ASI174 and ASI290 mini camera have very beautiful outlooks, small size, lighter weight, this is not a big deal.

We should consider much more…

How to  choose a good guide camera?

Many people may say : it must be small, suitable for different equipments(guide scope, OAG), stable working.

Yes, I think thoes are basic demand for a good guide camera, and ASI mini camera can do them well.

So, what else we do care in the deep of our mind?

I think there will be three potential requests: high sensitivity, precisely guiding, big FOV.


High Sensitivity

Sensitivity is the first thing we considered. it is very important to look for a guide star. So at the beginning, we were considering to use mono sensor to design our guide camera only. Because mono sensor has much higher sensitivity than color ones. After that, we carefully compared the sensitivity of our sensors. At last, we decide to use 290 and 174  mono sensor. As we know, 290 and 174 mono sensor have about 80% QE peak, can detect more stars in view. Also, we can shorten the exposure time in guiding.

Precisely Guiding



ASI290 mini is designed for precisely guiding. 2.9um pixel size can give you a higher arcsec/pixel than 224 or 120 camera. Which means in same guide scope, 290mini can detect slighter movement of stars. ASI290 mini can improve about 30% guide precision than 120mm.









ASI174 mini is designed for Big FOV guiding. This is very useful in OAG to looking for a guide star. When you using OAG guider to work with Ritchey-Chretien or Schmit-Cassegrain telescope, the hardest part is to looking for a guide star. ASI174 mini have 1/1.2″ big sensor which means you can have  4 times bigger Fov than 120mm.





Smiling Face

The back of ASI mini camera is like a smiling face, it’s mouth is Type C USB port, which is widely used in mobile phones. And it’s nose is ST4 port, for guiding. Every time, you use mini camera, there will always a smile face stay with you in the dark nights.

174miniVS290miniFocus like a eyepiece

ASI mini camera and eyepiece can  reach focus at same position. You can focus with an eyepiece, and put ASI mini camera into 1.25″ holder.

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Works on OAG

Mini camera is very suitable for OAG, it can have much biger focus range than normal ASI cameras. Never to worry about guide camera can not focus with main camera at same time.

OAGASI mini camera is available now! You can order it form us or our dealers!

Wish you all have clear skies!


11 Responses to ASI174/ASI290 Mini Camera – Upgrade Your Guiding System
  1. Would the main advantage of using the ASI 290mini in Celestron’s OAG be its bigger focus range. Because it seems as if the regular ASI 290MM would definitely be more versatile because it could readily be used for imaging as well?

    • Sam Wen

      you can use 290Mini for imaging too

      • Hi Sam,

        I knew it was possible … what I should have said was it was less suitable. At least, that’s what the folks up in the Cloudy Nights link upmthere are saying.

        So, as far as guiding is concerned (forgetting imaging of any kind) would the ASI290 mini or the ASI 174 mini be better than their regular counterparts?

  2. Hi Sam,

    So, if I’m using Celestron’s OAG with either my full frame Nikon D810 or my APS-C Nikon D300 for now, which of the two would be best to purchase for guiding … the ASI174 mini or the ASI290 mini? I’m using a Celestron 1100 Edge HD. I live in an area with a Bortle number somewhere between 5.5 and 5.6 … on the boundary area between yellow and orange, but most times I will be using the scope at a dark sky site. Thanks.

    • Sean Wang

      Hi Clayton. Your telescope have over 2000mm focus length, I think 174mm mini will be a good choise, it have big Fov for guiding, much easy to find a guide star.

  3. Hi Sam and Sean,

    I have a 120mm refractor and I have just bought an OAG to go with my ASI 071 Pro. At the moment I am going to try my ASI120MC-S as the guide camera, Do you think this would work? And if not which guide camera would work best with my set-up, the 174 or the 290? Thanks.

  4. Hi Sam,

    This may be a strange question, but
    1. Can the 174 mini be used with a filter wheel … ie the 7 filter EFW?
    2. If so, does it need any special adapters?

    • Sean Wang

      mini camera has 1.25″ standard output adapter can be used with a filter wheel, just like our usb3.0 cameras. not need more adapters.


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