What have you seen in a 5" Refractor, that you've not seen in an 8" newt?

[Flame Nebula]

The title says it all. 

Curious to know, on same night, same target, have you seen something in the refractor, you couldn't see in the larger reflector. 

Thanks 

Mark 

[dweller25]

Perhaps the question should be the other way around ?

[Telescope40]

52 minutes ago, dweller25 said:

Perhaps the question should be the other way around ?

Correct. I have a 5in frac BTW 👍

[wesdon1]

2 hours ago, Flame Nebula said:

The title says it all. 

Curious to know, on same night, same target, have you seen something in the refractor, you couldn't see in the larger reflector. 

Thanks 

Mark 

@Flame Nebula I think this Q should be reversed, but in my experience I've seen more DSO's in my 8" Newt. Reflector than my 5 inch Refractor ( well, 120mm Refractor, so not quite 127mm, but the difference is negligible ) You also have to bear in mind than the two different optical systems have strengths and weaknesses on both sides, it all depends what you're looking at, for example SSO or DSO. 

Hope this sort of helps you understand my friend.

Regards, Wes.

[bosun21]

Nothing.

[Gonariu]

I read some time ago that a 12-13 cm long focus achromatic refractor is equivalent to an 8" SCT on the Moon & planets; clearly in the deep sky and on double stars it is superior (1" versus 0.6"). In general, a reflector of diameter d and obstruction α is equivalent to a long focus achromatic refractor whose doublet diameter is D = d - α

[Flame Nebula]

2 hours ago, dweller25 said:

Perhaps the question should be the other way around ?

No, it's deliberate. 😉

[dweller25]

8 minutes ago, Flame Nebula said:

No, it's deliberate. 😉

Which implies you already know the answer, so I wonder why you asked ?

[Flame Nebula]

5 minutes ago, dweller25 said:

Which implies you already know the answer, so I wonder why you asked ?

It doesn't imply anything. I asked, because I wanted to know from anyone who has seen something. Maybe, due to better contrast perhaps? If you don't have specific experience of this, that's fine,isn't it. 

[MartianHill]

“What have you seen in a 5" Refractor, that you've not seen in an 8" newt?”
 

Nothing - the 5” refractor was an APO triplet.

Edited April 18 by MartianHill

[Elp]

I think the resolution and increased light gathering of the newt will trump the refractor, so I don't think you can have it questioned in this way as technically you should be able to see more with the Newtonian.

A question though as I've never looked through a larger than 6 inch scope, the larger the aperture and hence increased focal lengths don't the stars get ever so slightly bigger even by a minute amount so seeing also becomes more of an issue, I see it when I image as the larger scopes have larger star FWHM when fine focusing. The short FL camera lenses create the tiniest stars. This would part explain why I find my Z61 refractor incredibly sharp even if say Jupiter is tiny, the bands which can be resolved are tight, almost as if you're looking at it on a high quality, high resolution OLED screen, that's what it looks like visually.

 

Edited April 18 by Elp

[Flame Nebula]

1 hour ago, Elp said:

I think the resolution and increased light gathering of the newt will trump the refractor, so I don't think you can have it questioned in this way as technically you should be able to see more with the Newtonian.

A question though as I've never looked through a larger than 6 inch scope, the larger the aperture and hence increased focal lengths don't the stars get ever so slightly bigger even by a minute amount so seeing also becomes more of an issue, I see it when I image as the larger scopes have larger star FWHM when fine focusing. The short FL camera lenses create the tiniest stars. This would part explain why I find my Z61 refractor incredibly sharp even if say Jupiter is tiny, the bands which can be resolved are tight, almost as if you're looking at it on a high quality, high resolution OLED screen, that's what it looks like visually.

 

Thanks Elp, 

Interesting point about stars. I wondered if perhaps the diffraction spikes in the 8" newt might cause issues with say uneven doubles like Sirius, compared to the refractor? 

 

[Elp]

I don't think it's an issue when doing visual

[IB20]

Probably nothing but I prefer refractor views for most targets. DSOs and planetary nebulae are what I find the big newts excel on. 

 

[John]

10 minutes ago, IB20 said:

Probably nothing but I prefer refractor views for most targets. DSOs and planetary nebulae are what I find the big newts excel on. 

 

Yep. Thats where I am on this I think 👍

[IB20]

Just to qualify my statement, I’ll try and get round to observing some targets with the 5” that, from memory, really impressed me in the 8”.

Blue snowball nebula

M5

M51

Sombrero Galaxy (M104)

Hopefully in less moon affected skies than last night. Although I was quite chuffed making out two very faint smears of m65 and m66 in the 5”. I’ve struggled to see those with the 8” in bright moonlit skies.

 

[Elp]

Just replying to another thread saw this, but it's an imaging comparison so mileage will vary but generally shows the consensus:

https://youtu.be/U1G7wLNuesw?si=opzGjoHSG1pZgXOm

[Flame Nebula]

36 minutes ago, IB20 said:

Just to qualify my statement, I’ll try and get round to observing some targets with the 5” that, from memory, really impressed me in the 8”.

Blue snowball nebula

M5

M51

Sombrero Galaxy (M104)

Hopefully in less moon affected skies than last night. Although I was quite chuffed making out two very faint smears of m65 and m66 in the 5”. I’ve struggled to see those with the 8” in bright moonlit skies.

 

Hi IB20, 

Yes, that would be interesting. 👍

[John]

19 minutes ago, Elp said:

Just replying to another thread saw this, but it's an imaging comparison so mileage will vary but generally shows the consensus:

https://youtu.be/U1G7wLNuesw?si=opzGjoHSG1pZgXOm

Thats interesting.

I'm not an imager of any sort but when I look at the stills of the moon in the side by side comparison, from the perspective of a visual observer, I see pretty equal resolution and sharpness but the contrast between the lighter and darker areas on the surface seems more enhanced in the refractor. 

Whether that would be replicated in purely visual use, I don't know though.

 

[Elp]

From my view I think it's clear the newt shows more detail (IE resolution). Another thing to note, my Z61 is tiny but I can comfortably look at the moon unfiltered, when I tried it in my 130pds the light was blinding, so a testament to the difference of light gathering capability as aperture goes up. Note the camera capture will have had short exposures so that surface detail and contrast is well controlled, visually it will be much brighter.

[Flame Nebula]

28 minutes ago, Elp said:

Just replying to another thread saw this, but it's an imaging comparison so mileage will vary but generally shows the consensus:

https://youtu.be/U1G7wLNuesw?si=opzGjoHSG1pZgXOm

Interestingly, I found myself liking one more than the other then vice versa. I think the 200p was sharper, as one might expect with stacking, but in terms of light and dark areas, both were nice. I'd be happy with either. The refractor did very well considering the aperture difference. 

[JeremyS]

…images free from spikes.

[mikeDnight]

Better planetary definition. Never seen an 8"  Newtonian give sharper views than a good 5" refractor. 

[Flame Nebula]

3 minutes ago, mikeDnight said:

Better planetary definition. Never seen an 8"  Newtonian give sharper views than a good 5" refractor. 

Thanks Mike. 

[IB20]

Diffraction spikes on Jupiter really annoy me. Too much brightness also washes out planetary feature and colour detail to my eyes. I also think events like Galilean moon eclipses and transits particularly ingress and egress appear much better in refractors.