Sample variation and testing of TSN-883 (1 Viewer)

[Regimeta]

I have owned my TSN-883 for a little over three years now and have been completely content with it. I bought it from an online retailer when I was really getting into birdwatching. I did not know about sample variation then and decided to order one new as I got a pretty good deal. Only now I stumbled across the terms "lemon" an "cherry" used here. I am not a huge optics buff and still have problems understanding some terms and abbreviations related to optics in English from time to time.

My question is, how much difference does the sample variation from a lemon to a cherry make to a typical birdwatcher? How can a bad sample affect the image when, for example, following a bird in flight with high magnification? Is the variation between samples more important in scopes compared to binoculars because of the higher magnification?
Does a typical birdwatcher buying optics even pay attention to these differences when making a purchase? How are tests even made if you were to buy optics from brick-and-mortar store? Either my sample is fairly good or I am blind enough to see the problems. Ignorance is bliss, I guess. Whether my scope is a good or a bad sample, I have never regretted the purchase, as it has provided me so much and got me more into the hobby.

If I were to test my optics out of curiousity, where should I start?

Riku

 

[Binastro]

Iltaa Riku,

You have been happy with your scope, so there is no reason to worry or even test it.

Essentially perfect scopes are rare.

With high magnifications there is more influence if the scope is sub standard.

But following a bird in flight your eyes will not be achieving their best resolution.

For static use, the observer's eyesight is important. This varies from person to person and with age.

For birdwatching, the atmosphere seems to be more important especially on hot or cold days with varying temperatures.

Viewing from an elevated position will avoid much of the poor atmosphere at ground level.

Finland often has very good Seeing conditions, especially over lakes, sea or trees.

What magnifications do you usually use?

Terveisin,
B.

 

[Binastro]

The quality of the curves of the optical elements and general manufacture has to be higher with a scope than with a binocular.

One of the main problems with binoculars is keeping both tubes very precisely aligned.

This is not a problem with a scope, although a scope can also be out of collimation, which shows up in star testing.

Regards,
B.

 

[Regimeta]

Thanks for the clarifications and answers Binastro.
I use the 25-60x eyepiece and mostly on the lower magnifications, if I had to guess. I do also own the 1.6x extender but use it rather rarely.

I guess there is no real reason for a test, as I have been happy with the scope. I guess I'm just trying to understand how much of a difference it makes to own either a good or a bad sample. Are these issues something a typical birdwatcher would pay attention to? I certainly didn't.

Riku

 

[Binastro]

Hi Riku,

At 25x or 40x there will not be much difference with an average Kowa 88m scope or a cherry, unless you have exceptionally good eyesight.

I doubt whether 5% of average birdwatchers star test their scope or binocular so long as they are happy with their instrument.

I used a 150mm Maksutov at 95x Suomessa and never had a problem with Seeing conditions day or night.

With a Pentax 100mm astro refractor I used 200x and 300x on planets.
An exceptionally good telescope.

Regards,
B.

 

[GrampaTom]

Hi Riku,

At 25x or 40x there will not be much difference with an average Kowa 88m scope or a cherry, unless you have exceptionally good eyesight.

I doubt whether 5% of average birdwatchers star test their scope or binocular so long as they are happy with their instrument.

I used a 150mm Maksutov at 95x Suomessa and never had a problem with Seeing conditions day or night.

With a Pentax 100mm astro refractor I used 200x and 300x on planets.
An exceptionally good telescope.

Regards,
B.

Im with Regimenta. Shopping for my first real birding scope, Im a bit overwhelmed with choices and variables. I have had the same question as he re lemons and cherries vis a vis what birders need. Spending time over here in
"Scopes and tripods" the conversation seems to wander, as yours did here, to "astro use" leaving us mere birders to wonder at the relevance?

 

[Binastro]

Astro use on planets is much more demanding and requires very good optics.

With lowish magnifications a good Kowa 88mm will probably not be very different to a cherry Kowa 88.

Trying to find a near perfect specimen might mean testing six or more scopes very carefully.

If a scope performs well enough, why try perhaps fruitlessly to find a better one?

In actual fact the Maksutov 150mm was good enough at 95x but would not take much higher magnifications.
But the views were really good at 95x.

Good observations do not need the very best optics.
They need optics good enough for the observation.

Regards,
B.

 

[henry link]

Lemons and cherries are at the extremes. Lemons are nearly useless at 60x and noticeably off even at 20x-30x. Cherries are sensibly perfect in the field center, limited only by the size of the aperture. There is a range of not good to pretty good between those extremes. If I'm paying a large sum I don't want anything but a cherry.

 

[GrampaTom]

Lemons and cherries are at the extremes. Lemons are nearly useless at 60x and noticeable off even at 20x-30x. Cherries are sensibly perfect in the field center, limited only by the size of the aperture. There is a range of not good to pretty good between those extremes. If I'm paying a large sum I don't want anything but a cherry.

Thanks Henry, so there is hope we mere birders can, with a bit of sampling, detect a quality difference that matters…. Relative to what I guess is our much less demanding application? That is hopeful.

 

[SUPPRESSOR]

Look out for the new Kowa 88s a refined new scope with the 99 style, etc.

 

[andy79]

As already said in previous comments, high magnifications show when and how things brake down.
I tend to use my 883 with high mags, I often keep both 1.6x extenders on.
Most often, atmosphere limits the terrestrial views, than lens imperfections at 153x. But this is a way you can detect weaknesses if you want to get down that route.
It is not the optimal tool for astro, and stars are not perfectly pinpoint at 153x on my copy, but the amout light it captures and stars you can see compared to the naked eye, the look of the Moon, Saturn and Jupiter are just awesome. These are a great bonus to the 80% terrestrial look I use them for.
In short, this is a great instrument, whose limits you can still push, so enjoy.