Moving from 10x50’s to 8x42’s

[Scooot]

I’ve often read 10x50’s are the ideal binocular size providing a good balance of weight, aperture & magnification. I’ve had my 10x50’s for a long time now and they’ve given me some great views. However I’d often craved for a wider fov whilst scanning constellations, just a little bit extra to put the view into more context, so I recently bought some Victory 8x42’s with a 7.8° Fov.

I’ve now used them a handful of times & I’m really enjoying them. For such a relatively small difference in fov they provide a surprisingly different experience. I can’t quite see as many DSO’s, but I can still see the likes of M13, M15 & M38 (but not M36, so far anyway), or maybe the other way around. My light pollution made DSO’s quite difficult to see in my 10x50’s anyway, so I’ve come to enjoy the star clusters and patterns across the sky with binoculars. With this in mind  I can now see nearly all of Lyra, and more of some of the fainter constellations that are not visible to me naked eye, but with a good magnification and optical quality. It is much easier for example to pick out Delphinus and Equuleus and to hop between star groups whilst maintaining my bearings. M15 is easy to pinpoint as I can just triangulate from Enif & Delta Equ. Something new the other evening was the Circlet just South of Pegasus and whole head of Draco. I also had some stars visible in the same field as the full moon, I don’t remember this with the 10x50’s.

Although I haven’t had them long, I think 8x42’s are going to be much better for me than 10x50’s.

 

[ronin]

Strange but technically the 8x42's should be marginally brighter then the 10x50's. They are smaller aperture but the magnification is just such that the resultant image should be just a little brighter. Although a bit smaller in image size.

The rule was divide the aperture by the magnification and the bigger result is the brighter. 8x42's just win out. But there is the question of what is going on inside, however I would have expected that the 10x50's were if any the most likely to be reduced in aperture internally - a suitably placed internal baffle to reduce CA, stray light etc. Also the quality of the binoculars are a big factor.

 

[Stu]

4 minutes ago, ronin said:

The rule was divide the aperture by the magnification and the bigger result is the brighter.

This is the calculation for exit pupil so yes, it will give an indication of image brightness.

The 8x42s have a 5.25mm exit pupil vs 5mm for the 10x50s so will have a slightly brighter image, not much though.

I have some Barr & Stroud 8x42s and find them very nice. 8.2 degree fov and a nice compact unit to hand hold. They are both ED glass so do show some CA but at the lower power this is not so much of a problem.

[Scooot]

I haven’t had very dark skies yet so maybe that’s the difference, & Auriga is still not that high in the evening. Andromeda is certainly very nice  

The 10x50’s are the William Optics ED so very good optically as well but I didn’t compare them side by side on the same nights.

[Scooot]

Just had a bit more fun with the 8x42s. Conditions are very poor, the Sky is clear but very milky, can’t make out much with the naked eye so I’ve been lying back in a garden chair concentrating on cassiopeia. Using the square in the asterism “Cassiopeia’s Chair”, I could easily quickly get my bearings. I love the owl cluster in a scope so first looked for that. By placing Ruchbah, Navi & Shedar in left field it was easy to confirm the sighting. I could only see the two bright eyes of the owl, which looked like one star, but because of the overall view there was no mistaking it.

After this success I decided to try M103, so moving slightly down, and using similar tactics I placed Ruchbah and Segin in the same fov & low and behold there it was, exactly where it should be. A quite large faint dusty patch. What was even more surprising was I could also see Ngc 663, which was a larger dusty patch. I eventually confirmed this to myself by reference to the trail of 4 stars just above it. I really like these bins!  

 

[Sky-J]

On 15/10/2017 at 16:12, Scooot said:

I haven’t had very dark skies yet so maybe that’s the difference, & Auriga is still not that high in the evening. Andromeda is certainly very nice  

The 10x50’s are the William Optics ED so very good optically as well but I didn’t compare them side by side on the same nights.

Great topic/post, thanks!

Don't worry about Auriga, last summer I was round a friends house and she had a very old pair of 8 (or maybe 7) x 30's and we were easily able to make out the lovely Auriga run of Massiers 36, 37 & 38 along with a hint of IC405. I love this run of M's.

Also I recently bought a pair of 8x42 Celestron trailseeker bins and they're a joy to use on a clear night!

[Sky-J]

Slightly off topic, sorry, but can I ask what program or app you used for the screen grabs, this looks really interesting.

Thanks

Jeremy

[Scooot]

36 minutes ago, Sky-J said:

Slightly off topic, sorry, but can I ask what program or app you used for the screen grabs, this looks really interesting.

Thanks

Jeremy

Thanks for your comments

Its Sky Safari. A superb app. I'm using Sky Safari 5 Pro but all the versions are excellent.