Subject Distance vs Image Quality

[nmerc_photos]

Apologies if this has already been discussed. I couldn't find anything similar when searching.

Recently I've been comparing some lenses, namely the 300GM, 400TC, and 800PF when shooting at distance.

In my experience (nonscientific tests - so far), I have found that if you can get your subject near a lens' MFD - IQ is all very close. For example in my backyard, a Blue Jay shot at 20' with the 100-400, 180-600, 400TC, 800PF, or 300GM + 2x all look very similar.

But once I go in the field and add more "usual" working distances - some of the lenses IQ falls apart very quickly.

On the FM forums, users are repeatedly seeing that the 600GM/300GM + 2x are almost indistinguishable near MFD, but at further distances the 600GM gives significantly better results. A lot of users have asked why this is. "600mm should be 600mm". That is partly what started me down this rabbit hole.

For example - recently I've been photographing an Osprey nest that is 300' away. The 300GM + 2x resulted in zero keepers, the 800PF + 1.4x was a little soft, the 800PF naked was acceptable, and the 400TC + 2x provided the best IQ. All required some level of cropping. Pictures were taken on the same day, using the same tripod and location, seconds or minutes apart.

I've always expected (and been told) that the longest native focal length would produce the best results, so I thought the 800PF would be significantly better than the 400TC + 2x, not the other way around.

To the questions:

• Is this a standard situation?
• What factors can contribute to this? $6.5K lens vs $13K lens? front element size? specific coatings? other physics?
• Does the build quality of a lens affect how atmospheric distortions are handled?

I went with the 400TC/800PF combo because a lot of people said it was the best of both worlds. f2.8 on the short end, and the 800PF to cover your long range. But I am finding that in all situations, the 400TC + 2x, or even 400TC + 2x + 1.4x produces noticeably better images when shooting subjects that are further away. So the 800PF isn't actually serving as a long range option. It gets great pictures near MFD, but I didn't buy an 800mm lens to shoot subjects at 20' away. Maybe that's my first mistake.

This has me wondering if a 300/600 combo wouldn't be more advantageous. If what I am observing is pretty normal, losing 100mm on the short end would be less critical than 200mm on the long end. if I'm in a situation where I can get "close" (300 - 400mm), the differences between a 35-150, 70-200, 100-400, 300 2.8, or 400 2.8 will be smaller than in situations where I am shooting further subjects and the difference between 400TC, 600TC, 800PF comes into play. The thought being that the 600TC would be much better than the 800PF at distances and focal lengths from 600mm - 1680mm.

Does this make sense? Any thoughts or ramblings are welcome.

I can also post test images from the Osprey nest if desired. I plan to eventually go out in the yard and take some static shots getting each lens as close to "all else equal" as possible, but figured I'd toss this up first. Perhaps someone has an easy answer.

 

[John Navitsky]

A lot of users have asked why this is. "600mm should be 600mm". That is partly what started me down this rabbit hole.

in the end each lens is only so good. when you put a tc on, you magnify (no pun intended) the flaws in the lens. those flaws may have been small enough not to be noticeable or visible in the unmagnified image, but can start to creep in with a tc

and this probably also goes for distance and size in frame

 

[John Navitsky]

another issue is zooms will not provide the same quality over their zoom range

 

[John Navitsky]

in your specific case, the 400 might just be that much better

the gotcha with your 300/600 theory is you need a 300 that matches the quality of the 400 tc, and that doesn’t exist (although the 120-300 might do reasonably)

 

[nmerc_photos]

in your specific case, the 400 might just be that much better

the gotcha with your 300/600 theory is you need a 300 that matches the quality of the 400 tc, and that doesn’t exist (although the 120-300 might do reasonably)

but if my theory holds true, at shorter distances and focal lengths there will be less difference between a top tier optic like a 400/600TC, and a 70-200 or 300 2.8.

from what I've seen with the 300GM, it is very close to - if not as good as the 400TC when both are naked and shot near MFD. I hope Nikon comes out with their own 300 f2.8, preferably with a built in TC and that would seal the deal

 

[ricardo00]

I can also post test images from the Osprey nest if desired. I plan to eventually go out in the yard and take some static shots getting each lens as close to "all else equal" as possible, but figured I'd toss this up first. Perhaps someone has an easy answer.

I for one would love to see the Osprey nest shots. Often I have distant subjects where I can't get close, so would love to see the comparison between the 400 plus 2.0 TC and 800mm.

 

[Paul Grecian]

Not every lens is equally good at distance. Also, a PF lens may not fare as well if the subject is backlit when it comes to contrast.

 

[nmerc_photos]

I for one would love to see the Osprey nest shots. Often I have distant subjects where I can't get close, so would love to see the comparison between the 400 plus 2.0 TC and 800mm.

is it better to have them edited or raw? raw right? if so, how would I share them?

Not every lens is equally good at distance. Also, a PF lens may not fare as well if the subject is backlit when it comes to contrast.

that's part of what I'm thinking... any idea what factors could contribute to it? is it just an overall quality thing, where price is going to be our best indicator?

 

[ajrmd]

Let's address each idea individually and my apologies on the edits.

1) In my experience (nonscientific tests - so far), I have found that if you can get your subject near a lens' MFD - IQ is all very close. For example in my backyard, a Blue Jay shot at 20' with the 100-400, 180-600, 400TC, 800PF, or 300GM + 2x all look very similar.

My real world experience affirms this provided all other factors being equal.

2) But once I go in the field and add more "usual" working distances - some of the lenses IQ falls apart very quickly.

That is very dependent on the lens, lighting, and other factors.

3) For example - recently I've been photographing an Osprey nest that is 300' away. The 300GM + 2x resulted in zero keepers, the 800PF + 1.4x was a little soft, the 800PF naked was acceptable, and the 400TC + 2x provided the best IQ. All required some level of cropping. Pictures were taken on the same day, using the same tripod and location, seconds or minutes apart.

I think it would be helpful to define "keepers". Shooting Osprey at 100 yards away begs a longer FL for "best results". I am not surprised that the 300/2x combination was sub-optimal and that the 800/1.4 yielded images a "little soft" depending on the lighting. Though I like many aspects of the 800 PF, the longer that I've owned, the more deficiencies I've encountered compared to my older, heavier, primes. In good, clean light, the 800 PF can produce some really nice images with excellent color, contrast, etc. I find that compared to non-PF primes, this lens breaks down with any atmospherics and with certain lighting conditions such as high contrast, fog, etc. My old Canon 400 f/2.8, 500 f/4/1.4x, 600 f/4/1.4x produced superior images compared to the 800 PF. It doesn't surprise me that the 400 f/2.8/2x produces images better than the 800 PF in many circumstances.

4) I've always expected (and been told) that the longest native focal length would produce the best results, so I thought the 800PF would be significantly better than the 400TC + 2x, not the other way around.

That may have been true years ago, though newer TC's are optically better. 2x TC's have always worked better with longer f/2.8's like the 300, 400, and not as well with the f/4, 5.6 lenses.

5) To the questions:

• Is this a standard situation?
• What factors can contribute to this? $6.5K lens vs $13K lens? front element size? specific coatings? other physics?
• Does the build quality of a lens affect how atmospheric distortions are handled?

I'm not sure of the meaning of "standard" though I think the principles will hold across major brands. I'm not an optical engineer though though I can opine a bit. The PF lens is dependent on a fresnel element which has some benefits, namely lighter weight along with some optical compromises. The f/4 has larger optical elements and more light gathering and it may have better or additional coatings. As I mentioned, the PF lenses seem more susceptible to atmospheric effects though I am unable to answer whether that is a consequence of the PF design.

6) I went with the 400TC/800PF combo because a lot of people said it was the best of both worlds. f2.8 on the short end, and the 800PF to cover your long range. But I am finding that in all situations, the 400TC + 2x, or even 400TC + 2x + 1.4x produces noticeably better images when shooting subjects that are further away. So the 800PF isn't actually serving as a long range option. It gets great pictures near MFD, but I didn't buy an 800mm lens to shoot subjects at 20' away. Maybe that's my first mistake.

I don't regard those lenses as a "combo" and many people who buy an 800 do so because they are unable to afford a 400/600TC or want a smaller, lightweight lens. You might want to consider selling the 800 PF.

6) This has me wondering if a 300/600 combo wouldn't be more advantageous. If what I am observing is pretty normal, losing 100mm on the short end would be less critical than 200mm on the long end. if I'm in a situation where I can get "close" (300 - 400mm), the differences between a 35-150, 70-200, 100-400, 300 2.8, or 400 2.8 will be smaller than in situations where I am shooting further subjects and the difference between 400TC, 600TC, 800PF comes into play. The thought being that the 600TC would be much better than the 800PF at distances and focal lengths from 600mm - 1680mm.

I can't answer that because one would be operating with two different platforms as Nikon currently doesn't offer a 300mm. If you want to go Sony, then yes the 300/600 might be attractive. As far as determining an optimal combination, it's always a compromise between size, weight, optics, $.

 

[Nimi]

Apologies if this has already been discussed. I couldn't find anything similar when searching.

Recently I've been comparing some lenses, namely the 300GM, 400TC, and 800PF when shooting at distance.

In my experience (nonscientific tests - so far), I have found that if you can get your subject near a lens' MFD - IQ is all very close. For example in my backyard, a Blue Jay shot at 20' with the 100-400, 180-600, 400TC, 800PF, or 300GM + 2x all look very similar.

But once I go in the field and add more "usual" working distances - some of the lenses IQ falls apart very quickly.

On the FM forums, users are repeatedly seeing that the 600GM/300GM + 2x are almost indistinguishable near MFD, but at further distances the 600GM gives significantly better results. A lot of users have asked why this is. "600mm should be 600mm". That is partly what started me down this rabbit hole.

For example - recently I've been photographing an Osprey nest that is 300' away. The 300GM + 2x resulted in zero keepers, the 800PF + 1.4x was a little soft, the 800PF naked was acceptable, and the 400TC + 2x provided the best IQ. All required some level of cropping. Pictures were taken on the same day, using the same tripod and location, seconds or minutes apart.

I've always expected (and been told) that the longest native focal length would produce the best results, so I thought the 800PF would be significantly better than the 400TC + 2x, not the other way around.

To the questions:

• Is this a standard situation?
• What factors can contribute to this? $6.5K lens vs $13K lens? front element size? specific coatings? other physics?
• Does the build quality of a lens affect how atmospheric distortions are handled?

I went with the 400TC/800PF combo because a lot of people said it was the best of both worlds. f2.8 on the short end, and the 800PF to cover your long range. But I am finding that in all situations, the 400TC + 2x, or even 400TC + 2x + 1.4x produces noticeably better images when shooting subjects that are further away. So the 800PF isn't actually serving as a long range option. It gets great pictures near MFD, but I didn't buy an 800mm lens to shoot subjects at 20' away. Maybe that's my first mistake.

This has me wondering if a 300/600 combo wouldn't be more advantageous. If what I am observing is pretty normal, losing 100mm on the short end would be less critical than 200mm on the long end. if I'm in a situation where I can get "close" (300 - 400mm), the differences between a 35-150, 70-200, 100-400, 300 2.8, or 400 2.8 will be smaller than in situations where I am shooting further subjects and the difference between 400TC, 600TC, 800PF comes into play. The thought being that the 600TC would be much better than the 800PF at distances and focal lengths from 600mm - 1680mm.

Does this make sense? Any thoughts or ramblings are welcome.

I can also post test images from the Osprey nest if desired. I plan to eventually go out in the yard and take some static shots getting each lens as close to "all else equal" as possible, but figured I'd toss this up first. Perhaps someone has an easy answer.

My guess is that they look identical at MFD, but they are not. Distance, atmospheric, shake, VR behavior, AF behavior, TC, other factors will magnify the differences at a distance. That's why on MTF charts the 10mm lines may be identical while the 20/30 diverge.

Pixel peep on photos you think are identical, assuming hi reaolution monitor, uneditied files, I'm curious whether they really are identical at MFD.

 

[ricardo00]

is it better to have them edited or raw? raw right? if so, how would I share them?

I think a JPG posted here or on Flickr (higher resolution than here) or Smugmug or your own site would be fine for comparison. If they are pretty close on JPG, I would be "satisfied". Others might want the RAWs, in which case I believe you have to share via a dropbox. But for me personally, a high quality JPG would be fine for comparison.

 

[kanonka]

You mentioned that you are shooting from a tripod. If this is a case, it's much better to use 600TC; 800PF is only better if you are handholding, and not strong as Hulk...

 

[nmerc_photos]

Let's address each idea individually and my apologies on the edits.

1) In my experience (nonscientific tests - so far), I have found that if you can get your subject near a lens' MFD - IQ is all very close. For example in my backyard, a Blue Jay shot at 20' with the 100-400, 180-600, 400TC, 800PF, or 300GM + 2x all look very similar.

My real world experience affirms this provided all other factors being equal.

2) But once I go in the field and add more "usual" working distances - some of the lenses IQ falls apart very quickly.

That is very dependent on the lens, lighting, and other factors.

3) For example - recently I've been photographing an Osprey nest that is 300' away. The 300GM + 2x resulted in zero keepers, the 800PF + 1.4x was a little soft, the 800PF naked was acceptable, and the 400TC + 2x provided the best IQ. All required some level of cropping. Pictures were taken on the same day, using the same tripod and location, seconds or minutes apart.

I think it would be helpful to define "keepers". Shooting Osprey at 100 yards away begs a longer FL for "best results". I am not surprised that the 300/2x combination was sub-optimal and that the 800/1.4 yielded images a "little soft" depending on the lighting. Though I like many aspects of the 800 PF, the longer that I've owned, the more deficiencies I've encountered compared to my older, heavier, primes. In good, clean light, the 800 PF can produce some really nice images with excellent color, contrast, etc. I find that compared to non-PF primes, this lens breaks down with any atmospherics and with certain lighting conditions such as high contrast, fog, etc. My old Canon 400 f/2.8, 500 f/4/1.4x, 600 f/4/1.4x produced superior images compared to the 800 PF. It doesn't surprise me that the 400 f/2.8/2x produces images better than the 800 PF in many circumstances.

4) I've always expected (and been told) that the longest native focal length would produce the best results, so I thought the 800PF would be significantly better than the 400TC + 2x, not the other way around.

That may have been true years ago, though newer TC's are optically better. 2x TC's have always worked better with longer f/2.8's like the 300, 400, and not as well with the f/4, 5.6 lenses.

5) To the questions:

• Is this a standard situation?
• What factors can contribute to this? $6.5K lens vs $13K lens? front element size? specific coatings? other physics?
• Does the build quality of a lens affect how atmospheric distortions are handled?

I'm not sure of the meaning of "standard" though I think the principles will hold across major brands. I'm not an optical engineer though though I can opine a bit. The PF lens is dependent on a fresnel element which has some benefits, namely lighter weight along with some optical compromises. The f/4 has larger optical elements and more light gathering and it may have better or additional coatings. As I mentioned, the PF lenses seem more susceptible to atmospheric effects though I am unable to answer whether that is a consequence of the PF design.

6) I went with the 400TC/800PF combo because a lot of people said it was the best of both worlds. f2.8 on the short end, and the 800PF to cover your long range. But I am finding that in all situations, the 400TC + 2x, or even 400TC + 2x + 1.4x produces noticeably better images when shooting subjects that are further away. So the 800PF isn't actually serving as a long range option. It gets great pictures near MFD, but I didn't buy an 800mm lens to shoot subjects at 20' away. Maybe that's my first mistake.

I don't regard those lenses as a "combo" and many people who buy an 800 do so because they are unable to afford a 400/600TC or want a smaller, lightweight lens. You might want to consider selling the 800 PF.

6) This has me wondering if a 300/600 combo wouldn't be more advantageous. If what I am observing is pretty normal, losing 100mm on the short end would be less critical than 200mm on the long end. if I'm in a situation where I can get "close" (300 - 400mm), the differences between a 35-150, 70-200, 100-400, 300 2.8, or 400 2.8 will be smaller than in situations where I am shooting further subjects and the difference between 400TC, 600TC, 800PF comes into play. The thought being that the 600TC would be much better than the 800PF at distances and focal lengths from 600mm - 1680mm.

I can't answer that because one would be operating with two different platforms as Nikon currently doesn't offer a 300mm. If you want to go Sony, then yes the 300/600 might be attractive. As far as determining an optimal combination, it's always a compromise between size, weight, optics, $.

Thank you for the extremely well thought out responses!

3) I agree, defining keepers will vary from person to person. For me - it just means that as a noob photographer, I wouldn't post any of the images from 300GM + 2x in that shoot. I would grudgingly post the 800PF + 1.4x pics because although soft - they had good action (bringing in a fish), the naked 800PF shots were good enough to post, and the 400TC + 2x were absolutely postable.

I think I agree with your statements about the 800PF. In the beginning I was awe struck, but now I am seeing more of the tradeoffs whether it be that it's a PF lens, or just a "cheap" telephoto prime.

5) Sounds like I need to do more research into the PF technology and tradeoffs. I wonder if it's innately a PF thing that they are more susceptible to atmospheric effects and worse at shooting at distance

6) When I was coming over from Canon, I was trying to decide what lens setup to go with. I owned all of the RF primes (400 2.8, 600 4, 800 5.6, 1200 8) and after reading for many hours and watching videos - the majority of people were suggesting to buy both the 400TC AND 800PF as an alternative to just buying the 600TC. There are a number of users both on BCG and FM that swear by this "combo". if you're interested, I can dig up the threads/videos.

I'm leaning towards selling the 400TC/800PF in favor of the 600TC, but wanted to make sure I wasn't going crazy. I've seen so much praise for the 800PF (rightfully so - it's a budget banger!), but I never saw mention of subject distance come up in discussion.

7) From my testing, adapting the 300GM onto the Z9 works stunningly well. Much better than expected. I would have no qualms about using that as a stellar 300 f2.8, very good 420 f4, and good close-range 600 f5.6. If I swap to the 600TC, I will want either the 400 4.5, 600PF or 300GM to supplement me on the shorter side. 300GM wins for flexibility, 600PF wins for distance shooting, 400 4.5 is the happy medium.

 

[SCoombs]

I have some thoughts, but here is an important question to make sure everyone is on the same page: how much cropping is going on here as we go to longer distances? Are you talking about shooting something at longer distance and then just looking at the full frame image, or are we first cropping in to get the desired composition and then comparing the results from one lens to another?

 

[nmerc_photos]

My guess is that they look identical at MFD, but they are not. Distance, atmospheric, shake, VR behavior, AF behavior, TC, other factors will magnify the differences at a distance. That's why on MTF charts the 10mm lines may be identical while the 20/30 diverge.

Pixel peep on photos you think are identical, assuming hi reaolution monitor, uneditied files, I'm curious whether they really are identical at MFD.

For me - it is not identical, but close enough that it doesn't bother me as much as the discrepancy I am seeing between 400TC + 2x and 800PF.

I don't think I would be able to find any that I could claim were "identical".

FWIW - I edit and view media on my 55" 4K monitor which I think is pretty good at "exposing" any differences or deficiencies.

I think a JPG posted here or on Flickr (higher resolution than here) or Smugmug or your own site would be fine for comparison. If they are pretty close on JPG, I would be "satisfied". Others might want the RAWs, in which case I believe you have to share via a dropbox. But for me personally, a high quality JPG would be fine for comparison.

I've never shot JPG before with Nikon gear. If I can just convert raw to JPG, I can do that for you.

Otherwise I expect I'll be back at Ospreys soon and can take some SOOC JPG.

You mentioned that you are shooting from a tripod. If this is a case, it's much better to use 600TC; 800PF is only better if you are handholding, and not strong as Hulk...

Can you elaborate on why the 600TC is better? Even Steve's comparisons showed the 800PF sharper than the 600TC + 1.4x.

That may also be another variable - I was taking sharpness as the end all be all, but the cheaper lens or the PF elements may lead to other.. difficulties. inconsistency in getting good shots, atmospherics, haze, etc.

 

[arbitrage]

in your specific case, the 400 might just be that much better

the gotcha with your 300/600 theory is you need a 300 that matches the quality of the 400 tc, and that doesn’t exist (although the 120-300 might do reasonably)

I don't know, the Sony 300GM that he is using is one of the sharpest lenses I've ever owned. But I've never owned the 400TC so maybe it is that much better??
Sony 300GM is certainly a better optic than the 400GM when TCs are involved.

 

[nmerc_photos]

I have some thoughts, but here is an important question to make sure everyone is on the same page: how much cropping is going on here as we go to longer distances? Are you talking about shooting something at longer distance and then just looking at the full frame image, or are we first cropping in to get the desired composition and then comparing the results from one lens to another?

How do you prefer to measure the amount of cropping? Percentage wise? End pixel amounts?

In the comparison of the 400 + 2x / 800PF I'm shooting at 800mm, 300' away, and cropping from 8256 x 5504 to 4406 x 2937. 72% of the pixels thrown out?

I'm not super well versed on defining crop, and "viewing at 100%" or whatever. But I usually crop significantly in most situations.

In my examples I am talking about shooting both at the same focal length, cropping both to the same composition, and then comparing the results.

 

[arbitrage]

For me - it is not identical, but close enough that it doesn't bother me as much as the discrepancy I am seeing between 400TC + 2x and 800PF.

I don't think I would be able to find any that I could claim were "identical".

FWIW - I edit and view media on my 55" 4K monitor which I think is pretty good at "exposing" any differences or deficiencies.



I've never shot JPG before with Nikon gear. If I can just convert raw to JPG, I can do that for you.

Otherwise I expect I'll be back at Ospreys soon and can take some SOOC JPG.



Can you elaborate on why the 600TC is better? Even Steve's comparisons showed the 800PF sharper than the 600TC + 1.4x.

That may also be another variable - I was taking sharpness as the end all be all, but the cheaper lens or the PF elements may lead to other.. difficulties. inconsistency in getting good shots, atmospherics, haze, etc.

You can create a free Flickr account that allows like 1000 images or something and post some jpegs to that. I'm mostly just curious to how small the osprey/nest is in the frame at those different focal lengths.
Also did you try shooting the 400TC at 560mm? Curious how much of the poor IQ from the 300GM/2xTC was just too few pixels on target?? 400TC at 560mm would at least give a similar focal length to compare although of course the 400TC should best the 300GM with a 2xTC.

 

[ricardo00]

I've never shot JPG before with Nikon gear. If I can just convert raw to JPG, I can do that for you.

Otherwise I expect I'll be back at Ospreys soon and can take some SOOC JPG.

Yes a raw you convert to JPG without any modifications is fine for me. I didn't mean that you had to photograph it as a JPG.

 

[kanonka]

Can you elaborate on why the 600TC is better? Even Steve's comparisons showed the 800PF sharper than the 600TC + 1.4x.

That may also be another variable - I was taking sharpness as the end all be all, but the cheaper lens or the PF elements may lead to other.. difficulties. inconsistency in getting good shots, atmospherics, haze, etc.

His comparison showed they are "on par", and only for test charts, which is different from real life shooting. First, 600TC is two lenses in one. Sometimes I have a situation when 800 is just too much; with 600TC this would be less often, as you can switch FL in less than a second. And, secondly, 800PF is fantastic (I love mine a lot, and switched to Nikon only because of it), but - only when conditions are right, while 600TC is great no matter what. If I could shoot 600TC handheld, I wouldn't even look to 800PF. But I'm not that strong, and tripods is not my thing.

 

[nmerc_photos]

You can create a free Flickr account that allows like 1000 images or something and post some jpegs to that. I'm mostly just curious to how small the osprey/nest is in the frame at those different focal lengths.
Also did you try shooting the 400TC at 560mm? Curious how much of the poor IQ from the 300GM/2xTC was just too few pixels on target?? 400TC at 560mm would at least give a similar focal length to compare although of course the 400TC should best the 300GM with a 2xTC.

I didn't try shooting at 560mm at all. This spot is a reach even at 800mm, so it's not somewhere I would consider using 560/600. I imagine a large amount is just the fact that the 300GM + 2x was too few pixels. To get an equivalent composition it turned 8256 x 5504 into 2369 x 1579. 45M pixels to 4M pixels... 92% of the image cropped out.

I guess looking at in terms of mathematical pixels, I may be able to go back with the 400TC/800PF, stand further back and try to get a similar composition after throwing out 92% of the original image and see how they fare. with only 8% of the pixels remaining, I'd imagine that's quite a stress test for any lens.

I only tested the 300GM + 2X since I had it in hand. I was trying to find closer subjects (swallows, hummingbirds, robins), but the Ospreys are the main attraction at that area so it was difficult to do.

It sounds like I probably have my answer (swap to 600TC), but I'll go back and do some more clinical testing with some of the feedback from this thread.

His comparison showed they are "on par", and only for test charts, which is different from real life shooting. First, 600TC is two lenses in one. Sometimes I have a situation when 800 is just too much; with 600TC this would be less often, as you can switch FL in less than a second. And, secondly, 800PF is fantastic (I love mine a lot, and switched to Nikon only because of it), but - only when conditions are right, while 600TC is great no matter what. If I could shoot 600TC handheld, I wouldn't even look to 800PF. But I'm not that strong, and tripods is not my thing.

Fair enough. I don't think I've ever seen a lens test that measured at varying subject distances and crops. I would be very interested in something like that.

I do tend to agree with your comment "800PF is fantastic but - only when conditions are right, while 600TC is great no matter what." I find that sometimes I get great images with the 800PF, but it's a lot less consistent than the 400TC.

I owned the 600TC briefly, before I had the opportunity to swap it for the 400TC/800PF combo. so I know I can handhold the 600TC without much issue.

But, in my style of shooting it seems I am normally able to use tripods when shooting far distances. When using 200-400mm, I'm often able to get much closer to subjects (white tails, owls, song birds, etc.) and much more likely to be mobile. So I also value something like the 300GM over the 400TC there. When I'm shooting for distance, it's usually because I have no other choice and can't zoom with feet. Osprey nest that's across a lake, Short Eared Owls on private property, Bears that I don't want to get close to, etc.

 

[SCoombs]

His comparison showed they are "on par", and only for test charts, which is different from real life shooting. First, 600TC is two lenses in one. Sometimes I have a situation when 800 is just too much; with 600TC this would be less often, as you can switch FL in less than a second. And, secondly, 800PF is fantastic (I love mine a lot, and switched to Nikon only because of it), but - only when conditions are right, while 600TC is great no matter what. If I could shoot 600TC handheld, I wouldn't even look to 800PF. But I'm not that strong, and tripods is not my thing.

This is interesting. Why donyoubsay the 600tc is great no matter what but the 800pf is condition dependent? What sorts of conditions do you have in mind?

 

[Doug Herr]

I swore I'd stay out of this discussion but the misconceptions and broad generalizations are getting abused, misused and confused.

First, any lens can be optimized for any distance or magnification. There isn't a one-size-fits-all description of how lenses will behave. Lenses are usually designed to work quite well over a broad range of distances and magnifications, but how and where the optimum point can be found is up to the particular design of the lens, which aberrations are best minimized, the design philosophy behind the lens (i.e., is it designed to be used with software geometric and/or chromatic correction?) and the intended use of the lens.

Lenses can also be designed to be paired with TCs, either a dedicated TC as with the TC lenses or with a general-purpose TC which itself can be designed to work with a broad range of exit pupil angles or with a narrower range of exit pupils.

Yes there will be differences among lenses but the differences over a wide range of FL, apertures, MFDs or optical technologies (such as PF or TCs) shouldn't be simplified to "lenses perform best at MFD", "lenses without TCs perform better at distances". Test each lens or lens+TC in the working conditions you expect, find the combination that works best for your intended purpose, and go take some pictures. Oddly enough or not, spend more for the lens and you might find it works better under a broader range of conditions which could explain how the 800 PF is fantastic when conditions are right while a 600 TC is great no matter what. The same applies to other brands BTW.

If a lens is sharper at MFD than at infinity, it's because of the way the particular lens was designed. It's not because of its focal length. It's not because it's a PF or non-PF lens. It's not because of its maximum aperture or because it has a TC built in. It's that particular lens.

 

[wotan1]

I don’t think what you are describing is a “controlled experiment”. I also think there may be differences among specific lenses in a series and it is possible your lens may be different from others’.

I have never had access to the 400mm f2.8 tc so I have no basis for comparison. The general test results done by some reviewers has placed the 800 pf as marginally better than the 400 f2.8 with 2x tc.

All I know is what I can and cannot afford according to the standards set by She Who Must Be Obeyed. I can afford, and own, the 800mm pf and I also own/have owned the 400mm f4.5 and the 600mm pf. My experience with my copy of the 800mm pf is that it is very capable of producing sharp images at ”reasonable” distances even after significant cropping. In short my copy of the lens is the best available to me at this time and I am happy with what it produces. It is fair to say that I does the best I have ever seen at 800mm for any lens I have used.

It would not be surprising to me that a lens that costs close to three times as much as the 800 pf may be able to produce images that are sharper than the 800. I do aspire to get one of those one of these days and if I do get one I may well choose to finally replace my 800.

I bought my 800 from someone who was selling it because she had acquired the 600mm f4 tc vr. My recollection in discussions with her is that the 800 continued to provide high quality images in her judgment even after she had been working with the 600mm tc.

Of course the other issue is that with long focal length lenses when shooting distant subjects there are all sorts of factors that can affect image sharpness. Among those are atmospheric conditions and movement of the subject. And as has been shown with shooting in multiple bursts there can be wide variance in sharpness between images taken fractions of a second apart.

Did your experiment include shooting a number of shots at high frame rates and comparing the images that way?

 

[Lance B]

Firstly, what distances are we talking about? I mean, it would have to be a long distance with a large bird or animal for me to consider it long distance. Here we have heat haze issues and other factors to consider. For me, most shots are under the 20mt mark.

I would say that the more expensive lenses would definitely focus faster and possibly focus more accurately than the cheaper lenses at distance, but I have no proof of the second part to that statement. I guess it depends on the price equation we are talking about. Is my 180-600 that much worse at distance as far as focus accuracy is concerned compared to the 600 f4 + TC? Or even my 800 pf? I know it probably isn't as fast to focus, but as far as accuracy I haven't noticed this but it might be there. I guess if you are paying the money you would want better AF performance but whether that affects long distance accuracy is questionable. I mean, it is either in focus or it isn't. I have not noticed this in my circumstances taking photos, but I generally do not shoot at long distance if I can avoid it simply due to the fact that I always try to get as close as possible to avoid cropping and I don't want to have to deal with heat haze issues. Cropping increases apparent noise and does take the edge off. Having said that, I have cropped significantly with small birds at close distances, like under 10mts. Again, what distances are you getting issues at?

Using a TC on a slower lens is never as good as on a fast exotic to the point I generally will not use it on a zoom if it is a consumer f4 and slower lens. If it is a pro grade f2.8 or f4 lens that is different - the Z70-200 f2.8 VR S is hardly affected with the 1.4x TC. On a prime it is less of an issue but on an f2.8 exotic like my 400 f2.8E FL VR it is no issue whatsoever, but on say the 500 pf I would generally only do it when I needed to crop and use the 1.4x TC. Again, with any of them, I rarely shoot at distance because filling the frame is what using the TC is all about. Again, what distances are you talking about?

This is the 800pf shot at distance and about a 100% crop. It looks fine to me.

Z8 + 800 pf, 1/3200s f/6.3 at 800.0mm iso1000

Crop

Another but the bird was closer
Z8 + 800 pf, 1/3200s f/6.3 at 800.0mm iso1000

Crop

For comparison. Z9 + 400 f2.8E FL VR + 1.4x TCIII, 1/1250s f/5.6 at 560.0mm iso180. Different day, similar conditions but is it any better/ worse than the Z8 + 800 pf? Difficult to judge as it was a different day and the shutter speed here was only 1/1250sec compared to 1/3200sec with the 800 pf.

Crop

Here is a Rainbow bee eater at distance simply because it was on someone's private land and had a no trespassing sign and I couldn't get closer. This is with the 800 pf + 1.4x TC. This is not something I would ordinarily do - use a TC on a slow lens and crop - but the result was decent enough, actually impressive considering it was handheld, no bracing at all, a "slow" f6.3 lens with a 1.4x TC attached and cropped!

Z8 + 800 pf + 1.4x TC, 1/500s f/9.0 at 1120.0mm iso720

Crop