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Which camera(s) for guiding 8" SCT?

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#1 Spata

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Posted 05 April 2020 - 01:59 PM

With the pandemic forcing me to be home more I've been spending more time up at night imaging and what not. I have an 8" sct, a cgem mount, focuser, etc. but I want to try using my laptop to guide for better(longer?) exposures. Which sub $500 cameras would you recommend to pair with a 8in sct for guiding with an oag?



#2 bobzeq25

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Posted 05 April 2020 - 02:23 PM

With the pandemic forcing me to be home more I've been spending more time up at night imaging and what not. I have an 8" sct, a cgem mount, focuser, etc. but I want to try using my laptop to guide for better(longer?) exposures. Which sub $500 cameras would you recommend to pair with a 8in sct for guiding with an oag?

https://www.highpoin...mera-asi290mini
 



#3 nitegeezer

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Posted 05 April 2020 - 02:35 PM

A lot depends on your SCT. If it has a good mirror lock on it, I would go with guide scope and camera. I tried an OAG on my scope, but the edge of my light path provided very distorted stars. With the mirror lock I do not need the guider to compensate for mirror flop, so my guiding is better with a guide scope mounted right to the top of the SCT. During a full moon night I might experiment with an OAG again, but for now I am happy without it.

#4 petert913

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Posted 05 April 2020 - 02:37 PM

ASI120mm works great.  So does QHY 5L-II



#5 bobzeq25

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Posted 05 April 2020 - 02:51 PM

ASI120mm works great.  So does QHY 5L-II

You've used one on an off axis guider?  I failed.



#6 rgsalinger

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Posted 05 April 2020 - 03:12 PM

So, on the two long focal length (2500 and 4900mm) scopes that I use we have ZWO174 guide cameras which are $499. I owned another one of these previously as well. I have experienced zero problems with them. I don't care that I don't get full illumination because the chip is so big anyway. Both of these are F8 scopes and I have never found (even deep in galaxy season) that we don't get guide stars.

 

I see no reason to put up with all the possible problems that a guide scope brings to the party on an SCT. I've seen people get buy with guide scopes on the 8" Edges but the amount of money spent to get good results at that focal length seems just to high for no particular gain. I had to set up a ZWO174 just a week ago and it took me all of an hour to find focus and get it calibrated and guiding. 

 

Rgrds-Ross


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#7 bobzeq25

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Posted 05 April 2020 - 08:19 PM

So, on the two long focal length (2500 and 4900mm) scopes that I use we have ZWO174 guide cameras which are $499. I owned another one of these previously as well. I have experienced zero problems with them. I don't care that I don't get full illumination because the chip is so big anyway. Both of these are F8 scopes and I have never found (even deep in galaxy season) that we don't get guide stars.

 

I see no reason to put up with all the possible problems that a guide scope brings to the party on an SCT. I've seen people get buy with guide scopes on the 8" Edges but the amount of money spent to get good results at that focal length seems just to high for no particular gain. I had to set up a ZWO174 just a week ago and it took me all of an hour to find focus and get it calibrated and guiding. 

 

Rgrds-Ross

I have a 174, love it.  But you're paying $200 more than a 290 basically to get the larger chip.  My Celestron OAG has an unusually large prism, so I get the benefit of the larger chip.  With most OAGs, you'll see little or no improvement over the 290.
 


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#8 pgs/sdg

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Posted 05 April 2020 - 08:56 PM

I'll put in a vote for the ASI174. I'm not nearly as experienced as Bob & Ross....but when I got my 174 my guiding became a LOT easier. Still working on some other guiding issues (backlash problems...but those are mount issues)   but the 174 is a great camera for an OAG in my opinion. Never have a problem finding a guide star.


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#9 rgsalinger

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Posted 05 April 2020 - 09:36 PM

About 3 years ago I did a major upgrade on my F8 12.5" CDK imaging system. Shortly after that, when the ZWO290 mini came out, I bought one and replaced the SBIG STi that I had been using for about 6 years. The guiding deteriorated measurably. I attributed this to the image scale which was .5 arc seconds/pixel even when binned on that particular telescope. Once it was swapped out for a ZWO174, the guiding returned to normal for the mount and has stayed there ever since. I just think that calculating centroids when a single star covers 6 pixels or so is a challenge. 

 

Two other points. I used a QHY Medium OAG which has a larger prism than the OAG's that many others use. That might be a factor. Also, I was guiding with the SKYX or MaximDL, not PHD as many others do. So, I don't know what the problem was but I have the 174 and it works really well. About 15 months ago I put another one into a 24" RC that I use and that has made a huge difference over the ATIK that we were using. So, I just swear by these for long focal length scopes.

 

Maybe some brave soul can run a test (unlikely to be me) and see if what I found was just an oddity. 

 

Rgrds-Ross



#10 Hobby Astronomer

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Posted 05 April 2020 - 10:43 PM

Going to share my experience here.

 

Working with an 8' Edge HD. F/7 reducer. 1,422 mm fl.

 

The guide camera I use has 7.4 micron pixels. I bin 3x3 for guiding. I get one to four decent stars every time when doing using an OAG.

 

I also have used the Starlight Xpress Loadstar 2 guide camera. Pixel Size: 8.2 um x 8.4 um. This one has always produced suitable guide stars using and OAG when binned 2x2.

 

Good Luck!

 

HA



#11 bacon

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Posted 05 April 2020 - 10:56 PM

I vouch for the 174 / Celestron OAG / 8" SCT combo.  Even in tremendous light pollution (Bortle 8/9), finding good SNR guide stars has not been a problem.  



#12 Hesiod

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Posted 06 April 2020 - 12:40 AM

I am using the trusty lacerta mgen2 (400mm guidescope vs ca 1300mm reduced c8) and works like a charm.
Originally was above your budget but since it has just been replaced by the gen3 could fond good deals

#13 Stelios

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Posted 06 April 2020 - 01:33 AM

ASI174MM-mini to not have to worry about anything. Have it, love it, never came close to not finding stars.

 

ASI290MM-mini to save some money. You should be OK with an 8" + reducer. 


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#14 NuclearRoy

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Posted 06 April 2020 - 02:18 PM

I'm using the ASI290MM-Mini with a Celestron OAG and Edge 8.

So far, always been a few usable stars.




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