Un-Macroing my telephoto lens.

DrMindbender · 10-27-2018, 08:06 PM - **1 Like**

So after attempting to disassemble my Sigma λII 75-300mm and putting it back together again, it suddenly has turned into a very good Macro lens. While it does have interesting possibilities in this current state, that's not what I bought it for.

There were no leftover parts and I know that it has something to do with how the front elements are reassembled. However, I'm at a loss as to how to correct it. I am considering buying a second model as a parts source and I should be able to use it to solve the problem once I have it. However, I would like to figure out this problem before it would arrive.

Thoughts?

**UncleVanya** · 10-27-2018, 09:07 PM

I'm no expert. But I seem to recall that reversing an element or two can cause this.

Not a Number · 10-28-2018, 01:41 AM

Yes, as UncleVanya says, you probably reversed an element or group. See if you can find the diagram showing the layout for this lens. If not, trial and error works. There can't be that many combinations.

DrMindbender · 10-28-2018, 08:41 AM

Originally posted by UncleVanya

I'm no expert. But I seem to recall that reversing an element or two can cause this.

It's possible since the middle group was lose and may have gotten reversed before reassembly. I never got to the point where I had removed individual lenses and only did a partial body disassembly.

It's also a telescoping zoom if that matters to those with experience.

DrMindbender · 10-28-2018, 06:39 PM

And let this be a lesson to everyone: don't say that something is broken until you test it in your camera. Turns out that you can't determine if you reassembled your lens properly by merely looking through the barrel. It was only an optical illusion and I had put it back together correctly.

Unfortunately, I only found this out when I decided to see just how good this accidental macro was on the lens. :S

swanlefitte · 10-28-2018, 08:26 PM

Glad it's working.
If you look through it at a distance greater than the registration distance I suppose it's like macro extension tubes.

DrMindbender · 10-29-2018, 06:15 AM

And just like that, this Sigma lens has caused me to add another thing to my accessory shopping list.

pentasonic49 · 10-29-2018, 10:53 AM

Many years ago, I bought a Yashica tl electro with a 50mm f1.9 lens new. The lens would not focus on infinity, so it was returned immediately. It was either replaced, or repaired, the multi-start focussing thread in the lens had been assembled a couple of starts out and it wouldn't focus past about 3 feet.
I still have an old Vivitar Series 1 70-210 which had haze at the front end, so I stripped and cleaned the front lens group without realising that the infinity focus depended on fine tuning the seating depth. Fortunately, I had a film camera with a split image screen to get it adjusted and locked.

**pres589** · 10-29-2018, 11:56 AM

Should have shared some good macro images taken with it post-mod.

**UncleVanya** · 10-29-2018, 12:56 PM

Originally posted by DrMindbender

And let this be a lesson to everyone: don't say that something is broken until you test it in your camera. Turns out that you can't determine if you reassembled your lens properly by merely looking through the barrel. It was only an optical illusion and I had put it back together correctly.

Unfortunately, I only found this out when I decided to see just how good this accidental macro was on the lens. :S

Originally posted by pres589

Should have shared some good macro images taken with it post-mod.

The "mod" was a user error confusing looking at the lens unmounted. The lens wasn't changed and wasn't really macro - it was working normally the whole time.

**pres589** · 10-29-2018, 01:22 PM

Well that's boring.

**UncleVanya** · 10-29-2018, 01:50 PM

Originally posted by pres589

Well that's boring.

LOL - right???? But it's less traumatic for the OP.

DrMindbender · 10-30-2018, 05:56 AM

Originally posted by UncleVanya

LOL - right???? But it's less traumatic for the OP.

Although, I do plan to get another one of the same model to restore this lens. So I may take a stab at seeing what would happen if I were to create the error I thought I originally did.

10-27-2018, 08:06 PM - 1 Like	#1
DrMindbender Senior Member Join Date: Aug 2018 Location: GTA, Ontario Photos: Albums Posts: 103	Un-Macroing my telephoto lens. So after attempting to disassemble my Sigma λII 75-300mm and putting it back together again, it suddenly has turned into a very good Macro lens. While it does have interesting possibilities in this current state, that's not what I bought it for. There were no leftover parts and I know that it has something to do with how the front elements are reassembled. However, I'm at a loss as to how to correct it. I am considering buying a second model as a parts source and I should be able to use it to solve the problem once I have it. However, I would like to figure out this problem before it would arrive. Thoughts?

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10-27-2018, 09:07 PM	#2
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,409	I'm no expert. But I seem to recall that reversing an element or two can cause this.

10-28-2018, 01:41 AM	#3
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Yes, as UncleVanya says, you probably reversed an element or group. See if you can find the diagram showing the layout for this lens. If not, trial and error works. There can't be that many combinations.

10-28-2018, 08:41 AM	#4
DrMindbender Senior Member Join Date: Aug 2018 Location: GTA, Ontario Photos: Albums Posts: 103 Original Poster	Originally posted by UncleVanya I'm no expert. But I seem to recall that reversing an element or two can cause this. It's possible since the middle group was lose and may have gotten reversed before reassembly. I never got to the point where I had removed individual lenses and only did a partial body disassembly. It's also a telescoping zoom if that matters to those with experience.

10-28-2018, 06:39 PM	#5
DrMindbender Senior Member Join Date: Aug 2018 Location: GTA, Ontario Photos: Albums Posts: 103 Original Poster	And let this be a lesson to everyone: don't say that something is broken until you test it in your camera. Turns out that you can't determine if you reassembled your lens properly by merely looking through the barrel. It was only an optical illusion and I had put it back together correctly. Unfortunately, I only found this out when I decided to see just how good this accidental macro was on the lens. :S

10-28-2018, 08:26 PM	#6
swanlefitte Pentaxian Join Date: May 2015 Location: Minneapolis Photos: Gallery Posts: 4,068	Glad it's working. If you look through it at a distance greater than the registration distance I suppose it's like macro extension tubes.

10-29-2018, 06:15 AM	#7
DrMindbender Senior Member Join Date: Aug 2018 Location: GTA, Ontario Photos: Albums Posts: 103 Original Poster	And just like that, this Sigma lens has caused me to add another thing to my accessory shopping list.

10-29-2018, 10:53 AM	#8
pentasonic49 Veteran Member Join Date: Oct 2012 Location: weston-super-mare Posts: 395	Many years ago, I bought a Yashica tl electro with a 50mm f1.9 lens new. The lens would not focus on infinity, so it was returned immediately. It was either replaced, or repaired, the multi-start focussing thread in the lens had been assembled a couple of starts out and it wouldn't focus past about 3 feet. I still have an old Vivitar Series 1 70-210 which had haze at the front end, so I stripped and cleaned the front lens group without realising that the infinity focus depended on fine tuning the seating depth. Fortunately, I had a film camera with a split image screen to get it adjusted and locked.

10-29-2018, 11:56 AM	#9
pres589 Site Supporter Join Date: Jan 2014 Location: Wichita, KS Photos: Albums Posts: 4,529	Should have shared some good macro images taken with it post-mod.

10-29-2018, 12:56 PM	#10
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,409	Originally posted by DrMindbender And let this be a lesson to everyone: don't say that something is broken until you test it in your camera. Turns out that you can't determine if you reassembled your lens properly by merely looking through the barrel. It was only an optical illusion and I had put it back together correctly. Unfortunately, I only found this out when I decided to see just how good this accidental macro was on the lens. :S Originally posted by pres589 Should have shared some good macro images taken with it post-mod. The "mod" was a user error confusing looking at the lens unmounted. The lens wasn't changed and wasn't really macro - it was working normally the whole time.

10-29-2018, 01:22 PM	#11
pres589 Site Supporter Join Date: Jan 2014 Location: Wichita, KS Photos: Albums Posts: 4,529	Well that's boring.

10-29-2018, 01:50 PM	#12
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,409	Originally posted by pres589 Well that's boring. LOL - right???? But it's less traumatic for the OP.

10-30-2018, 05:56 AM	#13
DrMindbender Senior Member Join Date: Aug 2018 Location: GTA, Ontario Photos: Albums Posts: 103 Original Poster	Originally posted by UncleVanya LOL - right???? But it's less traumatic for the OP. Although, I do plan to get another one of the same model to restore this lens. So I may take a stab at seeing what would happen if I were to create the error I thought I originally did.