[traderdrew]

I have the Sigma 500mm F/4.5. Look at my links to see what I can do with it. Usually I want something longer but sometimes I wouldn't mind having a FF to compliment that lens. We don't have an 800mm F/5.6 available for us. I have thought of getting into digiscoping with the K-3. I have seen some very nice images from digiscopers so I think at least some of their scopes are sharp enough but I would say most of them don't know what they are doing or they got lucky.

https://www.flickr.com/photos/98462832@N04/
https://500px.com/andrewswildlife

[audiobomber]

I had a Sigma 150-500 and was not satisfied with the sharpness. I am perfectly satisfied with IQ of a DA*300 and Pentax 1.4X TC. You might think that this is step back in range, but actually at birding distances, the 150-500 has lost considerable length due to focus breathing, as shown here: Focal Length versus Subject Distance - Sigma 150-500mm

Being able to use the DA*300 bare for the extra speed is also a nice feature.

[derekkite]

Depending on the size of the wildlife subject and distance to subject, 500mm can be too long. Also, as the FL increases, the angle of view decreases, it becomes harder to frame the subject and the frame includes less of the background, atmospheric haze may appears depending on the humidity level and time of the day. Some of the best wildlife photographs are being taken with 300mm or less. If you are at 500mm and your subject is too small, realize that a 600mm lens will only provide 20% more. In this case, you'd actually need 1000mm at the expense of a huge lens, high cost, and/or less light. Hiding breaks through the never ending search for longer focal lengths.

Actually no. Close is 20-30 yards, and a 500mm gets you something that doesn't need much cropping. I miss shots with my 500mm when things are closer than 4 meters. An osprey at 8 yards fills the frame.

A bear cub I came across at about 20 feet didn't fit in the frame, at 30 feet it would have, carefully. That is very very close. The rationale for long lenses isn't to shoot things far away, it is to get better shots of things close in.


300mm requires 10-15 feet to get something that doesn't need cropping for magnification.

400-450mm is a nice middle ground between too short and too heavy.

[wildman]

in some situations 500mm can be too long, but I am currently into bird photography which I find to be challenging due to the small size of the subject.

I hear you.

First of all a "bird", here in Eastern N. America, can be anything from a Ruby Throated Hummer (L 3.75", WS 4.5", WT 0.1 oz) to a White Pelican (L 62", WS 108", WT 17 lb).
By far the most common birds we will actually see will be small, nervous, fast moving woodland and grassland passerines about 1/3 the size of a man's fist - a house sparrow size for instance (L 6.0", WS 9.0", WT 1.0 oz).

So first of all, for the purposes of birding, forget about thinking in relative terms like focal length and use the absolute term magnification. After all apparent magnification is what we are really ultimately after. I use the term "magnification" in the same same sense we use 8x or 10x "magnification" with binoculars.

It's been my experience when chasing after small woodland birds that their comfort zone is in the 30 to 40 foot range Get beyond 30 feet, set up, settle down and the birds will eventually accept your presence - no hide needed.

Assuming you define enough magnification at 35 feet so that a House Sparrow will take up about 1/3 the area of a frame you need about 40x magnification.
So doing the math we find the following FL needed by sensor size for 40x magnification:

Full Frame - 1720mm
APS-C ------ 1100mm (BTW a 500mm on a APS-C sensor gives you about 18x mag.)
4/3 ----------- 864mm
1" ------------- 635mm
1/1.7 (Q7) -- 380mm
1/2/3 (Q) ---- 306mm

I think the implications of these numbers are obvious - except for the Q sensors getting the magnification needed for most birds, is impractical for most of us on this forum - Too big, too heavy and too expensive. In a word - impractical.

Final conclusion - there is no free lunch when it comes to bird photography.

BTW go here (on this forum) if you want to see my bird pics taken with a Q-S1 and a 560mm scope at 60x magnification (over-kill but it's all I got right now) ......

https://www.pentaxforums.com/forums/122-lens-clubs/55946-300mm-plus-lens-club...ml#post3307819

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Last edited by wildman; 07-11-2015 at 10:58 AM.

[xenocide72]

I'm also in birding. I have a FA*300, FA*600 and until recently a A*1200. The 600 is my most used lens for birds; I work in hides most of the time; for respect for birds, I keep a safety distance particularly when they are nesting. 300 in APS-C is fine for big birds - egrets and so on. Also when by chance, bird come very close. 600 for small, shy birds : kingfishers... with full frame, even 600 will be a bit short, 600 + Pentax TC will be fine. I'd say, 70 % of shots with 600, 20 % with 300, 10 % with 1200.

I wonder if getting the new Pentax teleconverter for my 500mm would be worthwhile? I guess I would be concerned that the f stop would then be reduced to f/7 at full extension.

[snostorm]

Derek makes a good point, that long lenses aren't necessarily only for shooting distant subjects. I shoot a lot of songbirds at very close distances, and the 500mm + primes are not really suitable because of their @13 ft Minimum Focusing Distance specs. For the way I like to shoot, a 300mm prime (either f4/4.5 or f2.8) + 1.4x or 1.7x TC, or in the case of an f2.8, possibly both stacked is more suitable with MFD of @ 6-8 ft. A significant percentage of shots that present themselves for me are at distances of 8-12 ft and would not have been possible with, say a Sigma EX 500/4.5, but were easily accomplished with either my FA* 300/4.5 or FA* 300/2.8/Sigma EX 300/2.8 and a 1.7x AFA. I've had many opportunities to pick up the Sigma 500 for exceptionally good prices, but have always passed because the MFD was not really suitable for my style of shooting.

There are other considerations than just FL and lens speed. For me, especially with newer bodies with good higher ISO performance, the 300s + TC(s) are much more versatile and can give me the reach, IQ, and MFD that I want to work with.

Scott

[audiobomber]

I wonder if getting the new Pentax teleconverter for my 500mm would be worthwhile? I guess I would be concerned that the f stop would then be reduced to f/7 at full extension.

F-stop on a 150-500 would increase from f6.3 to f8.8 (multiply by 1.4X). The 150-500 is soft wide open, and with a TC, even one as good as the Pentax, IQ will only be worse, not to mention AF. You'll need lots of light.

[mohb]

The 150-500 is soft wide open

On what basis do you make this claim?

[derekkite]

On what basis do you make this claim?

Use? I concur. It is pretty nice at f8-f11.

[biz-engineer]

Actually no. Close is 20-30 yards, and a 500mm gets you something that doesn't need much cropping. I miss shots with my 500mm when things are closer than 4 meters. An osprey at 8 yards fills the frame. A bear cub I came across at about 20 feet didn't fit in the frame, at 30 feet it would have, carefully. That is very very close. The rationale for long lenses isn't to shoot things far away, it is to get better shots of things close in. 300mm requires 10-15 feet to get something that doesn't need cropping for magnification. 400-450mm is a nice middle ground between too short and too heavy.

Well, my comment was rather qualitative.
Quantitatively, for framing of the subject to occupy 1/3 of the frame (including some background), I consider a simple rule for myself: Distance [m] / Subject size [m] = FL[mm] / 10.
Example for an osprey of 58cm in size with 500mm FL lens: Distance = (500/10)*0.58 = 29 meters (about 32 yards).
Pretty much in line with wildman post above.

[mohb]

Use? I concur. It is pretty nice at f8-f11.

My copy is acceptably sharp wide open and could hardly be described as soft unless you are using unrealistic standards of softness and sharpness

[goubejp]

Depends on how you put the required sharpness.If it is to post a picture on the forum with 1024 pixels size, any lens will do the job...
My personal standard is to be able to make large prints of at least 50 cms wide (20 inches);and believe me, there is a huge difference between what you get from a 150-500 at 500 mm and a premium prime FA*600. It is much more than 20 % more reach given by 600 vs 500.
Again, if you are with prime, as me, you should have at least 2 : my personal experience is to use a 300 and a 600, and be able to use a TC if additional reach is needed. With a 600 a small bird as a kingfisher is well framed at 6-7 meters. That"s close and you have to be very carefull not to disturb it.
The idea is that, if you are in a hide, a 300 mm allows you to get good shots with birds coming close to 5 meters. Rather seldom. A 600 mm allows 10 meters - more for big birds. You add a lot of shooting opportunities.
Walking around with a 500 mm handheld and rely on chance gives poor results. You have to observe the bird habits, and when you have understand how he behaves, you place a hide at an acceptable (for the bird) distance, take in account the sun position - you have to shoot early in the morning for good light conditions and low atmospheric turbulences and shoot with a tripod. The 600 mm simply allows you to be more easily accepted by the bird as you'll stay away. You can get closer but with a stressed bird with unnatural attitude, no interest.
To illustrate, this is a hot from a hide 6 to 7 meters away with the FA*600 and a K3

On crop you should be able to see all Feather details

You should be away also so that the bird doesn't notice you are there and have natural attitudes like these stilts in love :

Here is a portrait of a stilt, relaxed (with 1200 mm)

and the same in alert, a couple of seconds later


Regards

[normhead]

F-stop on a 150-500 would increase from f6.3 to f8.8 (multiply by 1.4X). The 150-500 is soft wide open, and with a TC, even one as good as the Pentax, IQ will only be worse, not to mention AF. You'll need lots of light.

My A-400 is ƒ 5.6, and when I put the F 1.7 AF TC on there isn;t enough light to accurate focus. That's about ƒ 9.3 if memory serves me well.

I took an image of a tele[hone pole across the river, and the pole in the Vivtar M 135 was 363 pixels high, and the DA 18-135 was 366, so virtually identical. As it should be.

[audiobomber]

On what basis do you make this claim?

I owned one for a few weeks. if you didn't like my statement, you'll probably like this even less. It wasn't acceptably sharp at any aperture at full zoom. This review describes my experience with the 150-500mm.

•weak frame edge picture quality at wide aperture,
•too low picture quality at 500 mm focal length,
•f/6.3 already from 290 mm,
•average work against the bright light

Sigma 150-500 mm f/5.0-6.3 APO DG OS HSM review - Introduction - Lenstip.com

My comparators are the A 300mm f4 with Kenko 1.5X TC and DA*300 with Pentax HD 1.4X, both of which are sharp, even when cropped to pixel level. The Sigma was definitely not, beyond 300mm.

[goubejp]

Accuracy of AF is important here as depth of field is very small for 500 + lenses. Say 6 cms at 10 m for a 600 at f5.6 for a K5. One reason to have a combo that opens at f5.6 is to insure AF accuracy.