TS optics TL APO 804, a small review. (1 Viewer)

FernandoBatista · Jan 29, 2011

tjd said:
The simple and low cost alternative to Fernando`s high quality diaphragm may be obtained from the lens unit of an old bellows camera. This is what I am experimenting with at present. The largest opening diameter being around 20mm.

Just dis-assemble from original lens and solder on an extension to the original operating arm, and off you go. Setting it in optical train around 25% inside focus seems to suit my viewing.

Fernando, final thoughts on your flattener is that it is overcompensating, because you are using it at the lesser distance than infinity. As we know, a shorter f.l. of objective induces more spherical abberation, using at say 20 metres rather than infinity means using same objective at longer back focal length, this means less correction is needed, therefore in my view only two answers. First, move flattener as close as possible to focus plane so that its action on the image is lessened, and if this is not enough, then a weaker power flattener is possibly the answer.

Many many years ago, when I was more into astronomy, and photographing stars etc., i played with the idea of field flattening. As usual though, we had to make do and mend and I had some success with a very weak, the weakest you can get, single plano convex lens which used to do the job. I used the type of lens that used to be used in old fashioned round spectacles. Although it seems a single lens would induce colour fringing this was not the case, probably because the lens was so weak. The good old days, Ha ha.

Tom

A 20mm iris wont do, everything less than 35mm and I'm losing light, with my iris at 20mm I'd be more or less at F/8.

The though of over compensation also crossed my mind, and it's probably the cause. On the ED70 the flattener power wasn't enough as I still had soft corners, but I never had problems using it. On this scope, the correction is nearly perfect, perhaps even a bit more than needed so maybe it is indeed too much and this is what is causing my problems with it.
I will try some different placements in it's distance to the sensor to see how it works, but getting much closer would require some mods to the flattener or Trings.
But that will have to wait, for now I'm very happy with the scope as is, I've been using it a lot and I didn't get a shot yet where curvature really is an issue. And I've been shooting really close to birds with frame filling shots from nearly one end to the other.
So, for now I'm quiting on using the flattener. Also this will make my life easier to put the iris working automatically, since I have more space to place the mechanical linkages.

FernandoBatista · Jan 29, 2011

Paul Corfield said:
This isn't really the case. I found that anything bigger than around 25mm didn't let anymore light through to the camera so if you had something 2" then a lot of that would be wasted. The biggest one I have here is 28mm which came out of an old Tamron Adaptall lens and it has quite a few blades too.

I've got 2" and 1.25" telescope adapters that screw into my T-ring on the camera. The 1.25" one has an internal diameter of 28mm and that produces exactly the same photos as using the 2" one. No loss in speed, no vignetting etc. The image light cone is already small enough by the time it reaches that point that the smaller hole isn't an issue. Actually I think it's more beneficial as it acts as an extra baffle and improves contrast. You don't really need a ton of extra light causing internal reflection issues once you get near the camera.

Paul.

Paul, I said this before but to me there's something blocking your scopes full aperture. There's no way I wont use light with my iris at 25mm, that opening looses more than half a stop in this scope. I don't know how much I would loose on the ED80 but I tried it and it was a good bit too.

Also, the first adapter I built for the Vixen 80ss I had at the time was 1,25”, and it did put a good bit of vignetting and light loss on the images.

The only way I see for you to be using this diameter is if something is blocking the aperture of the scope, therefore not making a difference if you close it more at the back. A misplaced baffle could easily be doing that. I'm mentioning the baffles because the original location of my ED80 rear baffle was dropping a 1/3 stop of the full aperture.
If it's not that than I don't know how can you use such a small diameter iris without light loss...I can't.

Paul Corfield · Jan 29, 2011

So how come I get no vignetting with a 1.25" nose piece screwed into my T-ring? If it was cutting out light to the camera sensor then I'd see signs of vignetting. If I try and go smaller than the 1.25" then I do see vignetting.

I checked all the baffles in the scope and they are all in the same place as when they left the factory. If I move them then there is silver metal underneath where the black spray hasn't reached during manufacturing. I'll try taking them all out completely just for an experiment and see how my shutter speeds compare with the 2" and 1.25" adapters.

Paul.

cango · Jan 29, 2011

@paul/fernando: how long are both of yours extension tubes, and how big are your sensors compared to each others? If I recall one is using nikon and one canon, right? Just a thought of why you get different experiences.

FernandoBatista · Jan 29, 2011

Well, I'm not sure. But I can't get nowhere near the iris diameter you are getting without loosing light or get vignetting, and our sensors have roughly the same size.

My baffles where at the factory position too, but they came misplaced and tilted, the scope tube had the paint marks too but measuring on opposite sides, there was nearly 1cm difference between the sides. The ED80 is an excellent piece of glass, but the assembly could use more care IMHO, so I wouldn't be surprised if yours were a bit up front.

Really, I wont bet on this, but I can't think of any other explanation for this difference.

FernandoBatista · Jan 29, 2011

My extension is around 8cm total, on the ED80 it was roughly the same.
Both sensors are APS-C although Nikon's slightly larger, but I can't see that making so much of a difference. It's 23.6mm for Nikon D90 vs 22.2mm for Canon 450d.

Paul Corfield · Jan 30, 2011

Did the test today with the standard Skywatcher baffles in the scope and then I removed them completely and did the tests again. I did them with a 2" and 1.25" telescope adapter and shot them all at the same shutter speed.

Photo 1 - Baffles in scope with 2" adapter
Photo 2 - Baffles in scope with 1.25" adapter

Photo 1 - Baffles removed with 2" adapter
Photo 2 - Baffles removed with 1.25" adapter

Paul.

Paul Corfield · Jan 30, 2011

These two are taken with all the baffles removed completely and with 2" and 1.25" scope adapter at the same shutter speeds. No signs of vignetting with the 1.25" adapter.

Blackbird taken with no baffles also, the baffles don't seem to be doing much to my eyes.

Paul.

FernandoBatista · Jan 30, 2011

I really don't know what to say, there's no difference at all in those samples. My 1.25" adapter showed vignetting clearly on the ED80, it wasn't much, less than some photo lenses but it was clearly there.

Well, better for you anyway, at least it's cheaper to get an iris working

FernandoBatista · Jan 31, 2011

A few more samples, all without the flattener. This is what I was used to with the ED80, the focusing consistency is far higher that those with the flattener.

Two with the 1.4x TC:
http://photos.smugmug.com/photos/1173688543_oVYN7-O.jpg
http://photos.smugmug.com/photos/1173688817_7CKbJ-O.jpg

And these with the 2xTC (ISO800):
http://photos.smugmug.com/photos/1173688726_7U97j-O.jpg
http://photos.smugmug.com/photos/1173688673_nXkcK-O.jpg
http://photos.smugmug.com/photos/1173688538_8Pbme-O.jpg

And a 100% crop with the 2x TC:
http://fernandobatista.smugmug.com/photos/1173707491_Msu3q-O.jpg
Still I've seen sharper from this TC, but considering the light and the position from where I was shooting, it's actually not bad.

Remirath · Jan 31, 2011

Simply amazing Fernando... as usual. Did you shoot from a hide?

FernandoBatista · Feb 1, 2011

Nope, no hide for these, although I'm making one specially for these birds. Shore birds are somewhat easy to get close if you crawl after them, just do it very slowly and carefully, and avoid looking at them directly.

sparrowbirder · Feb 2, 2011

Im really thinking of buying one of these scopes to replace my mak,some of these images are superb,can you just attach a photo adaptor to them and shoot or is all the above stuff necessary as well,must admit its all over my head all this,my machining skills arent that great..TS have got offers on TS80 and SW 80 ED at the moment very tempting..

FernandoBatista · Feb 2, 2011

You can just put the adapter and shoot. The other things I’m adding are just improvements for special situations.
The flattener is well discussed above what it does and after more use with it I think it’s not worth the trouble with this scope.
The iris is nice when you’re shooting very close, the other day I was shooting a sanderling from very close (<4m), that gives me a DOF of 1cm wide open with the TC, the iris obviously helps there, but like I said it’s a special situation. In most cases I shoot wide open, still it’s nice to have it when you need it.
The dandelion is required if you want to use focus trap, but that’s easy, just get a Tring with a dandelion on, there’s plenty of them on ebay.
The adapter you can use any regular adapter, I just made mine for aesthetical reasons.

sparrowbirder · Feb 2, 2011

Thanks fernando,ive E-mailed TS for a quote with shipping on the SW but they have the TS80 on offer at the moment so may go for that,you have some superb shots in your gallery BTW..

FernandoBatista · Feb 8, 2011

Two flight shot samples from last weekend.
The photos are not so good, they were flying away from me and the light was from the sides and too harsh, but it shows how nice a short scope can be for this type of shots:

http://fernandobatista.smugmug.com/photos/1181437281_MjSGJ-O.jpg
http://fernandobatista.smugmug.com/photos/1181437229_DyuSQ-O.jpg

And two 100% crops of the same images:
http://fernandobatista.smugmug.com/photos/1181435826_o4Ebu-O.jpg
http://fernandobatista.smugmug.com/photos/1181435932_MYBbd-O.jpg

Obviously not the sharpest images that can be made with a scope, but these were hand-held with no support at all. And there's been sometime since I do flight shots so I'm quite rusty at it, I really need to work on my technique for this shots again.

Musoman · Feb 8, 2011

I think they're excellent Fernando :t:

That first Cormorant shot looks like someone has just fired him out of a Bow

fotonisse · Feb 8, 2011

The photos are not so good

..eh. Well I think they are quite acceptable for a handheld, manual focus shot :t:

Paul Corfield · Feb 8, 2011

fotonisse said:
..eh. Well I think they are quite acceptable for a handheld, manual focus shot :t:

I can see where Fernando is coming from. When you've taken hundreds of thousands of photos over the years you tend to just keep the real cream of the crop, those really special images. I can easily take a few thousand images in a day and delete every single one, the only reason being that none excited me in the way you feel when you get one where the bird has done everything you wanted of it.

Paul.

FernandoBatista · Feb 8, 2011

No doubt, Paul. Just getting a sharp bird in the frame doesn't really make me happy, I want other things right too, light being the most important for me, but composition and a decent background is very important too.

TS optics TL APO 804, a small review. (1 Viewer)

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