Astrodon

David,

Would you be willing to make a set of large Sloan filters (5" X 5" clear aperture) for a 24" Schmidt. If so, how much?

OK, I know that is too much without even seeing the price. But how about two of the five, g' and r'?

OK. How about only r'?

David, they would end up being thousands of dollars each. I can check, but is this within the budget? If so, please send a formal request for quotation to don@astrodon.com.

Sorry, I meant to say Don, not David.

Hi Don I've enjoyed reading your info on narrower narrow band filters. I have one question. Assuming equal transmission and no impediment due to fast optics, would it ever be the case that a wider narrow band filter would be desirable? For example, if you have limited exposure time with only mild light pollution, might a 3 nm OIII filter leave the background black point clipped while a 10 will give a smooth background?

Hi Bill,

Assuming no change with fast optics, the narrower OIII filter will produce higher contrast and S/N, but this depends upon keeping the same high transmission at the emission line as in the wider filter. This is our advantage in that we can make a 3nm filter with 95% transmission at 500.7 nm. Thus, you are not giving up signal in going from a 10 or 8 nm to a 3 nm narrowband. That goes direclty to the S in S/N. The narrower filter will linearly decrease your background, which is important when the moon is up. The narrower filters inproved contrast and bring out more structural detail for this reason so long as the S stays strong with high transmission. I use the same 30 min exposures for my 5 nm H-a and SII and 3 nm OIII for this reason. The exception my be H-a. The narrower 3 nm H-a filter strongly reduces the NII contribution and therefore, for certain objects you may not see an improvement in S/N due to the loss of the NII signal. Hope this clarifies. Don

Hi Don,

Which of your filter sets do you recommend using with an ATIK 314L+ camera? It uses a Sony chip and is an interline camera, but it isn't a Kodak interline chip.

Thanks,

-Jim

E-Series for the Sony ccds. Not a perfect choice but this gives you better OIII balance for doing planetaries. Your R:G:B should be 1.25:1:1.

Hi Don,

Another Atik question. Do the 1.25" E series filters fit in Atik's filter wheels? I have read that Astronomik filters will fit but some others will not because the filter mount is too deep and rubs against the cover. If you can provide the height of the mount, both the threaded and unthreaded parts, I can follow it up with Atik.

Thanks, Andrew

Andrew, I don't know. These are standard 1.25" filter holders that fit SBIG, TruTek and QSI CFWs. I think they all standardize on the screw-in thread specs. Don

Hello Don - I just received two sets of your filters (RGB and NB) with my new QSI camera and noticed what I would describe as very fine dirt particles on both filter surfaces which is visible under a strong light when the filter is held at an angle. A clean brush and air removed larger particles but the fine ones remain. Can you recommend a safe cleaning procedure or is it a non-issue?

Thanks - Jeff

Jeff, we clean and inspect every filter that leaves Astrodon. If they become dirty, here is my cleaning procedure: 1. Place a lint-free wipe (like a KimWipe) on a clean table 2. Wet it in a 2" spot with a few drops of 91% isopropyl alchohol that you can buy at Walgreens 3. Holding the filter from the sides, preferrably with finger cots, blow both sides of the filter with oil-free compressed air (just be careful not to spray on oil or water from a compressor or can) 4. Place the filter on the whetted area and using no vertical force, lightly drag it to a dry area on the wipe. 5. Remove and repeat for the other side. Don

Don - I am buying a Kodak ccd camera with the 8300 sensor with 3326 x 2504 array, and 5.4 micron pixels. Would your E series or I series filters be best for that sensor? Thanks.

E-Series, Dave.

Hi Don, I consider to order photometric filters from the UBVRcIc series for delivery to Germany. Is the price in this case the same as listed on your web-Site or are any taxes deduced (like e.g. VAT)?

Hi, Stephan, international shipping via USPS will be added to the price of the filters. You will likely have to pay your import duties or VAT to pick up your package in Germany. Don

hi don i want buy solar eclipse filter for my canon 5D camera pls give me advise iam a photojournalist in delhi india. Hi, Asif, i don't make anything specific for a solar eclipse. Sorry. Don

Hi Don, I am using your 3nm filters with a celestron 14" and Hyperstar adapter for F/1.9. I am imaging in Southern California and the filters have worked great. My questions is since I am shooting so fast would your 5nm filters give me better results.

Thanks

*****Hi, Gary. please the the Narrowband FAQ page at http://www.astrodon.com/Orphan/astrodonfaqnarrowband/ where this is discussed.

Could you provide a link to some images taken at f/2? There will be significant signal loss from the 3 nm filter at f/2 but, you're so efficient at grabbing photons at f/2 that it perhaps somewhat makes up for it. The issue is transmission loss vs. gain of perhaps 1/3 less sky noise due to light pollution at your location. I don't have much experience at f/2 as I do at f/3 with an E-180. My guess would be that you'd be better off with the 5 nm filter at f/2. Don

Thanks Don, I got the filters before I realized the difference made by fast F's. I have read your FAQ and wanted your opinion. I may have to get the 5nm filters from you but have pretty good results so far. I am using the QSI 583. I have put a 20 Minute unprocessed Ha at this site: http://www.linear-dims.com/out/Ha_20MIN.zip ****Hey, that's pretty good for f/2 wit ha 3 nm filter. Kevin Nelson at QSI indicated that there would be about 10% vignetting with our 31 mm inserts an that's about what I see in your image. I see the curtains in back of the HH, a clean Alnitak with almost no halo and a bright Flame nebula. If you stacked 5-7 of these, I think you'd get a good, high-contrast image. If you went with the 5 nm, you would add signal with increased transmission, but your bkg signal would also go up do the the wider filter, so the gain solely due to increased transmission would be partially cancelled, and the HH region and curtain are not a very strong emitting region. I think you're probably fine with what you have IMO. Don

Gary, may I use this 3nm H-a image of the HH on the site? What is your email?

Thanks Don, You are more than welcome to use the image. I post most of my images at: http://picasaweb.google.com/gary.gonnella I would be happy to send you high rez copies of any of these or just the raws if you want. The last 2 images in my ...LOOK HERE FIRST... folder were built with these images all at 10 Minutes with total exposure of about 2 hours for each filter. My confusion may be from the fact that short F's were said t cause filter shift. Being an old Ham I think of shift as moving the center frequency off of the desired point. From what I now think i understand it is not a frequency shift but a decrease on transmission. If this is the case I am thrilled with a little loss to get past my high light pollution. My email: gary.gonnella@gmail.com

********Please take a look at our Narrowband FAQ from the narrowband page. It is indeed a spectral shift of the bandpass with incident angle of light moving the peak transmission off the emission wavelength. So, instead of being on top of the curve, you're part way down the side. Don

Thanks again and I love the QSI with your filters.

Dear Sirs,

I have just purchased a set of LRGB E- Series Filters.

From Ian King here in the UK.

Could you please tell me how I can identify the anti-reflection surface, so I can face this towards the chip.

Many thanks

Kind regards

Simon

Sinmon, please see our Narrowband FAQ. The same applies to the RGB. http://www.astrodon.com/Orphan/astrodonfaqnarrowband/#h18 Don

I have seen reference to the diameter of the Astrodon LRGB unmounted 50 mm Gen 2 filters being 49.7 mm and 50.4 mm, can you tell me the actual size? 49.7 mm. Don

Hello,

Is the filter 50mm dia. H-a 5 nm (HA5_50R) mounted? Thank you.

No. It is unmounted. Don

Hi Don. I dont want to post in any of the user groups as it normally starts a heated discussion but I would like to know if the Astronomik 50mm sets for the Sbig range are causing my problem. I have taken images of various objects and I always seem to have dominant HAlpha over the OIII and SII in my final composit. I purchased these filters in 2006 and am starting to think that the OIII and SII are too wide for the 6nm HALPHA. I have a set of SCHULER 1.25nm filters that are 15nm (OIII) 9nm (SII) and 9nm (HA).

Is there a way of determining if the filters are at fault or if my processing is at fault? Very vague but hopefuly there is a short and simple answer to this.

Thanks

Hi Don. I dont want to post in any of the user groups as it normally starts a heated discussion but I would like to know if the Astronomik 50mm sets for the Sbig range are causing my problem. I have taken images of various objects and I always seem to have dominant HAlpha over the OIII and SII in my final composit. I purchased these filters in 2006 and am starting to think that the OIII and SII are too wide for the 6nm HALPHA. I have a set of SCHULER 1.25nm filters that are 15nm (OIII) 9nm (SII) and 9nm (HA).

Is there a way of determining if the filters are at fault or if my processing is at fault? Very vague but hopefuly there is a short and simple answer to this.

Thanks

Brett, 6 nm is still a good bandwidth for NB filters. We started that in 2004. There may be 2 things here. First, Astrodon guarantees >90% transmission at the emission line. That ensures that the signal will be strong for good S/N. I cannot comment on what Astronomik specifies or guarantees. Second, H-a is almost always stronger than SII and OIII by a considerable amount, and we have to stretch the OIII and SII data to make an image that looks like a Hubble image. My guess is that your processing needs to be modified. Don

Hi Don, I am curious if Astrodon's Sloan filter set is available (or will be) in 31 mm diameter for QSI or 36 mm diameter for the SBIG FW5-8300 filter wheel. If so, a cost guesstimate would be appreciated. Thanks.

Sorry for the delayed answer. All 1.25" Astrodon filters can be purchased in 31 mm size for QSI. Just add a comment "mount in 31 mm inserts for QSI". Same price. Don

Would you recommend using the Near IR Tri-Color filter set with a QSI-8300 (60% QE) versus your recommended KAF3200 (90% QE) ccd camera?

What shipping options do you have to Canada? UPS Express, USPS Express, etc.

Sorry I'm very late on this. It can be done with the 8300 but you'll need longer exposures. Shipping to Canada is always $40 via USPS. Don

Are there any plans to bring the 3nm narrowband filters out in the 36mm dia. unmounted format?

Yes, we are looking into this right now. Don

Are you sure there isn't enough of a market to start producing 31 mm filters (not 1.25" ones in an insert) for the QSI 583? I'd like to have the option to image at f/4.16 as well as f/5.2 (NP127is) without vignetting and the consequent extra set of flats and potential degradation of S/N ratio. The cost of a full set of 50mm filters (3nm) and, say, an FLI PL8300 is out of my comfort zone.

Yes, I know, if you only had 10 cents for every time you've been asked this...

Hi, Bob, no plans at this time because of our large diversity of 1.25" filters and the uncertainty of which filters would be ordered in the special size for 31 mm specific to only QSI. If we made the LRGB and 5 nm NB filters, the next day, we would get requests for 3 nm filters and then UVBRI photometrics, etc. Don

Hi Don,

Will be obtaining an STX16803 camera and wish to do both photometry and imaging. I will use the SDSS filters. I've been told that it is possible to put together a filter wheel with 7 filters if the guide chip for the 16803 is not covered. I will be using a Monster MOAG and an STX specific AO. Two questions.

Have you heard of anyone using 7 filters with an STX16803? ******Only if you use an Apogee or FLI filter wheel and have precise parts make a special adapter.

Do you know of amateurs imagers imaging with SDSS filter sets? ******Yes. Arne Henden is using a mix of SDSS and Johnson/Cousins. See the AAVSO link on the web site.

There's no inherent reason it would not be possible, once one sorts out ratios, just wondering if anyone is doing this to your knowledge. ********The hard-coatings are so much more durable than anything that existed before than many universities are ordering these filters because they need to repeat measurements over periods of years. Alot of our sales are going to universities and other research consortiums, but also amateur researchers. Don

Thank you

Hi Don, I am looking into a rotator for my WO 110 FLT I have been looking at your Tak a tator...:~) My question is will it work on the WO? It looks as though it was designed only for the Tak-line of refractors.

Thanx

*********Yes, it requires a 4" tube on the scope side and the TAK CAA rotator on the camera side. Don

Hi Don, Do you have any plans to produce the Sloan filters in 36mm size for the SBIG ST-8300 camera and FW8-8300 filter wheel system? If not, what would you recommend? I'll be using a system at f/10, will there be vignetting using your 1.25-inch filters? Cheers, Tyler **************Hi, Tyler. No plans. At f/10 there should not be a problem with vignetting. Has SBIG come out with the 1.25" inserts for the FW8300 that they promised some months ago? Don

Hello, I have two brief quetions.

First, I'm getting a new QSI CCD camera, and would like to order NB filters for it. Would Astrodon ship directly to Spain?************Yes

Second: I know with narrower bandpass there are several advantages in detail, S/N ratio, etc. However, I normally use a 102mm refractor. Would the limited light gathering capability of this tube be a problem for the narrowest (i.e. 3nm) filters? **********Good question. If you are referring to an FSQ or TeleVue 101 type of scope, there will be no problem imaging with the 3 nm filter af f/ratio slower than f/3.

Thanks!

Hi Don,

I would like a set of photometric filters (UBVRI) but am worried about if the 1.25" filters will fit inside the Atik EFW2 filterwheel. I discovered this problem after having inserted at set of borrowed Meade RGB filters. Their high over the mountplate is 8.0 mm (0.315 in) and prevents the filter wheel in rotating! What is the mounted high of your UBVRI-filters? Regards, Kim ********Sorry for my late reply. ~7.2 mm.

I will be purchasing a QSI camera with the 31mm filter wheel. I would like to use my Astrodon filters that are currently in my FLI filter wheel. Can I purchase the adpater rings only and install myself? I will need 7. Thanks Scott ******No, the 31mm inserts require you to epoxy the filter into the ring. For f/5 and slower, you can still use your 1.25" in the QSI FW. If you need to convert, please contact at don@astrodon.com for a quote. Don

Hello Don, I noted you sell separately a Takometer ASCOM Driver. Why? Is it not included in the Takometer purchasing? Is it possible to use this driver for other non-Astrodon devices? (for ex. a custom made rotator for RC with robofocus unit, that's similar device as Takometer).

Thanks

Massimo

*******Because we were forced to develop this by contracting a programmer and need to make up the extra cost. Since this is only needed for ACP, we were hoping the ACP would provide the driver. To our knowledge it has only been used with our TAKometer, but it really is just driving a ROBOFocus motor. So, I suppose if you calibrated it for another ROBO application like a focuser, it could work. Don

Hello Don, I am contiplating the purchase of an "Astrodon UVenus Filter" for imaging Venus and Jupiter. Are there any articles or information written concerning the use of this filter. I'm bored with imaging Jupiter and Saturn and looking for something more challenging. ******Sorry for the long delay. Your best bet for learning what is done with UV filters is to look and Don Parker's web site. He does fantastic work with these filters. Don

Hey Don, Been considering NIR imaging using your LRGB set. Could you explain since cutting out the visible light how the RGB creates a recognizable/true-like color image? Also how important is it to have the telescope mirror set with gold coatings? Apparently it is. Thanks, Barry ******Barry, please see our in-depth article linked on the NIR page. Like mapped narrowband color, you can map NIR1,2,3 to blue, green and red using a measured G2VB white point for your system. I have a comparison of a globular cluster done this way on the referenced link. The color differentiation is less because you are on the flatter part of the black-body curve for most stars. You'll also lose the distinction of some of the brightest (blue) stars. You don't need gold-coated mirrors. Standard, aluminized mirrors work just fine out the the limit of our typical CCD detectors. Don

Hi Don, just wondering whether you plan on releasing a 3nm NII filter in 36 mm format in the near future? Thanks!