[newarts]

Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here.

---

Very interesting thread indeed.....

I already have a 28mm lens (Vivitar 28mm f2.8) so I'd like to give this a go...

I would need to buy extension tube(s) and the reversing ring...my question is what length extension tubes do I need? Any recommendations?

Thanks.

You might buy two or more sets of tubes at the same time. That way you are sure they will screw together into one big tube in case you want to use a longer lens to get further from the subject. Magnification is extension/(focal_length), so 1:1 requires only 28mm extension for a 28mm lens but 150mm extension for a 150mm lens.

On the other hand, you might as well buy a bellows if you can find one for the right price (bellows are easier to use than tubes.)

Also, you might not need the reversing ring. I have heard that reversing a lens gives a flatter field (and it makes sense) but have seen no evidence this is noticeable in practice. I'd like to see some experimental results.

[jolepp]

Very interesting thread indeed.....

I already have a 28mm lens (Vivitar 28mm f2.8) so I'd like to give this a go...

I would need to buy extension tube(s) and the reversing ring...my question is what length extension tubes do I need? Any recommendations?

Thanks.

You don't necessarily need extension tubes, a 28mm lens gives quite a bit of magnification with a mount reverse ring (like this). Another option is mounting it by the threads to another (longer FL) lens with a double male thread reverse adapter (like this). These could be further combined with tubes (the very basic Ebay El-Cheapo like this has worked for me) for even more magnification (and loss of light), the tubes also work with a lens mounted in its normal orientation.

With the reverse rings the thing to look out for is that their size matches that of the filter thread of the lens(es) you plan to use. These are inexpensive and do work; one thing to note is that the normal focus adjustment becomes a fine tune and focus is adjusted by moving the camera so a tripod or other means to to support the camera is good to have; also because of this a macro focus rail is very handy (a crude El-Cheapo like this is better than having none).

[Mark Morb]

Thanks for the great replies and advice....I feel some experimenting coming on

[Purusam]

okey.

Option one. (macro kitt)



Option 2



With a new 100 mm lens

option 3



A new pentax 100mm macro wr lens

What do you think guys

[aliasant]

okey.

Option one. (macro kitt)



Option 2



With a new 100 mm lens

option 3



A new pentax 100mm macro wr lens

What do you think guys

Any of those would work well but I think this is more a matter of taste.
I think most Macro Geeks ( at least many of them) tend to tinker on their macro rig a lot. Changing, adding, removing and its an endless joy In other words: A macro rig is very personal and no rig is like the other... almost anyways.

That option one is probably the worst for you since you want to keep some distance from the kritters.
You could on the other hand pu a 100mm ( or similar) lens on that bellows instead of the enlarging lens you have on it now.
If you go that way you should probably get a fairly modern bellows so that you can focus wide open.

Best for you is a combination of 2 and 3.
Get the 100 2.8 WR AND the extension tubes. That way cover a lot of ground. Everything from portrait to micro. Those extension tubes are good for other lenses as well.

[JeffJS]

If I'm spending Your money? Go with option 3. Far less dinging around to get going. Just pop the lens on, focus and shoot. Option 1 is good if you want to take pictures of stuff using a tripod. Not very hand hold friendly. We've already discussed the drawbacks of option 2 (those are Canon tubes you show by the way) but you can add more Stuff to fumble with into the mix. Tubes are great if you Only want to shoot close up. Option 3, the lens, also is a very nice 100mm telephoto.

As I said, If I'm spending Your money. I've already spent mine on option 3.

By the way.. That looks like an Enlarger lens shown on the bellows. It Happens to be one of the better types of lenses for that purpose but if you go that way, you'll also need an adapter (likely M39-M42) to use one.

[Purusam]

I think i made upp my mind

I will buy the pentax 100 2.8 WR

If i only use the pentax 100 2.8 WR, how mutch close upps on insect can i photograph at most 1:1 says me nothing i need images :-)?

I mean if somebody have images taken with this lens and can show me, what it can do at highest magnification

[newarts]

okey.

Option one. (macro kitt)



Option 2



With a new 100 mm lens

option 3



A new pentax 100mm macro wr lens

What do you think guys

All of them. (I'd put tubes at the lowest priority use-wise and highest cost-wise.)

Seriously, the bellows with a 100mm enlarger lens will focus from infinity to 1:1, give excellent image results and be great for entirely manual use indoors - but will not be of much use in the rain, nor as an auto-focus etc portrait lens.

Only you can decide.... but the marginal cost increase for buying all of them is small if you really want the big lens!

on edit:

The Pentax lens has a shorter than expected minimum working distance.

Pentax specs say the minimum focusing distance is 11.93" (303mm) http://www.pentaximaging.com/camera-lenses/smc_PENTAX_D_FA_100mm_F2.8_Macro/ . This is less than expected for a 100mm lens (400mm, 15.75") because the lens has Internal Focusing features and isn't really a 100mm lens when fully extended.

Photozone.de has a nice review of the lens and shows it fully extended: http://www.photozone.de/pentax/129-pentax-smc-d-fa-100mm-f28-macro-review--test-report . Photozone reports a minimum working distance of 130mm - a few inches shorter than the 200mm expected for its nominal focal length . The lens is 81mm long when focused at infinity and almost twice that long when fully extended. This implies that the lens plus distance to the sensor is about 200mm long when fully extended, consistent with the other dimensions given.

[jolepp]

I'd get the dedicated macro lens. Be sure to consider the Pentax DFA 100mm, too: having the aperture ring would enable use on all tubes and bellows with the correct fittings. The WR doesn't have this. I have the DFA 100mm and would be hard pressed to find fault with it (ok, maybe a focus limiter instead of the focus clamp it has ...)

[aliasant]

1:1 says me nothing i need images :-)?

1:1 Ill try to explain.....

Lets say your bug is 1cm in length.
Lets say your sensor is 2.5cm in width.

Now imagine that you place the fly on the flat surface of the sensor.

That is 1:1

If you look at that picture on your monitor zoomed out so that you see the entire frame the fly will be 1/2.5 of your monitor.
If your monitor has the resolution 1600 width the fly will then be 640 pixels wide. From head to tail

Now since the sensor in the K5 has a resolution of 4928 x 3264 pixels your fly will be 1971 pixels wide.

https://www.pentaxforums.com/forums/attachment.php?attachmentid=80098&stc=1&d=1294415906

[JeffJS]

I think i made upp my mind

I will buy the pentax 100 2.8 WR

If i only use the pentax 100 2.8 WR, how mutch close upps on insect can i photograph at most 1:1 says me nothing i need images :-)?

I mean if somebody have images taken with this lens and can show me, what it can do at highest magnification

Somehow I doubt you are getting the measurement analogy or you just don't care (neither do I). I cannot show you bug photos because there is 3 inches of snow on the ground and the temperature is about 20 degrees F.



Are you familiar with the size of a US Quarter? It's about the size of a very large bumble bee. The above photo was taken at 1:1, with the DFA100 f2.8 WR

Here are all of them, one at 1:2, 1:3, and 1:4

Index of /Photos/HelpandStuff/100mmf28WR

None of the photos are cropped. That is, you are looking at the FULL photo. At 2:1 and you would need 100mm worth of extension tubes to do it (The Auto type) with this lens, we Might just squeeze George's face into the frame. Tube sets are generally sold in sets of 50mm.

Right now, that's the best I'm going to be able to do for you.

[Purusam]

I would like to thank you all who has writtten in this thred, you are all very helpfull, and i like this forum and pentax cameras alot.

I anyone of you have more images (1:1) please post them.

Thanks again.

[PHIL RUDIN]

Extension tubes and bellows are great but if you need to put a little distance between you and your subject you can't beat the 100 macro lens. Most of what I shoot would be long gone at 10-20 mm or even more. The 100 range allows me to get a clean shot without scaring my subject or worse crushing it.

Phil Rudin

[jolepp]

Another way of saying it would be that 1:1 means that you can fill the frame with an area that is ~24x16mm (so the image on the sensor is live size = 1:1)

[aliasant]

Heres another 1:1 not cropped and not resized.
Dont know how to post bigger images here so I linked to it instead.

http://martin.rodensjo.se/assets/Macro%20Examples/TamronSP35-80%20+21mm-%20F...%20example.jpg