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Before I discuss shooting in manual (we’ll do that in a later post), let’s learn about the most important aspect of photography: exposure. In a nutshell, exposure is the amount of light that enters the camera when you take a photo. This is dependent on 3 different factors — aperture, shutter speed, ISO. So let’s talk about understanding aperture, shutter speed, ISO and exposure. Aperture: Aperture is the size of the hole in your lens. This opening allows light to travel through and you can determine how much by adjusting the f-stop number. The lower the f-stop number, the bigger the hole and the more light that enters through the lens. The higher the f-stop number, the smaller the hole and the less light that enters through the lens. Aperture also controls depth of field. If you set your camera to a low f-stop number and the hole is wide open, you will get more blur or bokeh in your photographs. If you set your camera to a high f-stop number and the hole is smaller, more of the photograph will be sharp. I use lower f-stops for portraits and higher f-stops for landscapes. Your f-stop depends on the type of lens you’re using so let’s look at an example. If I were to look at my 50mm 1.4, I’d notice that the lowest number possible is f/1.4 for that particular lens. The highest number for my fixed lens is f/16. That means I can adjust my f-stop from 1.4 – 16 depending on the type of photo I want to take. Remember this if you ever get confused Low f-stop = big opening, more light, shallow depth of field (bokeh) High f-stop = small opening, less light, large depth of field Do you know how to adjust the f-stop on your camera model? Shutter speed: The shutter is what allows light to hit the camera’s sensor to record an image. It’s important to understand shutter speed so your images aren’t under or overexposed. The more light that is let in, the shorter the shutter speed needs to be to record an image. In low light conditions the shutter speed needs to be longer to allow enough light in to record an image. When hand-held shooting, I always remember that my shutter speed needs to be at least 1/60. If I’m using a lower shutter speed, I’ll pull out my tripod. Definitely use a tripod when you’re goal is to blur movement with a low shutter speed (i.e. lights from a car, people walking, etc). Here is a little graphic about shutter speed and action: ISO: This is the measure of the sensitivity of the image sensor. The lower the number, the less sensitive to light. The higher the number, the more sensitive to light. When you increase the ISO number, your sensor can capture images in low-light situations. However, increased sensitivity means more noise. Noise is another word for grain in a photo. The next time you increase your ISO to capture a picture in low light, examine it and I bet you’ll see grain. You should try to keep your ISO around 100-200 for highest image quality. And that’s your photography lesson for today. I’ll be back later with a few exercises to better your understanding of the exposure triangle. If you missed part 1 you can read it here. Filed Under: Photography26 Comments
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Promišljati fotografski – 4.dio Rukovanje fotoaparatom EKSPOZICIJSKI TROKUT: f-BROJ, BRZINA ZATVARAČA, ISO Pri fotografiranju je potrebno uskladiti tri međusobno povezana čimbenika ekspozicije. Ekspozicija je izloženost svjetlosnog senzora svjetlu. Ekspozicija će ovisiti o f-broju, tj. o otvorenosti objektiva (količini svjetlosti koju propušta objektiv ), o vremenu osvjetljavanja senzora (to vrijeme određuje zatvarač, tj. koliko je dugo otvoren) i o ISO vrijednosti (osjetljivosti senzora na svjetlo). Kad naučimo usklađivati ta tri čimbenika, spremni smo napraviti tehnički dobru fotografiju (osvijetljenu upravo onoliko koliko je to potrebno). f-BROJ (otvor blende) F-broj je vrijednost otvora blende (otvorenosti objektiva) i to je brojčana vrijednost koja po standardima udvostručuje količinu propuštene svjetlosti: f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16 i f/22, a može biti izražena i u raznim međukoracima: f/1.2, f/1.4, f/1.6, f/1.8, f/2, f/2.2, f/2.5, f/3.2, f/3.5, f/2.8, f/4, f/4.5, f/5, f/5.6, f/6.3, f/7.1, f/8, f/9, f/10, f/11, f/13, f/14, f/16, f/18, f/20, f/22, f/32. Otvor blende možemo kontrolirati na fotoaparatu. Dakle, fotograf sam određuje koliko će objektiv biti otvoren ili zatvoren za prolazak svjetlosti. Otvor blende (f-broj) je omjer žarišne duljine objektiva i promjera otvora objektiva. Što je f-broj manji to je otvor objektiva veći (blenda je veća). Svaki objektiv na sebi ima oznaku najveće moguće otvorenosti blende (1:4 – znači da se može otvoriti do f-broja f/4; 1:5.6 – znači da se može otvoriti do f-broja f/5.6). Objektivi s otvorom blende 1:1.2, 1:1.4, 1:2.8 svjetlosno su jaki i zbog toga su skuplji od objektiva s otvorom blende 1:4, 1:5.6 i sl. Svjetlosno jaki objektivi nazivaju se i „brzim objektivima“ jer je pomoću njih moguće povećati brzinu zatvarača i dobiti bolju fotografiju. Što to sve kontroliramo f-brojem? Dvije su osnovne stvari: količinu svjetla koja dolazi do svjetlosnog senzora i polje dubinske oštrine. Otvaranjem blende dovodimo više svjetla do senzora, dakle – brzina zatvarača bit će veća. Zatvaranjem blende do svjetlosnog senzora dovodimo manje svjetla, dakle – bit će nam potrebna manja brzina zatvarača. Uz to moramo istovremeno i kontrolirati osjetljivost senzora (ISO vrijednost). Na manje osjetljiv senzor morat ćemo „poslati“ više svjetla, a na osjetljiviji senzor manje svjetla. Navedeni tekst ulomak je poglavlja „4. Rukovanje fotoaparatom“ iz knjige „Promišljati fotografski“ autora Davora Žerjava. U 4. se poglavlju obrađuju teme: Držanje fotoaparata, Ekspozicijski trokut, f-broj (otvor blende), Brzina zatvarača, ISO (osjetljivost senzora na svjetlo), Fokusiranje centralnom točkom, WB (white balance, ravnoteža bijele boje), Korištenje histograma, RAW i JPEG. Impresum, sadržaj kao i neke od stranica knjige možete pogledati ovdje. Specifikacije: Cijena: 150 kn Format: 21 x 20 cm Broj stranica: 224, boja Uvez: meki Godina izdanja: 2011. Izdavač: Fotoklub Čakovec