Sensor Size vs Lens Quality Question.

[dr_gn]

Following on from my old thread on SLR image quality etc. :

http://www.pistonheads.com/xforums/topic.asp?h=0&a...

The concensus seemd to be that the kit lenses were pretty crap, and SLR images need more post-processing than those from a bridge camera, so I decided to stick with my FZ50 for the time being.

Hypothetically, if I take two cameras:

Full-frame SLR eg a Canon EOS 5D MKII (with a packaged 24-105mm Lens worth about £600)

Or an APS-C SLR (eg a Canon 550D, with the same lens as above as opposed to the kit lens which costs about £80).

How noticable would the difference in image quality be (resolution, sharpness) of identical A4 prints taken with both cameras?

My question really is: would a full frame sensor compensate for a cheaper lens, or would a high quality lens compensate for a smaller sensor? Obviously a full frame sensor and a high quality lens would be the best option, but the cost would be huge.

[Gruffy]

Have to think a better lens is going to give you better results than a larger sensor.

[dr_gn]

Gruffy said:

Have to think a better lens is going to give you better results than a larger sensor.

I'd assume that the difference in lens resolution would be orders of magnitude smaller than the difference in sensor resolution, but I'm not sure.

[markmullen]

A bigger sensor will show up inadequacies in a lens which might not have shown up on a smaller sensor, particularly at the edges of the image (the smaller sensor using the centre part of the lens won't show those issues).

TBH though at A4 you'd be hard pressed to tell the difference between a crop sensor and full frame, assuming you'd exposed the same.

[anonymous-user]

As Mark says, my understanding is also that even using 'average' quality full frame lenses on a crop camera can yield very good results and the crop sensor only uses the central 'best bit' of the lens.

Putting good quality full frame glass on a crop sensor would be my choice. This is what I actually do myself.

Then, if you ever change to a full frame camera in the future at least you have a few full frame lenses already bought to use with it.

[dr_gn]

Thanks for the comments.

So, my hypothetical combination of a Canon EOS 550 and a Canon EF 24-105 lens would be a good starter combination for around £1000 budget?

[markmullen]

The 24-105 is lovely, when I'm travelling it is my walkabout, nice focal range, qood IQ, IS is useful, it is compact and lightweight. That said I don't think 24mm is wide enough on a 1.6 crop body, I'd look at the 17-55 f2.8 or the 15-85 in that case.

[Craikeybaby]

Yes, in theory. It is more important to have good glass than a good body, however, at the wide end the lenses that work well on full frame, might not be ideal on a cropped sensor. I don't think 24mm on a cropped sensor would be wide enough for me. A similar lens for a cropped sensor would be the 18-85 (I think), although I've not used that lens.

My main advice if you are just starting in the world of DSLRs would be just just go for the basic kit, then work out how that restricts you and go from there.

[dr_gn]

Craikeybaby said:

Yes, in theory. It is more important to have good glass than a good body, however, at the wide end the lenses that work well on full frame, might not be ideal on a cropped sensor. I don't think 24mm on a cropped sensor would be wide enough for me. A similar lens for a cropped sensor would be the 18-85 (I think), although I've not used that lens.

My main advice if you are just starting in the world of DSLRs would be just just go for the basic kit, then work out how that restricts you and go from there.

To cut a long thread short (see link in original post), I've owned three film SLR's in the past, so I know which bit to point at the subject etc. I currently have a Panasonic FZ50 bridge camera, which I'm happy with most of the time, but I crave better image resolution and sharpness, and would like better shutter response time, fater AF etc etc. I tested a couple of DSLR's compared with my camera at the local camera shop, and found the results very disappointing - the images were only as good as or worse than my FZ50 *in my opinion*. Concensus was poor kit lenses on the SLR's, and the need for more post processing was the reason for the less than sparkling DSLR results.

Having accepted the above, there would seem no point me going for the basic kit (a DSLR with a poor standard lens), because I already know I'll not be happy with the results.

[LongQ]

dr_gn said:

To cut a long thread short (see link in original post), I've owned three film SLR's in the past, so I know which bit to point at the subject etc. I currently have a Panasonic FZ50 bridge camera, which I'm happy with most of the time, but I crave better image resolution and sharpness, and would like better shutter response time, fater AF etc etc. I tested a couple of DSLR's compared with my camera at the local camera shop, and found the results very disappointing - the images were only as good as or worse than my FZ50 *in my opinion*. Concensus was poor kit lenses on the SLR's, and the need for more post processing was the reason for the less than sparkling DSLR results.

Having accepted the above, there would seem no point me going for the basic kit (a DSLR with a poor standard lens), because I already know I'll not be happy with the results.

You could be right - there are some excellent bridge cameras around that in terms of perceived sharpness and colour saturation etc., for a given size of output file or even print, will produce very acceptable results in many, perhaps most, circumstances.

You can extend that to comparisons of RAW files too in some cases, although I would guess you were comparing jpgs in a shop environment.

I have a owned a Canon 400D for a few years. The 18-55mm kit lens that came with it performs rather well in my case, at least in terms of sharpness an general results. However the camera was bought originally to use with an old fully manual telephoto lens. These days I mostly use it with a fully manual 14mm wide angle lens as a 'second body'. Sometimes with the old tele, now and again with the kit lens (when travelling light) and on occasion with a 70-300 DO lens. For its zoom range the kit lens perfoms well although most of the time it's not offering a range I tend to shoot in.

The differences between decent point and shoots, bridge cameras and DLSRs come not when shooting regular subjects in half decent light but when you are on the edges of performance and handling. (Or more basically general composition if one considers the differences in sensor sizes and thus DoF and the 'artisitic' properties that are on offer. But that's a whole different subject.)

I thnk what you may need to consider is whether you may have a need to shoot RAW files. They usually lead to more post processing work to get the very best results (from any lens) but offer much more potential than jpgs for getting things just how you want them. In my expereince even bridge camera that offer RAW files often don't have (at the time they were current) the flexibility the full DSLR bodies usually offer in RAW recording potential. I'm not saying they are poor - not at all. But in the main they just don't offer the same opportunity when asked challenging 'questions'. Nor might one expect them to.

For your other desires - shutter response and AF etc. - mostly DSLRs (or 'Removable Lens systems' if you include the best of the latest crop of such devices) will tend to be far better than bridge cameras of the same era.

[jimmy156]

I'm not sure buying an SLR is going to solve the problem that you're seeing.

I reckon if you took a Canon 5dIII with 24-70II lens (about £5k worth) and took a shot in good light of a normal scene, and then took the exact same shot with your current camera and viewed them on a computer monitor, or as an 8x6 print or something, you may be hard pushed to tell which camera took which shot (assuming there wasn't an obvious DOF difference)

My point is SLR's only come into there own when you challenge them, be it with low light, fast moving subject, a high dynamic range scene etc.

Also the idea that kit lenses are rubbish is wrong, yes they're not as good as more expensive professionally glass but the latest ones certainly aren't rubbish.

Photo's from an SLR will tend to be flatter and less punchy by default, but you can change various settings in camera to get the look that you are after.

In answer to your original question, i would say you would be better off with a lens like the Tamron 17-50 2.8 (or canon's version, but its 2.5x the price) on a "crop" body SLR, this will give you more creative opportunities with DOF then the 24-105, the extra 7mm at the wide end is very useful as well.

[rxtx]

There are other things to take into consideration on top of sensor size and lens quality, such as any in-camera processing done (or not) by either type of camera, and the pixel pitch/density of the sensor can also affect perceived sharpness and resolution.

[RobDickinson]

My viewpoint is a bigger sensor is more forgiving on lenses than a smaller one unless the pixel density is the same.

Consider the 5DmkII and 7D.

The 5DmkII has a large pixel pitch vs the 7D (8mp vs 18mp in the same area).

This will show less issues with the lens than the 7D will.

Same works for medium format, a lens of equal overall quality will give much better results.

[y2blade]

Get comfy, this could be a long night.

[dr_gn]

Thanks for all the replies and information. I appreciate the time and advice.

I wonder what proportion of people who buy a DSLR use it to its full potential?

I've still got this DSLR itch that needs scratching (I'm increasingly frustrated with current restrictions such as in low light conditions, iso setting and AF speed / shutter lag), but there are still some niggling doubts. As an example, last year we went on holiday - Baltic coast, really nice place, excellent weather. I used the wife's Panasonic TZ10 compact. One of the relations had a huge new Canon SLR, several £k's worth. A few weeks after the holiday, a packet of photos arrived in the post and - being totally honest here - for whatever reason (priniting quality, misuse of settings etc etc), the overall quality - including resolution - was worse than those printed at Boots from the TZ10. Had I spent that much money for that quality of image I'd be absolutely gutted.

It really was a stark illustration of the reality of DSLR use outlined both here and in my previous thread.

[RobDickinson]

An SLR is the ultimate (portable and cost effective) tool for photography.

But like any tool its of little use if you dont know what your doing.

[Simpo Two]

dr_gn said:

Thanks for all the replies and information. I appreciate the time and advice.

I wonder what proportion of people who buy a DSLR use it to its full potential?

I'd like to think I wring the nuts off my D200s.

ATEOTD you can philosophise for ever about pixels and thingies; but all things considered a DSLR IS better than a compact or bridge camera. It may take more effort but if good things were easy we'd all be doing them. So really, jump in and see how you get on and try not to think too much

[flat-planedCrank]

As you mention, DSLRs aren't just about superior image quality - things like AF speed, shutter lag and customisation through lenses & accessories are part of the argument. It's all a compromise of course with the adaptability and performance comes size, weight and the requirement of some technical knowledge to use the tool to take the shot as you see it.

You can take rubbish photos with a DSLR of course - bad composition, mis-focusing or not watching your shutter speed can ruin a photo.

I suppose you could argue that DSLRs more readily give users options that can (if not used correctly) result in technically poor photos....

...but of course the creative opportunities for 'point & shoot' cameras can be more limited (or at least, less easy to access).


As long as people realise that their new shiny DSLR doesn't actually think for them and they are willing to learn a bit more about photography then buying an SLR camera is probably the ideal next step.



As for how much do people use the performance and abilities of their DSLR? No idea, but I see plenty used in 'auto mode'

That said, you might compare the same situation to something like Microsoft Excel - I doubt I use more than a small fraction of what Excel is capable of. I'm sure there are better ways of calculating figures, automating work-flow or creating graphs. Yet it does what I want, and when I want to learn more then I can easily read a tutorial or buy a book


Hope this helps.

[RobDickinson]

flat-planedCrank said:

I suppose you could argue that DSLRs more readily give users options that can (if not used correctly) result in technically poor photos....

Yep for most people the metering system and auto controls will result in a better image most of the time because they dont understand when you need to shift awya from auto and how auto holds your hand (re focus/shutter speeds etc).

Also SLR's default JPG engines are set up to add the minimum of processing also, yes you can ramp up the colour/contrast and sharpening but again this needs some knowledge that this is what P&S do already.

[LongQ]

RobDickinson said:

Yep for most people the metering system and auto controls will result in a better image most of the time because they dont understand when you need to shift awya from auto and how auto holds your hand (re focus/shutter speeds etc).

Auto?

I thought you were supposed to use "P" for Portrait/Panorama/Panning/Professional all the time. That tells the dslr to analyse the scene and set the best options for you. Or at least that's what the brochures claim. "The camera will interpret the scene and set all the best options for you", or words to that effect.

Edited by LongQ on Friday 13th April 11:02