sigma 35mm 1.4 IS vs non IS?

[iphonemaster93]

So I took this shot, shown below, with my 17-55 2.8 and later on, I tried doing it with the Sigma 35mm 1.4 and none of the shots came out to be this focused. Does anyone know if it's because there's no IS on the 35mm or is it because I just got unlucky with all of my photos? Is it possible to get this clean shot with the 35mm 1.4 or do I have to be on a smooth road to do this? I was trying it on 280N from Pacifica up to South SF trying to shoot a random drift car and all of them were too shaky. Thanks!

[ebiggs1]

"...  do you need a prime or a telescopic with a very wide aperture?"

DOF is dependant on several factors.  Blurred BGs are also dependant on several factors.  You best answer is to use the web site mentioned above, or any other that offers such calculations.

As a rough rule of thumb, the widest aperture will give the least DOF.  No matter whether is is a prime or zoom, wide or tele.

Of course a f1.2 50mm is going to have a very shallow DOF at f1.2.  More than the f1.8 version but either stopped down to f4 for example, the DOF will be the same.

[iphonemaster93]

Is there an app for that? I don't want to constantly be launching safari on my phone just to check the distance to get the best shallow depth of field LOL.

Also, What's the ball park equivalent of 1/30-1/40 F10 rolling shot if I were to do it at a shutter speed quicker than 1/100? would I have to widen or make the aperture even smaller? 

[ebiggs1]

Is there a reason you don't use normal f-stops?  But your query is basic photography stuff.  If you reduce one you increase the other by the same amount and vice versa.

When you gain more experience with your qear, you shouldn't need any chart or app.  It is just something you know.  I never use those charts anymore unless someone asks what is the exact DOF in inches.

[iphonemaster93]

tbh I'm just still playing around. I never really questioned how well the DOF worked with the 18-135mm, we just happened to get the new Lexus IS line on our lot and I wanted to get a good HD quality photo for myself and to upload onto Instagram. I've always just used the 135mm to shoot photos for our online picture database so I was wondering how far back I'd have to stand from the car to get a shallow depth of field. I ended up having to stand 10-15 feet away at F5.6 shooting at 85mm to get any decent blur in the background with the rear end of the car sharp. So far, I've had the best results with my 17-55, I'm still learning the 35mm.

[cicopo]

As an FYI the DOF changes between a full frame & a 1.6 crop body. The DOF is shallower on FF all other things being equal.

[iphonemaster93]

I've only played around with a crop sensor x'( I don't have and don't have the funds for a full frame right now. I would get one but with my current skill level, I don't believe it is time for me to get a full frame at the moment haha. I'm guessing that's why I use my 17-55 for mostly all my shots that have to do with DOF because I can use whichever focal length I want and keep a constant aperture, no matter how far I am from my subject. However, it still bothers me that sometimes, I can't get the DOF I want because I'm not standing at the correct distance to achieve that DOF.

[ebiggs1]

"I would get one but with my current skill level, I don't believe it is time for me to get a full frame at the moment haha."

Skill level is not the determining factor for getting or going FF.  The cameras work exactly the same. No matter whose hands they are in.  Lots of folks see the FF as an advancement.  It isn't in the terms of skill.  The product it produces has different properties.  That's all.  Up until the 1Dx, Canon's flagship full on pro camera was a crop sensor body.

[iphonemaster93]

So the full frame is just a huge benefit and an add-on for people who wanted to be able to capture exactly what they were seeing with their eyes?

[ebiggs1]

"So the full frame is just a huge benefit and an add-on for people who wanted to be able to capture exactly what they were seeing with their eyes?"

Wow, I don't even know how to respond that, except, NO.   That is not even close in any respect.  First every camera is FF.  I don't care if you have a G15 P&S, like I do.  Or, if you have a 1Ds Mk III, a FF, like I do.  You get what you see in the view finder. Nothing less, nothing more.

[iphonemaster93]

I don't understand. what's with the crop sensor factor then?