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10-04-2010, 05:54 PM   #1
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do i need a shorter range lens?

hey guys, im currently working with a 90mm tamron macro lens with my k200, and im wondering, should i get a shorter range lens for extreme macro shorts? im thinking perhaps a 50mm pentax macro lens, or even something shorter, what do you guys think? with they get closer shots than my 90mm?

10-04-2010, 06:06 PM - 1 Like   #2
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Many lens manufacturers use the term “macro” but a true macro lens can focus to what is called 1:1. This term refers to image size which should not be confused with a computers file size. Let’s say for example, you are photographing a postage stamp (23mm x 23mm) with a 35mm film (24x36mm in size) camera at 1:1. If you placed your processed film over the postage stamp, the image on film and the stamp would be the same size.

Another way to describe 1:1 is to double a lens focal length distance. Focal length is defined as the distance between the film or sensor surface (known as the focal plane) and the optical center or nodal point of a lens focused at infinity. So a 50mm lens’s optical center would be 50mm’s from the film or sensor plane at infinity. A 50mm lens’s optical center moved 100mm’s away from the focal plane (film or sensor) would be able to achieve 1:1. This is how large format photographers calculate macro focusing.

I’ll use Sigma’s Macro lens as an example. They make 4 fixed focal length macro lenses. The line up includes a normal 50mm lens, a 105mm, a 150 mm and a 180mm. At 1:1, the difference between the 4 lenses will be the Minimum Focus Distance. The 50mm lens will have a minimum focus distance of 7.4" (18.9 cm). The 105 will have a minimum focus distance of 12.2" (31 cm), the 150 would be 15" (38 cm) and the 180 1.5' (46 cm).

The differences of which lens to choose when shooting would be the desired working distance in-between the photographer and the subject. For example, if you were to photograph a flower in natural day light. Using the 50mm lens, you would be 7.4 inches away from the flower. You would more than likely block the natural day light, putting the subject in your shadow. Using a longer focal length lens would move you and your camera back, creating a more conducive working distance, allowing the natural day light to illuminate the flower you were photographing.

A shorter lens would be used when using a ring flash, for example. Keeping the flash as close to your subject as possible, would ensure the greatest amount of light reaching your subject, enabling you to use a small f-stop for the greatest amount of depth of field and sharpness.


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I thought this might help. I think the shorter range is just going to move you closer to the thing you are photographing unless I am wrong and that could be too!?
10-04-2010, 06:24 PM   #3
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QuoteOriginally posted by mantis Quote
hey guys, im currently working with a 90mm tamron macro lens with my k200, and im wondering, should i get a shorter range lens for extreme macro shorts? im thinking perhaps a 50mm pentax macro lens, or even something shorter, what do you guys think? with they get closer shots than my 90mm?
What do you mean by "extreme macro shorts (or I think you mean shots)" and "closer shots"? If your current 90mm Tamron gives you 1:1 magnification ratio, a 50mm macro lens capable of 1:1 will give you the same magnification ratio. The only difference is that for the same mag. ratio, you'll have to move closer to the object.

I don't know if exits any Pentax-mount lens without any attachment giving you mag. ratio greater than 1:1 (I know Canon has a lens like that).

If you need greater than 1:1, you may want to add extension tubes or aux. attachment (e.g. Raynox) in front of the lens.

Here's a photo at 1:2 mag. ratio (Vivitar 135mm Close Focus):



Same lens with Raynox 250 (I guess around 2:1):

10-04-2010, 06:30 PM   #4
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I own both the DFA 100mm macro and the DA 35mm macro Limited. The vast majority of the time, I use the 35mm for macro, but that is partly because I almost always use f-22 and fill with flash. As Little said, that works much better with the 35 than the 100 because of the close working distance. It 100 macro is better for bugs, but I usually can get them with the 35 as well, if I approach with stealth.
If you want, Google Ron Kruger and click on any link to Photoshelter, then click on Tiny Wildflower Macros. By the way, I'm filling with the hot-shoe flash, diffuser down and bounch plate extended.

10-04-2010, 06:59 PM   #5
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yes i meant shots haha

i mean extreme macro by really magnified shots such as



or even closer.

i searched raynox, but A couldnt really find one for a pentax, and B wasnt so sure on it because it uses a glass filter in front and was concerned that the quality would suffer.

what about reversal lenses?
10-04-2010, 07:20 PM   #6
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A shot like that is achieved by using extenders on a lens that is already a 1:1 macro, in order to boost the magnification. You can do it with the Tamron you have now for little extra money. Search around for info on macro techniques using tubes.
10-04-2010, 07:26 PM   #7
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i use a bellows, its really hard to work with

the other reason was because my ring light/flash i have may not work with the bellows, since the rails for it might hit the ring flash/light and stop it from mounting on the end of the lens.
10-04-2010, 11:53 PM   #8
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Mantis,

Please don't use the word "closer" when you mean "greater magnification ratio." For the same magnification ratio (same size on the sensor), a lens with shorter focal length requires the sensor to be closer to object.

As stated, currently there is no Pentax-mount lens that gives you greater mag. ratio than 1:1. If you don't want to use anything attached to the front of the lens (e.g. Raynox), the other way is to bring the lens further from the camera, using bellows or extension tube. This will allow the lens to focus closer and thus give greater mag. ratio. Note that there is a limit of the length of the extension tube before the front of the lens touches the object. For example, if you want 2:1 mag. ratio with your Tamron 90mm macro lens, you have to set the lens at 1:1, and add about 90mm length of bellows or extension tube.

At this magnification, you'll need a good tripod, a macro focusing rail, and a flash gun. The viewfinder will be dim and focusing difficult.

You can increase the mag. ratio without changing the focusing distance by using a teleconverter. But that will degrade the image quality. I'd rather use a Raynox.

10-05-2010, 01:55 AM   #9
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QuoteOriginally posted by mantis Quote
i use a bellows, its really hard to work with

the other reason was because my ring light/flash i have may not work with the bellows, since the rails for it might hit the ring flash/light and stop it from mounting on the end of the lens.
Are you saying that you use the Tamron 90 (f2.5 or f2.8?) on your bellows to shoot macro or the Tamron by itself? You have to be clear on your setup for those of us who are replying to your thread to understand your question.

You know that Tamron 90 will give you either 1:2 or 1:1 maximum magnification depending on the model that you have. I have had the Tamron 90/2.8 mounted on the Vivitar auto extension ring set and got maximum magnification greater than 2:1. If I mount the Tamron 90/2.8 on my Pentax Auto Bellows, and I think I might get about 2.5:1 magnification with the full extension of the bellows. If you want higher magnification with your bellows, you have to use shorter focal length lenses and to get even higher magnification, reverse the lens on your bellows. According to the table in the Auto Bellows manual, A-28/2.8 reverse mounted with the bellows extended 178mm from the focal plane will give you a magnification ratio of 6.6:1.

Here is my fooling around with M-50/2.0 mounted on the Auto Bellows, 1st the life size image of the flash hotshoe cover, 2nd full extension of the bellowson the Pentax logo. Both were shot with Soligor AR-20 Ring flash at 1/2 power on Sync mode in K20D, aperture for life size was f16 and the logo close up was f5.6 (I think).

Thanks,

Last edited by excanonfd; 06-15-2011 at 09:01 PM.
10-07-2010, 08:25 PM   #10
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using a bellows and my tamron

on a different note guys, is it worth getting an auto focus extension tube (so i can use my ring light) or dont bother since the camera will have trouble focusing anyway with any extension?
10-07-2010, 11:19 PM   #11
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QuoteOriginally posted by mantis Quote
is it worth getting an auto focus extension tube (so i can use my ring light) or dont bother since the camera will have trouble focusing anyway with any extension?
You don't need an auto focus extension tube to use the ring light. But to use p-TTL (which is great for macro photography BTW), you need an extension tube with electrical contacts.

Also, to use an extension tube with a lens without aperture ring (aperture controlled by the camera body), you need an extension tube with electrical contacts.

Extension tube with electrical contacts may be difficult to find, or pricey. You may have better luck with teleconverters with electrical contact, and remove the glass to use as extension tube, like the one on the right in this photo:

10-08-2010, 02:03 AM   #12
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Mantis, Raynox make diopters which fit to the front of your preferred lens. They use a clamp that allows for a few different front filter sizes. The longer the lens it is fitted to the greater the magnification. If you get a set of filter ring adapters you should be able to use your ring light on different lenses. My ring light I think fits a 67mm rim but by using adapters to reduce the diameter of the mount I can use on 49mm front rim size lenses.
10-08-2010, 12:19 PM   #13
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QuoteOriginally posted by xjjohnno Quote
Raynox make diopters which fit to the front of your preferred lens. They use a clamp that allows for a few different front filter sizes.... If you get a set of filter ring adapters you should be able to use your ring light on different lenses. My ring light I think fits a 67mm rim but by using adapters to reduce the diameter of the mount I can use on 49mm front rim size lenses.
There is a more convenient way to attach ring light, and you mentioned it in your post: using the Raynox universal adapter.

I post this a while back. The photos no longer exist, but you get the idea. I'll post some photos if I have a chance tonight.
10-08-2010, 03:28 PM   #14
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QuoteOriginally posted by SOldBear Quote
Note that there is a limit of the length of the extension tube before the front of the lens touches the object.
Just a slight correction. A non-reversed lens cannot focus closer than its focal length. Oh sure, you can ram the subject, but you won't be in focus.

QuoteOriginally posted by SOldBear Quote
There is a more convenient way to attach ring light, and you mentioned it in your post: using the Raynox universal adapter. I post this a while back.
And a good hack that is, indeed!
10-09-2010, 12:27 PM   #15
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QuoteOriginally posted by SOldBear Quote
There is a more convenient way to attach ring light, and you mentioned it in your post: using the Raynox universal adapter.

I post this a while back. The photos no longer exist, but you get the idea. I'll post some photos if I have a chance tonight.
Please post some photos of your setup, I have the same Soligor ringlight and changing lenses with the ringlight is time consuming.

Thanks,
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