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06-26-2022, 05:33 AM   #1
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Looking For a Macro

I've an assignment to photograph a knife collection with the intent of publishing the pics online to advertise and sell the knives.

While I've done some limited macro work, it wasn't much and it was quite a few years back.

I was wondering what a good focal length might be for such work. I was thinking along the lines of 90mm - 105mm or so, but I have some concerns about the depth of field with such focal lengths. I'm starting to lean towards something in the 50mm range. If I could get adequate DOF, the extra distance between lens and subject with the longer focal lengths might be nice to have.

So, what are your thoughts on this?


Last edited by SpotmaticGuy; 06-26-2022 at 06:08 AM.
06-26-2022, 06:42 AM   #2
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A longer lens potentially allows for more flexibility in lighting. What camera will said lens be mounted to and what's the size range of the subjects?
06-26-2022, 06:43 AM   #3
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I pretty much use my "A" 50mm 1.7 for most of my ebay pics. It's more about lighting and set up than which lens. For me, the conservatory with its translucent roof on a sunlit day is a near ideal natural lightbox. Use a lens that has the necessary field of view. I go to 28mm for larger items. Knives on a table or display board: doesn't sound like you'll need a lot of depth of field if you are photographing from above/straight on. If you do want a lot of depth of field, a smaller sensor camera (or even a phone) is the effective way to get that rather than introducing the distortions of UWA's.
I don't bother much with PP, essentially lighting adjust and levels adjust as necessary in Faststone. Medium sized jpg's, cropped, resized, sharpened up a bit.

Last edited by marcusBMG; 06-26-2022 at 06:51 AM.
06-26-2022, 08:26 AM - 1 Like   #4
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As Marcus notes above, lighting is probably going to be more important than lens choice. Care in lighting polished, reflective metal blades will be key. With the right studio setup, as long as you've got proper coverage at a useful focusing distance, almost any lens will do.

Where a macro lens will come in handy will be in close-ups of makers marks, particular details of construction, finish, condition, etc. Make sure you clean the knives thoroughly, too. It's amazing how much dirt, dust, and grime invisible to the naked eye suddenly shows up in macro shots. Lint free gloves are your new best friend. As far as DOF is concerned, once you're at, around, or beyond 1:1, there's no difference in depth of field between lenses of different focal length. DOF is determined by magnification and aperture. Longer focal lengths will give you greater working distance, but in the macro range, won't cost you DOF over and above shorter focal length lenses, if I recall correctly.

06-26-2022, 08:52 AM - 1 Like   #5
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Hello,

If autofocus is not a requirement, the M50 f4 macro is my favorite go to lens for product photography. But as others have said, lighting is very important.
I did this a while back to show my product photography setup.
How I photograph Scale Models and other objects - PentaxForums.com

Thanks,
Ismael
06-26-2022, 09:21 AM   #6
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QuoteOriginally posted by JohnMc Quote
A longer lens potentially allows for more flexibility in lighting. What camera will said lens be mounted to and what's the size range of the subjects?
K3 III, knives are between 6-7 inches and 12-13 inches.

---------- Post added 06-26-22 at 09:31 AM ----------

QuoteOriginally posted by ismaelg Quote
Hello,

If autofocus is not a requirement, the M50 f4 macro is my favorite go to lens for product photography. But as others have said, lighting is very important.
I did this a while back to show my product photography setup.
How I photograph Scale Models and other objects - PentaxForums.com

Thanks,
Ismael
Thank you so much. Seeing how far from the subject you were working strongly suggests that a 50mm or so lens may be fine for my needs.

I like the way you made the box. What material did you use for the sides to allow light through?
06-26-2022, 09:35 AM - 3 Likes   #7
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QuoteOriginally posted by SpotmaticGuy Quote
I was thinking along the lines of 90mm - 105mm or so, but I have some concerns about the depth of field with such focal lengths.
Too many people still believe that depth of field varies according to the focal length. It is false! Period.
Depth of field varies according to enlargement (and according to aperture value, and circle of confusion, the latter being fonction of the sensor dimensions).

At a given enlargement, e.g., 1:1, you will get the same DOF with a 24mm, with a 50mm, with a 100mm, with a 180mm, etc.



24mm


50mm


105mm


200mm


300mm

Same enlargement, same DOF, different bokeh.



However, as the bokeh and the geometric distorsion will vary according to the focal length, a lens between 50mm and 100mm will generally be the best choice if you use an aps-c sensor.


Last edited by tryphon4; 06-26-2022 at 09:46 AM. Reason: correction
06-26-2022, 09:38 AM   #8
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QuoteOriginally posted by marcusBMG Quote
I pretty much use my "A" 50mm 1.7 for most of my ebay pics. It's more about lighting and set up than which lens. For me, the conservatory with its translucent roof on a sunlit day is a near ideal natural lightbox. Use a lens that has the necessary field of view. I go to 28mm for larger items. Knives on a table or display board: doesn't sound like you'll need a lot of depth of field if you are photographing from above/straight on. If you do want a lot of depth of field, a smaller sensor camera (or even a phone) is the effective way to get that rather than introducing the distortions of UWA's.
I don't bother much with PP, essentially lighting adjust and levels adjust as necessary in Faststone. Medium sized jpg's, cropped, resized, sharpened up a bit.
Thanks. I've a smaller Lumix that allows for manual selection of aperture and which has good close-up abilities. I may try that as well as the Pentax to see which works better in my situation.

---------- Post added 06-26-22 at 09:40 AM ----------

QuoteOriginally posted by Thagomizer Quote
As Marcus notes above, lighting is probably going to be more important than lens choice. Care in lighting polished, reflective metal blades will be key. With the right studio setup, as long as you've got proper coverage at a useful focusing distance, almost any lens will do.

Where a macro lens will come in handy will be in close-ups of makers marks, particular details of construction, finish, condition, etc. Make sure you clean the knives thoroughly, too. It's amazing how much dirt, dust, and grime invisible to the naked eye suddenly shows up in macro shots. Lint free gloves are your new best friend. As far as DOF is concerned, once you're at, around, or beyond 1:1, there's no difference in depth of field between lenses of different focal length. DOF is determined by magnification and aperture. Longer focal lengths will give you greater working distance, but in the macro range, won't cost you DOF over and above shorter focal length lenses, if I recall correctly.
Thanks for the suggestions. Very helpful!
06-26-2022, 09:40 AM   #9
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For "generic" close-up work like this, my Tamron Adaptall-2 90mm f/2.5 continues to be my first choice (as it has been for the last 40 years!)
With a field of view of about 4.5cm at a minimum focus of 0.39m/1.3ft (1:2 magnification) I'm rarely too close to suffer from the perspective distortion or shadowing issues that can happen with shorter focal lengths, the f/22 minimum aperture will almost invariably allow sufficient depth of field.
The Tamron 90mm still commands a respectable s/h price, a more economical option (I'll not say "cheaper"!) could be a 135mm and an extension tube or two or even a screw-on close-up lens… depending on whether or not you've got any suitable hardware to hand.
06-26-2022, 10:38 AM - 1 Like   #10
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QuoteOriginally posted by SpotmaticGuy Quote
Thank you so much. Seeing how far from the subject you were working strongly suggests that a 50mm or so lens may be fine for my needs.

I like the way you made the box. What material did you use for the sides to allow light through?
Hello,

I have no idea how it is called in English, but we call it "Manila" in Spanish. It is similar to packing paper but white and translucent. I get it at craft stores. It comes in giant rolls and you buy by length. I think I bought like 3 yards for this project.

Thanks,
Ismael

Last edited by ismaelg; 06-26-2022 at 12:24 PM.
06-26-2022, 01:53 PM   #11
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You could get any * lens to work depending on your setup and needs. I'd try and go with something in the 75 to 100 mm range on the aps-c for working distance room given the larger reflective surfaces you'll be dealing with. Other points to consider is, if these are only going to be used online, how many MP's do you really need? 9 MP gives you a comfortable 4k screen, and that opens the door to a number of other possible lens choices, meaning your KIII affords you much headroom size wise. For example, as it was at hand on the desk, I mounted on a KP an adapted M645 55-2.8, and at closest focus filled the frame with 4.75" of ruler - I didn't measure the distance but it was about 10". I don't know what you have for glass, or what the budget/goal is, but I know my adapted lens would perform quite well and would be comfortable with it, perhaps moreso as it's fully manual and my macro's are not.

Last edited by JohnMc; 06-26-2022 at 01:55 PM. Reason: * macro lens
06-26-2022, 02:26 PM   #12
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QuoteOriginally posted by SpotmaticGuy Quote
I've an assignment to photograph a knife collection with the intent of publishing the pics online to advertise and sell the knives.

While I've done some limited macro work, it wasn't much and it was quite a few years back.

I was wondering what a good focal length might be for such work. I was thinking along the lines of 90mm - 105mm or so, but I have some concerns about the depth of field with such focal lengths. I'm starting to lean towards something in the 50mm range. If I could get adequate DOF, the extra distance between lens and subject with the longer focal lengths might be nice to have.

So, what are your thoughts on this?
What camera? Spotmatic (given your handle)?
06-26-2022, 05:17 PM   #13
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QuoteOriginally posted by texandrews Quote
What camera? Spotmatic (given your handle)?
K3 III

Spotmatic was my first camera, 1967, and I have fond memories of it and the places we traveled together.
06-27-2022, 10:03 AM   #14
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So, I'd be looking at the DFA 50 f2.8 macro for your APSC camera.
06-27-2022, 01:10 PM   #15
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If I understood correctly, you aim at performing proxi and/or macro stacks.
The lens is rather important -of course you will need a macro lens and there are plenty of good ones- but you will also need a stacking system if you want to achieve perfect stackings.

So do not forget to save some money for a tripod and a macro rail.
I personnally use a Velbon supermag slider, which is good enough for proxy and for macro when there is enough DOF but you could find cheaper options as there are chinese sliders which are not too bad.

Regarding the lens itself, you could buy almost any macro lens between 50 and 150mm as previously said, and the choice is huge.
If you are on a limited budget, an old Tamron 90mm will fit the bill (model 52B or 52BB or 72B in adaptall mount, model 52E or 72E in PK mount), I owned one 52B and one 72B, both are excellent. Please note that model 52B and 52BB only reach 1:2 and are F/2.5 while newer models reach 1:1 and are F/2.8. I currently own a 272E model which is AF but is also more expensive.
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