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Sky tracker SW/iOptron vs DIY

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#1 msacco

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Posted 19 January 2021 - 10:13 AM

Hey guys, I want the ability to image with a DSLR and a lens, a tracker is the best option for that I guess(portability is also a big part of it).

 

Obviously there are the common iOptron SkyGuider Pro and the SkyWatcher Star Adventurer Pro(there's also v2 or something like that now with wifi...).

 

Anyhow, there are tons of 3D printing projects for similar trackers, for example like this:

https://www.instruct...Mount-for-DSLR/

 

But I'm wondering about the quality between a branded one and a DIY one. This is a tough question I guess, cause a DIY project is up to the maker mostly, but I'm wondering about the differences between the DIY project I shared above compared to the skyguider or star adventurer.

 

I was not able to find any actual comparison between the 2, which is why I'm asking here for your opinions. The total price for me for a star adventurer for example is around $400 including shipping and fees, the DIY project total cost is around $40 or even less since I already own some of the needed materials.

 

Canon 750D, Equatorial mount, Canon 18-55mm stm (at 27mm), f/4, iso1600, 196s(THIS IS FROM THE LINK, NOT MINE):

F2RC4WVKAGSEDYE.LARGE.jpg

 

FF72NG0KAGSEDRT.LARGE.jpg

 

So that looks nice and all, but that is with 27mm(or around 43mm if you consider cropping for full frame), I'm wondering what would be the limit with such mount for higher focal length. The ideal focal lengths for me would be up to 200mm (full focal length), I also own a SharpStar 61 EDPH II which is 275mm, I don't expect it to handle it tbh, but I do have some hopes of that.

 

One of the issues I have with this specific design is polar aligning. While it is 'fine' for normal uses maybe, that might make a difference in rather higher focal lengths, which is why I thought of building my own design using a better stepper motor, and building it around the spare EQ5 polar scope I have so I'll be able to more accurately polar align.

 

Still, I'd like to get some advices from all of you, as your experience is always very useful.

Did any of you try making a DIY tracker? How did it go? Do you have the builds and pictures to share?

 

Not sure if I should ask it here or in DIY forum, but since it's about mounts...Thanks for the help! :)



#2 Hesiod

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Posted 19 January 2021 - 12:12 PM

"Crop factor" affects just the field of view, but for every other purpose the focal of the lens is the nominal one (but for the purpose of pin-point like stars matters the pixel pitch too: the same lens may yield different results on different cameras. Often, but is not a strict rule, full-frame cameras have bigger pixels and this is the reason why may be "more permissive" than smaller sensors).

Taking a 300" shot at 40mm does not require much effort, except that of finding a truly dark site (and even from there may "burn" a lot of detail: with a tracking mount is IMHO better to take non-overexposed shots and stack them), but for meaningful shots at 200mm I suggest to get a decent device.

Commercial products tend to work more or less around the same level of performance; while with a DIY project the quality of craftmanship, tools and materials can lead to vastly different results.

 

Personally have a Vixen Polarie, which is a device similar to Skytracker/Skyguider (in fact is a sort of "ancestor" to iOptron's original tracker) and use it with focals ranging from 24 to 320mm (the latter attained through a small telescope, Vixen FL55/300) and works exceptionally well, even if with my Canon 1100/R rarely go over 180".

Mind that at such focal all the process is very forgiving: more expensive devices and accessories make all this even easier but can do well with fairly basic equipment



#3 alphatripleplus

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Posted 19 January 2021 - 01:47 PM

 

One of the issues I have with this specific design is polar aligning. While it is 'fine' for normal uses maybe, that might make a difference in rather higher focal lengths, which is why I thought of building my own design using a better stepper motor, and building it around the spare EQ5 polar scope I have so I'll be able to more accurately polar align.

 

 

For polar alignment, if you can use SharpCap with a camera and lens giving at least half of degree FOV, you can use the SharpCap polar alignment routine. SharpCap only needs to be able to control the  camera, not the mount, for the PA routine.



#4 msacco

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Posted 19 January 2021 - 02:53 PM

"Crop factor" affects just the field of view, but for every other purpose the focal of the lens is the nominal one (but for the purpose of pin-point like stars matters the pixel pitch too: the same lens may yield different results on different cameras. Often, but is not a strict rule, full-frame cameras have bigger pixels and this is the reason why may be "more permissive" than smaller sensors).

Taking a 300" shot at 40mm does not require much effort, except that of finding a truly dark site (and even from there may "burn" a lot of detail: with a tracking mount is IMHO better to take non-overexposed shots and stack them), but for meaningful shots at 200mm I suggest to get a decent device.

Commercial products tend to work more or less around the same level of performance; while with a DIY project the quality of craftmanship, tools and materials can lead to vastly different results.

 

Personally have a Vixen Polarie, which is a device similar to Skytracker/Skyguider (in fact is a sort of "ancestor" to iOptron's original tracker) and use it with focals ranging from 24 to 320mm (the latter attained through a small telescope, Vixen FL55/300) and works exceptionally well, even if with my Canon 1100/R rarely go over 180".

Mind that at such focal all the process is very forgiving: more expensive devices and accessories make all this even easier but can do well with fairly basic equipment

Thanks for the comment! Yes a DIY project might vary from one to another, but I think that besides the different designs, here the build should be rather the same in most cases I guess.

 

I can in general 'spend $40 and just see if it's good enough', but I'm trying to understand if it's even worth the try.

I'm also not 100% happy with this current design, and thinking of making my own design, but I'm bad at designing lol.gif

 

I do love spending time on doing such things on my own, I really enjoy it, but I do prefer doing something that's actually useful and not something that will give bad results and end up sitting there with no use.

 

For polar alignment, if you can use SharpCap with a camera and lens giving at least half of degree FOV, you can use the SharpCap polar alignment routine. SharpCap only needs to be able to control the  camera, not the mount, for the PA routine.

I thought of it, but I plan on having this as a 'side gear' that will not require any computing in general, so simply have the mount tracking, my DSLR taking shots and that's it.

I could possibly use the ASIAIR, but still...that's not really my current plan.

 

Thanks :)



#5 Hesiod

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Posted 19 January 2021 - 03:14 PM

The accuracy of gears and printed parts may impact on the overall performances a lot but in any case shooting at 50mm or less does not require a lot in term of equipment and accuracy (may even eyeball the alignment to the Pole and still bring home a decent pic).

If have the cash, and want to use up to the 200mm without much troubles however I think that commercial products are the most reliable option.

All the commercial trackers are equipped with polarscopes, so do not have to worry about PA since at such focals the polarscope is IMHO the most quick and easy way to align



#6 msacco

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Posted 19 January 2021 - 03:23 PM

The accuracy of gears and printed parts may impact on the overall performances a lot but in any case shooting at 50mm or less does not require a lot in term of equipment and accuracy (may even eyeball the alignment to the Pole and still bring home a decent pic).

If have the cash, and want to use up to the 200mm without much troubles however I think that commercial products are the most reliable option.

All the commercial trackers are equipped with polarscopes, so do not have to worry about PA since at such focals the polarscope is IMHO the most quick and easy way to align

I totally agree with the gears point for 3D prints, which is why I said that I'm not happy with the design. There are plenty of cheap and useful gears/pulleys/belts available on aliexpress/amazon/ebay to use. A design that simply uses the 3D printing abilities for cases and assembling is awesome, but when it's used for printing gears etc I'm not really for it(I think it's good for prototyping and for things that doesn't require much accuracy, but not more than that).

 

Thanks for the help, I'll wait for other advices and think with myself what I'd like to do :)




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