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04-26-2011, 09:10 AM   #16
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QuoteOriginally posted by normhead Quote
Anyway the canikon guys have some razor sharp long lens wildlife shots out there. I'm just trying to be capable of competing on an even playing field.
The Sigma 500/4.5 is the only supertelephoto currently available for Pentax that can level the playing field against the canikon crowd. I recently saw some photos of birds online taken with the Sigma and was very impressed with the sharpness, contrast, and color rendition of the shots produced by that lens: definitely a big step up from what you get from those Sigma supertelephoto zooms, and comparable to what can be got from the DA* 300.

04-26-2011, 10:10 AM   #17
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QuoteOriginally posted by normhead Quote
...Anyway the canikon guys have some razor sharp long lens wildlife shots out there. I'm just trying to be capable of competing on an even playing field.
At those focal lengths, technique and tripod are also going to be important. If you can talk to those guys, that information should be about the same no matter the camera brand.
04-26-2011, 11:01 AM   #18
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QuoteOriginally posted by normhead Quote
Thanks for your replies one and all. I guess I should have been more specific. My wife and I are working towards an exhibition of landscape and wildlife work. I own a DA*60-250 that is giving me better images than I see from other Canikon types living in the area and that I'm quite happy with. Before I broke down and bought the 60-250 I returned two Sigma 120-400's, they just weren't sharp enough 300-400mm, I can't tell you how much I wanted that lens to work out for me.

Anyway the canikon guys have some razor sharp long lens wildlife shots out there. I'm just trying to be capable of competing on an even playing field. My DA* 60-250 gets me an advantage as far as it goes. I haven't had it a full season yet, so who knows, maybe it will be enough... but I'm preparing for the eventuality that I'll probably need more reach.

Thanks for your suggestions.
out of curiosity, how do my "dirt cheap" 500mm shots compare with your expectations?

Note, I also shoot a sigma APO 70-200F2.8 EX (Non DG Non Macro) with 1.4x and 2x TCs.

I also find it excellent, as shown by the attached shots
about 10% of the K10D frame at ISO 1600 (who says the K10D can't do ISO 1600

Full frame resized only

about 50% crop out of K10D frame


Again same question about your expectations.

Note, many here have commented previously that the earliest Sigma (non DG) is the sharpest at 200mm. I kind og agree with that, which is why i have never upgraded it to a newer version
04-26-2011, 12:16 PM   #19
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A hypothetical Pentax DFA* 500mm F5.6 ED(IF) SDMii

I just posted a request for a Pentax DFA* 500mm F5.6 ED(IF) SDMii at my blog:
-> Falk Lumo: A hypothetical Pentax DFA* 500mm F5.6 ED(IF) SDMii
It contains an image shot with a 500 mm too:



(cropped to correspond to 2600 mm equivalent focal length).


The above photo is with a 20 year old manual Sigma 500/4.5 APO lens (but automatic K mount aperture). With the 1.7x AF converter, it gives me a stabilized 850 mm f/7.7 lens with fast autofocus and focus delimiter

I've run a couple tests. I do not advice to stack a converter to a 300 mm to reach 500 mm. I made resolution tests and it is not the same. Moreover, you can do the same to the 500 mm. And while 1.7x 500mm is not the same as a genuine 850 mm, it clearly resolves detail I cannot see with 500 mm or 300 mm and an 1.7x converter. Like all scale bars in a millimeter scale 52 meters away ...

Here is an internet image of the lens I used:



Last edited by falconeye; 04-26-2011 at 12:22 PM.
04-26-2011, 11:34 PM   #20
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QuoteOriginally posted by falconeye Quote

I've run a couple tests. I do not advice to stack a converter to a 300 mm to reach 500 mm. I made resolution tests and it is not the same. Moreover, you can do the same to the 500 mm. And while 1.7x 500mm is not the same as a genuine 850 mm, it clearly resolves detail I cannot see with 500 mm or 300 mm and an 1.7x converter. Like all scale bars in a millimeter scale 52 meters away ...
I am curious about the tests you've run... You seem to be saying your hypothetical 850mm (500+1.7xTC) lens outresolves 300+1.7xTC or even a 500mm lens, like seeing all the scale bars on a mm scale placed 52m away. It's as if you are saying adding a 1.7xTC to a 500mm lens makes the said lens sharper, which is impossible. Supposing a 30cm ruler fills the Pentax cropped frame horizontally when shot with your 500+1.7xTC, if you replace the 500mm lens with a 300mm lens or remove the 1.7xTC from 500+1.7xTC, don't you have to physically bring the camera closer to the ruler until the ruler occupies the same frame space as the 500+1.7x combination? Otherwise you are no longer testing the lenses' resolution but the sensor resolution.

Like I've said, I am curious about your conclusion as I have never tested a lens like this. I'd like to hear about the procedure you have used so that I may try replicating the results, albeit on a more modest scale.

Thanks,
04-27-2011, 02:13 AM   #21
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QuoteOriginally posted by excanonfd Quote
It's as if you are saying adding a 1.7xTC to a 500mm lens makes the said lens sharper, which is impossible. Supposing a 30cm ruler fills the Pentax cropped frame horizontally when shot with your 500+1.7xTC, if you replace the 500mm lens with a 300mm lens or remove the 1.7xTC from 500+1.7xTC, don't you have to physically bring the camera closer to the ruler until the ruler occupies the same frame space as the 500+1.7x combination? Otherwise you are no longer testing the lenses' resolution but the sensor resolution.
What you say is correct. I am testing sensor resolution which can be considered a trivial thing.

But ...

A 500+1.7x combination may not be able to actually outresolve the sensor. MTF50 measurements (for the 20 y.o. Sigma 500/4.5) actually would suggest it does not. But it does (the mm scale at 52m is beyond the Nyquist limit of K-5 + 500 mm). The contrast at such high spatial frequencies goes down but it can be brought up again via sharpening. MTF(Nyquist) is small (5%) but if noise is low enough is still enough to be sharpened (for my 500 + 1.7 combo).

For an actual resolution comparison of lenses, I would have had to vary the distance indeed. But I actually wanted to know if the 500mm can resolve features my 300mm (with possibly adding a TC) can't. The 300mm has the better resolution but not by enough to prevent the 500mm to take the lead.

I would attach crops. But I didn't renew my donation and if nobody grants me the necessary attachment space, I can't attach anymore ...
04-27-2011, 05:10 AM   #22
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QuoteOriginally posted by falconeye Quote
What you say is correct. I am testing sensor resolution which can be considered a trivial thing.

But ...

A 500+1.7x combination may not be able to actually outresolve the sensor. MTF50 measurements (for the 20 y.o. Sigma 500/4.5) actually would suggest it does not. But it does (the mm scale at 52m is beyond the Nyquist limit of K-5 + 500 mm). The contrast at such high spatial frequencies goes down but it can be brought up again via sharpening. MTF(Nyquist) is small (5%) but if noise is low enough is still enough to be sharpened (for my 500 + 1.7 combo).

For an actual resolution comparison of lenses, I would have had to vary the distance indeed. But I actually wanted to know if the 500mm can resolve features my 300mm (with possibly adding a TC) can't. The 300mm has the better resolution but not by enough to prevent the 500mm to take the lead.

I would attach crops. But I didn't renew my donation and if nobody grants me the necessary attachment space, I can't attach anymore ...
If I read this correctly, what you are saying is that at some point, a bigger image on the sensopr has a better, higher resolving capability than achieving the same total magnification by cropping and enlarging to a higher ratio.

WHat I am still hoping to hear is what some people think is the limit of "acceptably sharp" relitive to the photos I have posted here. I know it is not your comment falconeye but it is very related to the resolving power of the entire system.
04-27-2011, 06:10 AM   #23
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QuoteOriginally posted by Lowell Goudge Quote
If I read this correctly, what you are saying is that at some point, a bigger image on the sensopr has a better, higher resolving capability than achieving the same total magnification by cropping and enlarging to a higher ratio.

WHat I am still hoping to hear is what some people think is the limit of "acceptably sharp" relitive to the photos I have posted here. I know it is not your comment falconeye but it is very related to the resolving power of the entire system.
Well, as long as the lens outresolves the sensor, a magnifier helps. That's the trivial part of my statement. The less obvious part is that I say that one must consult the resolution where MTF drops below about 10%. I.e., not the MTF50 figure for sharpened images all testing sites are so keen to publish.

Your images do all look tac sharp except for the 100% crop. IMHO, the 100% crop needs a scale down to 50% and an USM sharpening with r=1px to look tac sharp; YMMV.

It is normal for many 1.7x converter images to gain perceived sharpness when scaled down.

04-27-2011, 06:25 AM   #24
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QuoteOriginally posted by falconeye Quote
snip......
Your images do all look tac sharp except for the 100% crop. IMHO, the 100% crop needs a scale down to 50% and an USM sharpening with r=1px to look tac sharp; YMMV.

It is normal for many 1.7x converter images to gain perceived sharpness when scaled down.
I'll need to consider trying that at some point.

the 100% crop really would never make it into my printing list, but it does show what can be achieved with a DSLR and an old lens. What is not posted clearly here is this was a pure hand held shot (that's right 500mm at 1/40th of a second) with no secondary support (i.e. monopod, post to lean on, bean bag etc...) It really shows what the K7 SR can do, when combined with proper technique. The full frame image is quite good on it's own. I think this is a case of having the ability to look at things too closely sometimes

What I find with re-sizing and scaling down, depending on the image is some with very fine detail look much worse when rescaled, although that is usually to 25% of origonal to post,
04-27-2011, 07:13 AM   #25
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I'll take your word on the technical analysis, Falk, but as a practical matter, I still think that, without shelling out very large sums, the best way to 500mm is with a DA*300mm and AF 1.7x or A 2x-S TC.
04-27-2011, 07:33 AM   #26
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QuoteOriginally posted by dadipentak Quote
I'll take your word on the technical analysis, Falk, but as a practical matter, I still think that, without shelling out very large sums, the best way to 500mm is with a DA*300mm and AF 1.7x or A 2x-S TC.
I think you could go with any of pentax's 300F4's and the 1.7x.

An A series might be the cheapest way to get all the camera functions, and this can be an important issue when it comes to flash.

I wish pentax had maintained the dual mode flash of the *istD, i.e. TTL and P-TTL for that reason. It isone of the main reasons why I will still shoot the *istD Flash with legacy lenses. My chickadee was shot that way. K300F4 plus 1.7x and flash
04-27-2011, 07:55 AM   #27
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QuoteOriginally posted by Lowell Goudge Quote
I think you could go with any of pentax's 300F4's and the 1.7x.
Agree.
04-27-2011, 08:36 AM   #28
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I have a DA* 300mm and Kenko 1.5x teleconverter. With the crop that gives an equivalent of around 680mm.

Here are some past results:
Photography: In Flight | photographybanzai.com
Flickr: dslrninja's stuff tagged with inflight04042011

Photography Hunting Results | photographybanzai.com
Flickr: dslrninja's stuff tagged with photohunt10162010

The Moon | Flickr - Photo Sharing!

They are not full resolution photos, but should give an idea how the combo is at least.
04-27-2011, 09:43 AM   #29
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How about the K500/4.5? It’s fast, sharp enough, very well built and fully manual.
All for the low price of around $500-$600.

Phil.
04-27-2011, 10:18 AM   #30
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Did you explore the Bigma option?
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