Magnification of 45X or 60X. (2 Viewers)

[albatrosviajero]

Hello,

I am a question, which is the maximun magnification more usual for birdwatching ,45X or 60X...?

Paul

 

[Neil]

30x

 

[Guizotia]

I've heard it said that over 40x you don't get any more detail, just a bigger image. I don't have a source for that. but worth checking out if it's true or not.

 

[SteveClifton]

I've heard it said that over 40x you don't get any more detail, just a bigger image. I don't have a source for that. but worth checking out if it's true or not.

With respect, I don't think there's much truth in this statement. It does, however, depend on a number of factors, in particular:

The quality of the optics in the scope-in cheap/mid range scopes the above statement might very well be true.

The visual acuity of individual people's eyes-some people can see more detail at 30x than others, all things being otherwise equal with the scope and eyepiece involved, and assuming you are using a sharp, high quality scope. Personally I have a a 20-60x zoom on my Swarovski, and use it mostly at powers between 30-60x (when the apparent fov is also wider than at 20x)

I used a 30x wide angle for 15 years on my previous scope, and didn't realize I was missing anything until I had a look through a better scope. It still baffles me why most manufacturers, even of the best fieldscopes, still limit the max power of their zooms to 60x. Some of the latest ones such as the Kowa 883/4 are easily capable of yielding better resolution up to at least 90x or more, if suitable eyepieces were available.

I have a Televue 5mm eyepiece that gives 92x on my 80mm scope. The detail at this power is slightly better than 60x, but not dramatically, but it certainly is better than at 45x. I would say that around 50-60x is the sweet spot for gaining the best detail, balanced with ease of viewing, depth of focus and increased tripod shake at high powers.

Steve

 

[Flemingo]

I never see any mention of the users visual acuity. If you have poor visual acuity you will benefit from a higher degree of magnification than someone with good acuity. The resolution of a scope is fixed. Once the magnification results in this angular resolution equaling the angle of your visual resolution any further magnification just enlarges the image, dims it, reduces FOV and increases apparent vibration.

Although the resolution of a scope is theoretically dependent on the size of the objective lens other factors in design will come into play. To calculate the maximum usable magnification you need to measure the the actual resolution of a given scope and your own eyes and divide the former into the latter. Thus the higher the resolution of the telescope and the poorer the resolution of your eyes the higher the useful manification. (Under ideal conditions which are rarely present when sitting on top of a cliff with a gale blowing!) In the real world you try the scope out with different magnification eye pieces!

 

[SteveClifton]

David, sorry but I don't fully understand your post. Were you agreeing or disagreeing with my comments, or just offereing further explanation?

From my personal experience, when viewing with the same scope side by side, one with say a 20x or 30x fixed eyepiece, and the other with a zoom at 50 or 60x, I find it easier to see more detail with more magnification, and am happier seeing a bigger image in the viewfinder, regardless of the trade-off with respect to brightness, image shake etc.

Theoretical explanations are all well and good, but I prefer to make decisions based on what my own eyes tell me. Without the possibility of zooming in, I always feel that I'm missing out.

By contrast, I have birding friends who prefer a 20x or 30x wide angle, and seem to miss little compared to what I see with my zoom. I suppose to a certain extent my eyes are 'happier' with, and expect to see the bigger image because that is what I almost always use. It just doesn't feel right any more with a lower power EP, but I suppose I could re-adjust if I were forced to.

Steve

 

[Flemingo]

David, sorry but I don't fully understand your post. Were you agreeing or disagreeing with my comments, or just offereing further explanation?


Steve

I don't really understand me either! I think what I really meant to say was the optimum magnification depends on the telescope body (objective lens size amongst many things), the person using it (including their visual acuity) and the conditions its used in. To quote me:

"In the real world you try the scope out with different magnification eye pieces! "

To that end I have just spent an hour trying to convince myself that I can see more detail with a 30x versus a 20x eyepiece on my 80mm scope. And I believe I can (in ideal conditions-indoors), but only just! I generally use the 20xWW and the 30xWW has sat in a draw for along time but as I am doing a little more sea watching I thought I'd try it out again.

 

[Pinewood]

Hello Paul,

I wrote the following to a friend, two days ago:

The limiting factors for magnification include the tripod and environment. When the sun heats the ground and creates waves, anything over 40x deteriorates. So you should be buying something which your current tripod can handle.

The higher the magnification, the steadier and more substantial must the tripod be. I chose a 30x for my 'scope.

Happy bird watching,
Arthur Pinewood

 

[Kevin Conville]

Steve's obviously a fan of high mag. That doesn't make him right, or wrong.

In my neck of the woods I have little or no use for powers of 60x or more. The seeing (conditions) rarely support it. Some good points have been made (I think) about visual acuity and the role it might play in determining one's preference for high mag

There are certainly a lot of variables and only a couple of constants regarding this topic. One more variable I'd like to mention is distance. Using 60x or 75x at say, 75 yards is quite different from using it to compress the distance of a half mile. The amount of atmosphere and shimmer, and therefore seeing, are potentially quite different.

 

[Flemingo]

Some good points have been made (I think) about visual acuity and the role it might play in determining one's preference for high mag

I'm glad my explanation is obscure enough to warrant and "I think". :-O

 

[DRodrigues]

I add that is also important which type of birding you will do. If you want to also cr-birding power matters!!! Have a look at cr-telescopes on http://pt-ducks.naturlink.pt/

David

 

[Kevin Conville]

I'm glad my explanation is obscure enough to warrant and "I think". :-O

The emphasis should be on "I" and not "think", as in I think.

Your writing was fine |;|

 

[Fernando np]

As Steve, sometimes I use 5mmTV Radian for getting the 100X. In good conditions, it has shown enough discrimination power to get identification of birds, giving details wich were invisible at 60X, even through the Kowa 88. I forgot to say I use a Diascope 85. I'm sure 100X in the big Kowa would performance even better. But comming to the question with started this topic, YES 60 POWER ARE FULLY USABLE whith good optics and cooperative atmosphere. Even the Swarovski 65 can bear the 60X in the zoom with good light wich is unnusual in it's size. With 2" eyepieces the option of wide field ones doesn't feel with the same urgency than in the past. For "niche" employ other option different than the zoom 20-60 would be more interesting.

 

[Jim M.]

YES 60 POWER ARE FULLY USABLE whith good optics and cooperative atmosphere.

Fully agree. I make good use of 60x on my Kowa 883 almost every time I go out birding.

Best,
Jim

 

[pluvanut]

Hello,

I am a question, which is the maximun magnification more usual for birdwatching ,45X or 60X...?

Paul

Defer to greater knowledge of some of detail contributors abiove, but in my experience, "dim out" prevents any gain above 45x for 60mm-ish scopes.
You need 80mm-ish for real benefit of 60x.
If your budget is average (say, up to £1000), above holds true.
No doubt all of this will change with improving optics, but that depends on whether you are wealthy and worried enough to go chasing the optical cutting edge.
Personally, I would rather go birding.
I use 30xw/60mm - only eyepiece I have and so far unconvinced of any benefit to change.

Paul