is and whether it would be worth it to buy the 150pds instead which comes with a dual speed focuser. Thanks!

I'm surprised that it does not. Maybe to keep the price down, I see that F/4 version comes with dual speed focuser.

Dual speed focuser is important on faster scopes - anything at or below F/5 is considered to be fast scope, as critical focus zone is rather shallow and it helps to get the best focus - even for visual if you have dual speed. I installed dual speed addition to my 8" F/6 dobsonian and it was worthy investment - especially on planets that require very precise focusing, although I use that scope purely for visual.

Imaging also requires precise focusing, so if you plan on doing AP - I'd recommend that you get scope with better focuser (dual speed are usually a bit higher quality and can hold more weight as well).

If you have limited budget - using single speed will not prevent you from either observing or imaging - you'll just need to be more careful when focusing to get the focus just right.

[Xzenotrex]

49 minutes ago, vlaiv said:

Imaging also requires precise focusing, so if you plan on doing AP - I'd recommend that you get scope with better focuser (dual speed are usually a bit higher quality and can hold more weight as well).

 

Okay I think I will go for the 150pds as I would like to do AP and it looks cheaper to spend the money now than to have to upgrade later down the line.

Thanks for all your help!

[Louis D]

Can't you use an EQ mount as an alt-az mount by setting it to 0 or 90 degrees latitude?

[vlaiv]

8 hours ago, Louis D said:

Can't you use an EQ mount as an alt-az mount by setting it to 0 or 90 degrees latitude?

That makes perfect sense and it would solve a lot of things, but unfortunately, most EQ mounts can't move that far "up".

Take for example EQ5, which is sort of ideal mount for such a thing - wedge on it has a stop so it can be moved further. People have solved that with filing various bits so that they can move past each other.

Here is an example:

https://www.iceinspace.com.au/forum/showthread.php?t=130920

Apart from DIY it like in above example - there are goto mounts capable of this AZEQ5 and AZEQ6 - but they are powered (might not suit everyone) and are expensive. For example, AZEQ6 is £1,689 versus EQ6-R which is £1,449, so you pay additional £240 for this ability to convert - which should really come for "free" as it is feature of EQ mount if you set it as if you would on north pole. Software to switch between az and eq also comes for free - look at AzGTI - free firmware update let's you use it in both EQ and AZ mode (just need to provide a wedge for it).