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Takahashi Polar Scope reticle?

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#1 ecuador

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Posted 09 April 2015 - 11:47 AM

While I wrote a polar scope alignment app for my own "special" needs as an iOptron user, I thought it would be helpful to users of other polar scopes that have an accurately-graded reticle, so I added such reticles I could find and the Takahashi seems to be of the type ( with its users often swearing it is the best there is ;)  ). Anyway, none of my friends owns a Tak mount (they are otherwise great people!), so I just tried to follow the Takahashi app, which seems to be showing a reticle optimized for the years 1985-2015. Then I saw a post about someone getting a 2010-2050 reticle for his Tak mount, so I tried to add that as well. Since when I do something I like to get it right, so my question is, how did I do, is it close enough to the actual Takahashi reticles to make glancing at the app translate easily to what you see in the reticle? Is there a different reticle I should add (and perhaps you could photograph it?).

Attached Thumbnails

  • TakOld.png
  • Taknew.png


#2 GJJim

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Posted 09 April 2015 - 05:42 PM

Nice looking interface on the app. That reminds me, the reticle on my EM-10 expires this year, guess I'll have to set it out on the curb as a throwaway.  :grin:



#3 ecuador

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Posted 09 April 2015 - 06:44 PM

Nice looking interface on the app. That reminds me, the reticle on my EM-10 expires this year, guess I'll have to set it out on the curb as a throwaway.  :grin:

Right, you can't possibly use a mount past the expiration date!  ;)

However, depending your latitude, your reticle might have already expired a while ago, since when you include the atmospheric refraction effect (as you should if you are going for precise alignment via the reticle - although the Takahashi app does not calculate it), you would have been going beyond the 2015 circle already.

 

So your reticle is pretty much like on my first screenshot? I guess I am more concerned about the newer reticles as I would guess owners of older mounts like you would be starting to change their reticles now, right?



#4 waso29

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Posted 09 April 2015 - 07:34 PM

Here is a shot from EM10 mount:

 

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  • IMG_4552 em10 polarscope.JPG


#5 andysea

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Posted 10 April 2015 - 12:18 AM

Tak migh be able to update the reticle but it requires shipping the mount to Japan.



#6 jwheel

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Posted 10 April 2015 - 09:09 AM

Nice looking interface on the app. That reminds me, the reticle on my EM-10 expires this year, guess I'll have to set it out on the curb as a throwaway.  :grin:

Same goes for my NJP!



#7 Ken Sturrock

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Posted 10 April 2015 - 02:14 PM

Nice program!

 

I don't have my mount out right now but the EM-200's reticle is quite different from the others.

 

It looks like the picture in this review, but the picture doesn't show the long rectangle and graduated line in the middle of the field for northern, and southern, star alignment. Essentially, on the EM-200, you align the outer scales for time & month/day and then you place polaris inside of a box with the specific location depending on the year.

 

My reticle expires in 2030, FWIW.



#8 Tamiji Homma

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Posted 10 April 2015 - 07:12 PM

Here is iPhone shot through EM-200 polar scope with shaky hands :)

This is link to full resolution shot: http://www.pbase.com...707340/original

 

For Tak user,

 

http://www.otherwise...lign/index.html

 

large.jpg

 

Tammy



#9 Ken Sturrock

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Posted 10 April 2015 - 09:18 PM

Dang, Tammy! Even after 10+ years, I've never seen an em-200 reticle so clearly!  :lol:



#10 ecuador

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Posted 11 April 2015 - 05:31 AM

Here is iPhone shot through EM-200 polar scope with shaky hands :)

This is link to full resolution shot: http://www.pbase.com...707340/original

 

For Tak user,

 

http://www.otherwise...lign/index.html

 

 

 

Tammy

Nice. I guess this is quite a different type of reticle that normally doesn't need the help of an app. I will think about it, but perhaps it would be useful to people that are not living too far north in latitude to get a display with the displacement that the atmospheric refraction causes. For example if you are in Miami you get about a 2.2" offset for Polaris due to refraction, which corresponds for example to a Dec shift of polaris over almost 10 years...
 

Note that the reason I first decided to add Tak reticles to what started as an iOptron app, is exactly because of that app you linked to, which is not very accurate by not taking account of refraction. Surprising when we are talking about a reticle that seems to be designed for accuracy.


Edited by ecuador, 12 April 2015 - 05:40 PM.


#11 waso29

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Posted 14 April 2015 - 03:17 PM

From EM11 mount:

 

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  • IMG_6945.JPG


#12 ecuador

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Posted 17 April 2015 - 03:44 PM

Ah, this is an intermediate 2000-2030. Perhaps I could add that. So the point is that for aUMI you use an app to show you where to put polaris in the reticle, but for s Oct you have to rotate the reticle to fit t-Oct and s-Oct in the respective positions shown?



#13 ecuador

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Posted 21 April 2015 - 02:25 PM

Ok, that 2000-2030 reticle was simple to add.

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  • tak2000.png


#14 edif300

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Posted 21 April 2015 - 02:39 PM

From EM-200:

 

http://www.astrosurf...i EM-200/EM.htm

 

I can send it to you at higher resolution.



#15 ecuador

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Posted 21 April 2015 - 03:55 PM

From EM-200:

 

http://www.astrosurf...i EM-200/EM.htm

 

I can send it to you at higher resolution.

The question is, though, would a polar align app be helpful?

On an NJP etc the reticle does not rotate, so you rely to the app to show you where to put Polaris in the reticle pattern. On the EM-200 it seems that you align the inner circle with the outer circle based on the date/time and you get a circle to put Polaris in. I could of course show you how that circle is not exactly where you should put polaris, there is at least atmospheric refraction going on unless you live at the northern latitudes, but would that be of interest to EM-200 and similar type owners who are used to a rather simple process? I'd rather not add things that would just complicate the app and not be of much use, that's why I am asking.



#16 Ken Sturrock

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Posted 21 April 2015 - 06:25 PM

In the case of the EM-200 reticle, I am not sure how an application would add value to the work flow. On other designs, certainly yes.



#17 ecuador

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Posted 21 April 2015 - 07:35 PM

In the case of the EM-200 reticle, I am not sure how an application would add value to the work flow. On other designs, certainly yes.

Right, that's what I am saying. For example you are in Denver, meaning you should really be pointing your polar scope about 1.2 arcminutes lower than your reticle would indicate (which is about the movement Polaris makes towards the NCP in 5 years). If you normally need an app to point, then the app should include that correction. But if you don't normally need an app, I assume you could just try to make the correction yourself, not much point in loading an app just for that.

So I added the 2000-2030 from the EM11 mount for now, which does make sense.



#18 Iver

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Posted 21 April 2015 - 08:53 PM

There is a PC app. that helps with refraction and polar offset adjustment.

 

https://onedrive.liv...0E2A57E2625!125



#19 edif300

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Posted 22 April 2015 - 06:08 AM

 

The question is, though, would a polar align app be helpful?

Maybe yes... On the EM-200/400 you must adjust the offset of your current location for proper reticle inclination before polar alignment.

I am using Polefinder where must manually introducing the coordinates of current location.



#20 ecuador

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Posted 01 May 2015 - 11:27 AM

By the way, the version that includes the 2000-2030 EM11 reticle was just approved by Apple. I will probably include a display of offset adjustment for EM200/400 owners just for completeness sake, but that is in any case a polar scope reticle meant to be used without much need of calculators.



#21 ecuador

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Posted 08 May 2015 - 10:31 AM

Agh! The 2000-2030 reticle was not correctly added to the free version! Bad ecuador, not testing enough the free version  :blush:

Oh, well, another week for Apple to approve the next update...

 

 

Edit: I was granted an expedited review, so it is fixed already...


Edited by ecuador, 09 May 2015 - 07:25 PM.


#22 rfic1

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Posted 06 September 2015 - 07:18 PM

When using the Tak Align app with a EM-200 do you still adjust for offset or does the program take that into account?



#23 edif300

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Posted 13 October 2015 - 02:55 AM

Hi,

 

Will be available the reticle of the EM-200 & EM-400 for this app?

 

Currently the PSA app shows me EM200/400 and ofsted:-16.8º while a reticle for the EM-10/11/500/N-JP-z/ is shown. Also the offset value is wrong for my current location.



#24 ecuador

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Posted 20 October 2015 - 06:45 PM

Hi guys. Because I get a lot of requests about the EM 200/400 reticle I decided to include it, even though it goes way off the original intention of the app (i.e. reticles that do not rotate). It seems that adding the offset calculation in the existing Tak reticles only confused further, so I will be rectifying that. If somebody wants to test it out in beta, you can send me your email to add you to my beta list.

 

 

Hi,

 

Will be available the reticle of the EM-200 & EM-400 for this app?

 

Currently the PSA app shows me EM200/400 and ofsted:-16.8º while a reticle for the EM-10/11/500/N-JP-z/ is shown. Also the offset value is wrong for my current location.

 

Could you please give me an example, either a screenshot using version 1.8 (or just write me the offset it lists, your longitude and the time zone listed below the LST) and tell me what offset value you expected? 



#25 edif300

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Posted 21 October 2015 - 09:12 AM

Hi Dimitrios,

I expected a N value of -1.80 but actually a -16.8 is displaying.

 

The scale in the EM-200/400 goes from 0 to +-15.

 

In my case, -16.8 + 15 (ending of the offset scale and adding because to keeping a negative value as answer -or next time meridian-) = -1.8 (I think the value that must to be displayed).

 

The screenshoot: http://www.astrosurf...ak/IMG_3320.PNG

 

 

Thank you so much

Iñaki


Edited by edif300, 21 October 2015 - 09:18 AM.



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