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02-17-2020, 07:00 AM - 3 Likes   #1171
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So now I have it, and a small quick test.

Focus is on the left eye. Picture is SooC. Actually it's sharper - there is some sharpness loss due to the screen capture and conversion to lower quality png.

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02-17-2020, 11:32 AM - 3 Likes   #1172
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QuoteOriginally posted by Rondec Quote
I expect the DA *60-250 to be around for awhile. Certainly Pentax probably has a decent stock of them at this point. Beyond that, the 60-250 is an APS-C lens. It was supposed to fill the gap a 100-400 lens would fill in the full frame line up. The 70-210, at least to the average individual, isn't going to cover that range and so an APS-C user (who doesn't understand focus breathing) might be willing to pay for an extra 10mm on the wide end and 40 mm on the long end.
Focus breathing seems to be a much bigger deal in discussion groups than it is in the field.
When I want maximum focal length, it is generally at or near infinity focus. I am far less concerned by the focal length shortening at close distances.
It's nice that the new lens is better at this, but it wasn't something I ever noticed as an issue with any other lens I have owned. I was more concerned by the 60-250 AF failure than anything else with that lens.
Even the A100/2.8 macro, which is, apparently close to 60mm at 1:1 was never bothersome during use.
One adjusts to the equipment in use.
02-17-2020, 11:39 AM - 1 Like   #1173
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QuoteOriginally posted by Wheatfield Quote
Focus breathing seems to be a much bigger deal in discussion groups than it is in the field.
When I want maximum focal length, it is generally at or near infinity focus. I am far less concerned by the focal length shortening at close distances.
It's nice that the new lens is better at this, but it wasn't something I ever noticed as an issue with any other lens I have owned. I was more concerned by the 60-250 AF failure than anything else with that lens.
Even the A100/2.8 macro, which is, apparently close to 60mm at 1:1 was never bothersome during use.
One adjusts to the equipment in use.
I'm on the opposite end of the spectrum, I guess: the 60-250's focus breathing is the singular reason I'll never buy one. Maximum magnification is a significant consideration for any lens purchase of mine.
02-17-2020, 11:55 AM - 1 Like   #1174
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QuoteOriginally posted by luftfluss Quote
I'm on the opposite end of the spectrum, I guess: the 60-250's focus breathing is the singular reason I'll never buy one. Maximum magnification is a significant consideration for any lens purchase of mine.
My understanding is that maximum magnification doesn’t change with focus breathing.

It didn’t affect my A100/2.8 macro’s ability to hit 1:1, though I guess it did affect my camera to subject distance. I suspect that in use, it is something few people would notice. I know when it was pointed out to me 15 years or more ago that the 100 macro that I favoured lost 40% of its length at 1:1, I shrugged and kept taking pictures.

It seems to me it will only be an issue when getting closer is easy, and will go unnoticed in real world conditions.

02-17-2020, 12:10 PM   #1175
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QuoteOriginally posted by luftfluss Quote
I'm on the opposite end of the spectrum, I guess: the 60-250's focus breathing is the singular reason I'll never buy one. Maximum magnification is a significant consideration for any lens purchase of mine.
How much does the focal length get reduced at max zoom (aka 250mm) on the 60-250 by focus breathing?
02-17-2020, 12:15 PM - 3 Likes   #1176
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QuoteOriginally posted by Wheatfield Quote
My understanding is that maximum magnification doesn’t change with focus breathing.

It didn’t affect my A100/2.8 macro’s ability to hit 1:1, though I guess it did affect my camera to subject distance. I suspect that in use, it is something few people would notice. I know when it was pointed out to me 15 years or more ago that the 100 macro that I favoured lost 40% of its length at 1:1, I shrugged and kept taking pictures.

It seems to me it will only be an issue when getting closer is easy, and will go unnoticed in real world conditions.
QuoteOriginally posted by pres589 Quote
How much does the focal length get reduced at max zoom (aka 250mm) on the 60-250 by focus breathing?
This is a chart that @beholder3 put together:

02-17-2020, 12:34 PM - 2 Likes   #1177
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That's pretty wild. Seems like something that would be useful to show with test images in a four-way lens comparison!
02-17-2020, 01:05 PM - 1 Like   #1178
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QuoteOriginally posted by Wheatfield Quote
Focus breathing seems to be a much bigger deal in discussion groups than it is in the field.
totally agree - you frame a pcture with what you've got, not what you might have had and, as you say, it's only really an issue at close focus where your movements toward and away from the object can compensate easily in most cases

02-17-2020, 01:32 PM   #1179
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can anyone compare the focus speed:
Sigma 70-200 / 2.8 EX DG OS HSM with Pentax-D FA * 70-200 / 2.8 ED DC AW and then with Pentax-D FA 70-210/4 ED SDM WR, this third smallest and lightest with the fewest lens groups should be the fastest, can anyone confirm it
this comparison would show the right state of speed and determination, I hope that anyone can make this comparison in any way

Last edited by mbukal; 02-17-2020 at 01:38 PM.
02-17-2020, 01:32 PM   #1180
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QuoteOriginally posted by Wheatfield Quote
My understanding is that maximum magnification doesn’t change with focus breathing.

It didn’t affect my A100/2.8 macro’s ability to hit 1:1, though I guess it did affect my camera to subject distance. I suspect that in use, it is something few people would notice. I know when it was pointed out to me 15 years or more ago that the 100 macro that I favoured lost 40% of its length at 1:1, I shrugged and kept taking pictures.

It seems to me it will only be an issue when getting closer is easy, and will go unnoticed in real world conditions.
Maximum magnification is related to the combination of focus breathing and minimum focus distance. That is to say if you have a 250 mm that has no focus breathing but has a minimum focus distance of 10 meters, it is going to have a really bad magnification ability. The same with a lens that has lots of focus breathing, but a reasonably short focus distance.

But you already know that...
02-17-2020, 02:13 PM - 4 Likes   #1181
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I should receive my 70-210 in a couple of weeks. As I already have the DA* 60-250, DA* 50-135 and DFA* 70-200 I will endeavour to shoot some comparative images - specifically looking at focus breathing and maximum magnification (as well as general image quality of course!).
02-17-2020, 02:52 PM - 1 Like   #1182
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QuoteOriginally posted by Rondec Quote
Maximum magnification is related to the combination of focus breathing and minimum focus distance. That is to say if you have a 250 mm that has no focus breathing but has a minimum focus distance of 10 meters, it is going to have a really bad magnification ability. The same with a lens that has lots of focus breathing, but a reasonably short focus distance.

But you already know that...
One of the things I know is that if the manufacturers says the lens will hit a specific magnification target, say 1:1 which is common for macro lenses, or 1:4 which is more common for zooms, then the lens is going to hit those targets.
I think this is more useful than knowing if the effective focal length shortens up while focusing.
I know what the lens is capable of by knowing it's maximum magnification ratio. I'm not too fussed about how it gets there.
02-17-2020, 04:03 PM   #1183
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QuoteOriginally posted by Wheatfield Quote
One of the things I know is that if the manufacturers says the lens will hit a specific magnification target, say 1:1 which is common for macro lenses, or 1:4 which is more common for zooms, then the lens is going to hit those targets.
I think this is more useful than knowing if the effective focal length shortens up while focusing.
I know what the lens is capable of by knowing it's maximum magnification ratio. I'm not too fussed about how it gets there.
I've never though about lenses in terms of maximum magnification ratio (aside from macro, of course), and I'm beginning to wonder if I should. I have a dumb question, though... Is the maximum magnification for a lens quoted at a specific distance - i.e. infinity or MFD - and is it potentially variable throughout the focus distance range, or always constant? Is it possible to know if and how magnification is impacted at various distances without knowing the variation in focal length due to "focus breathing"?

Last edited by BigMackCam; 02-17-2020 at 04:19 PM.
02-17-2020, 04:58 PM - 1 Like   #1184
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QuoteOriginally posted by BigMackCam Quote
Is the maximum magnification for a lens quoted at a specific distance - i.e. infinity or MFD
I would have thought, by definition, it would have to be at minimum focus distance.
02-17-2020, 06:28 PM   #1185
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QuoteOriginally posted by Sandy Hancock Quote
I would have thought, by definition, it would have to be at minimum focus distance.
It should be at the minimum focus distance for some focal length, but it may not be at the longest telephoto setting.

I've had several point and shoot cameras that have all had their maximum magnification at somewhere around the middle of their zoom range.

In every case, they could focus more closely at the wide end of the lens, at a loss of magnification due to the wide setting, or they could zoom all the way end and lose the minimum focus distance.

The best magnification was always somewhere near the middle.

Combine that with focus breathing (which I think is an element of the same optical characteristic), and you can end up with a lens that doesn't give you quite what you expect on the long end...

-Eric
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