WTB: Used 100mm 2.8F macro lens or similar, K Mount compatible

[jerseycat10]

Recently bought a Pentax K-5 and I am looking for a macro lens to do some numismatic photography. Can't afford a $800 lens, so I am looking for an older, used lens. Please let me know what you have. I can pay cash or make a trade.

[Six Mile Rick]

jerseycat10, It may be a stretch but check at the camera counter in Best Buy. They will run the internet check on stores they purchase from and get your lens for you at a great price. I got a 18 month no interest credit account when I purchased mine in May with $0 down. They can get any lens for any camera.

 

 

Later---Rick

[blu62vette]

Also you can check KEH.com for used gear and there are Pentax forums that I sure have some BST places.

[brg5658]

Are you hell-bent on an auto-focus lens? You should be able to adapt an older 100mm f/2.8 manual focus lens to your Pentax K-5 body for appreciably less than an "all auto" lens. I guess it depends on how much you're interested in learning.

 

Based on what I can read, it seems the K-5 has exposure metering for older manual focus lenses, and people have had decently good experiences using them (See link here).

 

I think you might also find this table and article to be useful.

 

Best of luck!

-Brandon

[brg5658]

AJ, just found another bit of information. Apparently there is a fairly decent Macro AF lens out there that fits the K-5 that can be had for less than $200.

 

See this link and also see this link.

 

The lens in question is the Promaster AF 100mm f/3.5 Macro, and it generally comes with a 1:1 screw on adaptor (this just means you would be able to fill the entire viewfinder on your K-5 with a coin about the size of a USA dime). I'm not vouching for this lens (I shoot Canon with a bellows setup), but the information I can find is pretty positive. The caveats I read are to make sure you are getting the Autofocus (AF) version, not the MF (manual-focus) version.

 

There is one in almost-mint condition on eBay right now for $168 + $12 shipping. I'd say shop around a bit, and check out other sites like keh.com and you can probably be up and running for around $150 or so.

 

-Brandon

[jerseycat10]

Awesome info guys.

 

Brandon, the ProMaster lens you refer to...

The 1:1 screwon adapter is optional, and i would be ok imaging silver dollars without it?

 

I am going to take a stab at it.

[brg5658]

Awesome info guys.

 

Brandon, the ProMaster lens you refer to...

The 1:1 screwon adapter is optional, and i would be ok imaging silver dollars without it?

 

I am going to take a stab at it.

 

Yes, you can image 1:2 magnification without the screw-on adapter. That means, you can image anything 31mm or larger and fill the entire view finder. You can also image smaller coins of course, you just won't be able to focus close enough to the coin to fill the entire frame.

 

Your sensor is 15.6mm x 23.4mm on the K-5 (by what I can find 3284x4992 pixels). A magnification of 1:2 means that you can focus on something that is 15.6x2 = 31.2mm tall (or bigger) and fill the entire frame (i.e., the coin part of the image will be the full 3200 pixels tall out of the camera). That means, even for a small coin (like a dime = 17.9mm) it would still show up as nearly 1900 pixels tall out of the camera. Usually you are downsizing images out of the camera to around 800x800 pixels anyway, so even without the screw-on adapter you could image dimes and small coins just fine.

 

The thing you must be careful about on this lens is that the minimum focusing distance will be around 17 inches. That means, from the surface of the coin to the back of your camera (the sensor) will need to be 17" or longer (the lens won't be able to focus at any distance closer than that). Thus, you would need a copy stand or a focus rail that will allow you to get that far away from the coin. This distance is good news for lighting as you will have lots of room to place your lights without the lens getting in the way.

 

Let me know if any of this is confusing or doesn't make sense, and I can try to explain better.

 

-Brandon

 

 

[jerseycat10]

Thanks Brandon, good info. I spotted a few copy stands on ebay yesterday for reasonable prices, and will be hopping on them.

 

I sincerely appreciate your help.

[brg5658]

My pleasure.

-Brandon