Tento 20x60s

[F15Rules]

I recently sold my 10.5x70 Kunming BA8 binoculars..I really liked them but they were SO heavy and really I needed a bit more magnification to darken the sky background - I'm sure that in very dark skies the lower magnification would be fine. The images put up by the BA8s were very sharp in the central 60% or so but the sheer weight (2.5kg) made it virtually impossible to hold them manually for any meaningful length of time.

I decided I did want to stay with some astro bins for those (all too frequent) quick peeks between clouds or when time doesn't permit to get the fracs out. So I did some trawling/watching on ebay and found a really nice looking pair of 1980s Russian military spec 20x60s, branded Tento. I did quite a bit of research on the net and most of the reports were favourable regarding the optics, some very much so. Most criticisms I saw referred to the mechanics rather than the optics.

So I bit the bullet and bought these, mainly because they were claimed to be mint condition and ? never used.

They arrived safely and I have to say the packing by the seller was some of the best, most secure packaging I've ever seen for optics. It was like playing "pass the parcel" as layer after layer of bubble wrap and thick foam type material came off. Eventually I got to the business and a lovely black binocular case revealed itself, sure enough looking pretty much like new. The original paperwork suggests early 1980s manufacture and all the original caps, straps etc were present.

I opened it carefully and inside was a very attractive (to me, at least, I think all binos should be black, just as I think all refractors should be white LOL ) pair of new looking binoculars. They were very much lighter than the BA8s, approximately 1.4kg, and much easier to handhold. However, these chaps have a x20 magnification (some reviews suggest it's nearer x22) and so hand holding, whilst perfectly possible from a weight point of view, is not ideal for a steady view. But I knew that would be the case and a bonus was that the bins came with a tripod adapter which is neat but simple...it clamps around the central bridge bar that most older binos have, and is tightened up with a simple slot headed screw. The bottom of the adapter has a standard photo adapter thread and just screws into my tripod base. Incidentally, the odd looking tripod is made from a disco speaker stand which extends much higher than my 6ft height, and at the top is a little eq1 scope mount, which I have set up to be used in alt az mode, much better for binos. It means I can stand under the binos even at quite high elevations, in relative comfort.

As you will know, the skies have been rubbish just lately, but I have had a couple of very very short peeks and in daytime have had some very sharp views of a local tv aerial about 100m away which I often use to check out optics in daytime.

In common with most Russian bins, the Tentos have a slight yellowish tinge, but it's not intrusive to me and the main thing is that the on axis sharpness is stunning. Really, really sharp. The view starts to break down a bit from about 60% from the edge of the field, but that is common with most bins unless you spend silly money. The mechanics are ok - not as uber smooth, as Zeiss Jenoptems for example, but perfectly functional. The right hand diopter has independent focussing which is slightly too "loose" for my liking, but works fine. 

I did notice that with the rubber eyepiece cups folded out (as they need to be for the eyepiece covers to fit), the field is quite restricted. The actual field is claimed to be a respectable 3.3degrees, and in fact I can quite believe that this is the case once you fold back the eyepiece covers - it really does make a big difference. Eyerelief is fine for me, but would be tight if I wore specs to view - thankfully I don't as yet.

I did notice, when the eyecups were folded back, some distortion at the very edge of the field...I suspected it was something on the eyepiece lenses so I carefully disassembled them indoors, and sure enough, there was some thick, greasy "gunk" of a brownish colour which had got onto the very edges of the eps. I carefully cleaned the top lenses (its a doublet I think) with Baader Wonder Fluid and it made all the difference, the view is very sharp to the edge of a nice sized field now. No chromatic aberration noted anywhere in the field.

I attach a few pictures for your interest, including one which is a view of the distant aerial (which you can't really see on the first pic), then a picture of the aerial through the bins (bear in mind I simply took this on my Android phone through the right hand side eyepiece). One one of the other photos you can perhaps see some of the "gunk" on the edge of the eyepiece glass, I took the picture before cleaning them. All lenses came with well fitting plastic caps and good quality strap. The pictures show the eyepieces with their rubber caps folded back to maximise the visible field.

So far, I'm very happy with these Russian bins and really look forward to looking at the Moon, Jupiter and some clusters when conditions allow.

To allow for handheld viewing sessions, I've supplemented the Tentos with an absolutely mint set of "aus Jena" Jenoptems 7x50 (identical to Zeiss branded) and these will be subject to another short review when I've had a chance to try them out properly. This pair is literally, I kid you not, like new, and I think are of 1983 vintage.

Thanks for reading

Dave

[Peter Drew]

I've had a couple of these in the past, very nice optics, well worth looking out for secondhand. They also did a monocular with objectives interchangeable between 40mm and 60mm. 

[nightfisher]

They look to have lovely clear optics, maybe i should look for a set and put them on the skytee when i get it

[F15Rules]

Hi Jules, based on this pair I'd say "go for it!"..the extra mag really improves the contrast and real detail is visible vs x10-15 magnification..

Dave

[Fahndar]

I have Tento 20x60 as well as Tento 7x50 and 16x50. They are at least 25 years old but are very rugged, all metal body. 20x60 are the sharpest binoculars I own. I expect that only Helios Apollo series will beat them. You owned 10.5x70, how does their sharpness compared to 20x60? I wear glasses and the eye relief is a bit too short. Since I owned bigger binoculars, I don't really use them much, just sometimes to test LM. Even though they are sharp, my 20x80 are my preferred grab and go now, hand-held with no problems. The weight is actually helps to help them steady, not the other way around, of course if you can manage that weight. At 4.7 pounds my 20x80 feels like a toy after I handle 25x100 (10.1 pounds). I am surrently planning to buy a tripod for 25x100. I drilled a hole in the central hinge of 20x60 and threaded it, unfortunately this was when I used metric tripod.

[F15Rules]

I agree that the eye relief is a little tight, abd to see the full field you do need to fold back the eyecups (by the way the FOV is 3.55Deg not 3.3).

I think the Tentos are every bit as sharp as the BA8s, but the sky background is much darker due to the increased magnification, so the impression is of seeing more stars. I got a glimpse of the Double cluster last night between the clouds and it was truly stunning.

Dave

[Naplesnut]

I recently sold my 10.5x70 Kunming BA8 binoculars..I really liked them but they were SO heavy and really I needed a bit more magnification to darken the sky background - I'm sure that in very dark skies the lower magnification would be fine. The images put up by the BA8s were very sharp in the central 60% or so but the sheer weight (2.5kg) made it virtually impossible to hold them manually for any meaningful length of time.

I decided I did want to stay with some astro bins for those (all too frequent) quick peeks between clouds or when time doesn't permit to get the fracs out. So I did some trawling/watching on ebay and found a really nice looking pair of 1980s Russian military spec 20x60s, branded Tento. I did quite a bit of research on the net and most of the reports were favourable regarding the optics, some very much so. Most criticisms I saw referred to the mechanics rather than the optics.

So I bit the bullet and bought these, mainly because they were claimed to be mint condition and ? never used.

They arrived safely and I have to say the packing by the seller was some of the best, most secure packaging I've ever seen for optics. It was like playing "pass the parcel" as layer after layer of bubble wrap and thick foam type material came off. Eventually I got to the business and a lovely black binocular case revealed itself, sure enough looking pretty much like new. The original paperwork suggests early 1980s manufacture and all the original caps, straps etc were present.

I opened it carefully and inside was a very attractive (to me, at least, I think all binos should be black, just as I think all refractors should be white LOL ) pair of new looking binoculars. They were very much lighter than the BA8s, approximately 1.4kg, and much easier to handhold. However, these chaps have a x20 magnification (some reviews suggest it's nearer x22) and so hand holding, whilst perfectly possible from a weight point of view, is not ideal for a steady view. But I knew that would be the case and a bonus was that the bins came with a tripod adapter which is neat but simple...it clamps around the central bridge bar that most older binos have, and is tightened up with a simple slot headed screw. The bottom of the adapter has a standard photo adapter thread and just screws into my tripod base. Incidentally, the odd looking tripod is made from a disco speaker stand which extends much higher than my 6ft height, and at the top is a little eq1 scope mount, which I have set up to be used in alt az mode, much better for binos. It means I can stand under the binos even at quite high elevations, in relative comfort.

As you will know, the skies have been rubbish just lately, but I have had a couple of very very short peeks and in daytime have had some very sharp views of a local tv aerial about 100m away which I often use to check out optics in daytime.

In common with most Russian bins, the Tentos have a slight yellowish tinge, but it's not intrusive to me and the main thing is that the on axis sharpness is stunning. Really, really sharp. The view starts to break down a bit from about 60% from the edge of the field, but that is common with most bins unless you spend silly money. The mechanics are ok - not as uber smooth, as Zeiss Jenoptems for example, but perfectly functional. The right hand diopter has independent focussing which is slightly too "loose" for my liking, but works fine. 

I did notice that with the rubber eyepiece cups folded out (as they need to be for the eyepiece covers to fit), the field is quite restricted. The actual field is claimed to be a respectable 3.3degrees, and in fact I can quite believe that this is the case once you fold back the eyepiece covers - it really does make a big difference. Eyerelief is fine for me, but would be tight if I wore specs to view - thankfully I don't as yet.

I did notice, when the eyecups were folded back, some distortion at the very edge of the field...I suspected it was something on the eyepiece lenses so I carefully disassembled them indoors, and sure enough, there was some thick, greasy "gunk" of a brownish colour which had got onto the very edges of the eps. I carefully cleaned the top lenses (its a doublet I think) with Baader Wonder Fluid and it made all the difference, the view is very sharp to the edge of a nice sized field now. No chromatic aberration noted anywhere in the field.

I attach a few pictures for your interest, including one which is a view of the distant aerial (which you can't really see on the first pic), then a picture of the aerial through the bins (bear in mind I simply took this on my Android phone through the right hand side eyepiece). One one of the other photos you can perhaps see some of the "gunk" on the edge of the eyepiece glass, I took the picture before cleaning them. All lenses came with well fitting plastic caps and good quality strap. The pictures show the eyepieces with their rubber caps folded back to maximise the visible field.

So far, I'm very happy with these Russian bins and really look forward to looking at the Moon, Jupiter and some clusters when conditions allow.

To allow for handheld viewing sessions, I've supplemented the Tentos with an absolutely mint set of "aus Jena" Jenoptems 7x50 (identical to Zeiss branded) and these will be subject to another short review when I've had a chance to try them out properly. This pair is literally, I kid you not, like new, and I think are of 1983 vintage.

Thanks for reading

Dave

Dear Mr Tinning

I sold a 10x50 pair on ABS that had a specific serial number. I regarded these better than the £250 to buy those ridiculous astrobins of 20x100. The tento came with yellow filters to improve visual acuity. I sold them for £50 so the buyer got a good deal

atb stu

[F15Rules]

Sounds as though someone got a bargain..I paid £110 posted and consider them a good buy in exceptional condition.

Dave

[Merlin]

I use my 20X60 TENTO's on a homemade binocular mirror-mount. The first-surface mirror is a precision ex-military one and deserving of the bins.

[F15Rules]

Hi Merlin,

That's interesting, got any pictures you can post up?

What's your opinion of these binos, good and/or bad?

cheers

Dave

[Fahndar]

I have not noticed any yellow color. The coatings are good, and are light-blue. No CA on Jupiter. Jupiter is a perfect sphere both in Tento 20x60 and 16x50. The background is very dark both in 16x50 and 20x60, and exit pupil is only 3 mm, which is good at light polluted sites. Even then I prefer my 20x80 Orion binoculars as the increased size trumps the better sharpness of the smaller bins. I rather see stars down to 10.7 mag in 20x80 than very sharp stars but only to 9.6.

[Fahndar]

Another question I would like to ask, what is the minimum separation your eyes can see? I measured my right eye down to 5', but my left eye only down to 7.5'. I use binoculars and different double stars sets to measure that. For example 61 Cygni has the separation of 30" so in 20x80 it will be 10', in 15x70 it becomes 7.5" and in 7x5- it is 3.5'. At the same time I was able to see features on the moon down to 3.5'  Go figure.