Moonlight

by Jakub

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visits member for 4 years, 8 months
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2d
comment Can a Sigma dp3 quattro be used for Macro Photography?
@knb Focus stacking is used to extend DOF, it wont help with resolution at the focal plane. Essentially the DP3 Quattro will photograph a 70mm x 45mm area, any smaller than that will require cropping, how much cropping is required depends on how much smaller, and how much loss of resolution is acceptable is up to you. That's about all I can say to answer your question, other than the poor high ISO performance of the camera can avoided by using a tripod and longer exposure at ISO 100.
2d
comment Can a Sigma dp3 quattro be used for Macro Photography?
@knb Cropping to a 1cm x 1cm square at maximum magnification will drop you from 20 megapixels down to 0.6 megapixels, not exactly what I'd call "more than enough pixels"...
May
22
comment Imbalance in green pixels
Sounds like an instance of PRNU (photo response non-uniformity).
May
22
comment Do wide angle lens adapters maintain DOF but still keep the higher FOV?
Yes APS-C lenses will technically fit, and you can also mount the adapter on a full frame mirrorless body, but the image circle will not be large enough in both cases so it's not particularly useful...
May
22
comment Do wide angle lens adapters maintain DOF but still keep the higher FOV?
It's worth pointing out that the Metabones speed booster is a rear mounted wide converter and so only works with full frame SLR lenses on APS-C mirrorless cameras. It will not work on DSLRs, as there is no space for the adapter (due to the mirror box).
May
19
comment What determines the fastest shutter speed for an electronic shutter?
Yes there are CMOS sensors with global shutters, e.g. the one in the Blackmagic Production camera. It's more difficult to implement than in a CCD but it's perfectly possible.
May
19
comment What determines the fastest shutter speed for an electronic shutter?
That's only true for non global shutter CMOS sensors. CCDs or CMOS sensors aren't constrained by how fast data can be read out (in a global shutter architecture charge is transferred from the pixel to a buffer until the camera is ready to read it out). The first generation digital cameras with CCDs would often shoot at 1/1600s, faster than the fastest mechanical shutters available. They could have been made faster if the manufacturers desired (they're only limited by the switching speed of the sensor).
May
18
comment HDR and RAW dynamic range clipping, mapping, and compression
@feetwet The camera's JPEG engine probably clips the shadows a bit, as for lightroom it depends on what settings you apply - if you crank the exposure slider all the way up then it's going to clip the highlights!
May
17
comment Why is it called “macrofocus” and not “microfocus”?
@Skaperen you can attach a microscope to a camera just like you can attach a macro lens. It is not true that microscope refers to the intended subject and macro refers to what the lens does! They both refer to the size of the subject, which is larger with macro lenses. Please remove your original comment, which implies you're summarising my answer but instead says something completely different. You may leave your own answer if you wish!
May
15
comment Sony a7: Is there more noise for ISO <100?
@inkista only if you're shooting JPEG, if you're shooting RAW you can just keep the camera at ISO100 and overexpose if you're in dire need of a slower shutter speed, and get the same result.
May
15
comment Why is it called “macrofocus” and not “microfocus”?
@Skaperen not really, microscopes make even smaller subjects into big images. Macro lenses simply deal with larger subjects than microscopes.
May
14
comment Which has a faster write time: RAW or JPEG?
@RomeoNinov Of course (Canon's RAW compression uses JPEG and then does simple entropy encoding on the difference between the JPEG compressed version and the original), my point was that compression/processing are generally not the bottlenecks, writing data to the card almost always is.
May
14
comment Sony a7: Is there more noise for ISO <100?
Looking at the graph on Bill's page, the only anomaly appears to be the ISO80 result, the others are all very close to 10.5 EV. I don't think this can be the result of compression (I've been studying their algorithm a lot recently) all that happens in the shadows is that values are shifted a bit to the right (i.e. they go from 14 -> 13 bits). My guess is that there's some sort of systematic error in how the RAW values are corrected digitally for for ISO 80.
May
14
comment Which has a faster write time: RAW or JPEG?
JPEG compression is done in hardware and is very very fast.
May
14
comment Sony a7: Is there more noise for ISO <100?
@theJollySin it's important to note that you're unlikely to actually be able to see a difference of 0.3EV in DR, so the results are not exactly unpredictable, DR will appear to be pretty much the same at all settings between ISO50 and ISO200. As to why the feature exists, it's to allow for longer shutter speeds for people shooting JPEG, who would otherwise not be able to benefit from the extra headroom available.
Apr
29
comment Why are some big telephoto lenses so expensive compared to telescopes?
@BogdanWilli "fluorite will not "magically" reduce chromatic aberration" actually it will, but it's not magic - it's physics, fluorite is a low dispersion material which means different frequencies of light spread out less when passing through, so it will reduce chromatic aberrations compared to a similar element of standard optical glass.
Apr
29
comment Why are some big telephoto lenses so expensive compared to telescopes?
You don't need fluorite to make a lens shorter than it's focal length (telephoto), there are many telephotos at much lower price points. Fluorite reduces chromatic aberrations.
Apr
28
comment Why are some big telephoto lenses so expensive compared to telescopes?
Yeah it's mostly #4, many more elements and a much more sophisticated optical design to reduce aberrations in the corners of the image. You can spend $180,000 on a telescope, however.
Apr
22
comment What is the difference between 16-bit and 32-bit high dynamic range images?
Photoshop also uses a linear gamma curve in 32-bit mode so you get more accurate blending.
Apr
17
comment Why is the field of view of my lens narrower than my calculations show it should be?
@BenJO I would try and rule out lens correction first as it's the most likely cause. Are you shooting RAW or JPEG?