115 replies to this topic

[Astrojensen]

There's a nifty little 50/200mm (50mm f/4) mini-refractor on Aliexpress. It has a 1.25"/T2 crayford (!) with a load capacity of 2kg/4.4lbs (!!) and can be configured to use a 1.25" or T2 diagonal!!! The price is quite reasonable and the quality looks decent, especially for a finderscope. 

 

https://www.aliexpre...ou_1213512498.0

 

I wonder when/if we'll see it under brand names like TS, Altair or Stellarvue?

 

 

Clear skies!

Thomas, Denmark

[rerun]

Hi Thomas,

thank you for sharing with us.

Looks very nice, and it is very very small. You can have this little scope always with you. 

It would be interesting to hear about the performance of this scope.

Clear skies Markus 

[Tapio]

Price is good. But personally I have not seen the need for Crayford focuser in a guide scope.

[Jon Isaacs]

Thomas:

 

Did you purchase one?

 

It looks very nice.  As a finder, it looks heavy, i couldn't find a weight spec. As an RFT, it looks sweet.   

 

I am using an Astro-Tech 50mm RACI finder as a " Fifty Dollar Nifty Fifty".  It has a nice helical focuser, I am estimating the focal length at 250mm.  It splits Castor and Algieba which are about 5" and I was able to split Porrima which is about 3".  

 

 

(The plug for Astronomics:

 

https://www.astronom...-trim-3475.html  )

 

Jon

[Corcaroli78]

There's a nifty little 50/200mm (50mm f/4) mini-refractor on Aliexpress. It has a 1.25"/T2 crayford (!) with a load capacity of 2kg/4.4lbs (!!) and can be configured to use a 1.25" or T2 diagonal!!! The price is quite reasonable and the quality looks decent, especially for a finderscope. 

 

https://www.aliexpre...ou_1213512498.0

 

I wonder when/if we'll see it under brand names like TS, Altair or Stellarvue?

 

 

Clear skies!

Thomas, Denmark

Hi Thomas,

 

Sailing in the Aliexpress ocean?    The small refractor looks very nice. I wonder if its intended to work as a teleobjetiv for cameras or as the ultimate -RFT- travel scope. As many items, i do not doubt we will see it in TS soon...

 

Regards from Jutland

Carlos

[james7ca]

The more interesting fact may be that they offer a way to shorten the tube so that you can use a diagonal (which you can't on many products). But, this capability seems to be described somewhat awkwardly as "Remove a section of the lens barrel to install a 1.25-inch zenith lens for visual inspection." However, they do show a picture of the focuser with the shorten tube.

 

I already have a Stellarvue SV50ED that comes with a somewhat decent Crayford focuser, but it's an f/6.6 and a little large to be used just as a finder. Although I have used it as a guide scope and the optics are pretty good. It did, however, cost about three times as much as the scope on Aliexpress.

 

I guess the dovetail that is on the Aliexpress is a "standard" Synta/Vixen, although I've seen problems in getting those to fit in some finder shoes. 

[Astrojensen]

 

Thomas:

 

Did you purchase one?

 

It looks very nice.  As a finder, it looks heavy, i couldn't find a weight spec. As an RFT, it looks sweet.   

No, I haven't purchased one, but I thought it looked pretty good, so I just wanted to draw people's attention to it. 

 

 

Clear skies!

Thomas, Denmark

[guidoforrier]

i ordered one and it will arrive around April 7 . I wil use it first as a little wide field scope . could not resist !

Guido

[Astrojensen]

i ordered one and it will arrive around April 7 . I wil use it first as a little wide field scope . could not resist !

Guido

It'll be interesting to hear how the optics perform. 

 

 

Clear skies!

Thomas, Denmark 

[james7ca]

i ordered one and it will arrive around April 7 . I wil use it first as a little wide field scope . could not resist !

Guido

I'd like to know how the focuser works, since I've had inexpensive Crayfords that had so much image shift when focusing that they were almost unusable except at the lowest possible magnifications. Beyond that it would be nice if this scope had:

 

a.) Decent image quality (but I wouldn't really expect pin-point stars from a typical f/4 achromat).

b.) A rigid, well-fitting set of rings.

c.) A good fit to the typical Synta/Vixen finder shoe.

Edited by james7ca, 11 March 2021 - 06:57 AM.

[Jon Isaacs]

I'd like to know how the focuser works, since I've had inexpensive Crayfords that had so much image shift when focusing that they were almost unusable except at the lowest possible magnifications. Beyond that it would be nice if this scope had:

 

a.) Decent image quality (but I wouldn't really expect pin-point stars from a typical f/4 achromat).

b.) A rigid, well-fitting set of rings.

c.) A good fit to the typical Synta/Vixen finder shoe.

 

Are you talking image shift visually or photographically?

 

I've had a number of inexpensive focusers, I haven't had an issue with shift visually. Which ones have given you trouble?

 

Jon 

[james7ca]

Are you talking image shift visually or photographically?

 

I've had a number of inexpensive focusers, I haven't had an issue with shift visually. Which ones have given you trouble?

 

Jon 

Jon, it was the original Stellarvue Crayford  rack-and-pinion 10:1 focuser that came on my SV50ED. It was bothersome both visually and for imaging. But, Stellarvue replaced it and the replacement was much better (although now after several years of use the second one is starting to show a little more shift).

 

[UPDATE]

My mistake, it was actually a rack-and-pinion focuser. But, my original concern remains as to the quality of the focuser on the Aliexpress finder.

[/UPDATE]

Edited by james7ca, 11 March 2021 - 01:44 PM.

[bobhen]

This looks like something that might work with my image intensifier. By removing the center tube section my intensifier and a diagonal (maybe even a 2” diagonal) should come to focus.

 

This would give me a handheld, low power scope that I could use to observe the zenith without straining my neck like I do now with my current 50mm repurposed guide scope and intensifier.

 

I’ll keep my eye on this or its clones.

 

Thanks Thomas.

 

Bob

[N-1]

Nice-looking scope but at f/4 and just 200mm of focal length it might tax your EPs if the intended use is RFT.

Tried my ES68°24 in a 60mm f/4 guide scope once, and the view was warp-speedish to put it mildly.

[daquad]

What is the actual price in US dollars?

 

Dom Q.

[Passerine]

I like it, but I wish it was f/5.  Even then the field curvature is pretty hard to ignore with the widest 1.25" eyepieces, but I guess when it's f/4 it is more compact...

 

I like the simple Crayford focuser; I'd like to see more finder-sized scopes with that option.  And the ability to remove a section of the tube is a plus.

 

I guess what I keep hoping to see is those 2 features on a scope like this Skywatcher 50ED:

 

https://www.skywatch...0-apo-refractor

 

Or even the Astrotech AT60ED with a lighter Crayford focuser option would be nice.

 

Dave

[Rutilus]

This looks like something that might work with my image intensifier. By removing the center tube section my intensifier and a diagonal (maybe even a 2” diagonal) should come to focus.

 

This would give me a handheld, low power scope that I could use to observe the zenith without straining my neck like I do now with my current 50mm repurposed guide scope and intensifier.

 

I’ll keep my eye on this or its clones.

 

Thanks Thomas.

 

Bob

For handheld, I put the 50mm finder scope lens on front of a 2 inch diagonal. It works with my 1.25" and 2" eyepieces as well as my small imaging chip camera.  Also made some eyepieces from Celestron f/6.3 and Meade f/3.3 focal reducers which worked superbly well.

Attached Thumbnails

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Edited by Rutilus, 12 March 2021 - 05:51 AM.

[guidoforrier]

It'll be interesting to hear how the optics perform. 

 

 

Clear skies!

Thomas, Denmark 

i will keep in touch 

Guido

[*skyguy*]

Here's the same scope configured for use with the included star diagonal. Neat looking kit!

 

https://www.aliexpre...#3468#15616#784

[Jon Isaacs]

Jon, it was the original Stellarvue Crayford  rack-and-pinion 10:1 focuser that came on my SV50ED. It was bothersome both visually and for imaging. But, Stellarvue replaced it and the replacement was much better (although now after several years of use the second one is starting to show a little more shift).

 

[UPDATE]

My mistake, it was actually a rack-and-pinion focuser. But, my original concern remains as to the quality of the focuser on the Aliexpress finder.

[/UPDATE]

 

James:  

 

Rack and pinion focusers can have a variety of issues including image shift.   Crayfords also have their own issues but slop and image shift are nearly impossible simply because of the design.

 

Jon

[Jon Isaacs]

Nice-looking scope but at f/4 and just 200mm of focal length it might tax your EPs if the intended use is RFT.

Tried my ES68°24 in a 60mm f/4 guide scope once, and the view was warp-speedish to put it mildly.

I like it, but I wish it was f/5.  Even then the field curvature is pretty hard to ignore with the widest 1.25" eyepieces, but I guess when it's f/4 it is more compact...

 

 I prefer F/4 over F/5 for a finder simply because it provides a wider field of view.  I find eyepieces like the 16mm Nagler T5, the ES 20mm 68degree and the 22mm Panoptic (minus the skirt) work quite well in a 50mm F/4.  I usually give up a little center sharpness to less the field curvature.  

 

The $45 50 mm Astro-Tech finder seems to be somewhere around F/5.  I backed that out based on field of view measurements so it's kind of a guess.

 

Jon

[Jon Isaacs]

For handheld, I put the 50mm finder scope lens on front of a 2 inch diagonal. It works with my 1.25" and 2" eyepieces as well as my small imaging chip camera.  Also made some eyepieces from Celestron f/6.3 and Meade f/3.3 focal reducers which worked superbly well.

 

I made a handheld scope out of a 50mm ~F4 finder objective.  With the 21mm Ethos it's about 10 degrees at 10x.. Talk about field curvature..

 

 

Jon

[empiredown]

I went  one of these: https://optcorp.com/...hotography-lens

(No affiliation)

 

I'll finally decide if it guides/views/images... it's nice to have options at 1 lbs. Totally overkill and unnecessary, but I'm worth it. 

 

SS

[james7ca]

This is very intruiging

 

Actually, I was wondering when this was going to be done - it's basically a fully configurable system, like Borg, except it uses M42x0.75 threads. You can basically build your own scope

 

Hopefully this will catch on; there exists already a plethora of M42 accessories, including tubes of varying lengths, visual backs, camera mounts, filter slides, helical focusers - and now an M42 compatible crayford focuser. I'd love to see a range of small objective lenses with M42 threads, both achromatic and apochromatic.

 

You could build a guidescope, finderscope, visual RFT, astrograph, EAA scope, binoscope, heck even hand-held binoculars that utilise 1.25" eyepieces! (would love to see some sort of hinged dual-tube holder, and M42 roof prisms for this purpose)

Where did you read that this Aliexpress/Laida scope used M42 threads for anything other than the connection at the end of the 1.25" eyepiece holder? On the Laida scope it does NOT appear that the optical tube itself, the lens cell, or the Crayford focuser connect to each other using M42 threads.

 

Furthermore, it isn't that unusual for small scopes and lenses to terminate with M42 threads (I have several that do). In fact, my SVBony 30mm f/4 finder has M42 threads on both ends (at the eyepiece connector and for the lens cell itself).  Also, the Feather Touch 1.25" Crayford focuser that is on my Lunt LS50 solar scope terminates with an M42 thread (as well as accepting 1.25" eyepieces). And, for that matter, you can already get a Borg that uses M42 on the camera or eyepiece end of scope. But, admittedly my Feather Touch and any Borg scope is going to be more expensive that this Laida finder from Aliexpress and I do look forward to seeing how users rate the quality of its focuser.

Edited by james7ca, 13 March 2021 - 03:38 AM.

[james7ca]

Here is a thread from October 2018 entitled "Let's talk about short tube 50mm telescopes":

 

  https://www.cloudyni...s/#entry8866104

 

It looks like this was one of the first threads to talk about WO's 51mm RedCat (which was at that time still under development).

Edited by james7ca, 13 March 2021 - 04:27 AM.