Big bins

[+seven_legs]

Hi all

As much as I love my 14" dob I was Thinking about getting a pair of Helios Quantum 4 25x100 binoculars( and tripod) as a grab and go option for my back garden and for dark site. Was wondering if anyone had any experiences with these?

Thanks all

[Tweedledee]

I've owned some 25x100 bins, not the Quantums, but ones of similar quality and price, so I can give my take on them. If you like binoculars then these are very nice for the price. In my experience, people buy these, use them several times and sell them on. This is just what I did too, and here are the reasons in my opinion...

4" binoculars are far less grab n go than you might think. Remember, they are two 4" refractors with the added weight of built in prisms. They are quite heavy and unwieldy. They really need a substantial tripod/mount, preferably a parallelogram type, which is likely to be expensive or at least cost more than the bins. Anything less and you will eventually be irritated by the rickety top heavy structure that doesn't do these bins any justice at all. These binoculars are the straight through type, meaning that looking at any object above 45 degrees altitude is going to give you a nasty crick in the neck and have you contorting like a limbo dancer. The field of view is relatively small, just over 2 degrees, making it much more difficult than you'd think to locate objects. This will have you wanting to rig up some sort of finder attachment like I did. My other big gripe was that, of course, you only have one set of eyepieces, as supplied. You are stuck with the 25x as supplied and can't bump up the magnification or use wider angle 2" eyepieces.

These big bins will give some very nice views, but have far too many limitations for my purposes. I can have much more enjoyment using my ST120 on a simple AZ4 with my, various, wide angle 2" eyepieces and a very convenient 2" diagonal.

[+seven_legs]

Thanks for the info Pete.

That's something to think about.

I thought something like big bins would be easy and quick. For example, the other night I could not sleep and looked out of window it was clear. It was about 3 in morning and I could not assemble the 14" dob for fear of waking neighbours up.

Any suggestions? Thinking of sending £400ish

[+seven_legs]

Plus would like to use as a solar scope or bins.

I think I am willing to spend £400 to £500ish

[Tweedledee]

As we all find out, stargazing is full of comprises and just one scope is never enough. There are umpteen reasons why not many of us observe with a 48" goto dob, and why a pair of of 10x50s sometimes just doesn't do it for us.

Personally, I think I've cracked it without having spent too much money. My second hand ST120 is cheap enough, big enough, versatile enough, robust enough and so convenient to set up in a jiffy and is a pleasure to use. It gives excellent views if you can put up with a bit of CA on brighter objects. I toyed with the idea recently of replacing the ST120 with something of similar size but better quality. I decided in the end that as a quick grab n go, I was unlikely to substantially improve on its advantages whilst parting with a lot of hard earned cash.

I also have a solar objective filter for the ST120

[+seven_legs]

I am tempted with something like that myself. Got until payday 24th to make mind up. What do you think to mak scopes?

[Tweedledee]

I would like a small 127 mak as well as my ST120. I'd have the best of both worlds then in two grab n gos.

The mak will allow higher powers to be used more easily due to its long effective focal length and it would therefore be brilliant for quality views of planets, but it won't give wide fields or take 2" eps.

The ST120 is superb for wide fields and low powers especially with 2" eps.

These are my personal preferences, others may have differing views.

Compromises, compromises

[+seven_legs]

Thanks Pete, will have a good think. Will post when I buy my grab and go scope.

Oh, with the st120 would I need to up grade the diagonal? Or is that ok?

[Tweedledee]

My ST120 has a s/h Meade 2" diagonal! The original supplied diagonal will be fine. You really won't notice the difference in the light transmissions. If you really wanted to, you could pay more than the cost of the ST120 itself just to upgrade the diagonal and tell everyone that it may have 6% more light throughput on that once a year superb dark sky session. Just remember it is not a £5k Takahashi, so there is no point going overboard on the accessories. Use it and enjoy it for what it is and you will find it does a fine job without you having to worry about breaking anything expensive on it.

[+seven_legs]

Ta mate, think that's what i will get.

Thanks for the help

Tony

[BAZ]

As Pete said something like the 25X100's are going to weigh in the region of 5 Kg, so it will be a really sturdy tripod for those.

 

I seem to get on with my cheapo Revelation 15X70's. they are not too big for short hand held sessions in a garden chair, but big enough to get detail out of the fainter and smaller objects.

 

I am down near J26 at Watnall if you want to pop over sometime and have a look.

[Werisit]

Hi Tony. I recon the ST120 would be a good choice. I've got the 102 and love it for its ease of set-up. Pick it up, take it outside, look through it! You may be able to fit it with a bino-viewer, others can advise on that I'm sure. 

I was down at Tring Astro last week and was rather taken by the Vixen 110L. Beautifully made, robust and not too long at 1035mm focal length. That would be better for planets but wouldn't offer the lovely wide field views of the ST 120.

[+seven_legs]

Thanks Alan, will try the st120. As you say easy to use and move around the garden.

Thanks for the offer baz, may do one day. Or you going to Belper on Saturday if the sky is clear?

[+seven_legs]

Hi all,

Just to let you know that I have brought the st120. Order yesterday from harrisons telescope, came this morning:)

After the gym will hastily try to make a solar filter. It looks like it will be clear as well tonight as well.

Thanks everyone for all your help

Tony

[Tweedledee]

Looking forward to your first light report Tony.

[+Bino-viewer]

How about these.....? 

 

Russian made by Novosibirsk instruments. PNB-1 15 x 110mm.

Used by the Russian military since WW2, often at anti-aircraft missile batteries in border locations etc

Theres a picture online somewhere of Vladimir Putin using a pair.

 

You occasionally see them pop up on ebay. I remember watching a pair go for around £2000.

I quite fancied a pair a few years ago, but realised it was madness.

 

Heres the best bit.... they weigh 30kg a pair !!  You'll need gym membership. Boxed they weigh in at 48kg !

I'd love a look through a pair though. Maybe one day haha....

 

Photo1 by rob.0919, on Flickr

[Tweedledee]

These Russians seem to know how to build things to last. It is probably pretty bulletproof by the looks of it, and not at all grab n go at that weight. With a 7.3mm exit pupil it would be best suited to a teenagers eyes. I bet you'd see some breathtaking views through it from a dark site though.

[+seven_legs]

Hi all,

Just a quick first light report on my new st120.

The viewing tonight was very poor, Sky was misty.

I managed to look at Jupiter and was surprised how good it looked, sure there was some false colour but still Jupiter looked good using my es 11mm eyepiece could see banding and the moons. The Beehive cluster look lovely even throught the hazy sky.

I then checked out some double stars but the sky was getting worst so packed up.

I am very pleased with the scope. Very quick to set up. The az3 mount is surprisingly sturdy, I love the ease of the red dot finder.

The only problem is the diagonal. When I de-focused on a star I noticed a diagonal line running down the image slightly off the centre to the right. I think this has a slight negative effect on my views. Will called harrisons up tomorrow to see if I can replaces it. Was going to get a 2" diagonal in a few weeks time

Will do another report when we have better skies and diagonal:)

[Werisit]

Hi Tony. Glad to hear you're getting on with the ST120. Is your's a prism diagonal? I get a line down the middle when I throw it out of focus, I think that's normal for a prism. If it has any effect on the in focus image,I think it's very minimal. I tried my Vixen SLV 4mm on the 102 (125 x mag) and managed to spot the spot which I recon ain't half bad for a short focus achro. The correct view given by the prism is great for the moon and matches star charts.    

[+seven_legs]

Apparently that is normal for the erecting prism. I order a 2" dielectric skywatcher diagonal from flo. Hope my 38mm panaview works ok with it. But thanks anyway

[+Bino-viewer]

Apparently that is normal for the erecting prism. I order a 2" dielectric skywatcher diagonal from flo. Hope my 38mm panaview works ok with it. But thanks anyway

You may find they'll be insufficient out focus (i.e. the focuser fully raked out) for you to focus with a 2" diagonal / 38 Panaview combo.

Mention it to your dealer. You may need to factor in an extender.

[Tweedledee]

The other slight negative with a 38mm eyepiece on the F5 ST120, is that it will give a massive 7.6mm exit pupil. This would waste some light making the ST120 have the light grasp of only a 90mm objective. You will get a nice wide field of nearly 4.4 degrees at 16x though.

[+seven_legs]

Used it at Belper, good some nice views. Did not know that about the light grasp. What 2" eyepieces do you use.

[Tweedledee]

The 38mm eyepiece should give nice wide views, but you won't get the best out of it on fainter objects since some of the light is not taken in by the eye. Basically there is little advantage in using an eyepiece with a bigger exit pupil than your eye can take in, except perhaps for getting a very wide field. You'd be better off with a slightly shorter focal length that gives a higher power and matches your dark adapted pupil so all the light us utilised. By all means use the big 38mm eyepiece, but it would be better suited to a longer focal ratio scope.

The pupil of your eye opens up wider as you get dark adapted. The older you are the less it opens up. A child may have a dark adapted pupil of 7mm a fifty year old 6mm or less. The bigger it opens, the more you can take advantage of the exit pupil from the eyepiece to see faint objects. This is why kids can often see the Andromeda galaxy naked eye and adults can't. They receive more of the light than older people. You simply divide the eyepiece focal length by the scopes focal ratio to get the exit pupil. So 38 divide 5 is 7.6mm which is a bit big for most people's pupils so light is wasted making the scope have the light grasp of a smaller aperture. If your eye pupil is 6mm, and you have an F5 scope, then there is not much point using an eyepiece with focal length more than 6 X 5 = 30mm.

Having said all the above, if you enjoy the view, then use what you have. You might not get the best out of the 38mm on the ST120. It is just that each scope has its maximum focal length eyepiece limit, related to its F ratio.

The longest focal length/widest field eyepiece I use is a 25mm 100 degree which, on the ST120 gives 24x and a 4.2 degree field of view at a 5mm exit pupil. Being slightly higher power it gives better contrast which helps show up fainter objects, and having a 100 degree apparent field, it provides nearly the widest possible field available in a 2" barrel.

[+seven_legs]

Thanks for the help

Was thinking of getting something like myself before I got the st120.

Tony