Regarding your examples, the first one is quite nice, but the second have some basic flaws, like shooting f:8. You want to shoot stars wide open.
Yup. As long as the lens doesn't have any particular flaws like excessive coma when wide open. But in this case, it does look like massive user error has contributed to the poor results in more than one example.
That doesn't preclude the general gist of the discussion though.
You need all the light you can get.
The E-M1 is no king of low light photography, but is way ahead of what was available a few years ago, including FF DSLRs,
Hmmm. How many years are we talking about here? I have a feeling if you compared a 9 year old D3/D700 against a current EM1, the Nikon would still be noticeably better at astro stuff.
so is all about technique. Yes you can get a far better image with a FF DSLR or a Sony FF mirrorless, but at what cost in money and size/weight?
Interesting comment. I generally agree (although now I think about it, its NOT all about technique. Its about technique AND the right gear!), but lets look at an example of the problem in what to buy.
A large percentage of star shots that people want to take involve capturing a large swathe of the sky (get a large chunk of the milky way in for example) and often with also some land based content to give it context. Lots of people like a wide 14mm (in 35mm FF terms) type of lens. Its one of the reasons the 14-24mm f2.8 nikkor is so popular. It is however pretty chunky, and its not cheap.
This necessitates a wide angle lens. Now as an olympus shooter, you do have the new fast fisheye as an option, but a fisheye is rather restrictive, so most people would rather a rectilinear option. The Oly 7-14/2.8 is probably your best bet.
The Nikon lens is £1450. Phew. And its 970g. Double phew.
The Oly is £830 and 'only' 534g. Much nicer.
But the Nikon lens fits on a FF body that will give you considerably cleaner results. And it will be immediately noticeable at the settings needed for things like 20 sec ISO6400 shots. Equivalence can't save you here as you'll be shooting both systems wide open at f2.8 and the shutter speed will be limited to how long it takes for stars to streak. In this case, as FF sensor WILL give you noticeably better results.
So how much are you willing to pay for that extra quality FF will unquestionably give you in this particular scenario.
Not easy to answer. Especially as the Panasonic 7-14 f4 is cheaper (£740), considerably lighter at only 300g (why was it people started using MFT in the first place?) and 'only' gives up one stop penalty for this. Yet a number of people ARE prepared to pay the difference both in cost and weight for this. It seems to be worth it to them. Strange that so many will stop there though.
The other fly in the ointment of ultimate decision though is that the FF shooter has another choice. The 14mm f2.8 samyang prime. Its just as wide. Just as fast. Optically excellent. Low coma. Costs £270 and weighs a bit LESS than the Oly 7-14. Yet on the FF body, you would still get the superior noise performance without giving up anything else.
Wow. And its £560 CHEAPER than the Oly !!
All of a sudden a nice NEW Canon 6D at £1100 or a Nikon D610 at £999 to hang it off seems a much more attractive option when you factor the lens costs into things. Buying a second hand FF body even more so (especially with a load of FF mirrorless Sony's on ebay)
For most astro stuff, this is one of the situations where you are pushing up against the limits of ALL systems. Any weakness is going to show and you've basically got three options. You've either got to:
1. Accept the limitations (but don't deny they exist!!) and do what you can with what you've got
2. Don't shoot that type of image in the first place. Shoot something else.
3. Or buy some gear that will give you better results. And since you can't currently get a 7mm f1.4 MFT lens, that pretty much means looking at a FF setup.
Honestly, if one is thinking of doing astro seriously, picking up a 14mm 2.8 samyang and say a second hand FF body is a very, VERY compelling option. I don't understand why more people here don't consider it, especially when the conversation starts to get around to buying some pretty expensive mft lenses!
