Possible alternative to barlows/teleconverters (1 Viewer)

[Musoman]

Nice work again - i think you've just proved that 80-200 TN's are every bit as good as 100-200 TN's as long as they come from the right lens, results of trial and error by you on a selection of cheap zooms.

 

[Paul Corfield]

Nice work again - i think you've just proved that 80-200 TN's are every bit as good as 100-200 TN's as long as they come from the right lens, results of trial and error by you on a selection of cheap zooms.

I need to do some more tests but I think the 100-200 TN's are a fair bit sharper, even though they need some cropping. At this size on the screen the Canon ones look quite good though. I'll try on some longer range targets and see how they compare with each other.

A couple of interesting lenses I bid on at the weekend but didn't win were a Sigma 120-300mm and a Pentax 95-300mm. Would have loved to have tried the Sigma one as it's an odd size that doesn't come up all that often. Got some other lenses to bid on later this week.

Paul.

 

[goldenarrow]

Tamron

Paul,
Whatever happened to the Tamron 80-200 TN that needed taping together? Don't remember seeing the results of that one and how it compared to others. I have a couple of tamron's sitting around not doing much. One is a 103A 80-200 which looks like a standard design up front. The other is a 19A 70-210 that I don't think I want to mess with since I still use it now and then and it gives nice sharp photos. It is also an SP lens and made to be sharper. It also seems to be a more complicated design in the front looking at the adaptall-2.org diagram.

And an extra question if I may. What is the focus travel needed with your 2.5x TN setup compared to the distance for a normal telescope setup with diagonal and eyepiece? I am trying to figure out if I need to get a telescope like you have or if I can get by with a smaller one that has a helical focuser and use more magnification. I wonder if a helical focuser will run out of focus travel or not??? For the time being, I will experiment with a cheapo Synta (Chinese) 600mm f/6 with lots of color problems and average sharpness.

Thoughts?

GA

 

[Paul Corfield]

I posted a couple of images on this page here. Post #113.

The lens I had was the older 80-210mm model version 03A. Your 103A has better optical performance although looking on the adaptall website the teleneg part looks very similar.

Nearly bought a faulty Tamron SP lens the other day but it went just over what I wanted to pay.

Focus travel shouldn't be a problem no matter what scope you have because you just add in some extra extension tubes if the travel isn't enough.

Paul.

 

[Paul Corfield]

The Tamron SP 80-200mm model 30A looks to have an interesting teleneg. Possibly 5 elements in this diagram here.

Paul.

 

[goldenarrow]

Thanks Paul, will investigate when I have more time.

 

[goldenarrow]

The lens I had was the older 80-210mm model version 03A. Your 103A has better optical performance although looking on the adaptall website the teleneg part looks very similar.

Paul et. all,
The better lenses are built like tanks! Unscrewed the front easily from the 103A Tamron but the TN is buried inside of a casing that moves the zoom. Looks like I will have to drill out one of the screws. But the other screws holding the casing to the rest of the body won't budge either (it seems to move along a track on both sides of an inner steel tube with various screws which can only be seen if the zoom is rotated in either direction). All-metal construction, very impressive build quality just for their "average" non-SP telephoto zoom. Any helpful hints when you took apart the 03A would be appreciated! Do you use any special tools. All I have is some tiny screwdrivers used for electronics!
:-O

 

[Aegea]

All I have is some tiny screwdrivers used for electronics!
:-O

Get hold of a set of JIS (Japan Industrial Standard) screwdrivers - they are supposed to be a better fit for the screws than Philips head drivers.

 

[goldenarrow]

tools

Get hold of a set of JIS (Japan Industrial Standard) screwdrivers - they are supposed to be a better fit for the screws than Philips head drivers.

Thanks, I will look for those. Might be faster to just drill them out anyway.
:t:

 

[Paul Corfield]

Paul et. all,
The better lenses are built like tanks! Unscrewed the front easily from the 103A Tamron but the TN is buried inside of a casing that moves the zoom. Looks like I will have to drill out one of the screws. But the other screws holding the casing to the rest of the body won't budge either (it seems to move along a track on both sides of an inner steel tube with various screws which can only be seen if the zoom is rotated in either direction). All-metal construction, very impressive build quality just for their "average" non-SP telephoto zoom. Any helpful hints when you took apart the 03A would be appreciated! Do you use any special tools. All I have is some tiny screwdrivers used for electronics!
:-O

I used a big lump of Blu-Tac poster putty, stuck it to the teleneg and gave it a good twist. This should be enough to undo the retaining ring that holds in the teleneg glass. Because of the construction in my Tamron 03A I didn't want all the big casting that held the glass so I just took the glass right out. Most other lenses have the teleneg in a simple screw in unit that all comes out as one piece.

Apart from that if the screws don't budge then either drill them out of get some good screw drivers. I had my Birthday a couple of weeks back and got a decent set of small screw drivers with hardened tips and they made a big difference to taking lenses apart.

Paul.

 

[Paul Corfield]

Yesterday I had a Sunagor 80-205mm lens arrive in the post. Interestingly this one also has a low power cemented doublet telenegative. It gives 1.5X on the scope and is good quality. It's not the same teleneg as the one from the Sunagor 100-200mm, this new one has about 20% bigger diameter glass. Another one worth buying.

Paul.

 

[goldenarrow]

I used a big lump of Blu-Tac poster putty, stuck it to the teleneg and gave it a good twist. This should be enough to undo the retaining ring that holds in the teleneg glass. Because of the construction in my Tamron 03A I didn't want all the big casting that held the glass so I just took the glass right out. Most other lenses have the teleneg in a simple screw in unit that all comes out as one piece.

Paul,
Finally got it out. Tried the blu-tac but that did not work. So I attacked it from the other end, taking out whatever I could with a vise-grip and screwdrivers and hammer. I did get to the screws holding the TN assembly to the casing and it slid right out! The holder for the TN is very nice but a little bit too large for the intended extension tube in which I want to mount it. But I am closer to getting it usable. Thanks much for the advice.

GA

 

[Paul Corfield]

Managed to bag myself a Canon 100-200mm lens at the weekend for £10.50 which wasn't too bad a price. Hopefully it will be here in the next day or two and images will quickly follow. |=)|

Paul.

 

[alphan]

Yesterday I had a Sunagor 80-205mm lens arrive in the post. Interestingly this one also has a low power cemented doublet telenegative. It gives 1.5X on the scope and is good quality. It's not the same teleneg as the one from the Sunagor 100-200mm, this new one has about 20% bigger diameter glass. Another one worth buying.

Paul.

Does those Sunagor lenses you bought comes with metal mount or plastic mount. And their barrel metal or plastic?

 

[Paul Corfield]

Does those Sunagor lenses you bought comes with metal mount or plastic mount. And their barrel metal or plastic?

It's all metal.

Paul.

 

[alphan]

It's all metal.

Paul.

Thanks. Another question here from your experience. When a zoom lens got infected with fungus, do they normally start with the telenegative areas?

 

[goldenarrow]

fungus?

Thanks. Another question here from your experience. When a zoom lens got infected with fungus, do they normally start with the telenegative areas?

To throw in my opinion, I have seen a few different patterns of fungus infection. Depends how the moisture gets into the zoom lens, which is dependent upon each model and design. Some have fungus on the inside of the front element where water can seep into the front during a rainstorm (or overly aggressive use of lens cleaner) in front of the telenegative. Others have poor sealing in the middle and water vapor can get into the middle lens elements behind the telenegative, causing small bunches of fungus to colonize and grow across the whole surface of the inner elements. Similarly, is for someone to not use the lens for years and stored in a sealed container with a combination of evaporated oil, moisture + fungus happily co-existing on the middle lens elements. Some are in the back by the mount, and seems less often this way. At least that is my experience. Telenegatives can be affected just as easily as any other lens element, especially with the second kind I mentioned.

Fungus supposedly can be cleaned off the surface but it can also cause micro pits on the surface of the glass, ruin the multicoating, and generally spoil the lens' sharpness, contrast, and flare control. I hate the stuff and will not bid on ebay anything that even *might* have fungus. Even being careful, I have two fixed length lenses that have fungus, one which I can tolerate and the other having had to send off to get cleaned twice by an expert. No way to see it too unless you look at the lens from the mount end into very strong lighting just out-of-sight. It shows up as a white haze, or clumps of white individual specks smaller than dust. Cannot see it definitively when just looking through it normally by eye, you need a magnifying glass and the lighting mentioned.

Just my opinion.
B

 

[Paul Corfield]

Nearly all the lenses I buy on ebay are infected with fungus. I generally seek out the ones that have fungus because I know I will get the lens cheap. All the ones I've had so far the fungus cleaned off easily. Generally just a simple wipe with a cloth and it's gone. I've only ever had one that damaged the multicoatings but that was on a Tamron teleconverter.

Paul.

 

[alphan]

To throw in my opinion, I have seen a few different patterns of fungus infection. Depends how the moisture gets into the zoom lens, which is dependent upon each model and design. Some have fungus on the inside of the front element where water can seep into the front during a rainstorm (or overly aggressive use of lens cleaner) in front of the telenegative. Others have poor sealing in the middle and water vapor can get into the middle lens elements behind the telenegative, causing small bunches of fungus to colonize and grow across the whole surface of the inner elements. Similarly, is for someone to not use the lens for years and stored in a sealed container with a combination of evaporated oil, moisture + fungus happily co-existing on the middle lens elements. Some are in the back by the mount, and seems less often this way. At least that is my experience. Telenegatives can be affected just as easily as any other lens element, especially with the second kind I mentioned.

Fungus supposedly can be cleaned off the surface but it can also cause micro pits on the surface of the glass, ruin the multicoating, and generally spoil the lens' sharpness, contrast, and flare control. I hate the stuff and will not bid on ebay anything that even *might* have fungus. Even being careful, I have two fixed length lenses that have fungus, one which I can tolerate and the other having had to send off to get cleaned twice by an expert. No way to see it too unless you look at the lens from the mount end into very strong lighting just out-of-sight. It shows up as a white haze, or clumps of white individual specks smaller than dust. Cannot see it definitively when just looking through it normally by eye, you need a magnifying glass and the lighting mentioned.

Just my opinion.
B

Thanks for sharing your experience on fungus. It's our number one enemy to our equipment. Especially now with my scope, I"m still trying to get a suitable dry box for it.

What we are trying to do here are disassemble the whole thing for experiment and only lens infected with fungus comes cheap. We are the rare breed as far as photography are concerned, hacking old lenses for something still worth a good deal.

 

[alphan]

Nearly all the lenses I buy on ebay are infected with fungus. I generally seek out the ones that have fungus because I know I will get the lens cheap. All the ones I've had so far the fungus cleaned off easily. Generally just a simple wipe with a cloth and it's gone. I've only ever had one that damaged the multicoatings but that was on a Tamron teleconverter.

Paul.

Thanks Paul. I'll go grab that Sunagor 80-200, since you already gotten the Sunagor 100-200 and 80-205.