Newt or refractor

[Karlzburg]

What is better for imaging with a dslr ( for now ), a newtonian reflector say 8 inch or an 80mm refractor? Would like to hear opinions.
Cheers
Karl

[ChrisV]

Easy to answer. I've got both !


80mm refractor is easier though ... shorter focal length (my refractor and newt are 470 and 1000mm) and less fiddle with the refractor. No collimation and quick to set up. More time to worry about other things that go wrong !!!

[Karlzburg]

Thanks for that Chris. Does the refractor handle a barlow well with imaging

[Lee]

Start with the refractor for imaging, everyone must have an ED80 somewhere? Use the newt for visual. When you are ready for some punishment, grab a cheap f/4 newt and image with that.... :)

[Karlzburg]

I've got a f5 Newt now

[glend]

Use what you have. There is a learning curve with imaging, and a lot of it has to do with processing. Most folks start with a DSLR. Btw, not all newts are setup for imaging, if it is a visual Newt the camera may not reach focus. An imaging newt is preferred as they are designed for camera focal lengths, and usually require extension tubes to focus some eye pieces if used visually.

[Karlzburg]

I add the t- mount and with a 1 1/4 inch tube thingo and put into the focuser and focus is great. If I want to visual I need a 55mm extension tube.

[mental4astro]

I too say start with what you have. Don't worry about corrector this or flattner that. Get going and the learning curve will address everything in time and turn. You have a little Vixen Newt that is made for imaging - GREAT! You won't gain anything more or less than with a refractor. Ok, there's collimation, but big deal! It is easy to solve :)

Alex.

[speach]

If I had the cash I go for 150mm refactor

[silv]

This Field-of-View-calculator could factor into the decision, too.
https://astronomy.tools/calculators/field_of_view/

F5 newt from as small as 130/150mm upwards is great for DSO. The EQ-mount has to be stable enough to support the weight. With newts you get more mm per kg than with refractors.
Tube and focusser need to be able to handle the weight of you camera, as well, so I'd rather not buy a cheap 80mm refractor if you plan to dangle a heavy Canon from its end.

[cometcatcher]

Simple decision then. Use the F5 Newt. It will probably flog any smaller refractor anyway.

[raymo]

Following on from Kevin's remark, here's a single frame of 40secs taken
with my 8"SW f/5 Newt on HEQ5, unguided, Canon 1100D. Try that with an 80mm refractor.
It's not a quality image, but it shows what you can get with just a single shortish exposure with an 8" scope.
Best viewed at about 75% screen.
raymo

[Startrek]

I totally agree with Raymo and Kevin as well
I have a 6” f6 Bintel GSO reflector on a HEQ5 mount unguided
and have captured some great images this year with up to 60 second exposures
I’m using my wife’s old stock canon 600D no adapters needed reaches focus perfectly
Here’s my single image of Eta Carinae Nebula ISO1600 with a 60 sec exposure
By the way my 6” newt only cost me $299

[Karlzburg]

Thank you all for the advice. I had the Newt out the other night and sorted out the camera and focusing with it. A single shot at Alpha Cent was crystal clear, I couldn't see any coma at the edges

[xelasnave]

Hi Karl
I love my 80mm but the eight inch is all over it really...in my opinion.

The 80 mm is easy to handle etc etc but bang for the buck you cant go past the eight.

I went f5 over a f4 and I think such a choice is forgiving.

I have not adjusted the eight yet, I keep meaning too but it is acceptable for me at the moment.

And although I went with a coma corrector first up I am not sure that I needed it.

I am trying to set up the zwo now...and just realised the optical train has no coma corrector...so it will be interesting to see how that goes.

Five hundred for a big newt or two grand for a 80 mm ...start with the newt.
Alex

[raymo]

Sorry for the minor hijack, but Alex you'll find a significant improvement
with a coma corrector.
raymo

[jimmyh1555]

What's the difference between a big Newt or a small refractor? I find the smaller one is easier to set up, and doesn't vibrate so much in wind. Do you have to take longer exposures with a small refractor? An 8 inch Newt has 7 times the light-gathering power of a 3 inch refractor - does that mean you have to have 7 times the exposure with the smaller scope:shrug:

[cometcatcher]

With that 7 times, you also have to factor in focal length. The big Newt gives you more focal length and a fast F ratio. Focal ratio is what it's all about. Focal ratio = focal length / diameter of the objective. Your typical ED80 has 80mm objective with 600mm focal length. So 600 / 80 = F7.5. A typical 8" F5 is 1000mm FL / 200 (diameter) = F5. So the big fat Newt has both a longer focal length AND a faster F ratio.

If we even it out and make the focal length of the ED80 1000mm, the same as the 8" F5 Newt, the ED80 would have a focal ratio of F12.5. Which is very slow photographically.

Bottom line, DSLR's like fast scopes, up to about F7. You can get away with slower focal ratios but you have to acquire enormous amounts of capture time to make up for it.

On the other hand, yes a little ED80 is so much easier to handle with vibration, tracking and wind etc. It's much more forgiving in that respect.

[jimmyh1555]

I actually have a 100mm Esprit f5.5, a Bintel 200mm Newt f4 and a XLT 150mm refractor f5
I am using the XLT150 and Bintel 200mm for planets with barlow, and Moon. This is because I can set them up on tripod with clock drive and exposures are all video files - very short exposures, so no problem with tracking.
For DSO's using a few long exposures (ie 30 - 90sec so far) I am using my concreted-in pier with HEQ5 Pro and 100mm Esprit with corrector. Unguided at moment, but experimenting with Synguider 2 .
Would there be any advantage in putting the Bintel 200mm f4 on the pier for DSO?
My cameras are all ZWO 224 or 183 colour. No DSLR. Advantage being imaging time, I guess, or will I get better resolution (crisper photos) with the Esprit?
Maybe the 150mm refractor will be better than the Esprit 100 as it is bigger?
DECISIONS.....DECISIONS AAAAAAAAGGGGGGGGHHHHHHH:eyepop:

[Lee]

There should be.... but.... if you search/read in the forums about fast newts and imaging you'll get a taste for the trials that await with collimation/tilt/flexure and collimation. Did I mention collimation? When the fast newts sing, they are brilliant and quick. Getting them singing is tricky.

[cometcatcher]

Is your 183mc the cooled version? It has very tiny pixels and would match the 100mm Esprit nicely. The 150mm achro will likely give unacceptable CA.

[jimmyh1555]

Yes, Cometcatcher, my 183 is the cooled colour version. So it looks like the Esprit 100 and the 183 are the way to go. I thought that must be the case, and the Esprit has the flattener, AND... I have got the filter box in the optical train too, so can experiment with the Baader Nebula filter, OIII and sulphur job. And later, I will have a go using my secret weapon, the 1600-MM and LRGB filters:D