Need a prime: Help me to analyse my focal length

JeffreyG wrote in post #15875337
To me the huge number of shots the OP took at 85mm suggest that his next lens consideration should include something like a 70-200 or 70-300 zoom.

I don't see a 'love' of 85mm focal lenght there, I see somebody who really wants a lens that reaches longer than the current 85mm limit he has.

Since his original comment is that the 50mm is too tight, why would he want an 85mm or longer? I'm not saying that it might not be something for him to look at in the future, but if I'm reading him right, his immediate concern is for something wider than the 50mm for indoors in a social setting. I take that to mean family gatherings and parties and such. On a crop, something 28mm to 35mm might fit the bill. His chart shows a lot of use at 15mm, but that may just be landscape stuff, hard to say.

I'd say the 30mm 1.4 would be a great lens to buy in to. I personally didn't have the funds for it plus I wanted a lens that was somewhat less obvious on my camera than a 50mm which a 30mm really isn't it's just as big. I went with the 40mm 2.8 pancake though with that said if I stay crop for my next camera (possibly upgrading to a 60D or something similar soon) I'll definitely sell off a few of my less used lenses and buy a sharp copy of the 30mm 1.4

JeffreyG wrote in post #15875337
To me the huge number of shots the OP took at 85mm suggest that his next lens consideration should include something like a 70-200 or 70-300 zoom.

I don't see a 'love' of 85mm focal lenght there, I see somebody who really wants a lens that reaches longer than the current 85mm limit he has.

I noticed the same thing, was hoping he could give us some insight.

pulsar123 wrote in post #15874886
Sigma 30mm Art.

But if you don't have a flash, getting one should be your priority. Using f1.4 primes indoors without flash results in bad lighting and too narrow depth of field in most cases. Flash light bounced off ceiling and walls will give you a much more significant IQ boost than a f1.4 prime.

this...

since you're on a crop save some cash, and get the sigma 30mm over the 35mm...use the money saved and buy an external flash

I like my 35f2, the original, on the 60D.

JeffreyG wrote in post #15875337
I don't see a 'love' of 85mm focal lenght there, I see somebody who really wants a lens that reaches longer than the current 85mm limit he has.

I did look at that as well. And indeed many of the pictures I took with the 85 mm were people (candids). Here's my thinking: If I want to take a picture in these situations, I always can zoom with my feet (or crop it). These are not street candids, but social situations I am part of. But with a long lens I very often can not get wider - e.g. in a confined space of a room or similar. Does that make sense?

Apart from what is said about the peak at 85 mm there is a peak at 15mm, wich means that even 15 would be not wide enough.
I would suggest that the OP gets used to the idea of changing lenses when required, as a prime take one as wide as you can get or alternatively an UWA zoom. and at the long end a 135 or a 70-X00 zoom is the logical choice.
If you don't want to change lenses to often... get yourself another body.

As others have commented and given the spikes in your focal length plot at 15mm and 85mm, you probably need something wider than 15mm plus something longer than 85mm. The only "fast primes" I can think of that would do that are the Canon 14mm/2.8L (or the Sigma equivalent) and the Canon 135mm f/2. Sigma also has an 85mm/1.4 which is not longer but a lot faster than the 15-85. I have no personal experience with any of these lenses, but other members of this forum seem to think highly of them.

Consider this: a Canon 10-22 for the wide end and a 135/2L for the long end. The 10-22 is neither fast nor prime, but I find mine very useful in tight quarters.

I have a 15-85 and went through this process of choosing a fast wide(ish) prime for indoor lowlight work about a year ago. I ended up with the Sigma 30mm f1.4, after experimenting with both 35mm and 50mm.

Like the OP, I found the 50mm a bit too tight, and that was the main reason for choosing a wider lens. The choice between the Sigma 30mm and various 28mm and 35mm Canon lenses was not based on focal length, but the lenses available at the time (i.e. prior to the new Canon 24, 28 and 35 were released).

A year later, I don't use the 30mm as much as I thought that I would when I bought it. I like taking indoor portraits, and I find that a frame filling shot starts to show perspective distortion (or at least, more distortion than a similarly framed shot with a longer focal length), leaving a choice of backing off (a more environmental portrait) or accepting the distortion.

I find myself reaching for flash (430EXII) with the 15-85 on the camera more often than the fast prime, when I will be taking photos of people indoors. It is a very good combination, and the versatility of the zoom is handy (but obviously with a deeper DOF than the fast prime). As a previous poster mentioned, there is also less issue with inconsistent lighting.

That being said, I have taken some special shots with the Sigma. I'm currently looking at 50mm primes . . . .

Instead of looking at the focal lengths you used in ALL your "keeper" photos, try selecting your 100 favorite photos, then look at the focal length of those.

If you took 50% of your photos at 15mm but 0 of your 100 favorites were taken at 15mm, then you would be misguided to believe you need a prime near 15mm.

If you really want to know what you should get, then find your 50 or 100 favorites of each type of photography you enjoy for example...

favorite 50 portraits
favorite 50 landscapes
favorite 50 macros
favorite 50 wildlife photos
favorite 50 sports photos

do that, THEN analyze the focal lengths that were represented the most for each genre, then you'll know what kind of prime you need.

dodgyexposure wrote in post #15877002
A year later, I don't use the 30mm as much as I thought that I would when I bought it.

Thinking about this, I might end up at the same point as you did. Need to rethink things more carefully. Starting with using the 50mm more often and see, if I am missing the width of a 30mm or the versatility of a zoom more.

Thanks you all for your help and insight. Still didn't make up my mind. ----- This new sigma 35mm does sure look very nice.

Interesting data set.

While there does seem to be a non-trivial spike at 35mm, the Sigma 35mm f/1.4 is kind of pricey for a purchase which you're not entirely sure about. The Sigma 30mm f/1.4 Art is close to 35mm (while being farther from 50mm, the focal length of your other prime) and is quite a bit cheaper. That plus a flash will give you far more options than one 35mm lens for less money.

As a side note I have the original Sigma 30mm f/1.4 and have been quite happy with it. If you want to spend even less money you might get one of those.

i also recommend the 30 1.4, i owned the mk1 version when i had my 7d and it was on my camera almost all the time, it is an excellent lens all around and a perfect fit for an aps-c sensor. the new sigma 35 also looks great and I'm sure had i owned that lens instead of the 30 i would have loved it just as much. one question about your chart, what would it look like if you excluded the 50 f/1.4, would the 35mm range still trail behind the 50mm.

anyways food for thought.

bob

Thanks guys. The sigma 30mm/1.4 has indeed an attractive price. Two things I am worried about: barrel distortion and picture quality.

From the reviews I take that there is some distinct barrel distortion. This is also confirmed by dodgyexposure. Nothing more annoying then barrel distortion, if you thinking about taking pictures of people. How would you judge that and is LR capable of dealing with that properly?

Picture quality: The reviews shows a distinct softness at larger apertures. This worries me somewhat.

Can anybody comment on these two points for real life use of the sigma 30/1.4? A comparison with the new canon 28/IS would be great -

drmaxx wrote in post #15887338
Thanks guys. The sigma 30mm/1.4 has indeed an attractive price. Two things I am worried about: barrel distortion and picture quality.

From the reviews I take that there is some distinct barrel distortion. This is also confirmed by dodgyexposure. Nothing more annoying then barrel distortion, if you thinking about taking pictures of people. How would you judge that and is LR capable of dealing with that properly?

Picture quality: The reviews shows a distinct softness at smaller apertures. This worries me somewhat.

Can anybody comment on these two points for real life use of the sigma 30/1.4? A comparison with the new canon 28/IS would be great -

Ahh, I have assumed my distortion issue is perspective distortion - in order to get a frame filling portrait, I am close enough to the subject with the 30mm to get some foreshortening in the centre ('big nose' effect). There may be some barrel as well - I'll have to revisit some raw files and play around with the distortion correction a bit more.

Mine (current 30mm f1.4) is definitely softer wide open (I assume you meant wide open - smaller f number - when you mentioned 'smaller aperture'), much better by f2 and quite sharp by f2.8.

Those sharpness conclusions are based on focus chart test shots that I have performed (i.e. visual only, no imatest or anything like that). In real conditions, I am convinced that the more significant issue is AF variability. For a long while, I dismissed a lot of shots as soft that I think were more likely slightly out of focus. I have done some more AF focus chart test shots that have established (to my level of certainty, anyway) that my lens has AF variability - and that the variability is more noticeable wide open in low light (no surprises there).

Combining the 2 issues, I have found that I have some f1.4 shots that are more than acceptably sharp at the point of focus. This is what drove me to test AF reliability, as I had previously assumed that the lens was just soft wide open (I had also read the reviews).

So in practice I choose which to prioritise (sharpness or narrow DOF) for a particular shot, and select aperture accordingly - assuming that there is enough light. If it is really dark, then you have to open up and go with the results. I have had some lovely images at f1.4 - just not as reliably in focus/sharp as smaller apertures - so I continue to use the lens. Take duplicate shots.

Roger Cicala (Lensrentals) recently tested the new version against the current one. To paraphrase, he concluded that the new lens is not significantly better optically than the current lens, but appears to have better autofocus. That's not enough for me to upgrade, but if I was buying this lens now, I would spend the extra couple of hundred dollars for more reliable AF. Your priorities may be different.

EDIT: I just reread Roger Cicala's comparison. I misremembered his conclusion regarding focus. In brief, he concluded that corner performance improved in the new version, while centre performance was much the same. Manual focus is easier and more accurate, but he hasn't tested autofocus accuracy. Link to the article:
http://www.lensrentals​.com …-vs-sigma-30mm-f1-4-ex-dc