Buying the first telescope! I'm interested in deep space!

[Lady Fraktor]

Both are a good place to start from.
The Skywatcher comes with a larger finder and 2 eyepieces, the Bresser with a solar filter and tube rings though they would likely be not very useful.
Normally the best one will be the one that has suitable accessories to start with.
The mirrors are usually high quality so that will not be a problem.

[Bigzmey]

Thank you Bigzmey very much for that suggestion i couldnt find it my self, it seems nice and the cost in this link you sent me is 467 and with the shipping goes to 500 and is actually really good price from what i found in my general reaserch. I will think about it if 100E worth to buy a new one. But the truth is i dont know what are the main defferences beetween those two dobs ''SΚΥWΑΤCΗΕR Dobsonian 8 PYREX" ( https://planitario.gr/gr/dobsonian-8-pyrex.html) and ''Bresser Messier 8" Dobsonian'' (https://www.teleskop-express.de/shop/pr ... cuser.html). Why the newone is better? Its something that it will make any defference? Thank you in advance!!

As Lady Fraktor said, they should be of similar quality. I feel that for newcomers buying new is a safer choice, since you don't have yet much experience with DOBs to tell if there is something wrong or missing from the used one.

You could also use the link I sent you to negotiate a better price for the used scope.

[Mike Q]

For deep sky observing remember aperature is king. The more of it you have the deeper and fainter you will see. I am definitely a dob guy having a 10 inch and a 16 inch. The question is how big of scope can you transport if you are going to a dark site to observe? For me i can easily toss the OTA in the back seat of my truck with room to spare. Before you buy anything try and find some to actually look at them in person. Dobs are big. The more aperature you get the bigger they become. These are all things to consider. Lets be a bit honest here with the budget. 500 or so euro isnt really that much. It might get you a 8 inch dob, which is a decent starter scope, some call them lifetime scopes and they certainly can be. But the scope is just the initial outlay. Next comes the accessories and that is really where the money spending starts.

[helicon]

It looks like your choice has been narrowed down. There definitely is some good advice above. Get something you can move around fairly easily otherwise you may not feel like hauling the scope out sometimes if it is too big and bulky.

[SkyHiker]

For deep sky observing remember aperature is king. The more of it you have the deeper and fainter you will see. I am definitely a dob guy having a 10 inch and a 16 inch. The question is how big of scope can you transport if you are going to a dark site to observe? For me i can easily toss the OTA in the back seat of my truck with room to spare. Before you buy anything try and find some to actually look at them in person. Dobs are big. The more aperature you get the bigger they become. These are all things to consider. Lets be a bit honest here with the budget. 500 or so euro isnt really that much. It might get you a 8 inch dob, which is a decent starter scope, some call them lifetime scopes and they certainly can be. But the scope is just the initial outlay. Next comes the accessories and that is really where the money spending starts.

Aperture is king only if your budget is big enough to buy a mount that can support all that weight. In all other cases, go for small high-quality refractors like a SharpStar or Redcat that can be supported by a reasonably priced mount. Doing astrophotography with 20" optics on an EQ mount will require a mount that costs 10K to 20K, I am guessing. My Losmandy G11 is struggling with a 12" Newt astrograph already.

Tom Osypowski has made some inroads to AP for large Dobs with his very nice dual axis, auto-guidable equatorial platforms. These platforms can easily cost 3K though, and doing AP with it is not trivial, I think. There are some people who got excellent results, but most are not as nice as what you can get with regular EQ mounts with smaller optics. If you can afford a PlaneWave mount you would get better results but now we're talking about 100K total or so for a complete system that includes an observatory as a necessary feature.

[SkyHiker]

I did not mention the control system for Osypowski's EQ platforms. This typically Sky Commander or Argo Navis digital setting circles, and a SiTech goto system. For AP you probably need good encoders for that, as opposed to autoguiding-only, and those can cost thousands of dollars.

The recent surge of completely automated Alt/Az systems (SeeStar, Dwarf II, Stellina, Vespera) show that it can be done though. These systems take short exposures and stack them live, to get around and/or ease the problem of long exposures with a rotator.

The problem with autoguiding of a system with a rotator is that (a) the autoguider will make the image rotate around the guide star, and (b) the rotation axis of the rotator is generally NOT centered on the guide star. Unless you have a mount that has figured out how to get rotators to work properly (like PlaneWave), there are still problems that require you to take short exposures.

If you are good at DIY, such a solution is actually within reach. With OnStep you can easily build a motorized Alt/Az system with rotator that can be autoguided, for only a few bucks. Check out their page that shows how they adapted Dobs with 3D-printed mechanics, to control Alt/Az systems. If the mechanics are good enough and you add autoguiding to it, you might be able to do AP with a Dob converted that way.

BTW There have been people doing short exposure AP successfully with plain Skywatcher goto Dobs. Using short exposures becomes more and more feasible as read noise and dark current are virtually zero with the latest CMOS sensors. In addition, if you have tried DSS to stack your images, you should have noticed a significant speedup if you ran it on AVX-supported desktops. So, short exposures are increasingly feasible as a way to compensate for inadequate mechanics.

The way to go is to use OnStep for a controller, combine that with Ekos. The SeeStar for instance is based on indilib open-source code, which was created for Ekos. That shows that such an approach is feasible and should not be too hard to do if you set your mind to it.

[Juno16]

Hi Ethan and welcome!

It’s great to have you here and looking forward to your adventures!

[SkyHiker]

Lastly, I should mention a problem with Dobs on an auto-guided dual axis EQ platform. The dual axis mechanism leads to perpendicular axes only when the Dob is pointed near the meridian. When the Dob points away from the meridian, the controls are no longer orthogonal like with an EQ mount (assuming that the autoguider points in the same direction as the Dob, which it has to). This leads to an undesired coupling if you use standard autoguiding software that assumes that the axes are orthogonal, and that will deteriorate the results.

The way to get around it is to provide compensation in autoguiding software if you can retrieve the Dob's Alt/Az position, and that of the EQ platform as well. This has not been implemented yet in PHD2 or Ekos (which uses the same PHD2 open-source software BTW). I asked for it once and did not have success. Thus, autoguided Alt/Az systems with rotator are better for control purposes; however, most of these DIY built systems will inevitably have crappy mechanics that may favor Dobs on an EQ platform with somewhat inadequate autoguiding control software.

Then again, with short enough exposures autoguiding is not needed as shown by the recent automated scopes. But the mechanics of a small automated scope is easier to get right than that of a big ole Dob.

[Mike Q]

For deep sky observing remember aperature is king. The more of it you have the deeper and fainter you will see. I am definitely a dob guy having a 10 inch and a 16 inch. The question is how big of scope can you transport if you are going to a dark site to observe? For me i can easily toss the OTA in the back seat of my truck with room to spare. Before you buy anything try and find some to actually look at them in person. Dobs are big. The more aperature you get the bigger they become. These are all things to consider. Lets be a bit honest here with the budget. 500 or so euro isnt really that much. It might get you a 8 inch dob, which is a decent starter scope, some call them lifetime scopes and they certainly can be. But the scope is just the initial outlay. Next comes the accessories and that is really where the money spending starts.

Aperture is king only if your budget is big enough to buy a mount that can support all that weight. In all other cases, go for small high-quality refractors like a SharpStar or Redcat that can be supported by a reasonably priced mount. Doing astrophotography with 20" optics on an EQ mount will require a mount that costs 10K to 20K, I am guessing. My Losmandy G11 is struggling with a 12" Newt astrograph already.

Tom Osypowski has made some inroads to AP for large Dobs with his very nice dual axis, auto-guidable equatorial platforms. These platforms can easily cost 3K though, and doing AP with it is not trivial, I think. There are some people who got excellent results, but most are not as nice as what you can get with regular EQ mounts with smaller optics. If you can afford a PlaneWave mount you would get better results but now we're talking about 100K total or so for a complete system that includes an observatory as a necessary feature.

With a budget of 500 bucks i would opt for a used dob everytime as long as he can transport it. Sure he can buy a small frac but unless he goes AP with it (even more money) what can you really see in the deep sky, which is where he specifically mentioned with a small frac? This is why the suggestion of go look at them before you buy anything is so much more important then any recommendations we could possibly give him

[Jnicholes]

Thank you Bigzmey very much for that suggestion i couldnt find it my self, it seems nice and the cost in this link you sent me is 467 and with the shipping goes to 500 and is actually really good price from what i found in my general reaserch. I will think about it if 100E worth to buy a new one. But the truth is i dont know what are the main defferences beetween those two dobs ''SΚΥWΑΤCΗΕR Dobsonian 8 PYREX" ( https://planitario.gr/gr/dobsonian-8-pyrex.html) and ''Bresser Messier 8" Dobsonian'' (https://www.teleskop-express.de/shop/pr ... cuser.html). Why the newone is better? Its something that it will make any defference? Thank you in advance!!

Hello, and welcome to TSS!

I agree with everything everyone else has said. One small piece of advice, though. Don’t be discouraged if you can’t find a DSO or seeing it is not what you expect. When I first started doing astronomy, I struggled to find certain DSOs, particularly M57, the Ring Nebula. Some nights I would get discouraged I couldn’t find it with my telescope at the time, which was a 10” dobsonian. Eventually I found it years after I first started astronomy with a computerized 80mm refractor. In fact, I got a picture of it through the telescope on June 25, 2021.

It can be hard to find objects sometimes, so don’t be discouraged if you can’t find anything at first.

Let us know if you need any help with anything else. This is a good place for astronomers.

Regards,

Jared

[Thefatkitty]

Hi Ethan, and welcome to TSS!

I too would go with a 6-8 inch dob. I had a Skywatcher 8" for almost 20 years, and sold it for another purchase. I shouldn't have done that....

Either scope will show you a lot, and to me is the best bang for your buck.

You will have to learn about "collimating", but it's really not difficult. The site that taught me all about doing that to an f/8 4.5" (easy) to an f/4.5 10" (not as easy). All it takes is patience and the desire.

The site is here: https://www.astro-baby.com/astrobaby/he ... reflector/ Best guide ever!


And you can sort of do AP with it, in an afocal sort of way

If you don't know, afocal is just focusing your scope for visual, and holding a camera/cellphone to the eyepiece and hoping for the best!

I took this pic with a 1.2MP digital camera with my 8" and the stock 25mm lens back in 2002:

These are from 2010 with the same lens, just a better 12MP point and shoot camera

Venus, Mars, Jupiter and Saturn:

The 2010 Dec 21st Lunar eclipse was also a target with all this in the -9C (16F) temps starting at about 2:30AM. You need to let your scope sit out for a bit to acclimatize!

And if the local "rag" publishes your shot, it really proves what you can do by just having some fun

I'd say get a 6-8 dob; you'll be amazed at what you can see/do with it!


Hope this helps in your decision, a big keep it simple here.

All the best,

[Richard]

As other have mentioned a dobs 8 is the one to get , bet used to it , will show a lot depending on where you live

[Kilohertz]

Hi Ethan,

Even though I too am a (modern) newb, I have started to collect various scopes and accessories, still waiting for things to arrive but my first acquisition was a used Sky-Watcher Dob 8" that needed focuser repair, which I did, and a good mirror cleaning and last night I made my first images with it. It was a snap to setup and I used a T mount to M4/3 adapter for my Lumix G7 camera which screwed directly to the focuser tube. It was just a matter setting the exposure and delaying the shutter to allow the scope to settle. After a few lunar shots, Jupiter seemed a likely second target as it was close by and very bright. I was amazed to see 4 moons of Jupiter jump out on the camera display, COOL! These are right out of the camera, no photoshop, which I still need to do.

Have fun!

Cheers

ps I haven't figured out how to post correct image rotation on this site yet