Crop-frame = extra reach? Really?

Started Jun 4, 2010 | Discussions
Mink Forum Member • Posts: 75
Crop-frame = extra reach? Really?

I'm sorry if this opens a can of worms (or reopens it), but I'm really struggling with the assertion repeatedly made here that APS-C bodies provide extra "reach" with telephoto lenses.

I realise this is a touchy point, and I wouldn't raise it at all if it wasn't for the fact that this claim may influence some people to buy a crop-frame camera for the wrong reason. I believe there are plenty of good reasons to choose APS-C over FF - lower cost, lighter weight, different lens-choices and (depending on model) faster burst-speeds, better high ISO performance, live view, built in flash etc - but for the life of me I can't see how "reach" can be listed as a benefit in Sony's current crop-frame line-up.

The simple fact, surely, is that you can crop the image from an a850/900 so that the resulting photo is indistinguishable in terms of field of view and resolution from one captured with the same lens on an a700 or any of the other APS-C models. This cropping is unavoidable in a crop-frame body, while with FF you have the choice of whether to crop, and by how much, in post processing.

If (or "when") Sony produce an a-mount DSLR with an APS-C sensor with MUCH higher resolution (like > 20mp), coupled with better noise characteristics and perhaps improved image stabilisation with long telephoto lenses, then I believe we can talk about greater "reach" - because FF bodies simply won't be able to produce comparable results from the same lenses. I really believe this is going to happen, and that crop-frame will increasingly cater for a different market - mainly the action/sports/wildlife photographer - but it's wrong to suggest we're already there.

And on a related issue, I've seen posts saying that if you get a FF body you'll have to get rid of your DT/crop-frame lenses, and buy FF glass. This, in spite of the fact that the a850/900 will automatically adapt to a crop-frame lens, producing (once again) photos which are indistinguishable from those taken with the same lens on an APS-C body. Sure, you need a FF lens to use all of the pixels you've paid for, but there's absolutely no other downside to having a mixed bag of lenses. A FF body will make the most of any lens put on it - the same can't be said of an APS-C body.

Even if ALL your lenses are currently crop frame, choosing an a850/900 may still be the better choice if there's a chance you'll add FF lenses to your collection in future - and it means you will get the hugely useful micro-AF adjustment feature (currently only on the FF bodies) to overcome any back- or front-focus issues with each lens in your collection. IMHO this feature is an absolute must for those who use telephoto lenses, since they are working with much narrower depths of field (so accurate focusing is critical) which makes the claim that (existing) APS-C bodies are more suited to telephoto use than FF even more ludicrous.

I'm not a disciple for FF (I have an a850 but I bought an a330 only a week ago for a light travel/hiking kit) - I just believe that people coming here for advice should not be misled.

tompower53 Veteran Member • Posts: 4,261
Probably about 50 existing threads on this subject

People can do a search for those. Do we really need another one?

Have at it if you want though.
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MichaelRoth Forum Member • Posts: 85
Re: Crop-frame = extra reach? Really?

Mink wrote:

If (or "when") Sony produce an a-mount DSLR with an APS-C sensor with MUCH higher resolution (like > 20mp), coupled with better noise characteristics and perhaps improved image stabilisation with long telephoto lenses, then ...

then there is no problem to produce a FF camera with > 40 mp

you will be always able to crop the FF image (with equal pixel destiny on FF Sensor) to get exact the same result of aps-c camera

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jaja_m Regular Member • Posts: 256
you can find the answer at Robsphotography

he talks a lot about reach. Not my site

Maxxuman Senior Member • Posts: 1,761
You're forgetting one thing...

While I don't dispute much, if anything, you say, there is one area in which you do benefit from the extra "reach" of APS-C - the viewfinder. While you can crop your result to get the same size output as an existing APS-C camera provides, your view through the viewfinder at the time of taking the photo is reduced compared to what you have when using the same lens on an APS-C camera (at least one with a good viewfinder, such as the a700). Granted, you're starting with a great view through the a850 or a900 viewfinder, but you still won't have the same magnification as with the a700 using the same lens. So your ability to judge focus on the subject and depth of field suffer in relative terms.
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Gregory Kemp Contributing Member • Posts: 668
Re: You're forgetting one thing...

I agree on the viewfinder point and it does also make post processing a bit faster if don't have to crop. I haven't given a whole lot of thought to this whole argument because as the OP said with Sony there is no resolution advantage because 25mp image cropped is still the same or larger res than any of he current Sony aps-c cameras. With canon i believe it's a bigger issue becase the do have some higher aps-c models.

Greg
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stan_pustylnik Veteran Member • Posts: 3,927
Right on money.

All your points are right.
Last reply about viewfinder view is correct.

I know another tech advantage of APCs cameras - no vignette when shoting wide open with FF lenses. But if I will heavily crop A850 image, I will not see vignette either (if I choose to crop, because vignetter can add artsy effect).

Corner vignette sample when shoting A850+ 50mm f/1.7 at f/2.0

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dennismullen
dennismullen Veteran Member • Posts: 9,013
Re: Crop-frame = extra reach? Really?

A little bit off topic, but here is an interesting comparison of the A900 and A700 resolution.

http://www.artaphot.ch/dslrs/302-aps-c-vs-full-frame-2

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WaltKnapp Forum Pro • Posts: 13,857
Re: Crop-frame = extra reach? Really?

MichaelRoth wrote:

you will be always able to crop the FF image (with equal pixel destiny on FF Sensor) to get exact the same result of aps-c camera

That is where the whole FF argument falls down. Even the a700 is not the same pixel density as the current 24MP FF. Crop your FF and you get a 11MP image. And with 14MP becoming the standard for Sony APS the difference is even greater.

Personally I prefer that the viewfinder frame what will be my final photo or close to it. In fast shooting I don't have to try and keep track of some floating crop. And don't in PP have to take the time to do it. I don't shoot to crop.

So go enjoy the camera you have and quit trying to justify it by putting down some other camera. Your photos live or die on their own.

As an aside note that the camera being promoted as having the very best high quality sensor is an APS, the NEX.

Walt

WaltKnapp Forum Pro • Posts: 13,857
Re: You're forgetting one thing...

Gregory Kemp wrote:

I agree on the viewfinder point and it does also make post processing a bit faster if don't have to crop.

This is more real life usage than the argument that cropping can be done.

I haven't given a whole lot of thought to this whole argument because as the OP said with Sony there is no resolution advantage because 25mp image cropped is still the same or larger res than any of he current Sony aps-c cameras.

It's 11 MP, lower resolution for the same size final image than any of the current Sony aps-c. Even the a700 beats it with 12MP. And Sony's move to 14MP for APS makes it even lower resolution vs APS. You have it backwards.

Walt

WaltKnapp Forum Pro • Posts: 13,857
Re: Crop-frame = extra reach? Really?

dennismullen wrote:

A little bit off topic, but here is an interesting comparison of the A900 and A700 resolution.

Off topic is right, not at all the same as field of view matching, where the a700 will show more detail of the field it does take. 12/11ths more. And with the newer 14MP sensor that detail will be 14/11ths more. That is, of course, assuming the exact same processing, exact same lens shot at the same exact moment and so on.

Walt

Mike CH Veteran Member • Posts: 7,462
Re: Crop-frame = extra reach? Really?

For the same amount of money the APS-C body has a significant reach advantage; an aspect I don't think you really touched on. It will also show the expected result a lot better in the OVF.

There are a lot of other threads on this topic, though.

Regards,
Mike
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stan_pustylnik Veteran Member • Posts: 3,927
Don't full others and yourself.

Walt, your argument is not holding water either, because you basically saying that smaller sensor is as good as large, while forgetting FF lens factor.

In my opinion it is not smart to own expensive FF lenses and use 1/3 of projected light that passes through them. I literally imagine lighted surfaces around APSc sensor when FF lenses are attached.

You probably own 35mm f/1.4, 20mm f/2.0, 85mm f/1.4?

Then in each shot you do using APSc body and FF lens, only 1/3 of lens potential is used.

OP is correct.

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beakydave Senior Member • Posts: 2,140
Re: Crop-frame = extra reach? Really?

WaltKnapp wrote:

So go enjoy the camera you have and quit trying to justify it by putting down some other camera.

Why don't you practice what you preach?

OldClicker Senior Member • Posts: 2,322
Re: Crop-frame = extra reach? Really?

"I believe there are plenty of good reasons to choose APS-C over FF - lower cost, lighter weight, different lens-choices and (depending on model) faster burst-speeds, better high ISO performance, live view, built in flash etc - but for the life of me I can't see how "reach" can be listed as a benefit in Sony's current crop-frame line-up."

The only one I agree with is lower cost. You can find cropped sensor DSLRs that weigh more than the A850, you can use the cropped lens and get the same image as a result, and none of the rest of the reasons are specific to sensor size. Also, if file size shows up as a reason, you can shoot 'cropped' until you want that really good shot and the 24MP are available. APS sensors are fine (I used APS film), but you are right that the extra 'reach' is nonsense.

TF

WaltKnapp Forum Pro • Posts: 13,857
Re: Don't full others and yourself.

stan_pustylnik wrote:

Walt, your argument is not holding water either, because you basically saying that smaller sensor is as good as large, while forgetting FF lens factor.

You are trying to make a blanket argument about a specific instance.

Here is the specific instance since you have so clearly gotten lost as to the subject, directly quoted from the OP:

"I'm really struggling with the assertion repeatedly made here that APS-C bodies provide extra "reach" with telephoto lenses. "

In my opinion it is not smart to own expensive FF lenses and use 1/3 of projected light that passes through them. I literally imagine lighted surfaces around APSc sensor when FF lenses are attached.

That is your problem and certainly off topic, see the topic above.

You probably own 35mm f/1.4, 20mm f/2.0, 85mm f/1.4?

What makes you think that? Because they are lenses you would choose?

Walt

dennismullen
dennismullen Veteran Member • Posts: 9,013
Re: Crop-frame = extra reach? Really?

WaltKnapp wrote:

...the a700 will show more detail of the field it does take. 12/11ths more.

Don't you mean 1/11th more?

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Danjojo Regular Member • Posts: 414
Focal range

A lot of people confuse APS-C sensors as having a reach advantage when using the same lens as a FF...it's not necessarily the case. The field of view (frame) is cropped but the 50mm is still 50mm and 85mm is still 85mm. Whether some one crops or not with a FF image, doesn't matter much unless they are going to print HUGE. Even a 10mp image you downsize when making an 8x10.

Also the FF lens not using all of its potential with an APS-C camera.....that's fine if that is how you want to call it....usually it performs better with an APS-C because the corners are much nicer. Check out the majority of the Blur Index thingies for FF lenses at slrgear.com

dennismullen
dennismullen Veteran Member • Posts: 9,013
Re: Crop-frame = extra reach? Really?

Man, I can't believe I got sucked into buying an A900 when an A700 is better. Is there anybody out there who would consider trading their A700 for my A900? I could just kick myself!

Taken with A900 and Sigma 500/4.5 APO EX DG.

1/1600s f6.3 at 500mm iso200

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stan_pustylnik Veteran Member • Posts: 3,927
Re: Don't full others and yourself.

WaltKnapp wrote:

stan_pustylnik wrote:

Walt, your argument is not holding water either, because you basically saying that smaller sensor is as good as large, while forgetting FF lens factor.

You are trying to make a blanket argument about a specific instance.

Here is the specific instance since you have so clearly gotten lost as to the subject, directly quoted from the OP:

"I'm really struggling with the assertion repeatedly made here that APS-C bodies provide extra "reach" with telephoto lenses. "

"APS-C bodies provide extra "reach" with telephoto lenses" - wrong, because APSc "provides limited view" of what lens designed for film can do. Same for tele, wide or normal lenses.

In my opinion it is not smart to own expensive FF lenses and use 1/3 of projected light that passes through them. I literally imagine lighted surfaces around APSc sensor when FF lenses are attached.

That is your problem and certainly off topic, see the topic above.

My reply was addressed to you, expirienced photographer talking about APSc "advantage".

You probably own 35mm f/1.4, 20mm f/2.0, 85mm f/1.4?

What makes you think that? Because they are lenses you would choose?

Sure, these are great lenses...

Walt

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