Mars - barlow or cheap 2nd hand scope?

[rnobleeddy]

Still very new to this. Have a 130PDS and I'm finding my feet with DSOs when the clouds allow. Then I hear that mars is as close as it will be for the next 13 years and start to think that perhaps I should have a go at that.

 

In terms of camera, I just got a Canon 550D that I'm planning to mod myself, but that enables me to take videos. I also have  zwo 120mc I use as a guide cam.  The pixel pitch is roughly the same for them both.

The 130PDS seems like a non starter though. With 1.36" per pixel with the 550D, and Mars at maybe 25", that's not a lot of pixels. 

So question is: given a 2" 3x barlow is pretty expensive, would I be better off just paying a bit more for a cheap second hand OTA?

[alacant]

1 hour ago, rnobleeddy said:

2" 3x barlow

Hi

How about a 1.25" Barlow with your 120mc instead? That would work out far cheaper. Our 130 had a 2 to 1.25 adapter in the box but even if you don't have one, they're cheap enough items.

HTH.

[rnobleeddy]

1 hour ago, alacant said:

Hi

How about a 1.25" Barlow with your 120mc instead? That would work out far cheaper. Our 130 had a 2 to 1.25 adapter in the box but even if you don't have one, they're cheap enough items.

HTH.

Good shout. I'd actually assumed that I would use the Canon for some reason and only remembered the 120mc when I posted this. I have a 1.25" 2x  barlow already but could probably invest in a 3x as well. 

[Cosmic Geoff]

You should use the ASI120MC and the 2x barlow.  There is no point in using a DSLR for planetary imaging unless it is the only camera available. You do not need a large sensor for imaging a small dot.  As you say, it would be as well to have an x3 barlow (for use when conditions are good and to increase the image scale.)

If you want a better OTA, that means a bigger or longer Newtonian (which will probably overload your mount) or a 6" or 8" SCT (which will probably overload your budget).

[rnobleeddy]

3 hours ago, Cosmic Geoff said:

You should use the ASI120MC and the 2x barlow.  There is no point in using a DSLR for planetary imaging unless it is the only camera available. You do not need a large sensor for imaging a small dot.  As you say, it would be as well to have an x3 barlow (for use when conditions are good and to increase the image scale.)

If you want a better OTA, that means a bigger or longer Newtonian (which will probably overload your mount) or a 6" or 8" SCT (which will probably overload your budget).

Thanks. Does that apply to using a DSLR to record video? In either case, it makes sense to use the zwo with a 1.25" Barlow.

The thinking for the scope was a longer focal length would be better. I've recently got an EQ6 so should be ok for something bigger, but I expect I'll always be more interested in DSOs, and afaik, there's nothing that can be good at both?

[Cosmic Geoff]

11 minutes ago, rnobleeddy said:

Thanks. Does that apply to using a DSLR to record video? In either case, it makes sense to use the zwo with a 1.25" Barlow.

The thinking for the scope was a longer focal length would be better. I've recently got an EQ6 so should be ok for something bigger, but I expect I'll always be more interested in DSOs, and afaik, there's nothing that can be good at both?

With DSLRs, recording video is an afterthought, while recording high-speed video is the whole point of a planetary camera.

Planetary imaging - best with big SCT.

Deep space imaging - small high quality refractor (or a 130PDS) recommended.

[Alien 13]

I have used my DSLR with a 1.25 inch X2 barlow with both my scopes and although it does vignette a little it has no effect on planetary imaging. The frame rate with a DSLR will as said  be quite poor compared to a planetary camera but it does have a big advantage when trying to find the object (I struggle to get the Moon in the FOV sometimes ).

Alan

Edited October 7, 2020 by Alien 13

[rnobleeddy]

Thanks all.

Would I be correct to assume that a 5x barlow would be massive overkill given UK seeing conditions?

[johninderby]

5x barlows are pretty well only used by imagers. I’ve only needed a 2x barlow for visual use.

[nfotis]

A note: programs like Backyard EOS etc when shooting planetary imaging video, they capture the live view of the camera in approximately 5x zoom (they receive the video stream to the back screen directly).

This is approximately the same size as a planetary imaging camera (similar to ROI).

N.F.