# Thread: GSO 42mm Superview vs. Orion Q70 32mm

1. ## GSO 42mm Superview vs. Orion Q70 32mm

The 42mm GSO has been tested to be 53 degree. The 32mm Orion Q70 is a 70 degree. I will be using a 120mm f/8 refractor 1000mm. Which of the two will give me a wider view? I like the superview, because it is 4 ounces less in weight.

2. ## Re: GSO 42mm Superview vs. Orion Q70 32mm

How did you come up with 53°AFOV? It is listed as a 65°AFOV and though they are sometimes 1-2° outside spec, that is a very large difference.
Using the numbers you posted the FOV is 2.3° for both eyepieces.

N.A.A. Telescope Math Calculator

3. ## Re: GSO 42mm Superview vs. Orion Q70 32mm

How did you come up with 53°AFOV? It is listed as a 65°AFOV and though they are sometimes 1-2° outside spec, that is a very large difference. Using the numbers you posted the FOV is 2.3° for both eyepieces.

A reviewer/purchaser did a test that showed 53 degrees. Another reviewer/purchaser test showed 54 degrees.

4. ## Re: GSO 42mm Superview vs. Orion Q70 32mm

Can you post a link to those reviews?

5. ## Re: GSO 42mm Superview vs. Orion Q70 32mm

Originally Posted by Gabby76
Can you post a link to those reviews?
Size of the diagonal issue.

6. ## Re: GSO 42mm Superview vs. Orion Q70 32mm

Well I am not sure what his issue with the diagonal was other than he may have been using a prism which typically has a smaller clear aperture compared to a mirror which has 48mm clear aperture for a 2" and 27-28mm for a 1.25"

7. ## Re: GSO 42mm Superview vs. Orion Q70 32mm

Based on what I know of the relevant equations ....

TFOV = AFOV/Magnification
TFOVmax = 57.3*FieldStop/FocalLength. (max tfov possible for a particular fieldstop).
MinimumOf(TFOV,TFOVmax) is what you want.

Scope 120mm/1000mm

 EP FS TFOV TFOVmax Min GSO 42/65 41.5 2.73 2.38 2.38 Q70 32/70 40.0 2.24 2.29 2.24

GSO does not list the FS, but it is 41.5mm (EP retaining ring) as per user reports.

You could also input your data (including FieldStop) in the Stellarium Ocular Plugin and check what they show.
It will give you a better feel of the difference.

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