Canon T7i support

Left message earlier regarding issues with using my canon T7i with Prism. Whenever I connect it and try to image greater than 30 seconds I get this error message “ ERROR: exposure time greater than 30 seconds is not supported by bulb mode, change dial to bulb mode” there is no B setting on the dial of Canon EOS cameras, to get Bulb you must set the dial to M and select Bulb option from the cameras menu. I did that and did try many permutations of camera/computer/Prism power on/off/connect with the T7i without success. Tested the T7i in bulb mode with Prism today(new USB cables), same error message, disconnected Prism and tried exposures greater than 30 seconds using Astroart 7, BackyardEOS, and Sequence Generator Pro and had no issues, all programs were able to expose greater than 30 seconds on the same camera settings. I visited the Alcor Prism forum and there was a thread from 2018 about problems with Canon EOS type cameras. It was unclear whether the problems were ever solved; owning to the program authors limited access to Canon Cameras and Canons SDK. What I really need to know is whether this problem is unique to me and my T7 or is it systemic to the program? While I plan to upgrade to an Astro mono camera next spring/summer for the present time the T7i will be my primary camera. I really need some follow up on this issue otherwise I can’t justify the purchase of Prism… Thanks for your time.

My apologies about the delay and lack of information. I have found a possible workaround with an open source ASCOM driver for DSLRs, please have a look:

To know more, the best is that I would have the camera here and see what is happenning.
Also LOG file could help somehow.
Nevertheless, there is a wide wide variety of EOS camera around.

On top of that this is very confusing because camera name is different from EU / JP to US. Almost all behave differently from another. Especially B exposure is handled differently camera from camera…on some there is a knob to set, on other this is by jumping from 30s to B exposure by software … etc etc.

We have here “in house” 20D camera, 5DMkii , and an old 40D. This is not possible for us to have all cameras from CANON, this would necessitate to buy 40 cameras… and have them to be tested one by one.
We are thinking removing all DSLR cameras in Prism v11… or say that no support can be provided on this.
We recommend to use a genuine astro camera like ZWO, QHY, … that are much far superior and optimized astro camera compared to DSLR.
Another idea would be to find a suitable ASCOM driver for CANON camera (like Hamza reported), may be this would help out, but not sure that this is available.

There is an interesting thread here :

Thank both you for your responses. I installed the DSLR ASCOM driver last night and will test it out with the T7i/1200D today or tomorrow. In the meantime, I will use my wife’s T5/1200D which seems to work with Prism with only a few small glitches. I feel Prism is a fantastic piece of software and I want to continue to use it now and into the future. So, I think I will take Dr. Calvadore’s advice and change over to a dedicated Astro Camera. This is a little sooner than I planned, but I have an unused Primelucelab Eagle 3, I purchase over a year ago and is still in the box, never even powered up. I am going to put up for Trade on Cloudy Nights Classified section for an Astro Camera. We will see how that goes. In any case thank you for your suggestions, time and interest. I will continue to be a dedicated Prism user (be prepared for more questions). Best Regards, Bill