[Frog_Botherer]

Hi. I'm trying to figure out what some good options would be for a macro or close-up lens for my needs. I'm taking specimen photos of small frogs for ecological research, and I need large, crisp, distortion-free images. The subjects are between 25mm and 75mm long, and I would like them to fill the frame as much as possible without any part of the subject getting cropped or distorted; I need to be able to see the whole frog, and I need to be able to take measurements from the photos that are as accurate as possible (there will be a ruler in the frame for measurement calibration). I'm not sure exactly what magnification would work best for me – that's a big part of my question here.

Ideally I would like to focus them all at the same distance and zoom, so that it is easy to compare sizes between individual frogs across photographs. The frogs will sit still for me, and I will probably be photographing them using an external flash and possibly inside a portable light box. I will definitely be using a tripod. I'm shooting a Pentax K5, and my current main lens is the DA 18-135mm WR. Since I'll be in the field and need to carry all of my equipment with me (including all my camping gear and other research equipment) I can't carry a whole lot of lenses. The DA 18-135mm works well for me because it's as close to an "all around" lens as you can get for my budget, I'd be willing to add a macro lens or a close-up lens set to my kit, but swapping out my main lens isn't really an option. My budget is pretty tight as well; I'd prefer not to spend over $150, and less would be better as long as it can fulfill my needs.

Thanks for your advice, I really appreciate it. If there is any important information that I have forgotten to include here, just ask and I'll try to fill you in.

[jatrax]

I don't think you will find an actual macro lens within that budget. I was going to suggest the DFA 100mm Macro WR until I saw the budget you need to work with. Even old manual focus macro lenses will be more than that. There is a third party 100mm f/3.5 macro sometimes available used under several names that might be found at close to that price.

You might be better off looking at the Raynox close up adapters I've never used one but check here: https://www.pentaxforums.com/forums/122-lens-clubs/74221-raynox-macro-club.html

This old article might also be of some interest: https://www.pentaxforums.com/forums/54-pentax-lens-articles/152336-cheap-macr...lose-work.html

[gmans]

SMC Pentax-DA 18-55mm F3.5-5.6 AL WR Reviews - DA Zoom Lenses - Pentax Lens Reviews & Lens Database

The New 18-55 WR is very close focus lens 25cm and does fairly good job of it. within your budget and weather resistant. get yourself some extension tubes and you have very cheap macro.

[Kerrowdown]

IMHO the ideal lens for what you describe as your application would be SMC Pentax-A* 200mm F4 Macro ED, but its a good way away from your budget.

SMC Pentax-A* 200mm F4 Macro ED Reviews - A Prime Lenses - Pentax Lens Reviews & Lens Database

Maybe you could get some research grant funding to help with the purchase.

[grhazelton]

You might watch for the Vivitar 100mm f3.5 macro on the used market. It goes from infinity to 1:2 continuously, and with the furnished achromat plus lens on to 1:1. While the build quality is not remarkable it is very sharp, and can be had in both manual focus and auto focus. Good luck, and save the froggies!

[rbefly]

Hello Frog_Botherer, welcome to the Forum!
It's pretty difficult to find a good 1:2 macro within your budget, a true 1:1 would be nearly impossible.
The 100mm jatrax mentioned is probably your best option. In Pentax, it's the FA 100mm f/3.5 1:2 Macro, usually around $150-$175.
It was also sold as Vivitar, Promaster, Cosina and a couple others, I believe. Most around $100-$150. For any of these, you must make sure it's P-K A/F mount, they were sold in all major brand mounting.
Here's the review link; SMC Pentax-FA 100mm F3.5 Macro Reviews - FA Prime Lenses - Pentax Lens Reviews & Lens Database
There's some fine sample photos on the last post.
You might keep an eye on the Marketplace here, as well as eBay.
Good luck with your project!
Ron

[Frog_Botherer]

Right now I'm thinking that the DA 18-55mm WR might be exactly what I need. With a maximum magnification of 0.34x, a 75mm long subject will just about barely fit on the sensor, which is perfect. Since I want to take all my photos at the same magnification, I don't need to go larger for the smaller frogs. And I don't need (or want) extreme close up; these are frogs I'm photographing, not insects! The fact that it's a WR lens is attractive as well since I'm going to be using this out in the field where conditions aren't always clean and dry. (Part of the reason I went with Pentax in the first place, since nobody else makes a weather-sealed camera in my price range.)

Does that make sense to y'all? I'm never sure if I'm getting the magnification conversions right, there are always so many factors to worry about. In any case I don't think I need a true macro lens – if I made the image of the frog the same size as the sensor or larger, it wouldn't fit! But a close-up filter might still do the trick, and it would be easier to carry (and cheaper!) than a second lens. What do y'all think about that option? Are there any good close-up filters (or lenses, whatever you want to call them) for the K5?

[ausmoose]

If you keep an eye out on the marketplace, ebay and gumtree in the 50-100mm length for old pentax/third party lenses that have a K/M42 mount, occasionally a bargain comes up. I know this because I've been doing a lot of research trying to find some good lenses for me and at one point a really nice pentax-m 105mm lens came up for around $100, but unfortunately it was sold before I got the chance to buy.

[baro-nite]

Because you want to shoot at the same scale, with specimens up to 75mm long, you only need a 1:3 reproduction ratio (i.e., image size at camera sensor; the K-5 sensor is 23.7mm on the long axis). You'll want something where you can set the magnification reliably and simply, then focus by moving the camera. That means a long focus throw and an easy-to-read scale. The Pentax-M 50/4 macro lens fits the bill and your budget. It's an older optical design but still performs well, if not quite up to the latest and greatest designs and coatings. It is only usable in M mode on the K-5, however, meaning you would not be able to use P-TTL to set flash output. But given your budget, unless you already have one, you aren't getting a P-TTL flash anyway.

Speaking of flash, you may not even need a tripod to get good sharp images; flash duration is short enough to freeze out any motion blur, as long as flash is powerful enough to overpower the ambient light (which is easy to do with macro). A tripod does make fine focusing easier, and is certainly helpful if you intend to use focus stacking, but it's also more fiddly and time consuming.

[fretlessdavis]

On a lucky day, $150 will get you the STELLAR 100mm f/4 screwmout or SMC-M macro lens, which goes out to 1:2, which at full magnification on a APS-C should give you about a 50mm diagonal in your frame.

EDIT:

KEH has one for $120!

---------- Post added 02-15-14 at 03:31 PM ----------

Speaking of flash, you may not even need a tripod to get good sharp images; flash duration is short enough to freeze out any motion blur

I concur. I don't do much macro these days, but my standard procedure was to get my lens set to the right magnification ratio, and slowly move in and out until I found the focus point. With "focus priority" and a 285HV set at 1/2 power, f/11, with a small homemade softbox, I would slowly move in until it fired. Even without TTL/P-TTL, if your subjects are similar in size, it's easy to get a feel for how much flash you need. Shouldn't ever really need to move the aperture up or down 1/2-1 stop.

[DSims]

I need large, crisp, distortion-free images.

Make sure you are getting a prime lens which is a macro, like others have described here - not a zoom or other lens (e.g. Sigma 24mm 1:4 "macro") with a pseudo-macro capability. Macros are designed to have a flat field with minimal distortion, and should have at least a 1:2 reproduction ratio, as others have mentioned.

The Cosina 100/3.5 macro others have suggested (available in either AF or MF under various brands) should work for you, as well as various other older MF macros such as the one fretlessdavis mentioned.


Most any adapter or solution other than a true macro lens is likely to violate your criteria of being distortion-free.

[Doundounba]

If you only need 1:3 on a budget, many good options have been mentioned - the Pentax-M 50mm F/4 (1:2) is a beautiful piece of optics, for instance. As is, by all accounts, the M 100mm F/4 (1:2), but tough to find south of $150 these days, it seems. The Vivitar 100mm f3.5 (1:2), especially in MF, isn't super hard to find and also has a very good reputation. Some Tamron Adaptall zooms will also do 1:2.5 or 1:2.8 and have a very good reputation, for instance the SP 35-80mm F/2.8-3.8 (01A) or even the 35-70mm F/3.5 (17A), which usually sells for something like $35...

[baro-nite]

Right now I'm thinking that the DA 18-55mm WR might be exactly what I need. With a maximum magnification of 0.34x, a 75mm long subject will just about barely fit on the sensor, which is perfect.

Ah, I didn't pay close attention to your second post. The 18-55 is quite a decent lens but won't be as sharp as a macro lens, probably more so at minimum focus -- macro lenses are of course optimized for close focus while ordinary lenses usually aren't. However, since you already have the lens, the logical thing is to do some testing. The problem is finding a good test subject that will allow you to test for distortion as well as sharpness. Distortion will be lowest somewhere in the middle of the zoom range. I'm not sure but I think to get the maximum magnification you need to be fully zoomed in, where there will be some pincushion distortion. But note that such distortion is easy to correct in post-processing if you have a profile for the lens and a software tool that will apply it.

[Arrvon]

I'm not sure you want to deal with the distortion and lower resolution by using the da18-55wr. Although the weather resistance would be nice to have I'm sure!

Give some thought to the Tamron adaptall 90mm 52B 2.5. Its well within your budget, focusing down to 1:2, with very little distortion and great resolution.

Good luck regardless!

[monochrome]

^^ What he said. Cult Classic macro lens that can double as a MF portrait lens, for around $100 if you can accept the plain PK adapter, which means you set the aperture on the lens and meter with Green Button. The P/KA adapter that permits 'A' contact pass-through adds around $50 to the cost.