CanonTom Loc: Birmingham

Last night I was shooting my grandson's 4th birthday party. Flash photography was decidedly out as the only thing I had with me was the built in flash on my Canon 60D, a 1.6 crop factor camera. That simply made the photos too bright and harsh and negated the decorated theme of dim light and overall ghoulishness (assuming that is even a word).

Knowing I would be working with very dim light, I set my camera on manual with a shutter speed of 1 80th of a second (four year old boys can run pretty fast), aperture at 1.8 on my Canon 50mm prime lens and let the ISO float to 6400 after which the light would be reduced. With fast moving 4 year olds, I decided a tripod would be too slow so I did not take one with me.

Over all the shots were not too bad.....not to good either unfortunately, but many were acceptable.

Inside close quarters the 50mm got a little long with the crop factor so I decided to go to my 24mm prime 2.8. Have not had the 24 very long so I got to compare them side by side in low light. The 24 mm was definitely better in terms of focal length, but many more of these pictures were simply too dark to be worth much......the difference between the 1.8 and the 2.8 obviously.

My question is basically two fold:

First, had I been using a FF camera which I am still considering obtaining, would my aperture have been reduced by the crop factor giving me more effective aperture than I was obtaining with my current crop factor camera??? If so that would be a tremendous gain in terms of low light performance.

Second, from you advanced amateurs and certainly from you professionals, what else could I have done to improve my image quality in this situation based on your own personal experiences? Thank all of you for your input!

(I previously researched this last part of my question on the web and found that there seems to be opinions on this topic that do contradict each other, to say the least....I am confused on this issue but would really like to know as it will impact my decision as to purchasing a FF camera).

DaveO Loc: Northeast CT

Wish I could get away with 1/80! I always shoot the kids at minimum 1/250. As far as I know, aperture is aperture and the difference is only crop factor.

CanonTom Loc: Birmingham

Well DaveO.....I did have a few blurry photos.........I tried 125th first but things were so marginal, I decided that I needed the light more than I needed extreme clarity! Besides it made those little guys look like they were flying.............

repleo Loc: Boston

Your aperture wouldn't change between crop and FF cameras, but the FF may give you better ISO performance depending on the model. As you already observed, the 'equivalent focal length' or angle of vision is different by the crop factor.

The depth of field can be different depending on whether you are shooting from the same spot or zooming with your feet to get the same angle of vision although there seems to be differences of opinion on this. It is way over my head to argue the point one way or the other.

DaveO Loc: Northeast CT

LOL! Yes, it depends on what you're looking for and it's great that film is so cheap to experiment with! I'll follow the thread for more info and ideas!

Sorry, I was thinking you had a D500....confused it with another thread.

CanonTom Loc: Birmingham

[quote=repleo]Your aperture wouldn't change between crop and FF cameras, but the FF may give you better ISO performance depending on the model. As you already observed, the 'equivalent focal length' or angle of vision is different by the crop factor.

Repleo, in the interest of clarity, let me pose my question a little differently: Had I had a good FF frame Canon (since my 60D is a Canon, etc.) if I had moved the 50mm lens(FF), (I could not move the 24mm as it is a crop factor lens) to a FF Canon body, set in manual with the same settings as I had made on the 60D, and at the same distance from the subject, would I have had better light gathering ability and if so why? I am aware that the 50mm on a FF would have been wider angle than on the 60D (by the crop factor of 1.6) but I am addressing light gathering ability as to aperture....perhaps in other words......we all know that 50 mm on a FF is equivalent to 80mm on a Canon crop (50mm X 1.6=80mm). BUT would the 1.8 app on the FF still be the equivalent of 1.8 on the crop or would it really be the equivalent of 1.8 X 1.6 =2.8 on the crop?????? Or are you telling me the effective aperture as well as shutter speed would stay the same but the ISO float being adjusted by the camera automatically would give me a lower ISO on the FF than on the CROP? And if so, why is that? Sorry if I am being dense but I am really trying to fully understand this. Thanks to all who are knowledgeable and will comment back on this.....

OH.....................I may have just had a mental break through!! Or then maybe not, lol.........Repleo, I have come up with what I believe is correct and what you are trying to tell me......lets see if I am on it or not.......the field of view changes by the crop factor since I am remaining the same distance from the subject with the two cameras.....the aperture is unaffected by the crop BUT, because the FF lense is larger in diameter, that additional diameter in the lense gives me greater light gathering ability with the FF, hence, the camera can select a smaller ISO than on the crop.....and that is why the FF will always be able to give better light gathering ability than a crop once you get to the point that a wider aperture lens for the crop becomes either unavailable or unaffordable.........am I correct or am I still all wet?

CHG_CANON Loc: the Windy City

CT - you didn't post any examples, so based on your analysis of the images, please clarify:

1) Was the blurriness due to subject movement or camera shake, or both?
2) Did you try shooting slower than 1/80 with either lens?
3) You mention the difference between f/1.8 and f/2.8. But, were you still at 1/80? I'd argue that you should have been able to shoot a 24mm lens, on any camera body, at 1/30.

Regarding light gathering aspects of the lens at a given aperture: it is exactly the same regardless of camera body. There are differences in the apparent depth of field related to the crop sensor at various aperture values. This is not due to the amount of light hitting the sensor.

If it really was that dark and using flash was not an option, two other options exist:

a) Depending on the source of the blur, a fast IS-enable lens might have been an option. You'd still get blur in the kids not paying attention to the photographer. But, you should have been able to catch static situations or had the kids stop for a moment and smile before going back into their own world. Canon offers both 24 and 28 f/2.8 IS lenses in an EF mount. Canon also has an EF 35 f/2 IS that would have approximated the 50mm field of view on your 60D.

b) A new crop or full-frame camera would have offered better high ISO results than your 60D. I'd prefer not to take the 60D sensor above ISO-3200. But, it will shoot higher and maybe the results are acceptable vs no images at all in the dim light.

CanonTom Loc: Birmingham

Thank you CC for the observations. Blur totally caused by children playing. And yes I was able to catch some slow to no movement time. I did not and definitely should have tried slower shutter as there were times a 30th would have done fine. Yes I remained at an 80th of a second. Slower shutter would have helped and yes there were times it would have totally stopped action. In our earlier discussions of my earlier post we discussed in depth as to whether I should immediately invest in a full frame camera. I gathered, and believe you were hinting that I might be better off to at first invest in better FF high grade lenses as well as other periferials I do not yet own, before spending money on a new camera body. I have pretty much decided to do that. If I missed your drift pls correct me on that. Regardless do please re read the last part of my current post as to whether a FF camera will always give better low light performance that a crop and comment. I have been reading comparisons between the 7d mk ii and the 5d my iii and do wonder if there would be much difference and if so in what areas. I would love to hear your thoughts on any and all of my needs. Thanks for your help!

rehess Loc: South Bend, Indiana, USA

Simple answers to your simple questions:


f-stop has no connection to sensor size. If a light meter calls for f/4 @ 1/250 where ISO=200, then

with a FF camera, you should set ISO to 200, f-stop to f/4 and shutter speed to 1/250

with an APS-C camera, you should set ISO to 200, f-stop to f/4 and shutter speed to 1/250

with an MFT camera, you should set ISO to 200, f-stop to f/4 and shutter speed to 1/250

etc


However, DoF does depend on sensor size. For a given focal length lens focused at a given distance, a smaller sensor will result in a larger DoF.

CHG_CANON Loc: the Windy City

Hey Tom - yes to a few questions as in: a faster lens with IS probably would have given you more confidence to shoot slower. Yes, given cameras of equal generations, the FF will give better low-light / high ISO noise performance. Yes, there is a real difference between even a newer 7DII and an older generation 5DIII where the FF 5DIII images are cleaner (one is listed for sale now). But, an even newer 80D at much a lower cost is better than the aged 60D, not just for being 2 generations newer but also because of major noise improvements Canon made from the 70D onward. But, if this shooting situation was relatively 1-off and flash would be your normal approach, I'd still consider lenses or external flash gun as lower cost investments where the 60D is still a fine camera at lower ISOs.

Bill_de Loc: US

You probably could have used flash successfully if you dialed it down a little.

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blackest Loc: Ireland

maybe think of light as rain say you have a paving slab out in the rain say 1 mm of rain falls on it if you had another slab next to it then that would also receive 1 mm of rain. basically as long as the hole in the front of the lens is big enough the area of the sensor receives the same density of light across it. In the dx lens on a full frame camera the density of light on the exposed part of the sensor would be the same, areas not revealed would receive nothing.

repleo Loc: Boston

[quote=CanonTom]

Canontom.
Your question has me confused now. To simplify, the same aperture and the same shutter speed should have the same light gathering ability regardless of the sensor size or the focal length of the lens, so theoretically should give the same exposure. Although not really relevant to your question, different lenses have different transmission ratings or T-stops which effects the total amount of light arriving at the sensor. Think of the t-stop as the efficiency of the lens to allow light to pass through all of the elements. ISO only comes into play once the gathered light hits the sensor. Better ISO performance allows you to choose shorter shutter speeds for the same noise level. In general, FF cameras tend to have better ISO performance than crop sensors, but age of camera is a factor in that some newer crop sensors have ISO performance that equal or exceed FF cameras of just a few years ago. So to go back to your original scenario with the running kids, a new(er) FF should give you better ISO than a new(er) crop which would allow you to use a shorter shutter speed which would help 'freeze' the kids. The quality of the specific lens and sensor combination comes into play for the focus speed, low light focusing and tracking capability, which are probably even more important than aperture or ISO for shooting kids in low light.
All of the above is my current understanding of how all of these things interact. I am completely open to correction and willing to learn from other posters.

Notorious T.O.D. Loc: Harrisburg, North Carolina

Notorious T.O.D. Loc: Harrisburg, North Carolina

I am thinking that a carefully used flash could have added just a touch of light and improved the images without making them look like they were taken outdoors in the sunshine. With my Canon 600 flash I would have probably used ETTL if the distance from flash to subjects was changing rapidly or often. Then I would probably dial in -2 to -3 stops of flash exposure compensation and see where that put me. Adjusting from there.
I would also probably try to bounce the flash off a wall or ceiling too.

A FF will generally have better higher ISO performance than a crop sensor, assuming they are within a generation of each other age wise. Fast lenses are good but as the focal length increases the wide open lens can result in very shallow depth of field. The result can be images that look out of focus because the focus is so shallow. For example think about an 85 1.2 where in a portrait one eye can be in focus and the other one not. This is where I think it is often better to add light than to try to shoot existing light, unless you are seeking very shallow DOF. A DOF app can be an interesting thing to just plug different numbers into and get a feel for how different body, lens, aperture and distances impact DOF. Fast lenses are useful but if you can adding some light is often easier and less expensive.

Best,
Todd Ferguson