[tim60]

With the close up filter, if it does not give you anything satisfactory with the glass in the standard way around you might be able to take the glass out and reverse it. And, of course, the CU filters came in sets and one of the diopter choices might work interestingly even if not the others.

[marcusBMG]

The minimum focusing distance is 30 feet, so this might be a very interesting experiment. Maybe a 500mm f:4.5 macro lens?

Normal technique is to use an extension tube(s) to reduce the cfd.
On a couple of my Tamrons eg the 350mm preset I have been able to extend the focus throw.

[Dewman]

Normal technique is to use an extension tube(s) to reduce the cfd.
On a couple of my Tamrons eg the 350mm preset I have been able to extend the focus throw.

Very interesting! Thanks for the ideas. Lots to play with come daylight!

[RockvilleBob]

My SMC Pentax M-42 500mm lens arrived in the mail Monday. My cheapo adapter did, also, but it was a total and complete POS! So, while I'm waiting for my OEM adapter to arrive from B&H, I had an old adapter that would fit fine, but it would not let me focus to infinity.... only to about 80-100 ft. So, I decided to see what the old lens would do. This was shot at the longest distance it would focus and I was amazed at it's sharpness! I'm REALLY anxious for the proper adapter to arrive now!

Your posts have reminded me - I need to get my k 500 out and use it more. I enjoy that lens a lot. If you're like me you will start looking for a used Sigma 500. However the Pentax 500 is a great lens for manual focus, yes some Photoshop to clean up CA. You may want to look for Rear Converter-A 1.4x-L a Rear Converter-A 1.4x-L Reviews - Pentax K-mount Teleconverters and Adapters - Pentax Lens Reviews & Lens Database That will give you a 700mm Half-Track

I also like the sighting feature on the lens. With practice you will get good at getting your subject in the finder.

[lukulele]

Grab and go Titmouses

[Canada_Rockies]

I also like the sighting feature on the lens. With practice you will get good at getting your subject in the finder.

The sight on the end of my M 400 is a delightful addition to ease of use. I used the sight a lot last September with the M 400 mounted on my AFA 1.7X on my K10 on the Manfrotto three legged friend. I did find, however, that I really need a gimbal head. I think for my budget comparing reviews I'll get the $174 (at B&H) manfrotto one.

[dadipentak]

I think for my budget comparing reviews I'll get the $174 (at B&H) manfrotto one.

It's inelegant--but effective.

[rvannatta]

well my adventure for the day isn't learning how to use a real exotic lens. I've had so me of them around for a while. I'm at the other end and trying to assemble a 'travel lite' kit for a trip to alaska this coming summer. I sort of decided that 10 lb lenses
in a wooden truck weren't exactly what I needed for the airplane ride to alaska. Additionally my other half has a K-3 and wanted something to handhold. with a combination of LBA and a claim that it was a high quality lens that she could hand hold,
I bought on ebay what is pretty close to the world's smallest/lightest 300 mm f4.5 for FF. yep, a Pentax 300mm F*/4.5 --one which many of you have.

On getting it I was utterly shocked at how small it really was. In the past I've fiddled with the DA f4 and Pentax-a 300 f/2.8 and currently own and FA 300 f/2.8. This morning was a good exercise in low light photography. dreary and raining
settings ended up 1/60th at f4.5 IS0 3200 and I'm pretty happy with the result.

I've bought a HD pentax DA 1.4x since my old 1.4x-L and 2x-L are not friends with these newer/smaller lenses and I think i have a lightweight long kit. I reallly don't want to photograph the tonsils of a bear with a 15mm lens.

[Canada_Rockies]

I reallly don't want to photograph the tonsils of a bear with a 15mm lens.

I guess they wont have Pentax Forums where you end up after that ...

[rvannatta]

I guess they wont have Pentax Forums where you end up after that ...

Precisely my logic is preferring extreme telephoto glass.

[dane.dawg]

A couple more from the weekend.
.

[WPRESTO]

LONG LENS + TC TEST SEQUENCE, PART 1

Question: What is the best option for a long telephoto suitable to photograph, for example, a small bird? Central image IQ is most important, edge/corner sharpness and some vignetting are not a great concern. Will a TC actually record more detail or will it degrade IQ so that just-as-good-or-better IQ can be had by simply cropping/enlarging from a photo taken with the same lens without a TC?

Long K-mount lenses I have to test: 60~250; 300; 150~450; Tamron 400 f4 (PKA mount).
TCs I have for testing: 1.4X Pentax (newest); 1.4.XL and 2XL Pentax, but these will only fit the Tamron.

Test conditions:
1) Standard USAF resolution test sheet purchased many years back from Edmund Scientific, kept flat between cardboard sheets since it was purchased so it's in excellent condition, not faded by light exposure.
2) resolution chart pinned on a wall and illuminated by a single Cactus flash at the left, aimed at about a 45 degree angle and far enough back to give near uniform illumination..
3) Camera + lens mounted on a Bogen/Manfrotto 3221 tripod with a geared head
4) K3 camera set @ X, ISO 200, triggered by cable release with 2 second shutter delay; images recorded at highest quality JPEG.
5) Center column of tripod 21 feet back from the test chart (farthest it was practical within the confines of the basement where my "studio" is located).
6) Tripod elevated so the camera + lens was at the same height as the center resolution block of the test sheet.
7) Best IQ for most lenses is about 2 stops down, so I selected f8 for all lenses without TC. When a TC was attached, the lens was left 2 stops closed (= aperture set via camera to f8, but effective aperture either f11 or f16) so the Cactus flash had to be upped in power one EV step for all except the 400mm + 2XL combination, which required a 2EV increase in flash output.
8) For each lens or lens + TC combination I refocused six times: 3 times using live view, focus peaking and enlarged 8X for almost all shots (4X for the 400 + 2XL because the slightest touch on the focus caused so much vibration it was impossible to see if focus peaking had been triggered); 3 more images were taken by using the electronic rangefinder function. For both sets of three, at least once the focus point was approached from the opposite direction (= focus twice starting @ infinity and once starting at minimum focus distance, or once from infinity and twice from near).
9) select sharpest image from each lens & lens + TC combination
10) All the images were slightly dark (white background was gray), so all were brightened about 1/2 EV
11) The central group of resolution lines, black in color, were taken to be the equivalent of a small bird (ignoring the numbers around the periphery, the block measures very close to 2X2 inches) SO, for each lens & lens + TC just this central block was cropped out for comparison.
12) For deeper comparison, I also cropped out the smaller block of resolution lines within the 2X2 block. This block, again ignoring the numbers around the periphery, measures slightly more than 1/2 inch square.

As a starting point, to give perspective on the size of the original at a distance of 21 feet, the image below was taken with a 35mm f2.8 macro mounted on the tripod. The door through which I was shooting is, of course, not illuminated by the flash. Look carefully - - the subject of interest is the black group of resolution lines at the very center of the chart.

[WPRESTO]

LONG LENS + TC TEST SEQUENCE, PART 2

Here are the full-frame images for the ten lens and lens + TC possibilities. The only PP was brightening about 1/2 EV of all the images.

[WPRESTO]

LONG LENS + TC TEST SEQUENCE, PART 3

Enlargement/crop of the central set of resolution lines. Ignoring the numbers around the periphery, the block of resolution lines measures very close to 2X2 inches

[WPRESTO]

LONG LENS + TC TEST SEQUENCE, PART 4

Here is a deeper enlargement/crop of the small block of resolution lines within the larger black. Ignoring the numbers around the periphery the resolution block measures about 1/2 by 1/2 inch. Each image below would be entirely covered by a US penny.


---------- Post added 12-13-15 at 07:06 PM ----------

LONG LENS + TC TEST SEQUENCE, PART 5: MY CONCLUSIONS

1) The 60-250 with 1.4X does not match the IQ of the 300 with no TC.
2) The 300 + 1.4TC does not match either the 400 Tamron or the 150-450 without a TC
3) The 150-450 with 1.4X TC seems to be a compatible combination that shows only minor IQ loss and is an acceptable way to get to 630mm
4) The 400 f4 Tamron works well with all three TC's
5) The Tamron 400 + 2XL gives very good results, probably the best combination among those tried for photographing a small bird. CAVEAT: This combination is extremely difficult to focus, the slightest touch causes major vibration, and two stops down from wide open the effective aperture is f16. This is a combination for bright light, high ISO and a massive tripod, preferably with double support (lens & camera body).

ABOUT FOCUSING

All focusing for this test was done manually using either enlarged live-view with focus peaking, or electronic rangefinder while using the viewfinder. For each set of six images, the majority seemed to be as sharp as it was possible to obtain with the lens or lens + TC being tested, so that four or five of the six could not be differentiated in terms of sharpness. Sometimes one, or sometimes two of the images were markedly less sharp, and if an unsharp image were present, it might be either among the LV + FP or from ER set.

Focusing with focal lengths above 500mm (150-450 + 1.4X and 400 Tamron with any TC) was extremely difficult. Placing a finger on the focus ring would send the image bouncing wildly. As might be expected, the 400 + 2XL was the most difficult to focus, and in LV, the vibration @ 8X totally overwhelmed any effort to see if focus peaking had responded. CONCLUSION: with FL's above 500mm, if possible a double support should be used, one below the lens' tripod mount and a second below the camera body, either a second tripod or more conveniently a diagonal brace from camera body to one of the tripod legs.