This is a follow-up to your previous request #24741 "deep sky magnitude limit request"
I thought I'd try once more to see if there is any chance of changing the way the magnitude limit of deep sky objects changes as you zoom in and out. I may be the only one that is bothered by this, but it is a major annoyance in an otherwise excellent piece of software.
I use Sky Safari on an iPad Air with a 9.5" diagonal screen. I do only visual astronomy with a manual 20" Dobson scope. The issue is that I can set the field of view for one of my eyepieces, and then set the magnitude limit on DSO's to some value. This gives me an idea of what I can see at the eyepiece.
Then, if I zoom out or in, the magnitude changes dramatically, and I have to re-set it to the desired value.
I collected some data on this and it is shown in the attached image. The X-axis is the angular size of my screen (the vertical dimension, in landscape mode). The Y-axis is DSO magnitude. I start by setting the limit to +15 and the angular size to 0.25 degree. The dark blue curve shows how the magnitude limit changes as I zoom in and out. The change is exponential.
The pink line shows that the software is capable of retaining the +15 setting all the way out to a 10 degree field of view, and it only drops to +14 at 30 degrees.
The blue rectangle shows the range of field of view for my various eyepieces. I change eyepieces to get the best framing and exit pupil size for specific targets, yet I want the same magnitude limit. I also need to zoom out much further to look for other objects in the region.
Since magnitude varies on a logarithmic scale, it seems excessive to have that value change exponentially with the inverse of the field of view.
Thanks for your consideration. I still recommend Sky Safari to all my astronomy friends.