Tue, 02/22/2022 - 17:14
My question is, will Starlight Xpress Trius Pro-35 Monochrome be a good fit for my Celestron C8, (Non EDGE, w/ or w/o focal reducer). My tracking/guiding is decent with over 7 minute exposures succssesfull.
https://www.bhphotovideo.com/c/product/1572648-REG/starlight_xpress_trius_pro_35_monochrome_ccd.html/?ap=y&ap=y&smp=y&smp=y&lsft=BI%3A514&gclid=CjwKCAiAsNKQBhAPEiwAB-I5zU-Hlbyed67Aq9evI7hlVvenepxAuFeNmg75m8f1xhAqpY_tQaf0RxoCVfQQAvD_BwE
That looks like a very good match for photometry. Depending on your local seeing conditions you could use the native image scale or bin 2X2 and still have a nice wide FOV. You wouldn't need to use a reducer with the C8.
Phil
Thanks Phil...I was told the non edge will have adverse effects with a FF sensor. Is this not true for photometry?
See next comment.
Of course, distortion of star images at the edges and corners would be of concern for astrophotography. For photometry I'd say that is not as important. Even if you would not want to use the distorted and vignetted stars in the corners for comps, I think having that larger FOV makes is easier to find and identify targets, and gives you more flexibility in moving the target off center a bit to include a few extra comps.
That said, I have never used a full frame sensor in a standard C8. Perhaps we will get some comments from observers who have experience with this combination.
Phil
Phil, thank you so much,,,,,this has been very helpful,,,,i understood the point of paying for sensor that youre not using, however im getting it at a good price so i think its worth it,,,,thanks so much for your insight,,,,cant wait to get started in photometry
Phil - For the above setup, should I be using a 2inch Johnson V filter? If so, can you recommend one?
Alfredo,
Yes, start with a Johnson V. As for the size and manufacturer, it depends....
Do you have a filter wheel for the camera? If not, do you have a plan for how you will connect the filter to the camera/telescope system?
Phil
i have a 2in zwo filter drawer
The first consideration is that the filter must fit in the drawer. I don't know these specifications.
If the following will fit, I would consider the Custom Scientific and Badder Filters. The Optolong V would also be fine, but as far as I know the Optolongs are only available as full sets (UBVRI). With CS and Badder you can buy only the filter you want.
If you have a green astrophotography filter for this drawer you have another option. You can use the G filter as a substitute for V. In this case you would report your magnitude measurements as TG (tricolor green). Doing this would get you started with photometry while you wait for the availability and quality questions for the newer BVRI filters to be cleared up.
Phil
Hi Phil
the filter drawer fits 2 inch filtwers but has a 1,25 adapter, do you suggest getting the 2in or 1,25? ive seen the baader 2in that a green, do you know if these are good?
see below:
https://www.baader-planetarium.com/en/filters/photometric-filters/ubvri-bessel-v-filter-%E2%80%93-photometrisch.html
Hello! A lot of folks used the 8" SCT to do 35mm film astrophotography. You can probably get a good feel for edge effects by googling those photos. When I tried film with my 8" Meade LX200 classic, other than vignetting, I don't remember significant problems with the edge. Currently, I use it at 1200mm focal length and an ST-402 camera (at least, I will when I get it back up after my move!)
The Trius would be a good match in terms of pixel size for the C8. Without a focal reducer, it yields about 1 arc-sec per pixel (FOV about 1 x 0.7 degrees); with a focal reducer, about 1.5 (FOV about 1.5x1 degrees). The only problem with a focal reducer is that it would limit the excursion of the C8 on a fork mount when placed at the correct back focus. With a focal reducer, the image circle goes down to about 28mm, which is fine for an APS size chip, and should work even for larger chips with flat fielding.
The spectral response looks fine. The Trius appears to have anti-blooming? If so, that would limit the linear response compared to non-ABG cameras. I've read posts from folks who use ABG chips and they do good work, but if you're starting from scratch, the recommendation I've always seen is to try to get a camera without ABG.
Perhaps you could ask on the forum if anyone uses the Starlight Trius models? They can can give you first hand information about its response, linearity, and usefulness. Best regards.
Mike