[Rupert]

That's a great test. It's too bad there isn't a part of the site where these tests could be preserved. I've notice, not one of my early test threads can be accessed. I don't know if they're here and I can't get to them, or if they've been deleted.

Maybe Adam will take note of this and make a place for such extensive tests as these. Even for a non-techno amateur like me, this is educational and a great benefit in helping me understand what is happening with my equipment, and in determining my best needs for my particular goals. I know of no other site where a person can find such an education on a regular basis, in terms that most can understand.

In simplicity, this particular test means to my simple mind......150-450..Very Good! Buy It! Of course, I learned a few things about TCs and resolving power too...but the bottom line is a buying decision made easier and with more confidence.

Regards & Thanks again to WPRESTO for taking the time and trouble to do this for us!

[marcusBMG]

What a great set of tests! I really hope you post this as a separate thread so it's more easily searched for.

+1.
At least PF has good search options (unlike mflenses where I struggle to find anything...): by author, keywords... Google will pull something like this up as well particularly with a good title (use "advanced" when you post).
If you like rvanna I'll html what you've posted. It's then easy to pdf it all off a web page using eg print friendly

ps I'll also put in links, well specifically on the tamron 400mm review page.

[ChipB]

[COLOR=Red][B]LONG LENS + TC TEST SEQUENCE, PART 1

A lot of work - and VERY much appreciated!! Thanks for doing this and sharing the results!

[dadipentak]

Let me add my appreciation--most of all to WPRESTO for the arduous testing but also to the participants in a very thoughtful and enlightening discussion. It's very timely, too, as I'm expecting delivery of a Tamron 400/4, a Gitzo Mountaineer Series 2 tripod and a Wimberly Gimbal Head. All used--but still, "Santa been berry berry good to me."

[Rupert]

After all that hard work by WPRESTO my big ol' brain is tired from the learning...Otis says it's time to sit back and relax a while and think about something calming....like handsome squirrels...and what you might get them for Christmas?



....and we don't want to forget the Annual Donations for the poor little blind orphan squirrels! When you donate to PForums, Otis gives a days feed for the little orphans to get them through the cold winter months.



Regards! This is such a great thread......minus the squirrels, of course!

[WPRESTO]

Kitty is getting tired as well.
Another observation I made during the tests, and also noted several times using tripods in the field. I used the second heaviest tripod I own (the heaviest is a converted wooden surveyor's tripod that probably weighs in excess of 15 pounds, maybe over 20) and what is probably my most solid tripod head (a Manfrotto geared head), yet vibration was easily detectable at longer focal lengths - at 800mm, the merest finger touch on the lens would send the 8X live view bouncing beyond all hope of seeing what was happening. The limitation of holding a camera + long steady is not the weight of the tripod nor the solidity of the head, it's the fact that the camera + long lens can tilt up-down along the long axis so long as the rig is only supported at one point near the center. It's kind of a seesaw effect. The only way to eliminate it is to have a second support either below the camera body or attached as far out at the end of the lens as possible. Independent extension to the ground is fine, but even if the second brace simply comes down to one of the tripod legs, it will have a major impact an reducing camera/lens shake.

[rvannatta]

Kitty is getting tired as well.
Another observation I made during the tests, and also noted several times using tripods in the field. I used the second heaviest tripod I own (the heaviest is a converted wooden surveyor's tripod that probably weighs in excess of 15 pounds, maybe over 20) and what is probably my most solid tripod head (a Manfrotto geared head), yet vibration was easily detectable at longer focal lengths - at 800mm, the merest finger touch on the lens would send the 8X live view bouncing beyond all hope of seeing what was happening. The limitation of holding a camera + long steady is not the weight of the tripod nor the solidity of the head, it's the fact that the camera + long lens can tilt up-down along the long axis so long as the rig is only supported at one point near the center. It's kind of a seesaw effect. The only way to eliminate it is to have a second support either below the camera body or attached as far out at the end of the lens as possible. Independent extension to the ground is fine, but even if the second brace simply comes down to one of the tripod legs, it will have a major impact an reducing camera/lens shake.

I quite agree. but it's worse if the lens/camera are seriously off balance, because then the legs of the tripod on the heavy side are bowed
and act like a spring. I think I have a support leg like you mention that goes to a tripod leg, but haven't quite mastered using it.
I tend to use what I regard as an even better solution ------ --- a couple of bean bags on the hood of my car. It works pretty well
for animals on the ground, or other items at about the same elevation---- Not so good if you have no car, or the target is seriously above
or below you, but..... Failing that, I look for stumps, rocks, logs, trees, or what ever I can find. I carry a bulky jacket that I wad up
and use for the lense support. Not exactly a good test bed, but it works in the real world.

[swip]

A couple more from the weekend.
.

Love the second one.

[WPRESTO]

I quite agree. but it's worse if the lens/camera are seriously off balance, because then the legs of the tripod on the heavy side are bowed
and act like a spring. I think I have a support leg like you mention that goes to a tripod leg, but haven't quite mastered using it.
I tend to use what I regard as an even better solution ------ --- a couple of bean bags on the hood of my car. It works pretty well
for animals on the ground, or other items at about the same elevation---- Not so good if you have no car, or the target is seriously above
or below you, but..... Failing that, I look for stumps, rocks, logs, trees, or what ever I can find. I carry a bulky jacket that I wad up
and use for the lense support. Not exactly a good test bed, but it works in the real world.

A car is definitely a sturdier support than any tripod. Must remember to take mine next time I go walking in the woods.

[rvannatta]

A car is definitely a sturdier support than any tripod. Must remember to take mine next time I go walking in the woods.

I live in the woods --- so I don't have the car far away. At least half the bird photos I've taken though have been within 50 feet of my house.

[Canada_Rockies]

Looking carefully at this thread, thanks to WPRESTO and all the subsequent commenters, I am wondering if I can crop the K3 image from the M 400 to get the same multiplication as the AFA 1.7X gives. I am going to have to do some work with my fences. The 1.7x was a definite advantage with the K10 (10.2 mpx) but 1.7x10.2 is quite a bit less than 1x24.3 -- calls for more testing. Leaving the 1.7X out would certainly help with the aperture/shutter speed/ISO combinations.

[WPRESTO]

Looking carefully at this thread, thanks to WPRESTO and all the subsequent commenters, I am wondering if I can crop the K3 image from the M 400 to get the same multiplication as the AFA 1.7X gives. I am going to have to do some work with my fences. The 1.7x was a definite advantage with the K10 (10.2 mpx) but 1.7x10.2 is quite a bit less than 1x24.3 -- calls for more testing. Leaving the 1.7X out would certainly help with the aperture/shutter speed/ISO combinations.

The tests I ran suggest there's no sure way to predict the IQ of a particular lens + TC combination, so some controlled experiments are indicated, even a simple as a sheet of newspaper 20~30 feet away shot from a tripod with & without the TC, then crop out the same paragraph or part of a paragraph from each image file and see if the greater enlargement from the lens alone matches the lens + TC, or if the latter actually resolves more detail.

[Canada_Rockies]

The tests I ran suggest there's no sure way to predict the IQ of a particular lens + TC combination, so some controlled experiments are indicated, even a simple as a sheet of newspaper 20~30 feet away shot from a tripod with & without the TC, then crop out the same paragraph or part of a paragraph from each image file and see if the greater enlargement from the lens alone matches the lens + TC, or if the latter actually resolves more detail.

I've used the AFA 1.7X + M 400 successfully on the K10D, but have not tested the M 400 alone vs with the AFA 1.7X on the K3. Looking at the extensive testing you have done, I think I might be just as well cropping. The M 400 is a CA monster under f/8 and cleaner still at f/11 so that gets me working with ridiculous ISO when the f/stop becomes f/13.6 or f/18.7 to avoid rainbow contrast edges. This will take some good weather working with my chain link fence and trees - on the North edge of a forest of Lodgepole Pines = dark in bright summer sun.

Thanks again for the testing and back and forth. There are a bunch of really nice folks in this thread. You all have at least given me a place to start.

[jcdoss]

Your posts have reminded me - I need to get my k 500 out and use it more. I enjoy that lens a lot.

Would you mind posting some examples taken with the K500/4.5?

[RockvilleBob]

Would you mind posting some examples taken with the K500/4.5?

I have some posted earlier in this discussion but have not used the lens much since I acquired the Sigma 500. I plan to get it out after New Year's and post some pictures.

You can also check the the Forum's photo search Pentax Camera & Lens Sample Photo Search Engine - PentaxForums.com where you can filter by focal length and lens