On Sun, 2014-06-08 at 15:31 -0400, Patrick Shanahan wrote: > * Leonard Evens <[email protected]> [06-08-14 15:18]: > [...] > > Thanks for the help. I've downloaded the 2.8 version of slr-Nikon.xml > > and installed that. > > > > But that still leaves my question about whether or not I can use the > > corrections in there for my lens for use with my Nikon D800. The entry > > specifies 1.5X which is right for DX, but not for FX. It is a hassle > > for doing my own calibration, although I've done it in the past. > > If darktable works correctly, and I expect much ado to have occurred if it > did not, the (correct) crop factor *should* only be applied to DX cameras > and not to FX; ie: should follow definition. The dark horse would be > using the D7100 in 2x mode or an FX camera capable as my D3 of DX mode, > would the correct crop factor be applied.
I should have explained more carefully what I meant. I also have a D800, an FX camera. The entry in slr-nikon.xml for all 70-300 mm lens specifies the factor 1.5X, meaning that the calibration was done with a DX camera. When you do the calibration, you must specify that factor. If in fact you use the lens with an FX camera, for which the factor would be 1.0X, you might get different results. I plan mainly to use the lens with the D7100, but there may be occasions when I want to use it with my D800. In that case, to use darktable's Lens Correction, I would have to specify that the camera was some DX camera, in order to pull up the lens from the database, since there is no entry for my lens with a 1.0X factor. I can, of course, do that, but I suspect the corrections wouldn't be quite accurate. To get accurate corrections, I might have to calibrate the lens on my D800 myself, unless someone has already done that. I speak from experience since I've already been through this with my 70-200f/4 lens. The entry in the database for that lens is for DX format, and I had to calibrate it myself. I suspect these lens all have very little distortion, so the differences are in fact very small. > > I believe you have no problem using an FX lense on a DX body, most of my > lenses are FX. And many photos after editing crop show little need of > rectilinear correction or vignetting, the most affected areas are cropped > out. You did mention soccer and capturing a full frame (not indication > FX) keeper not immediately in front of you is extremely difficult. > > gud luk, Just yesterday, I got some shots using my D7100 and my new 70-300 mm lens, with VR activated. I took the pictures handheld, and I was surprised how well it worked. I was concentrating on my granddaughter, and unfortunately, she wasn't in the action very often, despite being the best payer on her team, so I didn't get any exciting shots. But I will have other opportunities. Unfortunately, her team lost, but closely to the best team in the league. I got the D7100 and the 70-300 mm lens after trying to use a 70-200 mm lens with my D800. I felt I needed higher resolution than my old d90 could provide. I even contemplated getting a $2600 80-400 mm FX lens, but it seemed to make more sense to upgrade my D90 to a D7100 with 4000x6000 resolution and get a 70-300 mm lens. I hope eventually to make some 16 x 20 prints with the new combination. -- Leonard Evens [email protected] Professor Emeritus, Department of Mathematics, Northwestern University ------------------------------------------------------------------------------ Learn Graph Databases - Download FREE O'Reilly Book "Graph Databases" is the definitive new guide to graph databases and their applications. Written by three acclaimed leaders in the field, this first edition is now available. Download your free book today! http://p.sf.net/sfu/NeoTech _______________________________________________ Darktable-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/darktable-users
