Best lens for PT gui

Matty W wrote:

Tom Axford wrote:

Matty W wrote:

what is it

Any lens.

I should have been more specific.

I'm making HDRI probes for on-set work.

So I want to take a minimum of exposures and get a good result. At most one or two minutes per location. Of course I need to bracket exposures for HDRI.

I use a Rebel XT and 4.5m Sigma but want to upgrade to a Panasonic S1.

I was looking at this:

https://www.adorama.com/rkhd8mn.html?CategoryID=246488

And a Nikon mount adapter, but it seems the image circle is a bit too big. I guess I could take another exposure pointing up? Thanks.

Fisheye doesn't mean what people think it means; a circular image doesn't imply 180 degree coverage, nor is there a standard projection formula used by all fisheyes.

I have the Opteka 6.5mm f/3.5 (which is pretty much the same optics as what you're looking at) and, if you do the math, expanding the APS-C crop to FF doesn't quite give 180. To give 180 corner-to-corner on APS-C, you need an image circle of about 28.4mm diameter (on 1.6X crop Canon APS-C it would be 26.82mm). However,FF is 36x24... and 24mm is less than 26.82mm. However, on a focal reducer on FF (yes, I said that right -- e.g., a focal reducer on my A7RII) it gives more like 190. Here's where I first discussed that trick .

Of course, there are tons of ways to get 180 circles on FF. However, don't expect things like the old Spiratone fisheye adapter to do it -- it says 180 degrees, but is more like 165. Sigma's 8mm f/3.5 is supposed to do it, as is the Peleng 8mm f/3.5 (which might be the cheapest solution). Some of the older conversion lenses also give more than 180; for example, my old Raynox gives about 185 with great image quality, but it is big, expensive, and very heavy to be sticking in a host lens filter thread....