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CLS Clip Filter with a Wide Angle Lens Experience


mint_mark
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Hi everyone,

My Astronomik CLS clip filter has really improved my images taken in the suburban soup where I live, but it can only be used with EF lenses on the camera. My widest EF lens is 35mm, which is wide enough for a largish constellation but not for a Milky Way extravaganza.

I have the 10-22mm zoom lens but it can't normally be used with the filter because it is an EF-S lens. However, you can remove the stopper from the back and then you can manage to mount the lens with the filter in place. I tried this last night with the lens at 12mm (to make sure the rear element wasn't touching the filter).

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The first two pictures show centre and bottom left from a 60s exposure at f3.5. As you can see, the stars in the corners are quite elongated. The other corners are the same, all radially stretched (so it's not a tracking error or vibration).

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I tried stopping down to f5, but that didn't help. I also tried shorter exposures and the stars had the same shape (so not tracking related).

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Here is what I got after removing the filter... the usual sorts of aberrations but much better star shape.

So, should I conclude that the CLS clip filter can't be used with wide angle lenses in general? Or is it because the rear element of this lens is so close to the filter that this happens?

I think my next test should be at a longer focal length (say 20mm) and see if I get more of a usable field.

Has anyone else tried this sort of thing? Are there any wide lenses (10-15mm) that work well with the clip filter? I'm reluctant to spend £500 just to try...

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Ive been using a Sigma 10-20mm f4.5 with that filter with no probs. Ill have to dig out a 5 minute sub I took last week. Hmm, couldn't find it. Just to put a spanner in the works, check out this single 5 minute sub I took on a CG-5 mount, unguided with a 50mm Canon f1.8@f4.5 lense.

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Excellent thread as I am about to mod my 1000D and start using the CLS clip filter.

That is an excellent image with the 50mm lens. It looks like the EF-S lens may be touching the filter at some point maybe causing the warp speed effect. I have a wide angle EF lens so when my camera is ready I'll give it a try and get some images up here to compare with.

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Thanks for replying... I'm still waiting to do tests with the same lens at longer focal lengths to see what happens... really kicking myself for not doing it that night.

I'm certain that the rear element is not touching the filter at 12mm because I can go back to 10mm (where it might be touching). My theory is that the closer the element is the more of an angle the light hits the filter at... maybe refraction?

Anyway, definitely agree with Phoenix that the filter is indispensable with any other lens

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OK, here are some test shots taken at various focal lengths. These are all 300x200 pixel crops from near the bottom left of the frame, starting with the problematic 12mm and increasing. The first 3 are f/4 and the last two are f/4.5. All are 1 minute at ISO1600.

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12mm f/4.0

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14mm f/4.0

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17mm f/4.0

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20mm f/4.5

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22mm f/4.5

So, the good news is that the situation improves as focal length increases. You can choose a level of compromise and use a focal length to match. The bad news is that with the CLS filter you can't use the widest settings of the lens, so what might have been a 10mm ultrawide shot becomes a 20mm quite wide shot.

I wish someone with a Tokina 11-16 could do the same tests... I wonder how well it works with the filter in place?

Anyway, now I know what to do... bring on the moonless milky way! I can always try a collage...

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Excellent thread as I am about to mod my 1000D and start using the CLS clip filter.

That is an excellent image with the 50mm lens. It looks like the EF-S lens may be touching the filter at some point maybe causing the warp speed effect.

It does tell you not to use EF-S lenses with clip in filters... although some people resort to "surgery" to make them fit...

Peter...

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It does tell you not to use EF-S lenses with clip in filters... although some people resort to "surgery" to make them fit...

Peter...

I'd read that aswell. I have a 28-80mm EF lens that I will revert to for widefields with the CLS clip filter in. I ordered mine today so hopefully should be able to get out there and start getting some nice widefields soon.

I'm on the lookout for a nice EF prime lens on ebay at the minute rather than using the telephoto lens so I'll have to see what I can find.

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