Locking focus on my telescope

[Space Oddities]

Hello!

I recently received my little TS-Optics PhotoLine 60mm f/6 FPL53 Apo. It's basically the same scope as the William Optics ZenithStar 61 and the AstroTech AT60 ED. 

It looks great, but I'm a bit confused. I would like to lock the focuser when I'm done focusing on a star, but I don't know how. Initially, I thought I should turn that big red knob on the top, but it doesn't seem to have any impact on the focusing system. Actually, it doesn't seem to have an impact on anything...

Did I miss anything? Or do i have a faulty scope?

Thanks for your help!

Pierre

[Cozzy]

IMHO It looks like the focus lockdown screw to me.

[RayD]

I'd go with it being a focuser lock too.  

There isn't one on the focus shaft, so this is the most likely.  As it is on the tube it doesn't need to do much to stop the focuser moving, so it will probably still be relatively easy to drive through it with the focus knobs as they are geared, but it will hold the tube.

[Space Oddities]

Thanks for your answers! 

Well, that was my initial guess, but when I tighten the knob, the focuser doesn't lock   I'm not sure if I should try tightening it more.

I'll try to contact the manufacturer!

PS: here is a pic from the bottom, and there's indeed no knob to turn:

Edited February 18, 2019 by Space Oddities

[RayD]

14 minutes ago, Space Oddities said:

Thanks for your answers! 

Well, that was my initial guess, but when I tighten the knob, the focuser doesn't lock   I'm not sure if I should try tightening it more.

I'll try to contact the manufacturer!

PS: here is a pic from the bottom, and there's indeed no knob to turn:

No it probably won't lock it.  All it needs to do in that position is to create sufficient drag on the focus tube for it to not slip.  You will almost certainly still be able to turn the focuser, but the tube sliding and turning the focuser only needs a small drag due to the gearing effect.

If you take it out and then operate the focuser, look through the hole to see if you can see the focus tube moving.  This will confirm that it is just pushing against it.

Edited February 18, 2019 by RayD

[Space Oddities]

Ah, I see what you mean! Well that's what I was afraid of: the weight of the camera changing the focus when the scope is in an exotic position. I'll do some tests when I get home!  

Thanks Ray!

[RayD]

1 minute ago, Space Oddities said:

Ah, I see what you mean! Well that's what I was afraid of: the weight of the camera changing the focus when the scope is in an exotic position. I'll do some tests when I get home!  

Thanks Ray!

No problem, Pierre.  If it is a lock, which I suspect it is, it is probably more accurately a drag creator.  There may even be a nylon liner of some sorts between the end of the screw and the focus tube, but the nett result would be the same, and should work just fine with a camera etc. pointing at the Zenith.

[Space Oddities]

So I tried with the scope up and the camera, and indeed, it's a "drag creator". The focus didn't change with the weight of the camera, in fact, even slightly pushing or pulling didn't have an effect. Which is convenient and well thought if I need to adjust focus during imaging  

Thanks for your guidance!

[RayD]

1 hour ago, Space Oddities said:

So I tried with the scope up and the camera, and indeed, it's a "drag creator". The focus didn't change with the weight of the camera, in fact, even slightly pushing or pulling didn't have an effect. Which is convenient and well thought if I need to adjust focus during imaging  

Thanks for your guidance!

Perfect. Looking at the one marketed by WO which is basically the same thing, they note it as a focus tensioner, so basically adjust it to a tension that is comfortable for you to operate your focuser, but prevents any unwanted movement. 

Glad it seems to be working, it's a really lovely looking little instrument. 

[Ruud]

The knob is probably to prevent focus creep, but everyone else already said that. I have a question:

I've been looking at this telescope. I thought I'd buy it for birding and as a super portable visual scope, as well as a bit of photography. Do you think this telescope would be a good choice for that?

[Space Oddities]

Hey Ruud,

So far, I have done only some quick tests on a tree, and yesterday on the Moon with a 1.25" eyepiece, but my first impression is good! I think it's a great little scope, very good optically and quite portable.

For general photography and birding, it might be a bit slow (f/6), and I can't imaging manual focusing on birds with it... Hand holding it isn't an option. On a tripod, that could work, but that's definitely not as convenient as a telephoto lens. My Canon 300mm f/4 is roughly the same weight, for a bit less focal length but a wider aperture, as well as autofocus.

For astrophotography and astronomy, though, it's much better than a photo lens. The focusing is very smooth and precise. I haven't tried it on stars, but from the reviews I've seen online, it seems very good.

 

[Sparsile]

I know this is old, but wanted to add an observation in case someone else comes across this. I just purchased an AT60ED and was wondering about the focus lock as well. The instruction sheet indicates that there is a "chrome lock knob under the focuser [that] lets you lock in that sharp focus." However, there is no chrome knob. The brass-colored screw in Space Oddities picture is the focus lock. It's not a chrome knob, but tightening it with a screwdriver prevents the focus from moving at all. The "big red knob" at the top is a "drag adjuster". However, I don't really feel much difference when I try to tighten it.

If anyone has successfully replaced the brass screw with a chrome knob, please let me know!

[Karl Perera]

It should be the focuser lock as others have said and maybe just adds enough friction to stop it slipping. Maybe there is a reason why it does 100% lock?