Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Rule of 500 with DSLR on SV80 Access telescope

  • Please log in to reply
1 reply to this topic

#1 perezbenitoa

perezbenitoa

    Lift Off

  • -----
  • topic starter
  • Posts: 6
  • Joined: 08 Nov 2017

Posted 21 October 2019 - 06:44 PM

hi all: I am interested in getting started with basic imaging using my canon DSLR (crop sensor), my 80mm refractor telescope (Stellarvue SV80 Access), and AVX mount.  I have been going through lots of tutorials/videos on astrophotography with DSLR and have learned about the rule of 500. Every instance of this rule, has been used with DSLR camera lenses. When I use this rule of thumb with my telescope, the numbers don't make sense to me and not sure what I am missing or how to adapt for use of eq mount.   I plan to use my telescope with 0.8 focal reducer, which results in 448mm foca length.  then accounting for crop factor of Canon DSLR (1.6), I get 716, which results in shutter speed of <1seconds.  I know that using an eq mount, I can have much longer shutter speeds. Is there an alternate rule of thumb to use when using an eq mount or am I using the formula incorrectly?



#2 bobzeq25

bobzeq25

    Hubble

  • *****
  • Posts: 17082
  • Joined: 27 Oct 2014

Posted 21 October 2019 - 07:15 PM

hi all: I am interested in getting started with basic imaging using my canon DSLR (crop sensor), my 80mm refractor telescope (Stellarvue SV80 Access), and AVX mount.  I have been going through lots of tutorials/videos on astrophotography with DSLR and have learned about the rule of 500. Every instance of this rule, has been used with DSLR camera lenses. When I use this rule of thumb with my telescope, the numbers don't make sense to me and not sure what I am missing or how to adapt for use of eq mount.   I plan to use my telescope with 0.8 focal reducer, which results in 448mm foca length.  then accounting for crop factor of Canon DSLR (1.6), I get 716, which results in shutter speed of <1seconds.  I know that using an eq mount, I can have much longer shutter speeds. Is there an alternate rule of thumb to use when using an eq mount or am I using the formula incorrectly?

The rule is for a camera/lens on a tripod.  You're using a mount with electric motor tracking, it simply does not apply.

 

If you haven't gotten the mount yet, I urge you to spend a few hundred more on a Sirius/HEQ5, or an iOptron 30PRO.  You'll be amply repaid in less frustration and better performance.  The mount is the most important part of the setup.  It's quite unintuitive how good a mount is needed, and what it costs to make a mount that good.

 

There's no similar rule of thumb with an electric mount.  You'll be shooting many subexposures, and determining the proper length of each is a site specific process, to be learned.  Part of the fun, but complicated, hobby.  This book will be quite helpful.

 

https://www.amazon.c...d/dp/0999470906


Edited by bobzeq25, 21 October 2019 - 07:18 PM.



CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics