Quote:
Originally Posted by JA
Which Fullframe DSLRs and Fullframe mirrorless cameras do you have and have you tried in a back to back comparison against which Astrocams?
There are many incredible images taken with DSLRs, just take a look on Astrobin. Also the fact that you have a budget which precludes a Fullframe Astrocam or APS-c Astrocam + Reducer led me to suggest a modern Fullframe DSLR or Fullframe mirrorless to use with your 90mm f/6 since you wanted a large FOV. The same field of view your 90mm f/6 is capable of in fullframe equivalent terms.
It's your money/choice, but whilst astronomy.tools may tell you the FOV with different focal lengths, does it also tell you how much light your telescope has collected and is now lost (not used) by the smaller sensor.
The Askar 400 has a full-frame image circle and if you image with anything other than a sensor capable of using all the light collected by the telescope, be it a 1) Fullframe sensor or 2) APSc sensor with reducer, then you are wasting the light collected by the scope - LOTS of it, in your case: , if you use a 4/3" sensor you will loose approx 2 stops of Light i.e: 75% light collected is lost or not used. It defeats the purpose of using multiscopes on the same image to save imaging time or go deeper in the same time.
What I am saying is that unless you use the full image circle of a scope you are loosing valuable light collected. In your case up to ~75% of the light your proposed Askar 400 collects will be lost/un-used.
Using the 135 f/2 lens wide open may not have been the best path forward for astrophotography as it is primarily designed as a general use and portrait lens and has some softness at f/2. I will add more info on this issue here later, if there is interest and if I can find some further data on this lens.
One further comment:
The budget you mentioned of $1500 to 1800, you don't say if that's $US or $AUD or other, but I would have thought that could have got you an APS-c astrocam possibly new (depending on the make/model) or certainly used for that budget. Then when you have more funds, or if you get a good deal on the APSc camera, you can purchase an appropriate focal reducer.... and then you are good to go on your 90mm f/6.
Best
JA |
Ok, if i really really can understand your points better then i will ask those questions based on what i understood from your answers/points.
1. So if using for example a RASA scope at F2 with 1" sensor will not be faster than using a 6" refractor for full frame with a full frame camera, say using Ha filter, so a full frame camera will always make faster data than F2 scope?
2. Why people don't use full frame cameras to have faster data if they bought like RASA or Celestron SCT with Hyperstar and end up using smaller sensors? No sense if a small sensor will eat up image circle which will reduce the light gathering, so either they are wrong or you are wrong or they don't care, and honestly speaking i don't care also because i don't want to like change many things.
You still missed the point of multiple scopes, even if i use a smaller sensor, if i use multiple scopes at once it will collect data as fast if not faster as using one scope with a full frame, i never had any night that i can capture a data for 4 hours or longer, so if one filter i need like 1-2 hours means i will not finish many targets in two nights, but if i can use more scopes at once, each filter can have like 2-4 hours of imaging individually at once, with a full frame mono i still need long time exposure, means i have to keep changing filters, and one full frame camera of astro is more expensive than my mount and my camera and filters almost.
I have Canon 1DX and Sony A7R as my latest full frames, i still have Canon 1Ds3 and 1Ds2 and 5D first one but mirror is off, i tried my A7R and 1DX only for Pleiades and Orion against my QHY163M with filters, i live under Bortle 8/9 with high humidity and heat, so noise is too much, i now have APS-C color camera cooled, so kind of i won't re think about DSLR for now, i still learn with this APS-C, and you know what, i used it with my 8" F5 Newt for a cluster for like 2 hours and it didn't do any good, in fact my QHY163M with RGB for 2 hours did better, but i didn't make more clusters with mono as i hate changing filters and re focusing to make sure they are all parfocal or in focus, and many times clouds is coming or guiding lost in the middle so i have to try make more data, simply put under my conditions a mono is always best, and i still will use a mono paired with data from color as well, all told me that the details are mostly coming from Ha and Lum filters, so doing Ha L RGB with one scope for 3-7 nights per target??? No thanks.
Should i show you results where people used multiple scopes and small sensors or you are not interested? Or they used magic to make it work, because sometimes i feel like some people they don't know things about it so they start to give advises and opinions without they did by themselves really, or they failed while others succeeded and they assume all others will fail as well.