ruthenium wrote:
By definition, the exposure is light per unit sensor area, and this is indicated by the ISO alone.
Cropping a 400 mm image to 600 mm means a crop factor of 1.5 - this is close enough to 1 stop; thus, the crop should be practically equivalent to 600 mm f/6.3 if the full-sized image was at 400mm f/4.5.
The other things that you have said are less clear. For example "We are not talking photons on the sensor, we are talking exposure" is contradictory, because the exposure is light (photons) per unit sensor area.
"DoF would in fact be almost the same after the crop" - the DoF shall be the same as that of a 600mm f/6.3 image. It is not going to be the same as that of a 600mm f/4.5 image.
"but exposures remain 1 stop apart" - yes, the ISO for the crop should be equivalent to 800 x 1.5^2 = 1800 (close enough to 1600).
The original argument "the 600 and 400 have the same light gathering abilities with ~ 89mm apertures" is confusing because it silently assumes the same luminous flux. There is a difference, however. The 600 and 400 mm lenses have different angles of view. I expect that the luminous flux from the larger field of view at 400mm should deliver more light (more lumens) than the 600 mm lens can gather from the more narrow field of view (assuming the same luminosity)....Show more →
Then how come in my camera if I switch from full frame to APSC mode, the exposure of a full blue sky image remains identical? By your thinking, the exposure for APSC should require an extra stop to equalize, but it doesn't.
Agree I was surprised. Need to see more comparisons. Possible he had a bad copy or did something wrong. But I wouldn't expect bad copies of a prime.
ChrisMak wrote:
These samples don't look right as far as the 600GM is concerned. If that is really as good as that lens gets, I will not buy it, the difference with the 600GM will simply be too big.
Wide open, the new 600/6.3GM should produce tack sharp results, with TC on it is credible that the samples will have a fuzziness that resembles looking through overdue glasses, or that they look like they suffer from slight motion blur, but I would not expect, neither accept that from a bare GM lens wide open, even when it has f6.3 as a maximum aperture.
Question is why the samples from the bare 600/6.3 lack true detail and sharpness. Dustin Abbott admits he is totally unaccustomed to shooting at 600mm, and perhaps the circumstances were not quite right, but really, the bare 600/6.3 GM should at the véry least beat the 400/4.5GM with 1.4TC.
And I believe a good copy will do that easily, otherwise the 600/6.3GM has no raison d'être, Sony could have just made the 400/4.5GM and left it at that, with a little promotion of its TC's. For those that would argue that you cannot get to 1200mm that way, I would say that I don't want to know how Dustin's copy looks with the 2xTC....Show more →
Dustin Abbott just released his 600 F6.3 GM review. I thought this was an interesting comparison that I was able to make by downloading some of his test chart images.
Looks to me that the 400 F4.5 + 1.4x TC is at worst indistinguishable, and most likely slightly sharper with better contrast, from the 600 F6.3 bare lens. The bare 400 F4.5 looks sharper than the bare 600 F6.3. This makes sense given the optical similarity of the lenses.
Where this falls apart is that the 400 + 2x TC is massively worse than the 600 + 1.4x TC, which was slightly surprising to me. Both lenses frankly look bad with the 2x TC. So the question is really do you want a 400/560 or a 600/840?
Personally, I'm still torn between 100-400 F4.5 + 600 F6.3 or just rolling with a 400 F4.5 + 1.4 TC for my telephoto needs for now. But this makes a compelling case to start with the 400 F4.5 and keep my 70-200 GM II and see how far those 2 lenses + TCs as needed gets me.
Slight correction on your comment : >>So the question is really do you want a 400/560 or a 600/840?<< It more accurately should read, do you want a 400/4.5 and 560/6.3, or a 600/6.3 and an 840/9?
Which is the rub for me... Aperture becomes significant enough with the 1.4 on the 600 for 840/9 to consider it a marginal use option, while 400/4.5 is definitely an attractive option, while 560 vs 600 with both at f6.3 becomes moot.
F8 on the 400-800 was already a bit marginal for me, f 9 more so. In which case since I already own the 1.4x would probably spring for the 400, and use it with the 1.4x in APSC mode as a casual, lower rez 900-ish at f6.3 birding option... I also think Sony missed an opportunity to build a 1.4x converter into the 400/4.5 -- it would have been an ideal quick-switch mammal lens.
With the second entry of "600GM", about the difference being too big, I meant the 600mm f4GM.
nick0954 wrote:
Agree I was surprised. Need to see more comparisons. Possible he had a bad copy or did something wrong. But I wouldn't expect bad copies of a prime.
Pixel Perfect wrote:
Damn so 2x slower than the 10-400 f/4.5 which has 4 XDL motors!
The 300GM only has 2 (as do the big boy 400/600).
I can tell you the 300GM can outfocus the 100-400/4.5 any day of the week and twice on Sunday.
I think the only reason they put 4 into the 100-400 is how heavy that creeping lens element is
I thought reviews of the Viltrox 2x were similar to the Sony. But Abbott's results with the Viltrox 2x look terrible. I wonder if the Sony would be better??
Jack Flesher wrote:
Then how come in my camera if I switch from full frame to APSC mode, the exposure of a full blue sky image remains identical? By your thinking, the exposure for APSC should require an extra stop to equalize, but it doesn't.
I think your argument confuses exposure (light intensity per unit area) with total light gathered across the whole image.
Equivalence describes output, not exposure. Saying a cropped 400 mm f/4.5 image is "equivalent" to a 600 mm f/6.7 image refers to field of view, depth of field, and total noise when enlarged to the same viewing size. It does not mean the light density changes or that your camera needs a different exposure metering setting. When you crop to 600mm, the additional field of view captured by a 400 mm lens falls outside the crop frame. Discarding light that falls on the edges of the sensor does not reduce the exposure level of the central subject.
Dustin Abbott just released his 600 F6.3 GM review. I thought this was an interesting comparison that I was able to make by downloading some of his test chart images.
Looks to me that the 400 F4.5 + 1.4x TC is at worst indistinguishable, and most likely slightly sharper with better contrast, from the 600 F6.3 bare lens. The bare 400 F4.5 looks sharper than the bare 600 F6.3. This makes sense given the optical similarity of the lenses.
Where this falls apart is that the 400 + 2x TC is massively worse than the 600 + 1.4x TC, which was slightly surprising to me. Both lenses frankly look bad with the 2x TC. So the question is really do you want a 400/560 or a 600/840?
Personally, I'm still torn between 100-400 F4.5 + 600 F6.3 or just rolling with a 400 F4.5 + 1.4 TC for my telephoto needs for now. But this makes a compelling case to start with the 400 F4.5 and keep my 70-200 GM II and see how far those 2 lenses + TCs as needed gets me.
I really hope that isn't the performance one is to expect from all copies of the 600/6.3.
Starting to question my decision to purchase it after seeing those. Although his in the field shots look pretty good.
That 400/4.5 looks excellent. I just can't believe it can be that much better than the 600 when the 1.4TC is mounted on it.
If I didn't have the 300GM, I'd be buying the 400/4.5 and maybe the 600/6.3.
I'll still likely go through with my 600/6.3 purchase as I really want something super lightweight that can get me to 840.
moyang_mm wrote:
I think your argument confuses exposure (light intensity per unit area) with total light gathered across the whole image.
Equivalence describes output, not exposure. Saying a cropped 400 mm f/4.5 image is "equivalent" to a 600 mm f/6.7 image refers to field of view, depth of field, and total noise when enlarged to the same viewing size. It does not mean the light density changes or that your camera needs a different exposure metering setting. When you crop to 600mm, the additional field of view captured by a 400 mm lens falls outside the crop frame. Discarding light that falls on the edges of the sensor does not reduce the exposure level of the central subject.
Exactly, IOW, aperture remains aperture for the initial exposure. And you cannot take an exposure at an aperture of f4.5 with a lens limited to f6.3. You can change the effective DoF of an f4.5 image into an an effective f6.3 DoF by cropping, but that didn't LOWER the original exposure at all! And in turn it did not require somehow increasing the exposure on the 400 lens to accommodate the crop! So claiming that exposing at f6.3 on a 600 is the same as exposing at f4.5 on a 400 is a ludicrous way to word it; one will require a 1 stop change in ISO or shutter speed, or stopping the f4.5 lens down to f6.3 to equalize them. Hence, having an actual aperture of f4.5 available remains an advantage for some users...
Chiming in on the tangent of cropping/exposure. The main thing here is the exposure doesn't technically change when you crop 400 4.5 to 600 equivalent, but the effective noise does increase by 1 "stop" since you're zooming in on a much smaller area of the photo. So there's no real advantage to the 400 4.5 over the 600 6.3 in this area since the noise will be the same either way.
nick0954 wrote:
Chiming in on the tangent of cropping/exposure. The main thing here is the exposure doesn't technically change when you crop 400 4.5 to 600 equivalent, but the effective noise does increase by 1 "stop" since you're zooming in on a much smaller area of the photo. So there's no real advantage to the 400 4.5 over the 600 6.3 in this area since the noise will be the same either way.
Steve Perry has a video that touches on this:
I am fine with that comment, noise increases with crop and the effective DoF changes with crop. But claiming that somehow makes the aperture vales equivalent is ludicrous. Aperture value is a constant in an exposure regardless of the focal length of the lens.
One other comparison. The 400 f4.5 vs the 100-400 f4.5. Pulled from the same Dustin Abbott reviews.
The 100-400 is very slightly worse than the 400 f4.5, especially in the mid-frame or with the TC, as you'd expect. To me it's definitely not so far behind that the choice is about more than the weight/price/versatility tradeoffs between them. Both are sharp.
This does make me think his 600 6.3 copy was bad, because the 100-400 f4.5 with TC looks better than the 600 6.3 did which would be a huge blunder.
nick0954 wrote:
The 100-400 is very slightly worse than the 400 f4.5
Given the excellent performance of both of those examples, I think that the word “worse” is not really appropriate. Perhaps the better example could be described as “even better.”
(I first looked at the first set in the post without looking at the ID of the samples… and I preferred the zoom version.)
He didn't do that comparison video yet, but he says it is coming. I took the test chart photos from his web site and mashed them together in one image because I'm impatient.
bcaslis wrote:
So I'm confused. I watched both 400 & 600mm videos from Dustin Abbott and I don't see the 400 & TC vs 600 comparison. Where exactly is this?
nick0954 wrote:
He didn't do that comparison video yet, but he says it is coming. I took the test chart photos from his web site and mashed them together in one image because I'm impatient.
Such a comparison video is really kind of pointless unless Dustin get's a different 600/6.3 copy or finds out what is going wrong shooting it.
As it stands now, based on the samples, he can simply say that the 400/4.5 with 1.4TC has the 600/6.3 beat outright.
I have seen some other early reviews and video's and it is clear that the 400/4.5 simply is a better match to the size and weight parameters of the design of both these lenses, which is entirely what can be expected. 26cm and below 1kg constitutes a package that hits the pure IQ of a 600mm lens harder than that of a 400mm lens.
But with that being said, even then the bare 600/6.3 should outperform the 400/4.5 + 1.4TC
To really significantly outperform the 400/4.5 + 1.4TC, Sony would have needed a 600/5.6 lens if it wants to follow the design philosophy of the new lenses (a lens I have been hoping for for ages now) but the 600/6.3 should really do a lot better than shown in the D.A. samples, and I trust that a decent copy does on an A1 or A7RVI.
I am still ordering the 600/6.3 because I believe it is indeed much better than shown here, and 600mm is always going to be better for wildlife and birding uses than endlessly cropping 400mm shots
nick0954 wrote:
He didn't do that comparison video yet, but he says it is coming. I took the test chart photos from his web site and mashed them together in one image because I'm impatient.
So the images you posted are not from a comparison but independently downloaded from different reviews? I think showing them like that is questionable and slightly misleading.
bcaslis wrote:
So the images you posted are not from a comparison but independently downloaded from different reviews? I think showing them like that is questionable and slightly misleading.
Different reviews by the same person that pretty much does the same thing every time he reviews...
But, if one doesn't want to compare, they can wait for accurate comparisons, and hope that they are comparing solid lenses and not one with a minor flaw...
Or, do it the way a lot would "Do I want to interject a tele in the mix?"
bcaslis wrote:
So the images you posted are not from a comparison but independently downloaded from different reviews? I think showing them like that is questionable and slightly misleading.
That method is certainly more reliable than trying to compare images from a compressed video.
